RU2683938C1 - METHOD FOR DETERMINING THE TOTAL CONTENT OF F-, Cl- AND Br- ORGANIC COMPOUNDS IN HAIR AT THE LEVEL OF TRACES - Google Patents

Abstract

FIELD: chemistry.SUBSTANCE: invention relates to the field of analytical chemistry and can be used to determine the content of organohalogen compounds in human hair and relates to the environmental control of human pollution. For this purpose the short-term washing of the hair sample with deionized water, free from detectable anions at the level of detection limits is performed, hair is separated from water, dry hair, quickly throw in a certain amount of hair in a quartz boat in the high-temperature zone of the reactor with a temperature of 900–1,000 °C, where high-temperature oxidative conversion occurs in a stream of high-purity oxygen at that rate of oxygen flow, which provides high-temperature conversion of organohalogen compounds present in the hair to anions F-, Cl-, Br-. Oxidative conversion of hair samples is carried out under conditions that exclude soot formation and the release of part of the absorbate from the absorber. Conversion products absorb in the absorber with deionized water, free from detectable anions at the level of detection limits, while the amount of oxygen passed through the reactor and such an absorber that in idle experience, the background level of the analytes in the absorber corresponds to the background level in deionized water filling the absorber before oxygen is supplied to the reactor. Then the absorber is transferred to a concentrating column, and then analyzed by ion chromatography under isocratic conditions, that ensure complete separation of the water peak from the F- and Cl- peaks and rapid detection of all analytes.EFFECT: claimed invention provides the ability of quick and selective determination the total content of trace amounts of volatile, medium-volatile and non-volatile halogen-containing compounds in human hair.1 cl, 3 tbl, 3 ex

Description

The invention relates to the field of chemistry and relates to the field of contamination of the internal environment of a person, namely, exogenous F-, Cl- and Br-containing organic substances, which are dangerous compounds.

Currently, the urgent problem is the rapid detection of contamination of the internal environment of the body by hazardous organic substances, which are components of complex mixtures, the composition of which is unknown.

The most dangerous are F-, Cl-, Br-, P- and S-containing organic compounds (various pesticides, polychlorobiphenyls, polychlorodibenzodioxins, (PCDC), polychlorodibenzofurans (PCDF), polychlorobiphenyls (PCBs), and their brominated analogues).

The problem of detecting pollution of the human internal environment by such dangerous compounds is relevant for all countries. Small doses of the considered compounds lead to harmful consequences, especially in the case of pregnant women and newborns. To solve it, various physicochemical methods (mainly chromatography-mass spectrometry) are used to analyze biosubstrates such as blood plasma, breast milk, urine, hair, nails, saliva, etc.

In the vast majority, in the determination of organic compounds, only given compounds are analyzed. At the same time, humanity produces and uses hundreds of thousands of compounds. According to the WHO, more than 40,000 of them are dangerous and more than 12,000 are toxic. The most dangerous of them are F-, Cl-, Br-, S- and P-containing.

For biosubstrates, the analysis is carried out on a limited number of given compounds.

At the same time, to detect contamination of the internal environment of the body, it is desirable to establish all dangerous organic compounds (known and unknown) containing F, Cl, Br, S, and P. In addition, a matrix (biosubstrate) should be selected for analysis in which such substances accumulate over time. Hair meets this requirement.

The determination of exogenous S- and P-containing organic compounds in the case of hair is not considered in this invention, since many endogenous compounds containing sulfur and phosphorus in the molecule are part of the hair.

To determine the content of a large number of elements (up to 50) in biosubstrate, including hair, (which are part of organic and inorganic compounds - endogenous and exogenous), one of the most promising methods for determining micro- and ultramicroelements in substrates is mass spectrometry inductively coupled plasma (ICP-MS). (see. Introduction to medical elementology / I.V. Radysh, A.V. Skalny. - Moscow: Russian University of Peoples' Friendship, 2015, pages 68-75 /) [1].

