RU2224996C1 - Method of gas-chromatographic determination of average shift doses of halogen anhydrites and anhydrites of carboxylic acids in air of working zone - Google Patents

Abstract

FIELD: research in labor hygiene. SUBSTANCE: invention is related to sanitary-hygienic laboratory investigation of labor conditions by indications of adverse and dangerous chemical factors of working environment, burden and intensity of working process. This task is solved by uninterrupted sampling of air with rate of lung ventilation in the course of shift through two parallel chromatographic columns. Separable porous filters containing specified amount of sorbent-silanized chromosorb with graininess of 0.125-0.200 mm with mixture of dialkylethers of heteroatomic polyatomic alcohols and heteroatomic amine applied in suspended state in the amount of 30% or more of mass of solid sorbent are installed at inlets and outlets of columns. Sorbent of first column has piperidine in equivalent amount exceeding corresponding lethal dose of halogen anhydrite or anhydrite of carboxylic acids, solid sorbent with applied mixture of dialkylglyms and hexahydroazepine with content of the latter in equivalent amount similar to first column is dispersed in second column. To determine average shift dose at beginning of shift or operation carrier gas is fed into chromatographic columns containing various heterocyclic amines, average shift dose is found by dependence of difference of chromatographic parameters of benzene holding relative to hexane in acyl-derivatives of heterocyclic amines on mass of analyzed substance. Method makes it possible to determine effect of chemical factor on organism of operator and to raise authenticity in evaluation of risk of morbidity under action of harmful substances by indications of adverse and dangerous factors of working environment, burden and intensity of process. EFFECT: improved authenticity of method. 1 cl, 3 tbl

Description

 The invention relates to sanitary-chemical methods of research in hygiene, and in particular to a method for gas chromatographic determination of medium-shift doses of reactive and toxic halides and carboxylic acid anhydrides in the air of a working zone (SPS) of industrial enterprises. It can be used for certification of workplaces in accordance with Guidelines R 2.2.755-99 "Hygienic criteria for assessing and classifying working conditions by indicators of harmfulness and danger of factors of the working environment, severity and intensity of the labor process" to determine average doses of harmful substances (HE).

A gas chromatographic method is known for measuring medium-shift doses of acetic anhydride in a water-vapor diffusion, based on concentration of anhydrides from an air sample by absorption into an aqueous solution, followed by adding an aliquot of a solution to the chromatograph's evaporator, determining the retention time of acetic acid (2 min 40 sec) at a chromatographic temperature of 150 ^o C in a chromatographic column of stainless steel 2 meters long and an inner diameter of 3 mm filled with Polysorb 1 with 5% polyethylene glycol 20,000 and a carrier gas flow rate, p implicit 30 cm ³ / min with quantitation of the concentration of the absolute calibration method using a flame ionization detector. The average daily dose is determined by graphoanalytical method according to Appendix 9 of the Guide. The lower detection limit for the concentration of acetic anhydride is 1.5 mg / m ³ (0.5 MPC) when passing 10 L of SPS through 2 series-connected absorption vessels cooled with ice water at a speed of 1 dm ³ / min. The gas chromatographic determination of organic acids is complicated by sorption phenomena in the column evaporator, a high detection temperature close to the maximum working temperature of the stationary phase, the association of organic acids in the vapor phase, dilution of the concentrate during chromatographic separation, therefore, the technique cannot be used to accurately determine the average shift doses of harmful substances by graphoanalytical method. In addition, vapors of acetic acid, also present in the SOP [MUK 4.1.169-96, interfere with quantification. Measurement of the concentration of harmful substances in the air of the working area: Met. Directions - Issue 29. - M .: Information Publishing Center of the Ministry of Health of Russia, 1998, p. 303].

