iodine deficiency product organism

Measuring instruments, auxiliary devices, reagents

• 1. Laboratory scales according to GOST 24104-88, 2nd class with the highest limit (weighing 200g and an allowable weighing error of not more than 0.002g).
• 2. Glass pipettes according to GOST 29227-91, with a capacity of 10 cm 3, 5 cm 3, 1 cm 3.
• 3. Flasks conical according to GOST 25226-82, with a capacity of 250 cm 3.
• 4. Burettes according to GST 29251-91, with a capacity of 25 cm 3, 5 cm 3.
• 5. Paper filters with a diameter of 9mm.
• 6. Distilled water according to GOST 6709-72.
• 7. Potassium iodide (KL) according to GOST 4232-74.
• 8. Sulfuric acid (H 2 SO 4) according to GOST 4204-77.
• 9. Sodium sulfate pentahydrate (sodium thiosulfate, Na 2 S 2 O 3 * 5H 2 O) according to GOST 27068-86 or fixanal 0.1g - equiv.
• 10. Soluble starch according to GOST 10163-76.
• 11. Sodium chloride, analytical grade, GOST 4233-77.

Preparation of reagents

1) 0.005M sodium thiosulfate (Na 2 S 2 O 3 * 5H 2 O). Dilute 1.24g of Na 2 S 2 O 3 * 5H 2 O in 1000 ml of freshly boiled distilled water. Since crystalline thiosulfate gains moisture during storage, which requires the introduction of a correction for its titer, then in case of doubt, it is recommended to use fixanal Na 2 S 2 O 3 * 5H 2 O 0.1 g equivalent, which is dissolved in distilled water, bringing the final volume up to 1000 ml, and the resulting solution is diluted 20 times (50 ml of solution + 950 ml of water) to a final concentration of 0.005M.

The resulting solution is stored in a cool dark place. Its volume is sufficient for the analysis of 100-200 samples, depending on their iodine content. Under proper storage conditions, the solution is stable for at least one month.

2) 2 n. sulfuric acid (H 2 SO 4). 6 ml of concentrated H 2 SO 4 are slowly added to 90 ml of water, then the solution is adjusted with water to a final volume of 100 ml. The amount obtained is sufficient for the analysis of 100 samples. The solution retains its properties indefinitely.

Note. In all cases, the acid must be poured into the water, and not vice versa, to avoid excessive temperature rise of the mixture and splashing of the acid. During the addition of the acid, the solution should be continuously stirred.

• 3) 10% potassium iodide (KL) freshly prepared - 10g KL is dissolved in 100ml of water. Store in a cool dark place. Its quantity is sufficient for the analysis of 20 samples.
• 4) Saturated sodium chloride solution (NaCl). In a 250 ml flask with 80 ml of water, NaCl is gradually added with stirring and/or heating until it stops dissolving. Stored under a cork. The solution retains its properties for at least a year.
• 5) Starch indicator solution. Add 1 g of soluble starch to a 250 ml flask, add 10 ml of water and heat until the starch dissolves. 90 ml of a saturated NaCl solution is added to the resulting hot mixture and mixed. The resulting volume is sufficient for the analysis of 50 samples. The prepared solution is stored in a cool dark place. The solution remains stable for a month.

Municipal budgetary educational institution

"Average comprehensive school No. 4 in Bryansk with an in-depth study of individual subjects "

CITY SCIENTIFIC AND PRACTICAL CONFERENCE OF SCHOOLCHILDREN

"FIRST STEPS INTO SCIENCE"

Determination of iodine in food products

(subject area biology)

Completed:

9th grade students

Anishina Anna

Serkova Darina

Supervisor

Biology and chemistry teacher

Bryansk 2013

Introduction

Most often, when we hear about iodine, we imagine a drug, or rather an iodine solution, which has long been used to disinfect wounds and relieve inflammation. Iodine also has an excellent absorbing effect: everyone knows how to make an iodine mesh on bruises, bruises, inflamed tissues, etc. However, first of all, iodine is chemical element, and its properties are truly amazing.

According to one of the famous scientists, it is iodine that is the element that is responsible for the normal growth of all mammals, including humans. If there were no iodine in nature, life forms would most likely develop very differently - it's hard to even imagine what animals and humans could look like.

Iodine enters the human body with water and food, as well as with inhaled air and through the skin - in small quantities, and accumulates in the thyroid gland.

However, every sixth inhabitant of the Earth suffers from iodine deficiency. An analysis of the scientific literature showed that in Russian Federation there are no territories where the population would not be at risk of developing iodine deficiency.

And this, despite the fact that the role of iodine in the body is simply colossal! Iodine is involved in the synthesis of thyroid hormones - thyroxine and triiodothyronine. It also contributes to the formation of cells necessary for our body - phagocytes, a kind of orderlies that capture and destroy foreign microorganisms and damaged cells. Iodine is very important for the normal growth and development of children and adolescents: it is involved in the formation of bone and cartilage tissue, protein synthesis, stimulates mental abilities, improves performance and reduces fatigue. Depends on the amount of iodine in the body normal work nervous system and the state of the psyche: cells grow and develop, an emotional background is formed, irritability is removed. Iodine is also needed for the process of lipid metabolism. The normal content of iodine in the body facilitates the burning of fat during dieting, keeps you active and gives energy, promotes healthy skin, hair, nails and teeth.

For children and adolescents, this iodine deficiency is manifested by a delay physical development, juvenile hypothyroidism, deterioration of physical and intellectual abilities, difficulties in schooling, high morbidity and a tendency to chronic diseases, in adolescent girls, violations in the formation of the reproductive system.

Thus, the purpose of our study was to study the problem of iodine deficiency and to determine the iodine content in some foods.

The objectives of our study included:

1. To study, according to the literature, the value and content of iodine in various foods;

2. To study the iodine content in edible and iodized salt, apple, banana, sea kale, pink salmon fish.

3. To identify the main measures for the prevention of iodine deficiency diseases;

4. Draw practical conclusions.

1. Characteristics of iodine

Iodine (lat. Iodum), I, a chemical element of group VII periodic system Mendeleev, refers to halogens (the symbol J is also found in the literature); atomic number 53, atomic mass 126.9045. Iodine was discovered in 1811 by the French chemist B. Courtois.

The intake of iodine in the body

The intake of iodine in the human body is 90% provided by food and only 10% due to water and air. Most iodine is found in seafood (squid, cod liver, crabs, sea fish), seaweed. From plant products, feijoa, dates, chokeberry and currants, prunes, apples, cherries, cucumbers, potatoes, beets, carrots, cabbage, eggplant, garlic, radish, lettuce, spinach, tomatoes, onions. Of the cereals, buckwheat and millet can be noted. A sufficient amount of iodine is found in meat, milk, cheese, cottage cheese, egg yolk.

The need for iodine for the human body. Iodine belongs to the so-called essential trace elements of nutrition, that is, to those that the human body is not able to produce on its own and therefore needs to be constantly supplied from outside.

The need for iodine depends on age. For infants, this is 50 mcg, at 2-6 years old - 90 mcg, at 7-12 years old - 120 mcg, in adults - 150 mcg, for pregnant and lactating women - 200 mcg of iodine per day.

That is, an elementary calculation shows that in a lifetime a person needs to get 3-5 grams. iodine (about 1 teaspoon).

Up to 90% of iodine requirements are met through food. But only with this way of its intake, the average Russian receives 40-60 micrograms of iodine per day. There is only one conclusion - one power supply is clearly not enough to solve this problem.

In order to prevent iodine deficiency diseases, the following doses of iodine are recommended: for children - 50-100 mcg, for adolescents - 100-200 mcg, for adults - 150-200 mcg, for pregnant and lactating women - 200 mcg of iodine per day. Therapeutic doses of iodine preparations are necessary in without fail agree with the doctor.

But it should be borne in mind that it is dangerous to exceed allowable doses iodine, especially with its previous deficiency, which takes place in our region, since side effects increase sharply and the development of a number of thyroid diseases is provoked.

Consequences of iodine deficiency in the body

The spectrum of iodine deficiency diseases is very extensive: abortions, stillbirths, congenital anomalies, endemic cretinism: hypothyroidism, dwarfism, overt hypothyroidism, mental and physical developmental disorders, childhood and adolescent endemic goiter, reproductive disorders, the risk of having a child with endemic cretinism, all ages - increasing the absorption of radioactive iodine during nuclear disasters, cognitive dysfunction

Thus, diseases caused by iodine deficiency are an important medical and social problem!

Iodine prophylaxis

In its pure form, iodine in our body, although it exists, does not do anything. We need it only in order to get into thyroid gland enter into the composition of its hormones. And the endocrine gland itself only works well and produces its hormones in sufficient quantities when in in full enriched with this micronutrient. Therefore, whenever they talk about a lack of iodine in a person, they mean the “hidden hunger” of the thyroid gland and its insufficient hormonal activity. And if there is little raw material (iodine) in the body, then the product (hormones) in the right amount take nowhere. Because of this, all cells, tissues and organs of our body begin to suffer, but first of all and especially seriously - those that need especially a lot of hormonal iodine (thyroid hormones).