To prepare samples of biosubstrates and preparations of amino acids and biologically active substances for analysis by ICP-MS, two decomposition methods are allowed: 1) acid dissolution in open vessels, without complete destruction of the organic matrix; 2) acid decomposition ("wet ashing") using microwave sample preparation systems. The open decomposition method is characterized by the following features: high performance with a low consumption of reagents, which is attractively small correction for blank experience. However, the method is not applicable for the decomposition of materials containing a lot of fatty substances and calculi (adipose tissue, neoplasms in internal organs); in this case, partial or sometimes complete loss of volatile elements is possible; the organic matrix retained in sample solutions can be a source of serious matrix noise in ICP-MS measurements that limit the determination and isotopic analysis of some elements.

The microwave decomposition method provides the following advantages: high decomposition performance; more complete oxidation of the organic matrix of almost any biosubstrates; a significant reduction in the loss of volatile elements during decomposition (see MUK 4.1.1483-03, Determination of chemical elements in diagnosed biosubstrates, preparations and biologically active additives by inductively coupled argon plasma mass spectrometry, ANO Center for Biotic Medicine (MD) A.V. Skalny, Ph.D. V.A. Demidov, Ph.D. M.G. Skalnaya, E.P. Serebryansky, A.R. Grabeklis] [2].

However, this method does not allow the determination of elements such as F and Cl, and the sensitivity in determining Br ^is not high enough. In addition, it does not allow highly sensitive and selective determination of organic impurities in hair containing F, Cl and Br (in terms of element) in the presence of inorganic impurities containing these elements. Inorganic impurities may be present in the hair.

A known method for the simultaneous determination of the total content of F-, Cl-, Br-, I-, S- and P-organic impurities in oil and oil products, based on the high-temperature oxidation of the analyzed sample in a stream of pure oxygen, absorption of conversion products with deionized water, free of elements. After the conversion products are absorbed in the absorber with deionized water, the CO ₂ formed during the high-temperature oxidation of CO _{2 is} blown off with an oxygen stream or with an inert gas supplied to the absorber, which is additionally supplied to the absorber. The entire volume of absorbate is introduced through a protective column and a concentration column connected to it, most of the water is displaced by eluent from both columns, and then the anion concentrate formed as a result of absorption of the conversion products by water is transferred to the analytical column by the same eluent, and water and anions corresponding to elements using ion chromatography in isocratic conditions (patent RU 2395805) [3].

When analyzing solid refined petroleum products, the selected sample is introduced into the boat in the colder zone of the reactor in an oxygen stream, followed by the boat moving to the hot zone and the operations described above are carried out. When analyzing oils, the sample is introduced using a microsyringe into the cold zone of the reactor in an oxygen stream, followed by moving the reactor to the hot zone of the furnace. However, such a sample injection can lead to a partial formation of chlorine during the oxidative conversion at a lower temperature, which, interacting with water in the absorber, can lead to the formation of ClO ₃ ^- and ClO ^- ions (along with Cl ^- ) [4]. The possibility of chlorine formation during the combustion of organochlorine compounds at 850 ° С was also noted in [5]. The formation of chlorine during the combustion of petroleum products can lead to a distortion of the results of determining the total content of organochlorine compounds for the reasons considered. However, the examples given in the description of the method in [3], reflected only the analysis results obtained by introducing samples of volatile and medium-volatile oil products into the hot zone of the reactor. Analysis of solid products not shown. It should also be noted that the prototype did not consider the possibility of the presence in samples of oils and solid refined petroleum products of inorganic compounds containing the determined elements F, Cl, Br and the need for selective determination of halogen and organo-sulfur compounds in the presence of inorganic.

The degree of purity of deionized water (residual halogen content) filling the container and absorber is not specified. It is not indicated that the incomplete displacement of water from the concentrating column limits the detection limits of fluorine due to the incomplete separation of the peaks of water and the anion F ".

