Method for simultaneous determination of toxicity of aniline and nitrobenzene in the air

 

(57) Abstract:

Usage: the invention relates to methods of research in occupational health, in particular to sanitary-hygienic laboratory conditions in terms of harmfulness and danger of chemical factors of the production environment. Essence: perform sampling of aniline and nitrobenzene from the air, characterized by weight not less than 50%. Dispersed the sample to the particle sizes of not more than 5 μm in the beginning of the chromatographic column using a pneumatic atomizer. Enter in column placed in thermostat, trace amounts of a mixture of benzene and hexane with air at a speed of helium up to 5 cm3/min. Determine the difference between the chromatographic retention parameters of benzene relative to hexane and air samples. Assess together the toxicity of aniline and nitrobenzene ratio between the total dose of aniline and nitrobenzene in air and hygienic standard. The technical result of the invention is to develop a method for simultaneous determination of toxicity of aniline and nitrobenzene in air of working zone, as well as to improve the reliability of the assessment of the toxicity. table 1.

The invention of odnosi harmful substances in the air and risk assessment of the incidence of industrial workers. It can be used for sanitary-hygienic laboratory studies (SGLI) workplace air (SAS) working on the production of aniline and aniline dyes, including certification of workplaces according to the Manual P 2.2.755-99 “Hygienic assessment criteria and classification of working conditions in terms of harmfulness of risk factors of production environment, severity and intensity of the labour process”.

The known method of determination of nitrobenzene or aniline in the air, including sample preparation, detection of nitrobenzene or aniline piezoelectric quartz sensor, pre-modified active sorbent, which is used as a nitrocellulose or polystyrene, polyol esters and ethers, oxides trialkylamines or phosphines in the number of 8-16 µg when the air flow 25-75 cm3/min with subsequent determination of toxicity in relation to the maximum one-time concentration to the maximum allowable [U.S. Pat. 2155333 Russia, Yugoslavia, IPC 7 G 01 N 30/00, 31/00; U.S. Pat. 2170416 Russia, G 01 N 5/02 from 16.06.99].

The disadvantage of this method is the inability to assess the risk of morbidity in the joint toxic action of a dose of aniline and nitrobenzene working on what elnett and low time of the polymer coating in the mode of sorption-desorption for a range of concentrations of a few MPC for time determine srednesemennyh concentration. Used piezoquartz resonator at-cut with silver electrodes and an operating frequency of 8 MHz is often covered with a film of gas chromatographic stationary phases polymeric nature, which are intended for separation but not binding of aniline and nitrobenzene, therefore, respond to the majority of low molecular weight contaminants in the surrounding air. After the initial sorption of aniline and nitrobenzene degree of selectivity modifiers leveled and almost equal to zero. When working piezoquartz resonator mode desorption by heating nitrobenzene undergoes a disproportionation reaction with the formation of policetraining and destruction of the surface modifier layer.

The release surface of the chemical sensor from the absorbed dose of aniline by heating in air leads to the formation of oxidation products and polycondensation, which modify the sorption properties of the modifier. The vapor absorption of aniline or nitrobenzene sensitive coating piezoquartz resonator leads to an increase of mass of the receptor layer, which causes the fall of the analytical signal of the operating frequency of the oscillations of the resonator, which depends on the resonance heh small and does not allow to determine the concentration, significantly in excess of the allowable moment load nitrobenzene as raw material and unloading of aniline, as the finished product. The method of determination of aniline and nitrobenzene using chemical sensors is not possible to determine the toxicity (dose) of harmful substances in the entire shift, and consequently, to assess the risk of morbidity workers aniline production according to the results of certification of workplaces.

The closest in technical essence and the achieved result is a method for simultaneous determination of the amount and toxicity of individual polar low volatile organic compounds in air, based on the fact that the air sample is treated with a volatile organic solvent to extract the amount of the polar low volatile organic compounds, are prepared sample on a solid sorbent, which is a chromatographic column of the first chromatograph equipped with a thermal conductivity detector, dried sample by passing an inert gas at a temperature of 30 To 60 seconds to complete volatile organic solvent, introducing a model mixture of hexane and benzene, measure the retention time of benzene relative to hexane and air at a temperature of those is as a carrier from 5 to 40 ml/min, and then subjected to a test of chromatically, which raise the temperature in thermostat first chromatograph to the boiling point of the low-boiling component and identify polar low volatile organic compound in terms of the retention volumes of benzene relative to hexane and air, and the concentration of the polar low volatile organic compounds is determined by the dependence of the volume of the retention of benzene relative to hexane from its mass. Toxicity in the joint presence in the air of several substances with a summation of the steps is determined by the sum of the relations of the detected concentrations of each to the value of its MAC [RF Patent №2165618 from 20.04.01].