There is also a known method for gas chromatographic determination of medium-shift doses of propionyl chloride in VRZ, based on the hydrolysis of propionyl chloride to a free carboxylic acid during its concentration from an air sample into an aqueous solution, followed by an aliquot of a solution in the chromatograph evaporator, determination of the retention time of propionic acid (2 min 35 sec) at a chromatographic temperature of 150 ^o C in a chromatographic column of glass or stainless steel 0.5 meters long and an inner diameter of 3 mm, filled Polysorb 1 (fraction 0.25-0.5 mm) and a carrier gas flow rate of 35 cm ³ / min, with quantitative determination by absolute calibration using a flame ionization detector. The average daily dose is determined by graphoanalytical method according to Appendix 9 of the Guide. The lower limit of detection of the concentration of propionyl chloride is 0.1 mg / m ³ (0.05 MPC) when passing 15 dm ^{3 of} SEC through an absorption device with a porous plate, cooled with a mixture of finely divided ice and sodium chloride, at a speed of 1 dm ³ / min. The determination of vapors of propionic acid and other carboxylic acids with a molar mass close to the molar mass of propionic acid interferes with the determination; therefore, the measurement error exceeds 20% due to insufficient separation of chromatographic compounds and overlapping chromatographic peaks [MU 6001-91, p. 199]. To improve the separation, organic acids are extracted with diethyl ether from an aqueous absorber with the addition of a salting out agent. However, this concentration method is time consuming and laborious. Therefore, the average shift dose cannot be determined with sufficient accuracy as the product of the shift average concentration by the total time of work operations during the shift.

The closest in technical essence and the achieved result is a method for the qualitative and quantitative analysis of low-volatile polar organic compounds in air, based on the fact that during the shift one-time air samples are taken in the volume and quantity recommended by Appendix 9 of the Guideline by treatment with a volatile organic solvent to extract amounts of polar low-volatile organic compounds, apply the prepared sample to a solid sorbent, which is located in the chromatographic column first a chromatograph equipped with a thermal conductivity detector, the sample was dried by passing the inert gas at a temperature of 30-60 ^o C until complete release of the volatile organic solvent is introduced into the model mixture of hexane and benzene, is measured relative retention time of benzene hexane and air thermostat at a temperature of 30 ^o C, determine the retention volume of benzene relative to hexane and air at a given velocity of the carrier gas of 5 to 40 cm ³ / min, and then subjected hromatodistillyatsii sample, for which the temperature was raised to thermostats those first chromatograph and the boiling point of a low boiling component and the identified low volatile polar organic compound relative retention volumes of hexane and benzene relative to air, and the concentration of nonvolatile polar organic compound is determined depending on the holding volume of benzene relative to its weight of hexane. The average daily dose can be determined by the graphoanalytical method according to Appendix 9 of the Guide by multiplying the average shift concentration by the total time of work operations during the shift [RF Patent 2165618 from 04/20/01].

 However, the method is not suitable for determining the average dose of volatile compounds, which include halides and anhydrides of carboxylic acids due to their slip during the sampling process, and their hydrolysis by the above methods with the subsequent determination of free carboxylic acids by the method of reverse gas chromatography according to the prototype leads to an increase in error determining the dose of a harmful substance associated with the adsorption of benzene on the interface: gas - polar stationary phase (carboxylic acids), gender The bright stationary phase is a solid carrier.

 The objective of the invention is to increase the accuracy of determining the average dose of halides and carboxylic acid anhydrides in the air of the working area.

The problem is solved by the fact that take a medium-shift air sample of the working area in a certified workplace during the time of operations of the technological process. To do this, a VRZ sample is passed through two parallel chromatographic columns at a rate corresponding to pulmonary ventilation during physical activity at a certified workplace, in which a silanized chromosorb with a grain size of 0.125-0.200 mm with at least 30% by weight of a solid sorbent of a mixture of dialkylether heteroatomic is deposited polyhydric alcohols (dialkylglymes) and a heterocyclic amine, the sorbent of the first column containing piperidine in an equivalent amount in excess of the corresponding liter The total dose of carboxylic acid halide or anhydride. In another column, a solid sorbent is dispersed with a mixture of dialkylglymes and hexahydroazepine applied in an equivalent amount similar to the first column. To determine the average shift dose at the beginning of the shift or operation, the carrier gas is fed into chromatographic columns containing various heterocyclic amines on the surface of the stationary liquid phase of the sorbent with a constant speed of up to 5 cm ³ / min; an aliquot of benzene-hexane is introduced at a temperature corresponding to the parameters microclimate of the workplace in each of the columns. Then measure the chromatographic parameters of the retention of benzene relative to hexane using a chromatographic detector. At the end of a shift or operation after removal of volatile impurities, the chromatographic parameters of the retention of the model mixture in both columns are measured in the same way, then the difference between the chromatographic parameters of the retention of benzene relative to hexane in 1-acylpiperidine (first column) and 1-acylhexahydroazepine (second column) per shift or work operation. The average dose of the halide and carboxylic acid anhydride is calculated from the equations for the dependence of the retention volume of benzene relative to hexane in both columns. The identification of the halide and the anhydride is carried out according to the logarithm of the ratio of the retention volume of benzene relative to hexane in 1-acylpiperidine to the retention volume of benzene relative to hexane in 1-acylhexahydroazepine.

