GBZ/T 300.128-2018Determination of toxic substances in workplace air -- Part 128: Methacrylate (English PDF)

4.1 Principle

The vaporized methyl methacrylate in the air is collected by a gas bag, directly injected, separated by a gas chromatography column, and the hydrogen flame ionization detector Detection, quantified by retention time, peak height or peak area quantified.

4.2 Instrument

4.2.1 Gas bag, the volume is 1L ~ 10L.

4.2.2 Air sampler, flow range from 0mL/min to 500mL/min, or two balls.

4.2.3 Syringe, 1 mL, 100 mL.

4.2.4 Microinjectors.

4.2.5 Gas chromatograph with hydrogen flame ionization detector. Instrument operation reference conditions.

a) Column. 30m × 0.32mm × 0.5µm, FFAP;

b) column temperature. 100 ° C;

c) gasification chamber temperature..200 ° C;

d) detection chamber temperature. 250 ° C;

e) carrier gas (nitrogen) flow rate. 1mL/min;

f) Split ratio. 10.1.

4.3 Reagents

4.3.1 Methyl methacrylate, the mass of 1 µL of liquid at 0.9 ° C is 0.936 mg.

4.3.2 Standard gas. accurately extract a certain amount of methyl methacrylate with a micro-syringe and inject it into a 100mL airtight glass syringe.

Dilute to 100.0 mL with clean air as methyl methacrylate standard gas. Or formulated with a nationally recognized standard gas.

4.4 Sample collection, transportation and storage

4.4.1 On-site sampling shall be performed in accordance with GBZ 159.

4.4.2 Short-time sampling. At the sampling point, the air sample is collected after cleaning the gas bag for 3 to 5 times with an air sample. Immediately after sampling the intake valve of the closed gas bag shall be transported and stored in a clean container. The sample shall be measured within 24 hours.

4.4.3 Sample blank. Take the gas bag to the sampling site, collect clean air, transport, save and measure with the sample. Each batch the sample is not less than 2 sample blanks.

4.5 Analysis steps

4.5.1 Sample Handling. Place the sampled gas bag in the laboratory of the measurement standard series for determination.

4.5.2 Preparation of standard curve. Take 4 to 7 100mL airtight glass syringes, and dilute the standard gas with clean air to 0.0µg/mL~ A standard series of methyl methacrylate in the concentration range of 1.50 µg/mL. Adjust the gas chromatograph to the best measurement according to the operating conditions of the instrument State, 0.50 mL was injected, and the peak height or peak area of each concentration of the standard series was determined. Measure the peak height or peak area to the corresponding methyl group the methyl acrylate concentration (µg/mL) is plotted as a standard curve or a regression equation is calculated, and the correlation coefficient should be >=0.999.

4.5.3 Sample determination. The sample gas and sample blank gas are determined by the operating conditions of the measurement standard series, and the measured peak height or peak area is determined by the standard.

The curve or regression equation gives the concentration of methyl methacrylate (µg/mL) in the sample gas. If the concentration of the analyte in the sample gas exceeds the measurement range, Determined by dilution with clean air and multiplied by the dilution factor.

4.6 Calculation

4.6.1 Calculate the concentration of methyl methacrylate in air according to formula (1).

10000 x= cC

In the formula.

C--Methyl methacrylate concentration in air, in milligrams per cubic meter (mg/m3);

C0--Measured concentration of methyl methacrylate in the sample gas (minus sample blank) in micrograms per milliliter (µg/mL).

4.6.2 The time-weighted average contact concentration (CTWA) in air is calculated in accordance with the provisions of GBZ 159.

4.7 Description

4.7.1 This method is developed in accordance with the methods and requirements of GBZ/T 210.4. The detection limit of this method is 0.001µg/mL, and the lower limit of quantification is 0.003µg/mL, the quantitative determination range is 0.003µg/mL~1.50µg/mL, the minimum detection concentration is 1mg/m3, and the lowest quantitative concentration is 3mg/m 3. The relative standard deviation is 2.3% to 8.9%.

4.7.2 This method can also be measured using equivalent other GC columns. Constant temperature measurement or temperature programmed measurement can be selected according to the measurement requirements.

4.7.3 This method can also be sampled with a 100 mL syringe.

4.7.4 The chromatographic separation of this method is shown in Figure 1. As can be seen from the figure, the methyl methacrylate peak is symmetrical and sharp, and the vinyl acetate pair is determined.

No interference.