For the joint toxicity of aniline and nitrobenzene in air method requires time-consuming Toxicological studies to establish the coefficients of the joint action of these harmful substances, as well as for air containing certain concentration of aniline and nitrobenzene, not installed, what is the effect (partial summation, potentiation, antagonism) have a steam-air mixture. Quantitative analysis of the amount of the polar low volatile organic compounds carried out on the value of the retention of benzene relative to hexane on the total weight of nitrobenzene and aniline and mass content of aniline in a sample of two components.

The construction of such calibration dependences for multicomponent mixtures with an unknown composition of interfering impurities requires time-consuming exploratory analysis by gas chromatography-mass spectrometry to establish the qualitative composition present in the air components. In addition, the definition of the nature of the interaction in the vapor phase nitrobenzene, aniline and impurities present (perfect positive or negative deviation from the law of Raul) rather time-consuming and does not allow to determine the values of correction factors in the calibration of the chromatograph. Because the toxicity of the production environment can be quantitatively determined with the simultaneous presence of the object of study of several harmful substances unidirectional action only when their known effect on the biological effects (summation, potentiation, antagonism) or multidirectional action at a known character specific effects, for steam-air mixture aniline-nitrobenzene mechanism of harmful effects is not known, it is therefore necessary to determine their joint toxicity conducting laborious Toxicological studies.

Task sobritchea zone (OCR), it allows to increase the reliability assessment of risk inhalation of these substances, as well as to simplify the method.

The problem is solved in that select srednesemennyh air samples at certified workplace where the stay of the worker is not less than 80% of the time, in a plant for the production of aniline by hydrogenation of nitrobenzene were mixed catalysts. To do this, pass the air through two parallel adsorption unit with a sealed porous glass plate, which is placed on 50,00 cm3pentadecane with a bulk velocity, without allowing leakage to absorb nitrobenzene and aniline in the concentration range up to 100 MPC and differ in the selection lines is not less than 50%, during the whole time of the work shift. After sampling air transfer absorption liquid in the receiver of the spray device connected to the beginning of the chromatographic column, serves a pneumatic spray with impaction incocopernicus aerosol size not more than 5 μm in a chromatographic column, placed in thermostat chromatograph. To test the sample in a chromatographic column effect model with a mixture of benzene and gematokritnoe system model of the mixture is conducted at a speed of helium, inert to aniline and nitrobenzene carrier gas, up to 5 cm3/min. Simultaneously engaged in idle experience, which use a clean pentadecane.

Then determine the difference between the chromatographic retention parameters of benzene relative to hexane and air samples SAS, which contain various rednisone dose of harmful substances, and idle experience pentadecane. Largest volume of the retention of benzene relative to hexane in the sample SAS with srednesemennyh concentration determine the amount of srednesemennyh dose of aniline and nitrobenzene, obtained a work by inhalation, and the relationship between the dose of harmful substances, expressed in a common scale of intermolecular interactions in benzene, and hygienic norms determine the toxicity of aniline and nitrobenzene.

The method is as follows.

Two parallel samples of workplace air is passed through the suction unit through two parallel adsorption unit with a sealed porous glass plate, in which place equal amounts of pentadecane, which has physical and chemical properties (viscosity, surface tension, temperature plavini is sealed after sampling plugs. Bulk bandwidth and the sampling time was set based on the need of control srednesemennyh concentration during the entire shift, and differences in the amounts of parallel samples shall be not less than 50%. Then transferred the absorption liquid in the sink sprayer, equipped with impaction for the separation of droplets of the aerosol samples. A dispenser coupled to thermally chromatographic column, which is the output before the detector is equipped with a filtering device. In the lower part of the filter chromatographic column has a nozzle through which the besieged pentadecane served in the capacity for spraying. Miss helium at a given speed to 5 cm3/min in the gas line chromatograph, equipped with a heat conductivity detector. Introduced with a syringe, depending on the sensitivity of the detector required amount of the mixture hexane-benzene with air in an equal ratio. On the resulting chromatogram determine the retention time of benzene relative to hexane or air dispersed on analytical sample with unknown content of aniline and nitrobenzene in the SAS, measuring the distance between the peak of hexane (air) and the maximum concentration of benzene.