 The method is as follows.

Two chromatographic columns are taken, in the initial and final segments of which interchangeable porous filters are installed that prevent the loss of solid sorbent. A predetermined amount of a solid sorbent is added to the first column in the form of a silanized chromosorb with a grain size of 0.125-0.200 mm with a 30% by weight mixture of diethylene glycol dialkyl ether or its polymers and heterocyclic amine applied, which is used piperidine in an equivalent amount exceeding the lethal dose of the analyte . The same amount of a solid sorbent with a fixed phase is introduced into the second column, only hexahydroazepine in the same equivalent amount is used as a heterocyclic amine. To determine the average shift dose of an acid halide and anhydride of carboxylic acids, the chromatographic retention parameters of benzene relative to hexane on an absorbing sorbent in each column are measured before the start of the shift. To do this, helium or nitrogen is fed into chromatographic columns at a constant speed of up to 5 cm ³ / min at a temperature of 20-30 ^o С, which corresponds to the microclimate of the workplace, and the required amount of hexane-benzene mixture is injected using a syringe or a dispenser tap, depending on the sensitivity of the detector in equal proportion. The obtained chromatogram determines the retention time of benzene relative to hexane on sorbents with piperidine and hexahydroazepine at the beginning of the shift, measuring the distance between the peak of hexane and the maximum concentration of benzene.

1 - расстояние между пиком гексана и максимумом концентрации бензола, мм;
F₀ - объемный расход газа-носителя, см³/сек;
v - скорость движения диаграммной ленты, мм/сек;
j - поправка на сжимаемость.The retention volumes of benzene relative to hexane are calculated by the formula

1 - the distance between the peak of hexane and the maximum concentration of benzene, mm;
F ₀ - volumetric flow rate of the carrier gas, cm ³ / s;
v is the speed of movement of the chart tape, mm / s;
j is the correction for compressibility.

Then, at the certified workplace, two parallel SSC samples are taken using an aspirator, passing during the shift at a rate corresponding to pulmonary ventilation during physical activity at the certified workplace, through two chromatographic columns with a sorbent in suspension, on the surface of which there are mixtures of dialkyl ethers of heteroatomic polyatomic alcohols (dialkylglymes) and heterocyclic amines, differing in ring size per methylene group and converting reactive halide Ides and anhydrides of carboxylic acids in non-volatile stable compounds. At the end of the work, sampling is stopped and the final chromatographic parameters of benzene retention relative to hexane are measured on an absorbing sorbent in each column. To do this, an inert gas is passed at a constant speed of up to 5 cm ³ / min at a previously selected temperature to remove adsorbed volatile impurities that can be analyzed by other methods, and the chromatographic parameters of the retention of the model mixture are measured in both columns. After that, the difference between the chromatographic parameters of benzene retention relative to hexane in the acyl derivatives of piperidine and hexahydroazepine per shift is determined. Parallel average dose calculated by the following equations:
ΔV _{Ap (b / g)} = K ₁ V _{gAp (b / g)} • x ₁ (2)
ΔV _{Aa (b / g)} = K ₂ V _{gAa (b / g)} • x ₂ (3)
where x is the content (mass) of the halide or anhydride in the sample, mg;
Vg _{Ap (b / g)} is the specific volume of benzene retention relative to hexane in 1-acylpiperidine, cm ³ / mg;
Vg _{Aa (b / g)} is the specific volume of benzene retention relative to hexane in 1-acylhexahydroazepine, cm ³ / mg;
K ₁ is the stoichiometric coefficient of 1-acylpiperidine with respect to the halide or carboxylic acid anhydride;
K ₂ is the stoichiometric coefficient of 1-acylhexahydroazepine with respect to the halide or carboxylic acid anhydride.