A known method for the simultaneous determination of the total content of F-, Cl-, Br-, S- and P-containing organic compounds in water and aqueous solutions, based on the isolation of these compounds from a water sample saturated with an inorganic salt, extraction with an organic solvent, concentration of the analyzed compounds from of the obtained extracts by removing the solvent with an inert gas stream in the presence of a sorbent, transferring the analytes by thermal desorption with an inert gas stream to a reactor into which oxygen is supplied. The conversion products are absorbed with deionized water, free from the determined anions, the entire volume of the absorbate is passed through the protective and concentrating columns, the part of water is removed from the free volume of the columns by eluent, and the concentrate of anions, the products of the conversion of the determined elements into the separation column, is transferred to them, and they are analyzed by the method ion chromatography under isocratic conditions. It is desirable to carry out the process in such a way that the feed rate of the concentrate and oxygen flow are such that the formation of soot on the walls of the reactor is excluded and the conversion products are completely transferred to the absorber and absorbed in the absorption zone (patent RU 2395804) [6].

The method enables the selective determination of impurities of medium-volatile organohalogen compounds in water and in the presence of corresponding inorganic compounds containing the same halogens due to the isolation of the first by liquid extraction and the high-temperature oxidative conversion of their concentrate free of extractant. A limitation of this method is that only those medium-volatile organohalogen compounds that are extracted from water by the selected extractant (i.e., not all) are subject to determination. Non-volatile and volatile organic compounds cannot be determined. In addition, the detection limits of detectable elements are increased due to impurities of medium volatile organohalogen compounds that may be present in the solvent extractant.

A limitation of this method is also that for unknown components of the mixture is not known the degree of their extraction by liquid extraction. In addition, the removal of water from the free volume of the column by the eluent is poorly reproducible, which increases the error in determining the F ^- anion and reduces the accuracy of determining trace amounts of F ^- due to the incomplete separation of the water peak and the F ^- anion.

The urgent task that is solved by the present invention is the rapid, simultaneous and highly selective determination of all (normalized and non-normalized) F-, Cl-, Br-organic compounds in the hair (volatile, medium-volatile and non-volatile) at the level of traces, which would provide the possibility of fast screening hair samples for the content of such compounds (in terms of element).

None of the previously known methods knew the method of direct simultaneous and highly selective determination of the total content of F-, Cl-, Br-organic compounds in the hair at the level of traces in the presence of inorganic compounds containing detectable elements.

The proposed new method for the simultaneous determination of the total content of F-, Cl-, Br-organic compounds in the hair in the presence of inorganic compounds containing the same elements is that they conduct a short-term washing of the hair sample with deionized water, the content of the determined anions in which does not exceed the limits detection of anions of ^{F -, Cl -, Br -} , hair separated from the water, the hair was dried, weighed and placed certain dried hair in a quartz boat, quickly throwing it into the high temperature zone D ctor with a temperature of 900-1000 ° С (as a rule, in a fixed zone with a temperature of about 950С), where oxidative conversion occurs in a stream of oxygen of a high degree of purity, at such an oxygen flow rate that ensures high-temperature conversion of organohalogen compounds present in the hair, to the anions F ^- , Cl ^- , Br ^- in the absorber, and at the same time, inorganic compounds containing F, Cl, Br remain in the reactor. The conversion products are absorbed in an absorber with deionized water, free from the determined anions at the level of the detection limit. In this case, the amount of oxygen passed through the reactor and the absorber is such that, in a blank experiment, the background level of analytes in the absorbate corresponds to the background level in deionized water, free of analytes, filling the absorber before oxygen is supplied to the reactor. The entire absorbate is transferred to a concentrating column and then the analyte concentrate (F ^- , Cl ^- , Br ^- ) corresponding to the determined elements F, Cl, Br is analyzed by ion chromatography under such isocratic conditions that ensure complete separation of the water peak from the F ^- and Cl ^- and the rapid detection of all analytes under conditions when the electrical conductivity of the eluent at the inlet of the detector is close to the electrical conductivity of deionized water. At the same time, the process of burning a hair sample is carried out under conditions that exclude soot formation and ejection of a part of the absorate from the absorber.