where l is the distance between the peak air or hexane and the maximum concentration of benzene, mm;

Fabout- volumetric flow rate of helium, cm3;

- the speed of the ribbon diagram, mm/s;

j is the correction for compressibility.

Presents a set of stated characteristics are provided by the solution of the invention:

- sampling transmission OCR through two parallel adsorption unit with a sealed porous glass plate, which is placed on 50,00 cm3pentadecane with a bulk velocity, which differs in the selection lines is not less than 50%, during the whole time of the work shift, allows to quantify individual determination of aniline and nitrobenzene without building a calibration based on individual components;

- the introduction of the dispersed sample in the form of incocopernicus aerosol with a particle size of not more than 5 μm in a chromatographic column, placed in thermostat chromatograph, and making the determination of toxicity when the temperature of the air bleed prevents decomposition of the analyzed substances, and also ensures the accuracy of determination of toxicity of contaminants due to the elimination of the parameters of the retention of benzene relative to hexane and air samples taking into account idle experience pentadecane allows you to define individual dose of aniline and nitrobenzene in the SAS, coming into the body by inhalation, as this difference quantitatively assesses the magnitude of the intermolecular interactions of aniline and nitrobenzene with the body and allows to determine the toxicity of the vapor mixture of aniline and nitrobenzene in a joint presence (class conditions) the ratio between the total dose of aniline and nitrobenzene in air and hygienic standard.

Thus, in the complete extraction of aniline and nitrobenzene from the air in the form of a dispersed liquid phase by means of two parallel adsorption devices onto a porous glass plate containing equal volumes of pentadecane with a bulk velocity, which differ from each other not less than 50%, during the whole time of selection, the dispersion of the sample to a particle size of not more than 5 μm in the beginning of the chromatographic column using a pneumatic atomizer is placed in thermostat chromatograph, the introduction into the column of the micro-mixture of benzene and hexane with air at a speed of helium up to 5 cm3/min, determine the difference between the chromatographic retention parameters of benzene relative to hexane and air samples that contain different doses is compared to the between the total dose of aniline and nitrobenzene in the SAS and hygienic standard.

The proposed method for simultaneous determination of toxicity of aniline and nitrobenzene in SAS is illustrated by the following examples.

Example 1. To determine srednesemennyh concentration of aniline and nitrobenzene in the SAS take samples analyzed air according to Annex 9 of the Guide R 2.2.755-99. Polluted air is passed through two parallel adsorption unit with a sealed porous glass plate containing 50,00 cm3pentadecane for 8-hour shift required for selection srednesemennyh concentration of aniline and nitrobenzene and calculation of individual exposure detecting the connection state changes health workers with their professional activities. The selection is performed by the apparatus for the hydrogenation of nitrobenzene in the download period, because this period is allocated the maximum number of harmful substances using the dual-channel sampler APP-7-2.

The speed of the sampling air for the first absorber was 100 DM3/min, and the second absorber - 50 DM3/min. Adsorption devices sealed after sampling plugs. Place the absorbing liquid in the receiver of the spray device. Races of the effect by means of the mounting ring with slots for lock type “Mount”, thus a tight seal is provided by o-ring seal. Serves pneumatic spray at the beginning of the chromatographic column incocopernicus aerosol with a particle size of not more than 5 μm, provided that the installation before dispersing capillary of impacter made of titanium. A dispenser coupled to thermally chromatographic column, which is the output before the detector is equipped with a filtering device. The tightness of the connection of the filter with the chromatographic column is provided with PTFE ring, by means of which through the pipe besieged sink drains back into the tank for spraying. In thermostat chromatograph LGM temperature is maintained at 25 C, which meets the parameters of the microclimate of this workplace. Enter the syringe, depending on the sensitivity of katharometer 1-10 ál of the mixture hexane-benzene with air in equal proportion.