But it would seem that it is very simple to make up for the lack of iodine: "Eat more food rich in iodine, and don't think about anything." All plant foods contain very little iodine. The only exception is seaweed. It has a lot of iodine. In Japan, there is no problem of iodine deficiency precisely because the inhabitants consume a lot of seafood and especially seaweed. We can recommend seaweed salad for prevention. But this is not a food product that is too familiar to us - you can’t eat a lot of it, especially every day, and it costs much more than iodized salt. As for sea fish, the iodine content in it is higher than in river fish. However, to satisfy the daily need for iodine, you need to eat almost a kilogram of sea fish - and at least 1-2 times a week! It is hardly possible. It is much easier to use high-quality iodized salt and drink drinking water specially enriched with iodine.

2. Method for determining iodine

In the course of the study, the iodine content in some foodstuffs was determined. The method for determining iodine in table salt is proposed in the State Standard of the Russian Federation (GOST R 51575 - 2000), the determination of iodine in food was carried out according to the method proposed in the article, "Determination of the iodine content in food" of the magazine "Chemistry at School".

20 g of iodized table salt is placed in a conical flask with a ground stopper and dissolved in 100 cm3 of distilled water. To the resulting solution is added with stirring 4 cm3 of sodium hydroxide solution and dropwise 5 cm3 of potassium permanganate solution, the solution acquires a greenish-brown color. After thorough mixing, 1.5 cm3 of sulfuric acid solution is added to the resulting mixture with a graduated pipette and heated to 70-80 °C.

Excess potassium permanganate is destroyed by adding 5 cm3 with a pipette oxalic acid and the solution becomes colorless. After the solution has cooled to room temperature, 10 cm3 of freshly prepared potassium iodide solution is added in a cylinder. mass fraction 1%, stopper the flask and keep in a dark place for 10-15 minutes. After the specified time, the flask is removed, 1 cm3 of a 1% starch solution is added, and the qualitative presence of iodine in this product is determined by the color intensity.

Determination of iodine in salt treated with potassium iodide.

A weighed portion of the test sample weighing 10 g is placed in a conical flask with a capacity of 250 cm3 and dissolved in 100 cm3 of distilled water. 1 cm3 of sulfuric acid solution (1 mol/dm3) is added to the resulting solution with a graduated pipette, a solution of potassium iodide with a mass fraction of 10% is added with a 5 cm3 pipette, mixed, the flask is closed with a stopper and placed for 10 minutes in dark place. After the specified time, the flask is removed, 1 cm3 of a 1% starch solution is added, and the qualitative presence of iodine in this product is determined by the color intensity.

2NaI + 2H2SO4 = I2 + SO2 + Na2SO4 + 2H2O

Determining the mass fraction of iodine in bread includes processing a sample of bread with a solution of potassium hydroxide, drying and ashing. After complete mineralization, potassium iodide is extracted from the sample with water. Acting on a solution of potassium iodide with bromine water, potassium iodate is obtained, which interacts with the added solution of potassium iodide with the release of free iodine. The iodine formed was determined by adding starch.

The determination of the iodine content in such products as fish and kelp was carried out according to the method for determining iodine in salt, a sample weighing 10 g was placed in distilled water, kept for a day, with the addition of sulfuric acid and potassium iodide, free iodine was released. Under laboratory conditions, the quantitative determination of iodine is impossible, therefore, its qualitative determination was carried out by the intensity of the blue color after adding starch to the solution.

3. Research results

After reviewing the literature, we divided our study into two phases. First, they conducted a survey of the middle level of the school, for signs of iodine deficiency. For this, a questionnaire was developed (Appendix 2). We conducted a survey among grades 5-9 of our school. In total, 318 people took part in the survey - middle-level students of MBOU secondary school No. 4. The results obtained were presented in the form of diagrams (Appendix 3). Conduct a survey on the presence of the main signs of iodine deficiency. The diagrams show that about half of the students in our school suffer from iodine deficiency. Therefore, the school should carry out the prevention of iodine deficiency.

At the second stage of our study, we determined the iodine content in food products. For the study, we tried to choose the products that schoolchildren most often use in their diets and those products that contain a large number of iodine.

Therefore, we chose edible and iodized salt, seaweed (kelp) salad, bread, fish, banana, apple. The data obtained during the study are presented in Table 1 and Table 2 (Appendix 1).

The main areas of the iodine deficiency eradication program include iodizing salt and bread, and eating seafood. However, a study of the iodine content in salt showed that not all samples contain this element. Ordinary edible salt, as one would expect, does not contain iodine. In iodized salt, iodine was found to be sufficient. Daily consumption of 5 g of this salt provides the daily requirement of the body. But you should be aware that if iodized salt is stored improperly, the iodine content in it will decrease. Iodized salt should be stored in hermetically sealed glass jars. normal temperature and in a dry place.

The content of iodine in the bread was not detected. This can be explained by the fact that iodine could be contained in bread in the form of iodocasein. Scientists have come to the conclusion that the human body best absorbs the iodine compound with milk protein. After much research, the food supplement iodcasein was obtained. Today it is the only drug that can withstand, without disintegrating, not only the boiling point of water, but also heating up to 200 ° C. It is recommended for iodine fortification of various foods. To enrich 1 ton of bread, only 5 g of iodocasein is enough.

A study of sea fish and seafood showed that the highest content of iodine in kelp and the average in pink salmon.

Foods such as banana and apple contain very little or no iodine.

So, in the studied products, there is an insufficient content of the most important microelement for the body - iodine.

4. Conclusions

1. The literature was studied and the value of iodine was determined, its content in various products and signs of its shortage were identified;

2. A survey of schoolchildren of MBOU secondary school No. 4 revealed signs of iodine deficiency in most children;

3. The qualitative presence of iodine in the selected objects of study was determined by the intensity of starch color;

4. The study showed that the necessary daily requirement of iodine is contained in iodized salt, as well as its high content in seaweed and pink salmon.

5. Offers for practical use results

Also, hold appropriate classroom hours at school, where students learn about the importance of iodine and measures to prevent iodine deficiency. And distribute leaflets (Appendix 4) from which children will learn why we need iodine.

For those who care about their health, you can attach a menu for the thyroid gland (Appendix 5). You don't have to include all of these foods in your diet, but eating fish, seafood, and iodized salt daily will provide you with your daily iodine requirement.

Literature

1. Journal "Chemistry at school" No. 2, 2009, pp. 11-13

2., socially - hygienic monitoring and prevention of iodine deficiency diseases. - M., 2000

3. the role of nutrition in the prevention of endemic goiter. - M., 1979.

4. Kozlov public health protection. - Abakan: March, 2002

5. State Standard of the Russian Federation GOST R 51575 - 2000 “Iodized table salt.

6. Aimetova, -valeological orientation of teaching chemistry // Chemistry at school. - 2005. - No. 5. - S.

7. Vorobyov, health / ev. - M.: Knowledge, 1987. - 192p.

8. Geldzhins, iodine content in foodstuffs / Yu. A.

Geldzhins, // Chemistry at school. - 2007. - No. 10. - S. 61-64.

9. http://thyronet. _spec/gerasimov. htm Tironet - all about the thyroid gland.

10. http://www. *****/ThyreoSchool/d_index. pht Two methods can be used to determine the level of iodine in salt.

Appendix 1

Table 1 - The content of iodine in edible and iodized salt

Color intensity (on a ten-point scale)

researched material		KI (indicated on package)	mcg per day salt norm (5g)
Food salt	No staining
Salt iodized	+ + + + + + + + + +

Table 2 - The content of iodine in food

Material under study
Seaweed salad (kelp)	+ + + + + + + + + +
Bread Bryansk	Not found
pink salmon fish	+ + + + + + +
	Not found

Annex 2

Questionnaire - a questionnaire to identify signs of iodine deficiency

Questions			Don't know
Do you often feel lethargic?
Do you often feel weak?
Do you get tired quickly from school?
Are you often in a bad mood?
Have you noticed a decrease in appetite? Most often, when we hear about iodine, we imagine medicine , which we need to treat wounds and relieve inflammation. Iodine also perfectly eliminates bruises and bruises. However, first of all, iodine is chemical element . Iodine was discovered a very long time ago - in early XIX century in France. Then scientists found that in small quantities it is almost everywhere: in soil and minerals, in water and plants. Iodine belongs to the so-called essential trace elements of nutrition, that is, to those that the human body is not able to produce on its own and therefore needs to be constantly supplied from outside. The values ​​of iodine in the human body: It is iodine that is responsible for our normal growth Participates in the work of the thyroid gland, metabolism Helps to form cells - orderlies that destroy foreign microorganisms and damaged cells ・Participates in education bone and cartilage tissue, protein synthesis Stimulates mental capacity Improves performance and reduces fatigue. ・Regulates work nervous system Promotes health skin, hair, nails and teeth. Sources of iodine: iodized salt Seaweed sea ​​fish Daily requirement for iodine: ·

120 mcg for school-age children (7 to 12 years old);

150 mcg for adolescents (12 years of age and older) and adults;

Unfortunately, today, in the context of constant iodine deficiency more than 65% of the population of our country are located. Among schoolchildren iodine deficiency is common, and its deficiency can lead to negative changes heredity - disorders in chromosomes and predisposition to cancer.