 The stoichiometric coefficients of 1-acylpiperidine and 1-acylhexahydroazepine with respect to fluoro-, chloro-, bromo-, iodohydrides and carboxylic anhydrides are shown in table 1.

 The values of the specific retention volumes of benzene relative to hexane in 1-acylpiperidine and 1-acylhexahydroazepine in the temperature range of vital processes were determined previously by applying these substances on selected sorbents by reverse gas chromatography and are presented in table 2.

By comparing the logarithm of the ratios of the retention volumes of benzene relative to hexane in 1-acylpiperidine and 1-acylhexahydroazepine, the halide or carboxylic acid anhydride is identified in the air sample of the working area. If these relations in the VRZ sample do not coincide with those previously determined for pure substances, then the average daily dose is determined by the additive method. For this purpose, two weighed portions of 1-acylpiperidine weighing from 1 to 10 mg are successively added to the selected daily average sample on a sorbent containing piperidine and the retention volume of benzene relative to hexane is calculated similarly to the above measurement. On the graph of the dependence of the retention volume of benzene relative to hexane in 1-acylpiperidine on the weight of the sample, the mass of the derivative corresponding to the average daily dose of halide or anhydride of carboxylic acids is determined and converted by multiplication by a stoichiometric coefficient K ₁ to obtain the mass of the analyte.

 Distinctive essential features of the claimed method are the following.

 - Continuous sampling during a shift by passing ARZ through two chromatographic columns at a rate corresponding to pulmonary ventilation during physical exertion at a certified workplace allows you to more accurately assess the effect of a chemical factor on the health of the worker, since a single sampling for a shorter period of time leads to distortion of the results of determining the average daily sample due to intermittent or with a different rate of explosive arrival during a shift in various technological operations Processes.

 - The use in suspension of a solid sorbent with at least 30 wt.% Of a mixture of dialkyl ethers of heteroatom polyhydric alcohols or their polymers and heterocyclic amines in an equivalent amount exceeding the corresponding lethal dose of an acid halide and anhydride allows the labile toxic substance to be completely converted into non-volatile and low reactive derivative, the mass of which can be determined with great accuracy by the method of reverse gas chromatography. The use of this sorbent in suspension allows the efficient capture of halides or anhydrides both in vapors and in the sorbed state on the particles of water aerosol at high moisture content of VHW.

 - The use of a benzene-hexane model mixture to measure the chromatographic parameters of retention in acyl derivatives of heterocyclic amines by reverse gas chromatography improves the accuracy of determining the average daily dose of the analytes in comparison with polar model substances, in particular dialkyl ketones, pyridine, nitromethane, due to the absence of their adsorption on the gas interface - liquid stationary phase, liquid stationary phase - solid sorbent.

 - The use of piperidine and hexahydroazepine as heterocyclic amines in comparison with aziridine, azetidine and pyrrolidine allows us to more accurately measure the chromatographic retention parameters of the model mixture, since they have significant volatility even in mixtures with esters of heteroatomic polyols.

 - The use of piperidine and hexahydroazepine as heterocyclic amines in comparison with compounds with a cycle size of more than 8 atoms makes it possible to more accurately measure the chromatographic parameters of benzene relative to hexane, since the hydrocarbon retention parameters in compounds with a large cycle size are not additive, which leads to a smaller error in calculating the daily average doses of carboxylic acid halides.

 The presented set of claimed features provides a solution to the problem of the invention - improving the accuracy of determining the average dose of halides and anhydrides of carboxylic acids in the air of the working area.

 The proposed method for gas-chromatographic determination of medium-shift doses of halides and carboxylic acid anhydrides in high-temperature products of industrial enterprises is illustrated by the following examples.