The rate of helium (inert to aniline and nitrobenzene) was up to 5 cm3/min. Simultaneously engaged in idle experience, which use a clean pentadecane. On the resulting chromatogram measure the distance between the peak of hexane (air) and the maximum concentration of benzo shall the retention volumes of benzene relative to hexane and air according to the formula 1.

The amount of the retention of benzene relative to hexane at identifying common content of aniline and nitrobenzene in the SAS for the first trial was 649,6 ml, and the volume of the retention of benzene relative to the air for a second sample was 366,3 ml. Content of aniline and nitrobenzene determine the sample analyzed OCR solution of a system of two equations.

The specific volume of the retention of benzene nitrobenzene and aniline against air Vkg(b/b)was determined by the method of inverse gas chromatography in terms of dispersion of the liquid phase, which used a diluted solution of nitrobenzene and aniline in pentadecane. The solutions were prepared by making sample aniline (according to GOST 5819-70 brands including D. A., the content of nitrobenzene less 0,000001%) and nitrobenzene (according to GOST 5846-51 brands including D. A., and test for the absence of aniline positive) in synthetic pentadecane (brand X. H., MRTU 6-09-4664-67). Vkg(b/b)made for nitrobenzene and aniline 0,8465 ml/mg and 0,7032 ml/mg, respectively, and the specific volume of the retention of benzene nitrobenzene and aniline relatively hexane Vkg(b/b)- 0,7504 and 0,6603 ml/mg.

where x is the content (weight) of aniline (An) in the sample, mg;

VDnB(b/g)- the specific volume of the retention of benzene relative to hexane in NR, ml/mg;

VDan(b/W)- the specific volume of the retention of benzene relative to the air in An, ml/mg;

VDnB(b/W)- the specific volume of the retention of benzene relative to the air in NR, ml/mg.

Values of specific withholding volumes of benzene relative to hexane and air at aniline and nitrobenzene in the temperature range of human processes defined previously by dispersion of dilute solutions of nitrobenzene and aniline in the chromatographic column by GLC.

Substituting the obtained experimental data, have a system of two equations:

0,660 x+0,750 y=649,6

0,703 x/2+0,846 y/2=366,3

Solving the system, we find that the content of aniline and nitrobenzene in a sample of average daily concentration on certified workplace when loading nitrobenzene in the reactor well is 1.58 mg and 864 mg Then srednesemennyh concentration of aniline or nitrobenzene in SAS can be calculated by the formula:

where m(x)- weight of the individual component found in the analyzed sample, mg;

V - volume of air in the working area, etc is 4.1.498-96 “measuring the concentration of harmful substances in the air of working zone”.

Rednisone concentration of aniline and nitrobenzene on certified workplace equal 0,033 0.006 mg/m3and 18,0 4,0 mg/m3. Calculation srednesemennyh dose of aniline and nitrobenzene, obtained a work by inhalation, carried out by the formula:

Dcc=CccV1, (5)

where DSS- srednespinka dose of harmful substances, ml;

WITHSS- srednespinka concentration of harmful substances is 13.5 3.4 ml/m3;

V1- the volume of pulmonary ventilation during the shift, 12 m3;

Srednespinka dose of aniline and nitrobenzene when loading raw materials amounted to 162 40 ml in a single scale of intermolecular interactions in benzene.

The ratio of srednesemennyh concentration of aniline and nitrobenzene to the maximum allowable concentration of toxicants judge class working conditions depending on the content in the SAS harmful substances chemical nature on the certified workplace (chemical factor). In the workplace when loading nitrobenzene content of aniline 0.33 MPC, which corresponds to a valid class working conditions, and the excess concentration of nitrobenzene is 6 MPC, which corresponds to the class of harmful working conditions of 3.2. Joint toxicoloy scale of intermolecular interactions in benzene, and hygienic standard for the substance, which has the most high class and degree of harmfulness. Hygienic standard in the uniform scale of intermolecular interactions is equal to aniline 6,603 ppm and for nitrobenzene 225,1 ppm, and the toxicity is determined from the expression: DSS225,1 ppm by volume of pulmonary ventilation per shift. For the workplace when loading nitrobenzene srednespinka dose of harmful substances (toxicity) is 162 40 ml compared with the hygienic norm of 27.0 ml.