In addition, in those people who are constantly iodine deficient, general indicators of mental abilities decrease by 10-15%: they rarely show initiative and are practically unable to make decisions on their own.

In order to correct the situation, it is necessary increase consumption iodine at least three times.

Annex 5

Menu for the thyroid gland

Products Iodine content (mcg)

BREAKFAST

100 g bread 8.5

20 g butter 0.9

100 g cheese 4

Only about 20 mcg

LUNCH

DINNER

meat fish

200 g meat 6

200 g sea bass 148

200 g potatoes 7.2 7.2

200 g lettuce 10.5 10.5

100 g cottage cheese 3.4 3.4

Total27,1 169,1

AFTER SNACK

Per cup 10 g (teaspoon)

tea leaves or powder 0.8

coffee - instant,

ground

100 g pie 11.6

Total12,4

DINNER

100 g (½ cup) milk 3.7

100 g bread 8.5

20 g butter 0.9

100 g meat 3.9

I approve

Chief State

sanitary doctor

Russian Federation,

First Deputy

Minister of Health

Russian Federation

G.G. ONISCHENKO

Introduction date -

4.1. CONTROL METHODS. CHEMICAL FACTORS
DETERMINATION OF IODINE IN WATER
METHODOLOGICAL INSTRUCTIONS MUK 4.1.1090-02

1. Developed by d.b.s. A.G. Malysheva, Ph.D. N.P. Zinovieva, Ph.D. L.F. Kiryanova, Ph.D. EAT. Sevostyanova, D.B. Kamenetskaya (Research Institute of Human Ecology and Hygiene environment them. A.N. Sysina RAMS), Ph.D. V.E. Krutilin, L.S. Turkina, N.V. Bystryakova (center of state sanitary and epidemiological supervision in the Smolensk region), E.A. Kostyuchenkova, Ph.D. A.V. Avchinnikov (State Medical Academy, Smolensk).

2. Approved and put into effect by the Chief State Sanitary Doctor of the Russian Federation - First Deputy Minister of Health of the Russian Federation G.G. Onishchenko January 4, 2002

3. Introduced for the first time.

1 area of ​​use

Guidelines for the control of iodine in water are intended for state sanitary and epidemiological supervision centers, sanitary laboratories industrial enterprises, laboratories of research institutes working in the field of environmental health. Methodological guidelines have been developed to ensure the analytical control of iodine in water bodies (drinking, surface, artesian, packaged mineral, etc.) and assessing the compliance of the level of its content with the hygienic standard.

2. General provisions

Iodine is widely distributed in nature. In small quantities, it is found everywhere: in sea water, earth's crust, plant and animal organisms. Iodine compounds are found in some sewage chemical and pharmaceutical industries. AT natural waters iodine is found predominantly in the form of iodides. Iodine is one of the most important biogenic elements necessary for normal functioning the human body, but at elevated concentrations it poses a health hazard. In natural waters and in the process of water treatment, the iodine content can range from 0.005 to 1 mg / cu. dm. In this regard, the control of iodine in water at the level of hygienic standards is of particular relevance.

Due to insufficient sensitivity, the existing photometric determination method does not allow controlling the iodine content in water at the level of the maximum allowable concentration (MPC 0.125 mg/cubic dm). A significant drawback of the iodometric technique is the lack of metrological certification.

These Guidelines make it possible to establish a quantitative titrimetric analysis of water bodies to determine the iodine content in them in the concentration range of 0.01 - 1 mg / cu. dm. The method is metrologically certified and provides the determination of iodine with a detection limit of 0.08 MPC.

The guidelines have been developed in accordance with the requirements of GOSTs R 8.563-96, 17.0.0.02-79.

3. Physical and chemical properties, toxicological

characteristics and hygiene standards

Molecular weight - 253.84.

Iodine - solid crystalline substance with a pungent odor. Melting point - 113.7 ° C, boiling point - 182.8 ° C, density - 4.93 g / cu. see Dissolves in chloroform, carbon disulfide, alcohol, ether, carbon tetrachloride. It is slightly soluble in water (0.028 g per 100 g at 20 ° C).

Iodine is irritant. The maximum permissible concentration in water (MPC) is 0.125 mg / cu. dm.

4. Measurement error

The technique ensures the performance of measurements with an error not exceeding +/- 30%, with a confidence level of 0.95.

5. Measurement method

The measurement of iodine concentration is based on the oxidation of iodides to iodates in an acidic environment with bromine water with the reduction of the latter to free iodine according to the formula:

- - + -

I + 3Br2 + 3H2O -> IO3 + 6H + 6Br;

KIO3 + 5KI + 3H2SO4 = 3I2 + 3K2SO4 + 3H2O;

I2 + 2Na2S2O4 = Na2S4O6 + 2NaI.

Quantification is carried out by iodometric titration. The lower limit of iodine measurement in the analyzed sample is 10 μg. The determination is not interfered with by other halogens.

6. Measuring instruments, auxiliary devices,

materials, reagents

6.1. Measuring instruments

Laboratory scales VLA-200g-M 2nd

accuracy class with an error of 0.02 g GOST 24108-88E

Measures of mass G-2 - 2106 2 class GOST 7328-82E

Pipettes graduated by capacity

1, 2, 5, 10 cu. see GOST 29227-91

Volumetric flasks, 1000 cu. cm, 100 cu. see GOST 1770-74

Measuring cylinders with a capacity of 100, 1000 cubic meters. see GOST 1770-74

Microburet with a capacity of 5 cu. see GOST 20292-84

Thermometer laboratory scale TL-2 GOST 215-73E

6.2. Auxiliary devices

Dividing funnels, VD-3-2000 GOST 9613-75

Porcelain cups N 2, 3 GOST 9147-73

Flat-bottom flasks with a capacity of 25, 50 cu. see TU 92-891.029-91

Glasses heat-resistant with a capacity of 1000 cubic meters. see GOST 25336-82

Laboratory glass funnels GOST 25336-82

Chamber resistance electric furnace

laboratory, providing

mode from 150 to 500 °С TU 79-337-77

Drying cabinet providing

maintenance of the set temperature

mode from 40 to 150 °С TU 16-531-639-78

Household electric stove or gas burner GOST 14919

Water bath, sand TU 64-1-2850

Melted glass sticks GOST 25330

6.3. materials

Ashless filters "blue tape"

diameter 5 or 7 cm TU 6-09-1678-86

Talc GOST 19729-74

6.4. Reagents

Iodine GSO N 6088-91

Distilled water GOST 6709-72

Rectified ethyl alcohol GOST 5962-67

Potassium iodide, chemically pure GOST 4232-74

Potassium carbonate (potash) GOST 4221-76

Phenolphthalein GOST 5850-72

Sulfuric acid, chemically pure GOST 4204-72

Hydrochloric acid, chemically pure GOST 3118-77

Starch GOST 10163-76

Sodium thiosulfate GOST 27068-86

Bromine GOST 4109-64

Methyl red TU 6-09-5169-84

Formic acid GOST 5848-73

Methyl orange TU 6-09-5171-84

Chloroform, chemically pure TU 6-09-4263-76

It is possible to use other measuring instruments, auxiliary equipment, materials and reagents with metrological and technical specifications not less than the above.

7. Security requirements

7.1. When working with reagents, the safety requirements established for working with toxic, caustic and flammable substances in accordance with GOST 12.1.005-88 are observed.

7.2. Electrical safety requirements when working with electrical installations in accordance with GOST 12.1.019-79.

8. Qualification requirements for operators

To carry out measurements, persons with a qualification not lower than a chemical technician and who have the skills to work with titration are allowed.

9. Measurement conditions

When performing measurements in accordance with GOST 15150-69, the following conditions are observed:

The processes of preparing solutions and preparing samples for analysis are carried out at air temperature (20 +/- 5 °C); atmospheric pressure(630 - 800 mm Hg. Art.) and air humidity not more than 80% at 25 °C.

In the room where iodine is determined, there should not be any iodine-containing preparations.

All reagents used and distilled water must be free of iodine.

10. Preparing to take measurements

Before taking measurements, carry out following works: preparation of solutions, sampling.

10.1. Preparation of solutions

All solutions are prepared in iodine-free distilled water.