To ensure high reliability of the registration of the analyzed anions in the products of oxidative conversion of hair, the composition of which is unknown, at the inlet of the eluent to the detector preferably include a column that selectively binds F ^- , Cl ^- and Br ^- anions.

The prepared specific weight of the hair is placed in a quartz boat and the boat is quickly thrown into the high-temperature zone of the reactor, the temperature of which is usually 900-1000 ° С. Small changes in temperature do not significantly affect the result. The preferred temperature in the zone of the reactor is 950 ° C.

The boat is thrown in such a way that it is fixed in this zone (due to the narrowing of the reactor).

The experiments showed that under the selected conditions of high-temperature oxidative conversion of hair, the possibility of Cl ₂ formation was excluded and only peak Cl ^{- was} recorded in the analysis of the absorbate.

In addition, the oxidative conversion at a fixed position of the boat with hair in the high-temperature zone of the reactor after being thrown into it eliminated its accidental entry into the low-temperature zone and ensured a higher reproducibility of the analysis results.

To clarify the possibility of highly selective detection of F-, Cl-, Br-organic compounds in hair in the presence of inorganic compounds containing the same elements in molecules, an analysis of samples of aqueous solutions of NaF, NaCl and NaBr of various concentrations was carried out.

Samples with a volume of 1 μl were introduced into the boat, water was evaporated, and the boats with analyte were thrown in a stream of oxygen into the reactor at a zone of 950 ° С. It was shown that for amounts of elements lower than 4 × 10 ^-6 g (10 ^-1 %), the F ^- , Cl ^- , Br ^- anions were not recorded in the absorbate, which indicated the possibility of direct highly selective detection of F-, Cl-, Br-organic compounds in the presence of inorganic ones that remain in the reactor (the total content of organohalogen compounds in the hair is orders of magnitude less than this value).

The proposed method differs from each of the previously known methods described above by the initial studied object, its sample preparation, and conditions of high-temperature oxidative conversion, which enable direct, highly selective and reliable detection of trace amounts of organohalogen compounds in the hair in the presence of halogen-containing inorganic compounds.

The method provides the possibility of highly selective determination of the total content of F-, Cl-, Br-organic compounds in the hair at the level of traces with a complete conversion of the corresponding organic compounds to F ^- , Cl ^- , Br ^- . The number of these elements recorded in the analysis of dozens of hair samples (1-2 mg sample) in the vast majority of cases was less than 10 ^-11 -10 ^-12 g, indicating a highly selective detection of organohalogen compounds in the hair. The analysis by ion chromatography under isocratic conditions, which ensure the separation of the water peak from the F ^- and Cl ^- peaks and the rapid detection of all analytes under conditions when the electrical conductivity of the eluent at the inlet of the detector is close to the electrical conductivity of deionized water, provide the maximum sensitivity of the determination. Thus, the proposed method provides the possibility of direct, fast, highly selective and highly sensitive determination of the total content of volatile, medium-volatile and non-volatile halogen-organic compounds in the hair (in terms of element) in the presence of inorganic halogen-containing compounds.

Methodology of the analysis procedure and its features

1. Sample preparation for analysis

A hair sample (not more than 10 mg) 3-5 cm long is placed in a 5 ml vial, washed with deionized water containing no analytes (F ^- , Cl ^- , Br ^- ) at the level of detection limits by ion chromatography (10 ^-11 -10 ^-12 g / μl) and washed with a stream of the same water from the installation for the preparation of deionized water with a resistance of 18.2 mOhm for 2 minutes. Such a time was taken in the analysis of hair for the content of elements by the ICP-MS method. Then the hair is separated from the remaining water and dried with a stream of helium. After drying, a sample of 1-2 mg is separated from the hair sample.

Each of the samples is placed in a quartz boat, previously calcined at 950 ° C in a stream of pure oxygen.

2. The procedure for the selective determination of the total content of F-, Cl- and Br-organic compounds (in terms of element) in a hair sample.