Example 1. To determine the average shift concentration of acetic anhydride in the SOP of the cellulose acetylation shop of the Plastpolymer plant, samples of the analyzed air were taken at a rate of 25 dm ³ / min according to the recommendations of Appendix 9 of Guide R 2.2.755-99. Two parallel samples are taken at the certified workplace using the APV-4-220V-40 four-channel aspirator by passing through a chromatographic column with a sorbent, one of which contains a suspension of diethylene glycol dibutyl ether and piperidine (weight 0.8435 g) in an amount 30 wt.% By weight of a silanized chromosorb with a grain size of 0.125-0.200 mm, and in another, a mixture of the same ether and hexahydroazepine (weight 0.9823 g), for the quantitative conversion of acetic anhydride to 1-acetylpiperidine and 1-acetylhexahydroase in. At the end of the work, the sampling is stopped and the chromatographic parameters of benzene retention relative to hexane are measured on an absorbing sorbent in each column. For this, an inert gas is passed at a rate of up to 5 cm ³ / min at a previously selected temperature until the adsorbed volatile impurities are removed, after analysis of which the presence of benzene 5.34 ± 1.30 mg / m ³ , which is used as a solvent at acetylation. The difference in chromatographic parameters of benzene retention relative to hexane in 1-acetylpiperidine and 1-acetylhexahydroazepine per shift, which was 431.1 cm ³ and 409.5 cm ^3, respectively, was determined. The average shift dose is calculated according to equations 2 and 3, and the specific volume of benzene retention relative to hexane in 1-acetylpiperidine was 1.2341 cm ³ / mg, and the specific volume of benzene retention relative to hexane in 1-acetylhexahydroazepine 1.0559 cm ³ / mg, and the ratio is 1.169. At the same time, the stoichiometric coefficient of 1-acetylpiperidine with respect to acetic anhydride is 0.8038, and the stoichiometric coefficient of 1-acetylhexahydroazepine with respect to acetic anhydride is 0.7240.

The specific retention volumes of benzene relative to hexane in 1-acetylpiperidine (MPTU 6-09-360-63) and in 1-acetylhexahydroazepine in the range of 20-30 ^o C were determined by reverse gas chromatography.

By comparing the logarithms of the ratios of the retention volumes of benzene relative to hexane in 1-acetylpiperidine and 1-acetylhexahydroazepine in the sample and the data in Table 3, the presence of acetic anhydride in the SOP sample is determined, since this ratio in the SPS sample taking into account the molar masses is 1.1688, and according to the table 3 1,1687, they almost coincide. The calculation of parallel medium-shift doses of acetic anhydride was carried out according to the above equations, and they are equal to: x ₁ = 281.9 mg; x ₂ = 280.7 mg (x _avg = 281.8 mg). The maximum deviation from the average value is 0.04%.

 The obtained values of daily average doses make it possible to assess the risk of incidence of workers exposed to harmful substances.

Example 2. To determine the average concentration of chloride of propionic acid (propionyl chloride) in the SPS during the production of promedol at the stage of acylation of lithium alcoholate 1,2,5-trimethyl-4-phenylpiperidol-4, samples of the analyzed air were taken at a rate of 25 dm ³ / min according to the recommendations of the Appendix 9 of Guidance R 2.2.755-99. Two parallel samples are taken at the certified workplace using the APV-4-220V-40 four-channel aspirator by passing through a chromatographic column with a sorbent, one of which contains a suspension of triethylene glycol diethyl ether and piperidine (weight 0.9561 g) in an amount 30 wt.% By weight of a silanized chromosorb with a grain size of 0.125-0.200 mm, and in the other a mixture of the same ether and hexahydroazepine (weight 1.1134 g), for the quantitative conversion of propionic acid chloride to 1-propionylpiperidine and 1-pro pionylhexahydroazepine, for which, at the beginning of the work, the initial chromatographic parameters of benzene retention relative to hexane were measured. At the end of the work, the sampling is stopped and the chromatographic parameters of benzene retention relative to hexane are measured on an absorbing sorbent in each column. For this, an inert gas is passed at a rate of up to 5 cm ³ / min at a previously selected temperature until the adsorbed volatile impurities are removed, after analysis of which the presence of methylamine 0.005 ± 0.001 mg / m ³ and benzene 0.26 ± 0.05 mg / m ³ , which is used in the synthesis as a solvent.