Distilled water. Distilled in the presence of K2CO3.

Rectified alcohol. Distilled in the presence of K2CO3.

Sulfuric acid, 5% solution. 30 cu. cm of concentrated H2SO4 (sp. weight 1.84) is poured carefully into distilled water (400 - 500 cc) in a liter flask, after cooling, bring with distilled water to 1 cu. dm.

Bromine water is saturated. To 100 cu. cm of distilled water add approximately 5 g of liquid bromine and shake vigorously, occasionally opening the cork. Use freshly prepared.

Sodium sulphate, 0.1 N solution. Prepared from fixanal. Quantitatively transfer the contents of the ampoule into a volumetric flask with a capacity of 1000 cubic meters. cm and dilute with bidistilled water.

Potassium iodide. Tested for iodine by adding 5% H2SO4 (2 - 3 drops) and starch. The yellowed preparation is aged in air until it turns white.

Talc. It is treated with concentrated hydrochloric acid in a ratio of 1:3, washed, dried and calcined.

Phenolphthalein, 1% alcohol solution. 1 g of phenolphthalein is placed in a volumetric flask with a capacity of 100 cubic meters. cm and dilute to the mark with 96% alcohol.

Starch, 1% solution. Mix 1 g of soluble starch with 10 cu. cm of distilled water and poured into 90 cu. see boiling distilled water. The solution is preserved with a small amount of chloroform (1 - 2 drops).

Methyl red, 1% alcohol solution. 1 g of methyl red is placed in a 100 cu. cm and dilute to the mark with 96% alcohol.

Methyl orange, 1% alcohol solution. 1 g of methyl orange is placed in a 100 cc volumetric flask. cm and dilute to the mark with 96% alcohol.

An aqueous solution of K2CO3 is prepared at the rate of 1 kg per 810 cu. see water. The solution is shaken for 5 minutes in a separating funnel with 10 cc. see alcohol and share. The treatment of the solution with alcohol is repeated several times. The bottom layer is used for measurements.

10.2. Sample selection

Water samples with a volume of 0.5 - 6 cubic meters. dm is taken into a dark glass container in accordance with GOST R 51592-2000, GOST R 51593-2000. Samples are stored when cooled to 2 - 5 °C. Analysis - on the day of sampling.

11. Taking measurements

11.1. Sample concentration and extraction of iodide from water

When analyzing 1 liter of the sample, the content of iodides is determined, starting from 0.01 mg / cu. dm. Samples with a lower iodide content are pre-concentrated by evaporation. For determination, such a sample volume is taken so that the iodine content in it is in the range of 0.01 - 1 mg. A test water sample is placed in a heat-resistant beaker, 10 drops of a 1% phenolphthalein solution and a K2CO3 solution are added until a bright red color does not disappear when stirred. The sample is evaporated on an electric or gas stove to a volume of 300 - 400 cubic meters. cm (with a sample volume of less than 0.5 cubic dm, evaporation should be carried out in a porcelain cup N 3 in a water bath). Then the sample is transferred to a No. 3 porcelain cup, evaporated to a dry residue in a water bath, dried in an oven, and calcined in an electric furnace at temperatures up to 450 °C. To avoid loss of iodine, it is necessary to ensure that the temperature of the electric furnace is not higher than 500 ° C. Ignition is continued until complete charring organic matter, without achieving its final combustion (the residue may be gray). The calcined residue is moistened with water prepared in accordance with paragraph 10.1 (3 - 4 drops), and triturated with a glass rod until a homogeneous mass. If the residue is hard, K2CO3 is added dropwise and triturated until a soft mass is obtained. Then add 8 - 10 cubic meters. cm of alcohol prepared in accordance with paragraph 10.1, mix thoroughly and decant the extract into another smaller cup (No. 2). If the residue is mealy and does not settle, add a concentrated solution of K2CO3 while stirring with a glass rod until the precipitate is completely curtailed. The extraction is repeated with new portion alcohol (8 - 10 cubic cm). After that, 2 - 3 drops of a concentrated K2CO3 solution are added to the residue, dried in a water bath, then in an oven and again calcined in an electric furnace, moistened with water and again extracted twice. The alcoholic extracts are combined. Thus, the extraction of iodine from the dry residue is carried out in 2 steps after calcination with the preliminary addition of K2CO3. The total volume of the extract is approximately 40 cu. cm.

The resulting extract is evaporated on a water bath, adding 2 drops of concentrated K2CO3 solution. After that, the cup is dried in an oven and calcined in an electric furnace. Since in the extract minerals small, under these conditions there is a rapid and complete combustion all organic matter. After cooling the cup, add 3-4 drops of distilled water and again extract with small portions of alcohol (10 cubic cm). The extract is carefully evaporated in a water bath that is not very hot so that the alcohol in the cup does not boil.

Attention: The dry residue in the cup should be colorless, otherwise it is moistened with a few drops of water, 1-2 drops of K2CO3 solution are added, dried and calcined again, but without subjecting it to extraction with alcohol.

11.2. Convert potassium iodide to iodate

and release of free iodine

The colorless residue is dissolved in 1 - 1.5 cu. cm of distilled water and filtered through a funnel into a conical flask with a capacity of about 25 cubic meters. see. The volume of the filtrate together with the wash water should be about 4 cubic meters. cm. To the filtrate add 2 drops of methyl orange solution, carefully titrate with 5% sulfuric acid solution and add another 2 cu. see titrant. Then bromine water is poured in portions of 20 - 25 drops until the solution turns into yellow, due to an excess of bromine water, and placed in a preheated sand bath (about 100 ° C). For uniform boiling, a pinch of talc is added to the solution at the tip of a knife. After the solution boils, continue boiling for exactly 5 minutes. Cool the flask with the solution under a tap cold water up to a temperature of 25 °C. To restore bromine, 2-3 drops of formic acid are added to the flask and gently shaken, the contents are tested for bromine by smell after 2 minutes. Add a drop of methyl red solution. Discoloration of the indicator indicates the presence of bromine, in which case add 1 drop of formic acid. If the pale pink color of the solution does not disappear, add a few grains of potassium iodide, 2 drops of a 1% starch solution and after 5 minutes titrate with 0.001 N thiosulfate solution until a faint pink color is obtained.

12. Calculation of measurement results

The concentration of iodine in water (mcg / cubic dm) is determined by the formula:

C \u003d 1/6 x V x T x g mcg / cu. dm,

where:

V - volume of 0.001 N sodium thiosulfate solution, cu. cm;

T is the titer of 0.001 N iodate solution, expressed in μg, equal to 127;

1/6 - amount of iodine from KIO3 during titration (see reaction equation);

g is the volume of the test sample, cub. dm.

For a sample volume of 1 cu. dm iodine concentration is calculated by the formula:

C \u003d V x 21.15 mcg / cu. dm.

With a sample volume of 3 cu. dm - C \u003d V x 7.05 mcg / cu. dm.

The final measurement result is taken as the arithmetic mean of the results of two parallel measurements, performed up to the first decimal place. Calculate the average value of the concentration of iodine in water:

C = 0.5(SUM Ci).

Calculate the relative difference between the results of two parallel measurements of one sample:

|C1 - C2|<= 0,01 x d x C,

where d - operational control of convergence, 22%.

13. Registration of measurement results

The average values ​​of the results of measuring the concentrations of substances in 2 parallel water samples are drawn up in a protocol in the form:

Protocol N

quantitative chemical analysis

Date of analysis ______________________________

Sampling location ___________________________________

Name of laboratory _________________________________

Legal address of the organization ____________________________

Results of chemical analysis

Cipher or number samples	Defined component	Concentration, mcg/cu. dm	Error measurements, %

Head of the laboratory:

Executor:

14. Measurement error control

14.1. convergence control. Perform according to clause 12. If the standard for operational control of convergence is exceeded, the experiment is repeated. When the standard is repeatedly exceeded, the reasons leading to unsatisfactory control results are found out and eliminated.

14.2. Operational error control. Carried out when changing

reagents. Samples for control are real samples of drinking

and surface water, to which iodine supplements are made in the form

solutions. 2 samples of water are taken and an additive is made to one of them

so that the content of the analyte increases

compared with the original by 50 - 150%. Each sample is analyzed in

in strict accordance with the prescription of the methodology and get the result

analysis of the original working sample Cish. and with the addition of C.

The results of the analysis of the original working sample Csh. and with the addition

C is obtained under the same conditions as far as possible, i.e. gets them

1 analyst using one set of volumetric utensils, one

batches of reagents, etc.

The control results are considered satisfactory if the following condition is met:

|C - Ref. -C|< Kg,

where:

C - additive of the substance, mcg / cu. dm;

Kg - standard for operational error control, mg / cu. dm.

With external control (P = 0.95) take:

_________________________

/ 2 1 2

Kg = \/DELTA C + DELTA Ref.,

Where DELTA Ref. and DELTA C - error characteristics

measurements for the original sample and the sample with the additive, respectively,

mcg/cu. dm.