Exceeding the hygienic standards during the shift was 5 times that characterizes the risk of morbidity desktop when loading nitrobenzene.

Example 2. To determine srednesemennyh concentration of aniline and nitrobenzene in the SAS carried out the sampling of the apparatus for the hydrogenation of nitrobenzene during the unloading of the finished product, because in this period there is a maximum rise in the concentration of harmful substances. This polluted air were taken as in example 1, for 8-hour shift required for selection srednesemennyh concentration of aniline and nitrobenzene and calculation of individual exposure detecting the connection state changes health workers with their professional activities is Itala was 100 DM3/min, and the second absorber - 50 DM3/min. Absorbers sealed after sampling plugs. Transfer the sample on the basis of pentadecane in the receiver of the spray device, placed in thermostat chromatograph LHM supporting a temperature of 25 C. is Injected by syringe to a mixture of hydrocarbons with air in an amount that allows you to obtain the necessary analytical signal depending on the sensitivity of katharometer.

Parameters carrier gas are similar to those in example 1. No experience of the use of pure pentadecane. On the resulting chromatogram measure the distance between the peak of hexane (air) and the maximum concentration of benzene dispersed in the sample solution of aniline and nitrobenzene in pentadecane for the first and second absorber. Then determine the retention volumes of benzene relative to hexane and air the same way as in example 1.

On certified workplace the amount of the retention of benzene relative to hexane at identifying common content of aniline and nitrobenzene in the SAS for the first trial was 69,84 ml, and the volume of the retention of benzene relative to the air for a second sample totaled 38.9 ml of the Content of aniline and nitrobenzene experimental data, have a system of two equations:

0,660 x+0,750 y=69,8

0,703 x/2+0,846 y/2=38,9

Solving the system, we get that the content of aniline and nitrobenzene in a sample of average daily concentration on certified workplace unloading of aniline from the reactor well - 24,05 mg and 71,95 mg Rednisone concentration of aniline and nitrobenzene in the SAS, calculated by formula 4 on the certified workplace equal to 0,50 0,12 mg/m3and 1.50 0,37 mg/m3. Calculation srednesemennyh dose of aniline and nitrobenzene, obtained a work by inhalation, carried out according to the formula 5.

On certified workplace unloading aniline ratio srednesemennyh concentration of aniline and nitrobenzene to the maximum allowable concentration of toxicants defines the class working conditions. In the workplace when unloading the excess concentration of aniline is 5 MPC, which corresponds to the class of harmful working conditions of 3.2, and the content of nitrobenzene is 0.5 MPC, which corresponds to a valid class working conditions. Toxicity was determined by the ratio between the dose of harmful substances, expressed in a common scale of intermolecular interactions in benzene, and the hygienic standard for aniline with the highest class and C4,30 ml compared with the hygienic norm of 0.79 ml

Exceeding the hygienic standards during the shift was 21 times that characterizes the risk of morbidity working when uploading aniline.

Example 3.

For the comparative characteristics of the method for simultaneous determination of toxicity of aniline and nitrobenzene in air received binary calibration mixture of nitrobenzene and aniline concentration 3,20 0.06 mg/m3and 1.54 0.03 mg/m3gas-dynamic method according to the author's certificate of the USSR No. 336563 and passed through two parallel absorber with pentadecanol within 8 hours. The transmission rate of the vapor mixture to the first absorber was 100 DM3/min, and the second absorber - 50 DM3/min. Transfer the sample into the receiver dispersing device (thermostat chromatograph LHM supporting a temperature of 25 C. is Injected by syringe model mixture of hydrocarbons in a quantity that allows you to obtain the necessary analytical signal depending on the sensitivity of katharometer.