Before starting the experiments on oxidative conversion, the background of deionized water is checked in a quartz container with this water using analytes (F ^- , Cl ^- , Br ^- ), and this container is repeatedly washed with freshly obtained deionized water until the background level is below the detection limits for analytes.

Similar measurements are carried out for pure deionized water from a quartz container placed in a 2-5 ml vial used as an absorber.

With the same quality of pure deionized water from the quartz container and from the absorber, a stream of pure oxygen from the reactor, the temperature inside which is 950 ° C, is passed through the absorber.

The experiments on burning a hair sample are carried out after the background water level according to the analytes in the absorber after passing oxygen through the reactor will be the same as in the original clean water from a quartz container.

A quartz boat with a hair sample is quickly introduced into the fixed zone of the reactor in a stream of oxygen of high purity, the temperature of which is about 950 ° C and at such a flow rate of O ₂ , which ensures the burning of hair and high-temperature oxidative conversion of organohalogen compounds to anions F ^- , Cl ^- , Br ^- (in the absorber) and at the same time inorganic halogen compounds remain in the reactor (in an amount of less than 10 ^-6 g). High temperature oxidative conversion of a hair sample is carried out under conditions that exclude soot formation and release of conversion products from the absorber. The conversion products are absorbed from the stream of pure oxygen in an absorber with deionized water, free from the determined anions at the level of the detection limit, and the entire absorbate is transferred to a concentration column. The amount of oxygen passed through the reactor and the absorber is such that, in a blank experiment, the background level of analytes in the absorber corresponds to the background level of deionized water filling the absorber before oxygen is supplied to the reactor.

Then, the anion concentrate (F ^- , Cl ^- , Br ^- ) corresponding to the determined elements F, Cl, and Br is analyzed by ion chromatography under such isocratic conditions that ensure complete separation of the water peak from the F ^- and Cl ^- peaks and the rapid detection of all analytes under conditions when the electrical conductivity of an aqueous solution passing through the detector is close to the electrical conductivity of deionized water.

The invention may be illustrated by the following specific embodiments.

Example 1

In accordance with the procedure for determining the total content of F-, Cl- and Br-organic compounds, an analysis of the corresponding compounds in solutions was carried out. The data obtained are shown in Table 1.

The relative standard deviation (Sr) did not exceed 0.2.

About 1 μl of the pesticide solution was introduced into the boat and, after evaporation of the solvent, the boat was quickly introduced into the fixed zone of the reactor at a temperature of 950 ° C.

As can be seen from the data in Table 1, the results of determining the content of the corresponding elements (Cl ^- and Br ^- ) when using the proposed determination method are correct (the discrepancy between the set values and the experimental ones does not exceed the determination error).

Example 2

In accordance with the procedure for determining the total content of F-, Cl- and Br-organic compounds, the analysis of the same compounds was carried out as shown in Table 1, applied to hair samples placed in boats from a solution in acetone (after evaporation of the solvent). A portion of the hair was about 1 mg, the sample volume of the applied solution was about 1 μl.

The data obtained are shown in Table 2.

As can be seen from the data in Table 2, the results of determining the content of Cl and Br elements when applying the corresponding compounds to hair from a solution in acetone and subsequent evaporation of the solvent do not significantly differ from the set values and obtained when applying a solution of acetone to the boats (in the absence of hair) and solvent evaporation.

Example 3

In accordance with the procedure for determining the total content of F-, Cl- and Br-organic compounds in the hair (in terms of element), an analysis of hair samples obtained from various people (from Russia and Bangladesh) was carried out.

The results are shown in Table 3.

Sr - relative standard deviation, did not exceed 0.3.

As can be seen from the data in Table 3, in the overwhelming number of hair samples, the total content of F, Cl, Br included in the composition of the molecules of organic compounds did not exceed the detection limits by mass in%. However, in three cases out of 40 samples, a significant increase in the content of F, Cl, Br was observed.