They are calculated according to the formula:

DELTA Ref. = 0.01 x sigma. x Ref.;

DELTA C = 0.01 x sigma. x C.

With intralaboratory control (P = 0.90) take: K g =

0.84 kg.

If the operating error control standard is exceeded, the experiment is repeated. If the specified standard is repeatedly exceeded, the reasons leading to unsatisfactory control results are found out and eliminated.

Bibliography

1. Determination of concentrations of chemicals in water of centralized drinking water supply systems: Compilation guidelines. MUK 4.1.737-99 - 4.1.754-99.

2. Unified methods for studying water quality. Methods chemical analysis water. Part 1. M., 1977. S. 424.

3. GOST R 8.563-96. GSI "Methods of performing measurements".

4. GOST 17.0.0.02-79 "Nature protection. Metrological support for monitoring the pollution of the atmosphere, surface water and soil. Basic provisions".

5. Drinking water. Hygienic requirements for water quality of centralized drinking water supply systems. Quality control. SanPiN 2.1.4.1074-01.

The Association assists in the provision of services in the sale of timber: at competitive prices on an ongoing basis. Timber products of excellent quality.

Thyroid diseases are widespread in the world and are the most common endocrine pathology, especially in regions with insufficient iodine in the environment. deficit iodine today fairly widespread. According to the WHO, under conditions deficit iodine more than 2 billion people live, among them 740 million people have been diagnosed endemic goiter, 43 million people due to lack iodine mentally retarded, more than 6 million people suffer from cretinism. to iodine-deficient or endemic goiter areas include mountain ranges, hills and any areas remote from the sea, which leads to an increase in the likelihood of having children with endemic cretinism It should be noted that iodine salts they dissolve well in water, are washed out of the soil and go into the oceans with water flows, while entire areas live in conditions of iodine deficiency .. With a long-term existence of iodine deficiency, compensatory mechanisms are depleted, which leads to the formation of nodes (both benign and malignant). In addition, under conditions of iodine deficiency, the function of the thyroid gland may be impaired, hypothyroidism may develop - a decrease in its function with a decrease in the synthesis of thyroid hormones, or thyrotoxicosis - an increase in the function of the gland with an autonomous uncontrolled synthesis of thyroid hormones in its nodes, thyrotoxic adenomas or multinodular toxic goiter, followed by formation of multinodular toxic goiter.

Don't suffer deficit iodine, living on the coast of the seas and oceans, people who eat a large amount of seafood. It is also difficult to create an excess of iodine in the body, since 95–98% of the iodine entering the body is excreted in the urine, and 2–5% through the intestines. Iodine deficiency diseases are all pathological conditions that develop in the population as a result of iodine deficiency, which can be prevented with normal iodine intake. According to WHO, the minimum physiological intake of iodine per day is 200 mcg. per day is also undesirable, it is already potentially harmful. Although in different countries the recommended norms differ, which is associated with the genetic factors of the population. In Australia, iodine intake up to 2000 mcg/day is considered safe. for adults and up to 1000 mcg / day. for children, in the UK - up to 17 micrograms of iodine per 1 kg of body weight per day, but not more than 1000 micrograms / day. .

For a number of years, in order to reduce possible iodine deficiency, iodine salts have been introduced into food products and additives to milk and dairy products, soft drinks, tea, salt, coffee, bread, dietary supplements, etc. Considering the negative consequences of both low iodine intake and excess , precise control of its content in them is necessary. It is also necessary to control food water, soil, agricultural products and livestock, biological fluids, etc.

The analytical determination of iodine to this day, despite the availability of many methods, remains very complex and laborious. This is due to its volatility, the ability to enter into redox reactions with the components of the analyte, polyvalence and, in some cases, with a low concentration. In this regard, the correct choice of sample preparation method is of particular importance. In this case, 2 main factors must be taken into account - a (the presence of organic substances in the sample interferes with the analysis, b) there is no ideal method for preparing samples - in most cases we are faced with the loss of iodine in this process, the question is how to minimize them.

To date, a number of methods for sample preparation are known. Let's consider some of them.

a) alkaline dry combustion method when the sample is treated with a solution of sodium hydroxide or sodium carbonate, the so-called. dry ashing, at a temperature of 400 to 500 ° C, or liquid ashing - pre-treatment with strong acids in the presence of oxidizing agents. To reduce the loss of iodine in these processes, various additives are introduced, for example, potassium carbonate, zinc sulfate, ethanol. In a number of works, sodium nitrate or potassium permanganate are used as oxidizing agents, which allows, on the one hand, to get rid of the influence of organic substances, on the other hand, to obtain iodine in one oxidized form, followed by neutralization of the sample, after ashing, and reduction. In "wet" ashing, various mixtures are used, for example, a mixture of sulfuric, nitric and perchloric acids, a mixture of chloric-chloric acids, a mixture of concentrated sulfuric acid and perchloric acids.

According to our data, the minimum loss of iodine can be achieved only in the case of using the method of decomposition and further processing in a closed space, the so-called method of using "bombs". A modification of this method can be considered the combustion of a sample in a closed space in an oxygen atmosphere in a conical or round-bottom flask made of heat-resistant glass with a thin section, with simultaneous dissolution of the resulting combustion products in an absorbing liquid and determination of iodine in solution [13].

It should be noted that, according to the authors, the method is applicable only for samples with a certain iodine content and hardware allows the use of a sample of the order of 0.05-0.1 g. it is permissible to use samples with a mass of about 10 g.

Consider the existing methods for the quantitative determination of iodine.

Titrimetric method. The titrimetric method of analysis is one of the most common methods for the quantitative determination of iodine. It is recommended for the determination of iodine in drinking water, bread and bakery products, in table salt with potassium iodate and is used in a number of countries. in assessing absorbed and double-bonded iodine in oils and fats. It is simple and accessible to be performed under any conditions, has high sensitivity in the determination of all forms of iodine - molecular, iodides and iodates.

The most commonly used titrant is sodium thiosulfate (in the presence of starch as an indicator). Iodometric titration underlies the quantitative determination of both iodates and iodides. An excess amount of potassium iodide is added to a solution containing iodate to release free iodine, which is quantified titrimetrically. The quantitative determination of iodides in solution is also carried out by the titrimetric method, iodides are first oxidized with bromine in an acidic medium to iodates, which are reduced with the help of iodides in an acidic medium to molecular iodine and titrated with sodium thiosulfate in an acidic medium.

Iodometric titration must be carried out in the cold, since at elevated temperatures there is a loss of iodine due to its volatilization from the solution.

Photometric methods,

Photometric methods for the determination of iodine can be divided into 2 groups. The first is a relatively simple method for determining iodine in extractive organic solvents - chloroform, benzene, 4-x carbon chloride, as well as photometric methods based on the formation of a complex compound of iodine with various reagents, for example, with sodium nitrite in an acidic environment. This group of methods is easy to perform, simple, but can be performed with sufficient reliability at a relatively high content of iodine salts in the sample. Of course, they are preceded by sample preparation, the conversion of iodine into a specific form. The second is kinetic methods of analysis, which are more sensitive, but the reactions must be carried out under strictly controlled conditions, subject to precise control of time, temperature and pH.

Known, for example, cerium-arsenite. Based on the catalytic action of iodine on the process of reducing tetravalent cerium with trivalent arsenic in an acidic medium. The rate of decrease in the color intensity of the solution is measured by the photometric method at a wavelength of 405 nm. Currently, there are various options for the kinetic determination of iodides based on the cerium-arsenite reaction, which differ mainly in the methods of preparing samples for analysis. The rhodanide-nitrite method is known, which is based on the oxidation reaction of the rhodanide ion with a mixture of nitrate and nitrite ions, catalyzed by iodide ions. A method for the quantitative determination of total iodine based on the catalytic destruction of the ferro-thiocyanate complex by nitrite catalyzed by iodide and subsequent photometric determination at a wavelength of 450 nm is described. Methods are used quite widely for the determination of iodine in a number of biological fluids, food products of plant and animal origin, in feed and plants, for example, in potatoes. carrots, apples, milk, seafood, tea, sweets and many others.

Chromatographic Methods.

The gas liquid chromatography method has been developed for the determination of total iodine in foods. For sample preparation, after ashing, iodide is dissolved in water. Its oxidation to free iodine is carried out with potassium dichromate in the presence of sulfuric acid. The iodine released in this process interacted with 3-pentanone, and the resulting compound was extracted with n-hexane or another similar solvent, after which it entered the chromatograph. Various modifications of the method are possible, but its principle remains constant. The method is quite sensitive and is used for objects with low iodine content.

One relatively new technique is high performance liquid chromatography. When using high-performance liquid chromatography, preliminary thorough preparation of samples is necessary, removal of fats, proteins, mineral impurities, etc. from them. Detection is carried out using an electrochemical or ultraviolet detector. The high sensitivity and selectivity of the method allows its use in a wide range of tasks.