The parameters of the carrier gas and the gases of the detector are similar to those in example 1. No experience of the use of pure pentadecane. On the resulting chromatogram measure the distance between the peak of hexane (who is in the first and second absorber. Then determine the retention volumes of benzene relative to hexane and the same way as in example 1. For certified air-steam mixture, the volume of the retention of benzene relative to hexane at identifying common content of aniline and nitrobenzene for the first trial was 164,0 ml, and the volume of the retention of benzene relative to the air for a second sample was 216,1 ml. Content of aniline and nitrobenzene determine the sample analyzed air-steam mixture solution of a system of two equations 2 and 3. Substituting the obtained experimental data, have a system of two equations:

0,660 x+0,750 y=164,0;

0,703 x/2+0,846 y/2=216,1

Solving the system with the amount of missed steam-air mixture, get rednisone concentration of nitrobenzene and aniline calculated by the formula 4, equal 3,26 0.13 mg/m3and 1.57 0.09 mg/m3respectively.

The hazard class of the working conditions was determined by the ratio srednesemennyh concentration of the vapor of a mixture of nitrobenzene and aniline maximum allowable concentrations of toxicants. For nitrobenzene in appraisee steam-air mixture, this relationship is 1,09 MAC, and the ratio of concentration to DMP for aniline is 15,7 MAC that sootoo into a single scale of intermolecular interactions in benzene and hygienic standard for aniline, with the greatest degree of harmfulness. Srednespinka dose of nitrobenzene and aniline is 3,42 0,17 ml compared with the hygienic norm of 0.79 ml Toxicity, expressed as the ratio srednesemennyh dose to hygienic norm equal to 4.33.

The toxicity of the prototype was determined by monitoring the total concentration of nitrobenzene and aniline in the certified air-steam mixture with periodic sampling at a flow rate of the vapor mixture of 25-75 cm3/min according to the patent of Russian Federation №2165618. The steam-air mixture control was performed within 8 hours after 15 minutes and was determined srednesemennyh concentration according to p. 4. P 2.2.755-99. Rednisone concentration of nitrobenzene and aniline in air-steam mixture, defined on the prototype, equal 3,71 0.16 mg/m3and 0,53 0,14 mg/m3respectively.

The hazard class of the working conditions was determined similarly with respect srednesemennyh concentration of the vapor of a mixture of nitrobenzene and aniline to the maximum allowable concentration of toxicants. For the prototype for nitrobenzene in appraisee steam-air mixture ratio is 1,23 MAC, and the ratio of concentration to DMP for aniline is 5.3 MPC, which corresponds to the toxicity class of 3.2. Toxicity ODA is th on benzene, and hygienic standard for aniline with the greatest degree of harmfulness. Srednespinka dose of nitrobenzene and aniline is 2,85 0.7 ml compared with the hygienic norm of 0.79 ml Toxicity, expressed as the ratio srednesemennyh dose to hygienic norm equal 3,61.

Given the parameters of the prototype and the claimed method, see the table.

As follows from the data of example 3 according to the proposed method for simultaneous determination of toxicity of aniline and nitrobenzene in air relations concentration of aniline to the MPC, the toxicity index is equal to 4.33 (hazard class 3,4), and the prototype 3,61 (hazard class 3,2). The proposed method can more reliably determine the class of conditions depending on the content in the air of workplace hazardous substances chemical nature (the exceedance times), and therefore, more properly assess the risk of working in contact with aniline and nitrobenzene according to P 2.2.755-99.

Thus, in the sampling of aniline and nitrobenzene from the air of the working zone, characterized by the number of harmful substances is not less than 50%, the dispersion of the analyzed samples to a particle size of not more than 5 μm in the beginning of chromatographing of the micro-mixture of benzene and hexane with air at a speed of helium up to 5 cm3/min, determine the difference between the chromatographic retention parameters of benzene relative to hexane and air samples that contain different doses of harmful substances taking into account idle experience, can work together to determine the toxicity ratio between the total dose of aniline and nitrobenzene in the SAS and hygienic standard.

The positive effect of the proposed method for simultaneous determination of toxicity of aniline and nitrobenzene in the air is to increase the reliability of determination of toxicity 2.9 times anilino, correct hazard class 3.4 claimed method instead of a lower hazard class, therefore, a more correct assessment of the risk of the incidence of industrial workers.