The difference in chromatographic parameters of benzene retention relative to hexane in 1-propionylpiperidine and 1-propionylhexahydroazepine per shift, which was 147.1 cm ³ and 132.3 cm ^3, respectively, was determined. The average shift dose is calculated according to equations 2 and 3, and the specific volume of benzene retention relative to hexane in 1-propionylpiperidine was 1.1392 cm ³ / mg, and the specific volume of benzene retention relative to hexane in 1-propionylhexahydroazepine 0.9316 cm ³ / mg, and the ratio is 1.223. At the same time, the stoichiometric coefficient of 1-propionylpiperidine with respect to propionyl chloride is 0.6561, and the stoichiometric coefficient of 1-propionylhexahydroazepine with respect to propionyl chloride is 0.5969.

The specific retention volumes of benzene relative to hexane in 1-propionylpiperidine and 1-propionylhexahydroazepine in the range of 20-30 ^{° C. were} determined by reverse gas chromatography.

By comparing the logarithms of the ratios of the retention volumes of benzene relative to hexane in 1-propionylpiperidine and 1-propionylhexahydroazepine in the sample and the data in Table 2, the presence of propionyl chloride in the SEC is determined, since this ratio in the SPS sample taking into account the molar mass is 1.223 and practically does not differ from the table value. Therefore, the calculation of parallel medium-shift doses of propionyl chloride was carried out analogously to example 1: x ₁ = 84.64 mg; x ₂ = 85.17 mg (x _avg = 84.90 mg). The maximum deviation from the average value is 0.32%.

 The obtained values of daily average doses make it possible to assess the risk of incidence of workers exposed to harmful substances.

 Example 3. In order to determine the average shift concentration of acetic anhydride in the SOP during the production of aceclidine at the acetylation stage of 3-hydroxyquinuclidine, samples of the analyzed air are taken analogously to Example 1 through chromatographic columns with a sorbent in suspension, one of which contains a mixture of diethyl ether of tetraethylene glycol and piperide (weight 1.2453 g) in an amount of 30 wt.% of the mass of the silanized chromosorb with a grain size of 0.125-0.200 mm, and in the other a mixture of the same ether and hexahydroazepine (wt. ca 1.4502 g) for the quantitative conversion of acetic anhydride to 1-acetylpiperidine and 1-acetylhexahydroazepine. The remaining operations for determining the initial and final chromatographic parameters of the model mixture of benzene-hexane on columns with various heterocyclic amines are carried out according to the algorithm of the method described in example 1.

For comparative characterization, the SEM samples were simultaneously taken at the same workplace similarly to the algorithm of the method for the qualitative and quantitative analysis of low volatile polar organic compounds in air, followed by the calculation of medium-shift doses of harmful substances by the graphoanalytical method according to Appendix 9 of the Guide, that is, by the prototype method. The technological process in the surveyed area was divided into 4 stages in one shift. At the first stage, 3 samples were taken, at the second and third stages, 2 samples and 1 sample at the fourth stage, which were analyzed by the method indicated above. The results of measuring the concentrations in increasing order were compared with the duration of the sampling. The sampling time of all samples was summarized and taken as 100%. After that, the accumulated frequency of the sampling time was determined by sequentially summing the time of each sample. The values of concentrations along the abscissa axis and the corresponding accumulated frequencies (in%) along the ordinate axis were plotted on a logarithmic probability grid. A straight line was drawn through the plotted points and the median value was determined by the intersection of the integral line with a 50% probability value. The value of x _{84 was} determined and the standard geometric deviation characterizing the limits of the concentration fluctuation was calculated. According to the formulas given in Appendix 9 of the Guide, the average shift concentration was calculated. The average shift dose was calculated as the product of the average shift concentration by the shift time, as for the proposed method. Table 3 presents the results of a comparative characteristic of the gas chromatographic method for determining intermediate-shift doses of halides and carboxylic acid anhydrides in the air of a working zone of industrial enterprises and a method for the qualitative and quantitative analysis of low-volatile polar organic compounds in air.