Electrochemical methods.

This group of methods can be divided into several types - voltammetric, polarographic, amperometric, etc. The first is based on the conversion of all forms of iodine into the electrochemical active form of iodide, followed by the determination of iodide ions using stripping voltammetry. Iodide ions accumulate on the surface of the mercury electrode in the form of a poorly soluble compound with mercury, followed by its cathodic reduction at pH 2 in an inert gas medium. The method is quite sensitive, the detection limit of iodides is 0.5 μg per 100 g of product.

The method of potentiometric titration is based on determining the potential of an indicator silver electrode in the process of titration of iodide ions with silver. The amount of silver used for potentiometric titration corresponds to the concentration of iodide ions. The method can be used in a wide range of concentrations - 0.2 to 500 mg/kg.

In recent years, there has been an increasing use element-selective electrodes, including iodide-selective ones, the membranes of these electrodes consist of a sparingly soluble salt of silver iodide mixed with silver sulfide. In fact, this method can be attributed to electrochemical methods of analysis. The method is mainly used in assessing the quality of natural and food waters.

One can also note a number of highly efficient methods for the determination of iodine, but feasible only in special laboratories, in particular, the method of isotope dilution and the method of neutron activation analysis, mass spectrometric method with inductively coupled plasma.

The data presented show that there is an extensive set of methods for the quantitative determination of iodine in various food products, water and biological objects, etc. Each of them has its own advantages and disadvantages. At the same time, it should be noted that many of the methods that are used to determine iodine, which have high sensitivity and reliability, are inaccessible for use in mass, wide analytical practice. More accessible and simpler methods (titrimetric, photometric, etc.) are used more often, although they are less sensitive. It all depends on the nature of the analyzed object, the content of iodine salts in it, and the required accuracy of determination.

Bibliographic list

1. Gerasimov G.A. Iodine deficiency in the countries of Eastern Europe and Central Asia - the state of the problem in 2003 // Clinical thyroidology, 2003. V. 1. No. 3. P.5–12.
2. Thompson C. Dietary recommendations for iodine around the world//IDD Newsletter.2002, Vol. 18. No. 3. P. 38–42.
3. Gerasimov G.A. Safety of iodine and potassium iodate // Clinical thyroidology, 2004. V. 2. No. 3. P. 10–14.
4. GOST 25832-89. Diet bakery products.
5. Perihan V., Fatma Y.F., Zymryt B. // Analyst. - 2000. - Vol. 125.-p. 1977-1982.
6. Khotimchenko S.A. Zhukova G.F. Savchik S.A. Methods for the quantitative determination of iodine in food products and food raw materials. Questions of Nutrition, 2004, 147p.
7. General methods verification and analysis food products. www. normacs. ru / Doclist /…/670500000. ht .
8. Method for the determination of iodine in iodine-containing organic substances: Pat. 2163377 Russia, MPK7 G 01 N 27/48. 02/20/2001.
9. Rao R.R., ChattA. // Ibid. - 1991. - Vol. 63, no. 13. - P. 1298-1303.
10. Rao R.R., ChattA. // Analyst. - 1993. - Vol. 118, no. 10.-p. 1247-1251.
11. State. Pharmacopoeia of the USSR, no. 11, v.2, p.
12. MUK 4.1.1481-03, Determination of the mass concentration of iodine in food products.
13. Methods of determination content iodine in food raw materials. window.edu.ru/library/pdf2txt/653/…/1795.
14. Podkorytova A.V., Kadnikova I.A. Quality, safety and methods of analysis of products from hydrobionts. Issue. 3. Guide to modern research methods of seaweeds, herbs and products of their processing. M. 2009, 198s.
15. definition of iodine in edible salt. www. lawrussia. ru /…/ doc 469 a 391 x 913. htm ‎
16. MUK 4.1.1090-02. Determination of iodine in water.
17. MUK 4.1.1106-02. Determination of the mass fraction of iodine in food products and raw materials by the titrimetric method.
18. A OA C Official Method 920-158. // Official Methods of Analysis of the Association of Official Analytical Chemists / Ed. Sydney Williams. – Arlington, 1995. – Ch. 41. - P. 6.
19. State. Pharmacopoeia of the USSR, no. 11, v.2, p.377.
20. Yavich P.A., Churadze L.I., Rukhadze T.A. and others. Iron and iodine in vegetable raw materials and foodstuffs. Chem. well. Georgia, 2002, No. 2, pp. 355-261.
21. Yavich P.A., Churadze L.I., Rukhadze T.A., Khositashvili V.L. and others. To the deficiency of iron and iodine in the human body. Sat. radiological research, 2009, v.6, p.210-214, Tbilisi.
22. Dragomirova M. L. Methods for determining trace elements. M.: Chemistry, 1950. - S. 23-31.
23. Laurberg P. //J. Clin. Endocrinol. Metab. - 1987. - Vol. 64.-p. 969-974.
24. GOST R 51301-99 - Food products and food raw materials.
25. Photometric definition of iodine in water. laws. law 7. ru / base 07/ part 2/ d 07 ru 2984. htm
26. Afkhami Abbas, Zarei Ali Reza // Talanta. 2000. - V. 53. - No. 4. - P. 815-821.
27. G. Knapp, B. Maichin, P. Fecher, S. Hasse, P. Schramel. Iodine Determination in Biological Materials. Options for Sample Preparation and Final Determination Anal. Chem. 1998. - V. 362. - No. 6. - P. 508-513.
28. Dan Denzhong. Iodine Determination in Urine by "on-line" Flow-Injection Catalytic Spectrophotometric Method . Anal. Chem. 2000. V. 28. - No. 4. - P. 486-490.
29. Dan Dezhong, Li Ping, Zhang Kun, Shi Bo. Iodine Determination in Urine by Catalytic Spectrophotometric Method Using Microwave Sample Decomposition . Anal. Chem. 2000. 28. - No. 7. - P. 918.
30. G. Knapp, B. Maichin, P. Fecher, S. Hasse, P. Schramel. Iodine Determination in Biological Materials. Options for Sample Preparation and Final Determination . Anal. Chem. 1998. - V. 362. - No. 6. - P. 508-513.
31. Dan Dezhong, Li Ping, Zhang Kun, Shi Bo. Iodine Determination in Urine by Catalytic Spectrophotometric Method Using Microwave Sample Decomposition-(2) . Anal. Chem. 2002. - . 30. - No. 4. - P. 1258.
32. Zhang Aimei, Wang Shuhao, Du Lingyun. Zhang Aimei Simultaneous Determination of Micro Bromide and Iodide by Kinetic Spectrophotometric Method . Anal. Lett. 2000. - V. 33. - No. 11. - P. 2321-2339.
33. Kumar S. D. Determination of Iodate and Sulphate in Iodized Common Salt by Ion Chromatography with Conductivity Detection . Talanta. 2000. - V. 53. - No. 4. - P. 701-705.
34. Bichsel Yves, V. G. Urs Determination of Iodide and Iodate by Ion Chromatography with Postcolumn Reaction and UV/Visible Detection . Anal. Chem. 1999. - V. 71. - No. 1. - P. 34-38.
35. Liu Xiang-Nong, Yu Bi-Yu, Ji Sheng-Quan. Gas Chromatographic Determination of Inorganic Iodine in Salt . Chin. J. Spectrosc. Lab. -2000. V. 17. - No. 6. - P. 635-636.
36. M. Sanjeev, S. Vandana, J. Archana, V. K. Krishna. Determination of Iodide by Derivatization to 4-iodo-N, N-dimethylaniline and Gas Chromatography Mass Spectrometry .Analyst. - 2000. - V. 125. - No. 3. - P. 459-464.
37. Maros L, Kaldy M, Igaz S. // Anal. Chem. - 1989. - Vol. 61, no. 7. - P. 733-735.
38. Otter F.I. stripping voltammetry. – M.: Mir, 1980. – 265 p.
39. MUK 4.1.1187-03. Voltammetric determination of iodine in food products.
40. MUK 4.1.1481-03. Determination of the mass concentration of iodine in food products, food raw materials and dietary supplements by the voltammetric method (I).
41. MUK4.1.1481-03. Determination of the mass concentration of iodine in food products, food raw materials and dietary supplements by the voltammetric method (II).
42. Voltammetric definition of iodine in food products. http://www.fcgsen.ru/DOC/ .
43. Method for quantitative determination of iodine by stripping voltammetry patent RU 2459199.
44. Bozina T.V. Biamperometric determination of iodine in food products and environmental objects. technical sciences. Krasnodar, 2003, 140s.
45. Pisarevsky A.M. The selectivity of redox electrodes is the basis for the creation of new analyzers. "Sensor-2000": Proceedings. report Vseros. conf. with international uch. St. Petersburg. state un-t. - St. Petersburg, 2000. - S. 25.
46. AM Pisarevsky, IP Polozova. Selectivity of iodine-modified redox electrodes and their application in potentiometric analysis of oxidants (active chlorine, ozone, hydrogen peroxide, molecular oxygen) . Tez. report Vseros. conf. with international uch. St. Petersburg. state un-t. - St. Petersburg, 2000. - S. 26-27
47. Alexandrova T. P. Stripping voltammetry of bromide and iodide ions on a renewable silver electrode. Journal. analyte chemistry. 2000. - T. 55. - No. 6. - S. 655-658.
48. Belbaeva N. N. Spectral determination of chlorine, bromine and iodine in inorganic and organic compounds using a condensed spark and high-frequency induction argon plasma. Diss ... cand. chemical sciences, M. 1999, 183p.
49. Zakharova E.A., Slepchenko G.B., Kolpakova E.Yu. Electrochemical methods for monitoring the iodine content in drinks // Food Issues. 2001. N3. C.32-36.
50. Brainina Kh.Z., Sapozhnikova E.Ya. Concentration of substances in polarographic analysis. Determination of iodine ions // JAH. 1966. V.21, Issue 11. S.1342-1347.
51. Vtorushina L.A. Determination of chlorine, bromine and iodine in water bodies and samples with an organic matrix by inductively coupled plasma atomic emission spectrometry using gas generation. www.dissercat.com/…/opredelenie-chlora-b.