Method for simultaneous determination of toxicity of aniline and nitrobenzene in the air, including sampling, identification of hazardous substances and the assessment of their toxicity, characterized in that the air flow through two parallel adsorption unit with a sealed porous glass plate containing 50,00 cm3pentadecane, with a bulk velocity, which differ from each other not less than 50%, during the whole time of selection, Perinatology, serves pneumatic spray incocopernicus aerosol with a particle size of not more than 5 μm in a chromatographic column, placed in thermostat chromatograph affect the chromatographic system model with a mixture of benzene and hexane with air at a temperature corresponding to the parameters of the microclimate, and the speed of helium up to 5 cm3/min, determine the difference between the chromatographic retention parameters of benzene relative to hexane and air samples that contain different doses of harmful substances taking into account idle experience, determine the individual dose of aniline, nitrobenzene in air entering the body by inhalation, and assess the toxicity ratio between the total dose of aniline and nitrobenzene in air and hygienic standard.

 

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2 cl, 1 dwg, 1 ex

FIELD: analytical methods.

SUBSTANCE: to determine methyl alcohol in water, sample to be assayed is preliminarily subjected to distillation with sulfuric acid added in amount required to provide its concentration in mixture to be distilled c(1/2 H2SO4) = 0.002 M, while strippings constitute 6-7% of the volume of sample. Stripped liquid is thrice rinsed with hexane or Nefras at 1:1 hexane (Nefras)-to-strippings ratio. Rinsed material is then introduced into packed column filled with diatomite modified with 1,2,3-tris(β-cyanoethoxy)propane having deposited fixed phase thereon, which phase is prepared by way of consecutively keeping glycerol each time for 4 h at ambient temperature, 100°C, 130°C, 160°C, and 200°C, and then for 8 h at 230°C and for 40 h at 200°C under nitrogen bubbling conditions. Calculation of methanol content is performed taking into consideration calibrating coefficient.

EFFECT: enabled determination of small concentrations of methyl alcohol in water with sufficient selectivity and reliability.

2 cl, 2 tbl, 6 ex

FIELD: analytical chemistry.

SUBSTANCE: invention relates to method for quantitative determination of thiotriazoline and pyracetam in complex drugs by high performance chromatography, wherein silicagel with grafted 3-(chlorodimethyl)-propyl-N-dodecylcarbamate having particle size of 5 mum is used as sorbent; and degassed 0.05 M aqueous solution of potassium dihydrophosphate is used as mobile phase. Mobile phase velocity is 1 ml/min, and column temperature is 30°C. Method of present invention makes it possible to determine content of two abovementioned active ingredients simultaneously.

EFFECT: simplified process of sample preparation.

3 ex, 3 tbl

FIELD: biotechnology, in particular content determination of polymer chitosan molecules, chitosan-chitine polymer molecules and molecules of chitosan-protein complex in finished form of chitosan.

SUBSTANCE: claimed method includes application of high performance chromatography column filled with polyvinylbenzene sorbent with refractometer detector. As eluent and for dissolving of chitosan preparation samples acetic acid aqueous solution is used. Chain-length distribution is determined on the base of first chromatography peak, and polymer molecular content is calculated on the base of area of first, second and third chromatography peaks, divided up to zero line and belonging to polymer chitosan molecules, chitosan-chitine polymer molecules and molecules of chitosan-protein complex, respectively. To calculate chain-length distribution of polymer chitosan molecules separately calibration curve is plotted using dextran polymer standards.

EFFECT: new effective method for determination of polymer chitosan molecules in chitosan preparations.

4 cl, 3 dwg

Express-chromatron // 2300764

FIELD: the invention refers to laboratory chromatographic devices for conducting high-speed chromatographic analysis.

SUBSTANCE: the express-chromatron has an injector, a chromatographic column located in a thermostat, a detector, an amplifier of the signal of the detector, an analog-digital converter, a control system, a pneumatic system. The column is fulfilled either in the shape of a short capillary column or either in the shape of a polycapillary column. The injector is fulfilled with possibility of introduction of the test for the time of 5-50 ms. The detector and the amplifier of its signal are fulfilled with possibility of ensuring constant time of no worse then 10-3 sec. The analog-digital converter is fulfilled with possibility of ensuring speed of no less then 200 measurements in a second.

EFFECT: ensures conducting high-speed chromatographic analysis.

11 cl, 2 dwg

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