 As follows from the data of example 3, the proposed method allows a more accurate comparison with the prototype to determine the average daily dose of halides and anhydrides of carboxylic acids in VRZ.

 Table 3 presents the results of a comparative characterization of the use of various amines in mixtures with dialkylglymes in a gas chromatographic method for determining intermediate-shift doses of halides and carboxylic acid anhydrides in the air of a working zone. The concentration of acetyl chloride was created using the Mikrogaz gas-dynamic setup 2.966.057, intended for the preparation of gas mixtures when calibrating chromatographs under operating conditions described in the article "Barbituric acid - an analytical reagent for determining the content of freons in the circulating concentration method" [VINITI. - Dep. scientific work. - 2, 1989, p. 188]. Acetyl chloride (GOST 5829-51) was used as the dosed substance.

 As follows from the data of table 3, the proposed method allows much more accurate than the use of aziridine and azetidine, azetidine and pyrrolidine as heterocyclic amines to determine the average daily dose of acetyl chloride due to the significant volatility and lower basicity of small cycle heterocyclic amines. At the same time, the use of aliphatic amines with greater basicity (dimethyl and diethylamines) does not lead to a significant improvement in the accuracy of the proposed method. Less accuracy was achieved when using a system of heterocyclic amines with a cycle size of more than 8 atoms, in particular azacyclooctane and azacyclononan, in mixtures with dialkylglymes.

 Thus, as a result of continuous sampling of air with the rate of pulmonary ventilation during a work shift through two parallel chromatographic columns, at the beginning and end of which replaceable porous filters are installed with the sorbent in them in suspension, which is used as a silanized chromosorb with a grain size of 0.125- 0.200 mm with not less than 30 wt.% Of a mixture of dialkyl ethers of heteroatom polyhydric alcohols or their polymers with piperidine in the first column and hex agidroazepine in the second column in an equivalent amount exceeding the lethal dose of the analyzed substances, preparing samples for chromatographic analysis by removing volatile compounds, measuring before and after sampling the chromatographic parameters of benzene retention relative to hexane on an absorbing sorbent in each column, identification of harmful substances by the logarithm of the volume ratio retention of benzene relative to hexane in acyl derivatives of piperidine and hexahydroazepine, differing in the size of the cycle by 1 meth enoic group can more accurately determine the mean-shift of the dose dependence of the difference of chromatographic retention parameters benzene relatively hexane acyl derivatives of heterocyclic amines, by weight of the analyte.

 The positive effect of the proposed method of gas chromatographic determination of medium-shift doses of halides and carboxylic acid anhydrides in the air of the working zone of industrial enterprises is to increase the accuracy of determining the effect of a chemical factor on the working organism and increase the reliability of assessing the risk of morbidity when exposed to harmful substances according to harmful and hazardous factors of the working environment and the intensity of the work process.

Claims (2)

1. The method of gas chromatographic determination of medium-shift doses of halides and anhydrides of carboxylic acids in the air of the working area, including sampling air during the shift, preparing the sample for chromatographic analysis, determining the amount of analytes, characterized in that air samples are taken continuously during the shift at a speed of appropriate pulmonary ventilation during physical exertion at a certified workplace, through two parallel chromatographic columns, which are placed in a suspended In the given state, a given amount of sorbent is measured; before and after sampling, the chromatographic parameters of benzene retention relative to hexane on an absorbing sorbent in each column are measured; the average dose is determined by the difference between the chromatographic parameters of benzene retention relative to hexane in acyl derivatives of heterocyclic amines on the mass of the analyte. 2. The method according to claim 1, characterized in that the sorbent uses a silanized chromosorb with a grain size of 0.125-0.200 mm, on the surface of which is applied at least 30 wt.% A mixture of dialkyl ethers of heteroatom polyhydric alcohols or its polymers with piperidine in the first column and hexahydroazepine in the second column in an equivalent amount exceeding the lethal dose of the analyte.

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