The drug "Balm Revival"

It stimulates the immune system, has an antimicrobial, antiviral effect, is used for liver diseases, hormonal disorders (such as diabetes, thyroid disease), a powerful antioxidant. Impressive results are obtained by the use of the “Renaissance balm” for the prevention of such serious diseases as tuberculosis, oncological lesions, joint diseases, heart attacks and strokes.

As a preventive measure, it is recommended to dilute 1 tablespoon of the suspension in 100 ml of water at room temperature and take the entire solution once a day half an hour before meals. The course is from 1 to 6 months. This scheme is used to prevent iodine deficiency, oncological, gynecological, cardiovascular, broncho-pulmonary diseases (including tuberculosis, pneumonia, obstructive bronchitis, etc.), increase overall activity, resistance to colds and viral infections. The use of the balm helps to eliminate the consequences of taking antibiotics, chemotherapy and radiation therapy; relieves alcohol and drug intoxication, prevents the occurrence of infections of the genitourinary system, gastrointestinal tract, allergic reactions and skin diseases (see instructions for the drug). Balm Revival normalizes both strengthened and weakened immune states.

In a tablespoon of suspension - almost 50 mg of iodine! Outstanding discoveries in the field of immunology were the basis for the creation. This is the ability of molecules to transmit information, or the ability to turn on the “Self-destruction” program to everything alien in the human body.

1.10. Spectrum of iodine deficiency diseases:

The problem of goiter worries the minds of people throughout the history of mankind. Goiter was first described before our era. The connection between iodine deficiency and goiter was first established only in the century before last, when the French scientist Courtoisier obtained iodine from seaweed ash, and the scientist Bauman determined the presence of iodine in the thyroid gland. Iodine is necessary for the normal growth and development of animals and humans. Stocks of iodine in the body are small. In the body of 5 people, it is present in a very small amount - 15-20 mg. The daily requirement for iodine is also small - only 100-150 mcg. The important biological significance of iodine lies in the fact that it is an integral part of the molecules of the thyroid hormones - thyroxine and triodothyronine. Iodine deficiency is a major health problem in many parts of the world. According to WHO (1990), 1570 million people (30% of the world's population) are at risk of developing iodine deficiency diseases, including more than 500 million people living in regions with severe iodine deficiency and a high prevalence of endemic goiter.

• 
  Abortions, stillbirths.
• 
  congenital anomalies
• 
  Increased perinatal mortality
• 
  Endemic neurological cretinism
• 
  Endemic myxedema cretinism: hypothyroidism, dwarfism
• 
  Neonatal, early childhood, neonatal goiter
• 
  Overt or subclinical hypothyroidism
• 
  Disorders of mental and physical development
• 
  Childhood and adolescent endemic goiter
• 
  Hypothyroidism
• 
  Goiter and its complications
• 
  Reproductive Disorders
• 
  Risk of having a baby with endemic cretinism
• 
  All ages increased uptake of radioactive iodine in nuclear disasters
• 
  Cognitive impairment

The table shows that the spectrum of iodine deficiency diseases is very wide, however, the most severe of them are directly related to reproductive disorders or develop perinatally: congenital anomalies, endemic cretinism, neonatal goiter, hypothyroidism, decreased fertility. Thus, endemic goiter and other diseases caused by iodine deficiency are an important medical and social problem. Carrying out measures to prevent iodine deficiency and endemic goiter can significantly improve the health of the population of large regions of Russia and practically eliminate iodine deficiency diseases without large material and technical costs in a short time. To overcome iodine deficiency in nutrition, methods of individual, group and mass iodine prophylaxis are used. Mass iodine prophylaxis is the most effective and cost-effective method of replenishing iodine deficiency and is achieved by adding iodine salts (potassium iodide or iodate) to the most common food: table salt. Group iodine prophylaxis is carried out by organized administration of drugs containing iodine (Jodomarin) by population groups with the highest risk of developing iodine deficiency diseases (children, adolescents, pregnant and lactating women). Individual iodine prophylaxis is carried out in individuals by long-term administration of preparations containing physiological doses of iodine (Jodomarin). The recommended intake of iodine for children 0-5 years old is 90 mcg; children 6-12 years old - 120 mcg; adolescents (>12 years) and adults - 150 mcg; pregnant and lactating - 200 mcg. Special attention should be given to the prevention of iodine deficiency in children of the first year of life. If the mother is breastfeeding, then it is enough to take iodine preparations in the amount of 200 mcg daily, this is enough for both the child and the mother. From the age of 7 months, with the introduction of complementary foods, it is necessary to resolve the issue of giving an additional dose of iodine in the form of pharmacological preparations of potassium iodide (Jodomarin). If the child is formula-fed or mixed, then it is necessary to choose formulas for feeding with an iodine content of at least 90 mcg per 1 liter or to correct iodine deficiency by adding iodine to food in the form of pharmacological preparations of potassium iodide. Carrying out measures for the prevention of iodine deficiency can, without large material and technical costs, in a short time significantly improve the health of the population of large regions of Russia and practically eliminate iodine deficiency diseases. Additional efforts are needed to achieve this goal. These include exposure and education at all levels, implementation of legislation governing salt iodization, and implementation through trading network, systematic monitoring of iodine intake, protection against iodine deficiency in pregnant women and children, and prevention of uncontrolled iodization of food products with various iodine-containing food additives.

1. 
   Research part

2.1. Methods for determining iodine

2.1.1. Voltammetric determination of iodine in powdered milk, chicken eggs, food and other environments.
Laboratory staff conducts comparative studies of food iodization methods, including conducting scientific work in the field of planning and forecasting the process of iodizing chicken eggs.

Laboratory	egg weighing

Stripping voltammetry method (device AVA-3) IODINE in milk, chicken eggs, food, animal feed and other media.

Research is carried out according to certified measurement methods, quality control is implemented using international quality standards and is confirmed by comparative interlaboratory tests.

Device AVA-3

AT recent times iodized foods, drinks and biologically active additives (BAA), as well as the traditionally used iodized food sodium chloride, have become widespread. The control of the content of the element in conventional and iodine-enriched products is an important analytical problem. To determine the iodine content in food and beverages, various methods: titrimetry, test methods, potentiometry, voltammetry, electrophoresis, spectrophotometry, chromatography, atomic absorption, mass spectrometry, neutron activation analysis. The results of the interlaboratory experiment showed a high convergence and a small error of the stripping voltammetry method proposed by us using graphite electrodes. Based on the data of the interlaboratory experiment, the given method was recommended for use and was certified by the Ministry of Health and registered as guidelines (MUK 4.1 1481-03).