The data obtained provide the ability to quickly screen hair samples for the total content of F-, Cl-, Br-organic compounds at an ultra-low level.

The results obtained using the proposed method provide concise information on the total content of hazardous organic compounds (known and unknown) present in the hair and throughout the body. If necessary, the sample taken as a result of screening can be analyzed by conventional chromatography-mass spectrometry methods.

The achievement of the result in the conditions of the proposed method is not expected or obvious for a person skilled in the art with direct highly selective simultaneous determination of trace amounts of the total content of F-, Cl-, Br-organic compounds in the hair in terms of an element in the presence of inorganic compounds, these same elements containing, at the ultra micro level. Evidence of this is the lack of publications on direct highly selective determination of the total content of known and unknown F-, Cl-, Br-organic compounds in the hair at the trace level and in the presence of F-, Cl-, Br-inorganic compounds.

References:

1. Introduction to medical elementology / I.V. Radysh, A.V. Rocky. - Moscow: Russian University of Friendship of Peoples, 2015 .-- 198 p.

2. MUK 4.1.1483-03 Determination of the content of chemical elements in diagnosed biosubstrates, preparations and biologically active additives by mass spectrometry with inductively coupled argon plasma, ANO Center for Biotic Medicine (MD A.V. Skalny, k. Ph.D. V.A. Demidov, Ph.D. M.G. Skalnaya, E.P. Serebryansky, A.R. Grabeklis).

3. Patent No. 2395805, 2010. A method for simultaneously determining the total content of F-, Cl-, Br-, I-, S- and P-organic compounds in oil and oil refining products, I.A. Revelsky, A.I. Revelsky, E.N. Capinus

4. Chemical Encyclopedia, Volume 5, Great Russian Encyclopedia, M., 1998 pp. 280.

5. Kursta S., Volinsky A., Kurta M., Environmental Friendly Organoclorine Waste Processing and Recycling // Journal of Cleaner Prodiction 2013 V. 54 P. 150.

6. Patent No. 2395804, 2010. A method for simultaneously determining the total content of F-, Cl-, Br-, I- and S-organic compounds in water and aqueous solutions I.A. Revelsky, A.I. Revelsky, E.N. Capinus

Claims (2)

1. A method for simultaneously determining the total content of F-, Cl- and Br-organic compounds in hair at the level of trace amounts in the presence of organohalogen compounds containing the same elements, characterized in that they conduct a short-term washing of the hair sample with deionized water, free of the determined anions F -, Cl-, Br- at a level below the detection limits, separate the hair from water, dry the hair, place a certain amount of dry hair in a quartz boat, quickly throw it into the high-temperature zone of the reactor with at a temperature of 900-1000 ° C, where a high-temperature oxidative conversion occurs in a high purity oxygen stream at an oxygen flow rate at which a high-temperature conversion of organohalogen compounds present in the hair is achieved to anions F-, Cl-, Br-, and at the same time, inorganic compounds containing F, Cl, Br remain in the reactor, the conversion products are absorbed in the absorber with deionized water, free from the determined anions at the level of detection limits, while the volume of oxygen, p lowered through the reactor and the absorber such that, in a blank experiment, the background level of analytes in the absorbate corresponds to the background level in deionized water free of analytes, filling the absorber before oxygen is supplied to the reactor, the entire absorbate is transferred to a concentrating column and then the analyte concentrate (F-, Cl - and Br-), corresponding to the determined elements F, Сl, Br, are analyzed by ion chromatography under such isocratic conditions that ensure complete separation of the water peak from the F- and Cl- peaks and the fast detection of all analytes in conditions when the electrical conductivity of the eluent at the inlet of the detector is close to the electrical conductivity of deionized water, while the high-temperature oxidative conversion of the hair sample is carried out under conditions that exclude soot formation and ejection of part of the absorbent from the absorber. 2. The method according to p. 1, characterized in that the dried specific weight of the hair, placed in a quartz boat, is quickly thrown into a fixed part of the high-temperature zone of the reactor, the temperature of which is about 950 ° C.