Iodine and its compounds play an important role in the metabolic processes of humans and animals. Sources of iodine in the body are mainly food. Installed daily rate element consumption - 100-200 mcg, which, as a rule, is not provided by normal nutrition. In this regard, iodized foods, drinks and biologically active additives (BAA), as well as the traditionally used iodized food sodium chloride, have recently become widespread. On the other hand, the intake of excess iodine in the body can lead to toxic effects. Therefore, the control of the content of the element in conventional and iodine-enriched products is an important analytical problem. Various methods have been proposed to determine the iodine content in foods and drinks: titrimetry, test methods, potentiometry, voltammetry, electrophoresis, spectrophotometry, chromatography, atomic absorption, mass spectrometry, neutron activation analysis. It should be noted that the control of iodine content in biological fluids (primarily in urine and blood) is of no less importance, since it allows us to estimate the amount of the element absorbed by the body. For routine laboratory analysis, stripping voltammetry using graphite electrodes is quite applicable, which makes it possible to exclude work with any form of mercury. This method is based on the ability of iodine (I 2) to form sparingly soluble precipitates of the composition I 2 HalR, which are salts of the hydrophobic cation R + and the mixed trihalide I 2 Hal - (where Hal is chloride or bromide) according to the following scheme:

Iodide ions at a sufficiently positive potential are oxidized to elemental iodine I 2 (reaction 1), after which a precipitate is formed in the presence of a halide ion Hal and an organic cation molecule R (reaction 2). Further, during the cathodic polarization of the indicator electrode, iodine is reduced in the composition of the associate, while a peak is recorded on the voltammogram, the height of which is proportional to the concentration of iodide ions in the solution (Fig. 1). This method has been successfully applied in the analysis of individual food products, natural and industrial facilities. Optimization of a number of experimental parameters was carried out by us earlier in the work. The effect of the nature and structure of R, the electrode material, the composition and concentration of the background electrolyte, and the parameters of recording voltammograms on the value of the cathodic dissolution current I 2 HalR has been studied.

Electrochemical parameters are given in table. 1. Determination of the concentration of iodide ions was carried out by the method of additions.

Metrological data processing of the interlaboratory experiment was carried out in accordance with GOST R ISO 5725-2002.

Since it is impossible to replace questionable measurement results with more correct ones, they should be excluded as "genuine" emissions according to GOST R ISO 5725-2-2002.

Table 1..Metrological characteristics of the stripping voltammetric method for the determination of iodine.

General average	ñ	0,862
Repeatability dispersion	s 2 1	0,0219
Interlaboratory variance	S 2 L1	0,068
Reproducibility dispersion	S 2 R1	0,090
Standard deviation	S	0,251
Confidence error (P=0.95)	Δx	0,138
Confidence error of the method (Р=0.95)	é, %	16,03
Systematic error (P=0.95)	σ, %	6,42

2.1.2. Titrimetric method for the analysis of the determination of iodine in bread.

When conducting a titrimetric analysis, accurately measured volumes of solutions of 2 reacting substances are used. The basis of the titrimetric method of analysis is the oxidation-reduction reaction according to the scheme:
21-=12+2e~ (1).

Potassium iodide solutions are used to increase the solubility of 12. In this case, iodide complexes 13~ are formed, which practically does not affect the value of the potential of the 12/ G pair. In this reaction, free iodine (or 13~) in solution is an oxidizing agent, and iodide (1~) is a reducing agent. The iodine released as a result of the oxidation of the iodide ion is usually titrated with sodium thiosulfate (in the presence of starch as an indicator) at a concentration determined by the equation:
2S2032-+I2=S4062-+2I- (2).

Iodometric titration underlies the quantitative determination of iodates (103~) and iodides (I). The basis of the iodometric determination of iodates (U3 ~) is the reaction:
KV + 5I~ + 6H+=3I2 + 3H2O (3).

An excess amount of iodide (I) is added to the test solution containing iodate (103") in order to carry out a redox reaction in an acidic environment with the release of free iodine. A further procedure for the quantitative determination of free iodine formed from iodate is carried out titrimetrically in accordance with equation 2.

The quantitative determination of iodides (G) in solution is also carried out by the titrimetric method, in which iodides are first oxidized by bromine in an acidic medium to iodates according to the reaction:
I- + 3 Br2 + 3H2O = 103~ + 6 Br- + 6H+ (4).

To eliminate excess bromine, sodium sulfite and (or) phenol or salicylic acid is introduced, which prevents further oxidation of iodide. Then iodates are reduced with the help of iodides in an acidic medium to molecular iodine according to equation (3), and free molecular iodine dissolved in potassium iodide is titrated with sodium thiosulfate in an acidic medium (in accordance with equation 2).

The titrimetric method of analysis is one of the most common methods for the quantitative determination of iodine in various environmental objects. This method is recommended for the determination of iodine in drinking water, bread and bakery products. The method is recommended by the Ministry of Health of the Russian Federation for assessing the degree of iodization of table salt with potassium iodate and is used in a number of countries (in India, South Africa, etc.). The International Association of Official Analytical Chemists (AOAC) recommends the titrimetric method as the official standard method for determination of free iodine in standard solution , iodine in foods , salt iodization , analysis of iodine in medicines containing iodine , as well as absorbed iodine in oils and fats and double - bound iodine in fats and oils . Assessing the titrimetric method for determining iodine in environmental objects, one should note its availability and simplicity, as well as high sensitivity in the determination of all forms of iodine - molecular, iodides and iodates. Along with this, it should be borne in mind that the objects of study, in particular food products and food raw materials, may contain substances (of organic and inorganic origin) that can both oxidize and reduce various forms of iodine, significantly affecting the result of the analysis. Freshly prepared 1% starch solution is used as an indicator in iodometry. When iodine interacts with starch, 2 processes occur - complex formation and adsorption, as a result of which compounds are formed of blue color. Starch should be added to the titrated solution only when the main amount of iodine has already been titrated, otherwise the starch forms a very strong compound with an excess of iodine; in this case, an overconsumption of sodium thiosulfate is observed, which leads to a distortion (overestimation) of the analysis results. Iodometric titration must be carried out in the cold, since at elevated temperatures there is a loss of iodine due to its volatilization from the solution. In addition, with increasing temperature, the sensitivity of the indicator starch iodine reaction decreases. Titration must not be carried out in alkaline solution, since in an alkaline environment iodine forms hypoiodide and some other reaction products. In this regard, it is recommended to carry out titration in an acidic environment (pH 3-5). During titration in strongly acidic solutions, there is a danger of oxidation of iodide (I) by atmospheric oxygen.

When carrying out the titrimetric determination of iodine, in addition to the above analysis features, it must be taken into account that sodium thiosulfate used for titration, when standing, can turn into sulfite under the action of an acid (even as weak as carbonic acid), which leads to an increase in the thiosulfate titer. In addition, when the solution is standing, a decrease in the titer of thiosulfate is observed due to the oxidation of the latter by atmospheric oxygen to sulfates. The oxidation process is catalyzed by negligible amounts of copper salts. To stabilize the solution, it is recommended to introduce a small amount of sodium carbonate. Another reason for the decrease in thiosulfate titer is its decomposition by a number of microorganisms that are always in the air. Starch solutions are also destroyed when stored for several days under the influence of bacteria. In order to prevent the action of microorganisms on the solution
ru thiosulfate add a small amount (up to 0.5 ml) of chloroform and (or) sodium carbonate.

2.1.3. Method of high performance liquid chromatography for the determination of iodine in bread.

high performance liquid chromatography

High performance liquid chromatography (HPLC) has been applied to the determination of iodides in liquid milk and milk powder. Proteins and insoluble material of liquid and reconstituted milk were removed using membrane filters. The iodide in the filtrate was separated from other ions by reverse phase ion pair liquid chromatography and analyzed by selective detection using an electrochemical detector. At a concentration of 0.5-4.6 µg of iodine in 1 g of milk powder average value determination of iodine is 91%, the value of convergence is 9.0%, the degree of reproducibility is 12.7%. With a content of 300 μg of iodine in 1 liter of milk, the correctness of the method is 87%, the convergence value is 8.2%, the degree of reproducibility is 8.3%. Designed new method ion chromatography using direct ultraviolet (UV) detection at 210 nm of inorganic anions in saline solutions (artificial sea ​​water) using an octa-decyl silicone column modified with zwitterion (3-(N,N-dimethylmyristylammonio) propanesulfonate. Limit of detection of iodide -0.80 µg/kg, relative standard deviation
Isotopic dilution methods

Isotopic dilution is a method of quantitative chemical analysis using radioactive or enriched stable nuclei.
dov as indicators. The method is based on change isotopic composition of the element to be determined as a result of dilution when mixed with the analyzed sample. characteristic feature method is the ability to carry out a quantitative determination with incomplete isolation of the analyte. AT classic version the determination of iodine is based on the change in specific radioactivity upon dilution during the assay. To the analyzed solution containing iodine, add a known amount of isotope III (or 1311). After mixing the solution and achieving an equilibrium distribution of isotopes between the introduced and analyzed substances, a part of the analyzed substance is isolated from the solution, its mass and radioactivity are measured. Moreover, its specific radioactivity is equal to that of the substance in solution after mixing. The results of the analysis of iodine in food products by isotope dilution are in good agreement with the data obtained by neutron activation analysis and inductively coupled plasma mass spectrometry. When determining the concentration of iodine in salt, milk and urine, the isotope dilution method was used. Sample preparation by the “dry burning” method was carried out only when analyzing milk. 1311 was used as an indicator solution. The electrophoretic separation of the mixture was carried out in a polyacrylamide gel at 300°C for 2 h. The sensitivity of the method was 1 μg/L; relative standard deviation - 14%.