Description.

1-vinyl acetate;

2-methyl methacrylate.

Figure 1 chromatogram

5.1 Principle

The vaporized n-butyl methacrylate in the air is collected by an activated carbon tube, and the carbon disulfide is desorbed and injected, and separated by a gas chromatography column.

Ionization detector detection, qualitative by retention time, peak height or peak area quantification.

5.2 Instruments

5.2.1 Activated carbon tube, solvent desorption type, containing 100mg/50mg activated carbon.

5.2.2 Air sampler, flow rate 0mL/min ~ 500mL/min.

5.2.3 Solvent desorption bottle, 5mL.

5.2.4 Micro syringes.

5.2.5 Gas chromatograph with hydrogen flame ionization detector. Instrument operation reference conditions.

a) Column. 30m × 0.32mm × 0.25µm, FFAP;

b) column temperature. 120 ° C;

c) gasification chamber temperature..200 ° C;

d) detection chamber temperature..200 ° C;

e) carrier gas (nitrogen) flow rate. 5mL/min;

f) Split ratio. 2.1.

5.3 Reagents

5.3.1 Carbon disulfide, chromatographic identification without interference peaks.

5.3.2 Standard solution. Add carbon disulfide to the volumetric flask. After accurate weighing, add a certain amount of n-butyl methacrylate.

Amount; add carbon disulfide to the scale, calculate the concentration of the solution from the difference between the two weighings, which is the standard stock solution. Diluted with carbon disulfide before use 500.0 µg/mL n-butyl methacrylate standard solution. Or formulated with a nationally recognized standard solution.

5.4 Sample collection, transportation and storage

5.4.1 On-site sampling shall be performed in accordance with GBZ 159.

5.4.2 Short-time sampling. At the sampling point, a 15 min air sample was collected with an activated carbon tube at a flow rate of.200 mL/min.

5.4.3 Long-time sampling. At the sampling point, an air sample of 2h to 8h is collected with an activated carbon tube at a flow rate of 50 mL/min.

5.4.4 Immediately after sampling, the ends of the activated carbon tube are closed and transported and stored in a clean container. The sample can be stored for 15 days at room temperature.

5.4.5 Sample blank. At the sampling point, open both ends of the activated carbon tube and immediately close it, then transport, store and measure with the sample.

Not less than 2 sample blanks per batch.

5.5 Analysis steps

5.5.1 Sample treatment. Pour the front and rear activated carbon into two solvent desorption bottles, add 1.0mL of carbon disulfide each, after blocking, solve Suck for 30min, shake it from time to time. The sample solution is for measurement.

5.5.2 Preparation of standard curve. Take 4 to 7 volumetric flasks and dilute the standard solution with carbon disulfide to a concentration of 0.0µg/mL to 500.0µg/mL.

The standard range of n-butyl methacrylate. Adjust the gas chromatograph to the best measurement state according to the operating conditions of the instrument, and inject the sample.

1.0 µL, respectively, to determine the peak height or peak area of each concentration of the standard series. Measure the peak height or peak area value for the corresponding butyl methacrylate the ester concentration (µg/mL) is plotted as a standard curve or a regression equation is calculated, and the correlation coefficient should be >=0.999.

5.5.3 Sample determination. The sample solution and the sample blank solution are determined by the operating conditions of the measurement standard series, and the measured peak height or peak area is determined by the standard curve or regression equation gives the concentration (µg/mL) of n-butyl methacrylate in the sample solution. If the concentration of the analyte in the sample solution exceeds the measurement range was determined by diluting with carbon disulfide, and the calculation was multiplied by the dilution factor.

5.6 Calculation

5.6.1 Convert the sample volume to the standard sample volume according to the method and requirements of GBZ 159.

5.6.2 Calculate the concentration of n-butyl methacrylate in air according to formula (2).

Vcc

21)( = ...(2)

In the formula.

C - the concentration of n-butyl methacrylate in air, in milligrams per cubic meter (mg/m3);

C1, c2-- measured concentration of n-butyl methacrylate in the sample solution before and after (minus the sample blank) in micrograms per milliliter (µg/mL);

V--the volume of the sample solution in milliliters (mL);

V0 -- standard sampling volume in liters (L);

D -- desorption efficiency, %.

5.6.3 The time-weighted average contact concentration (CTWA) in air is calculated in accordance with GBZ 159.

5.7 Description

5.7.1 This method is developed in accordance with the methods and requirements of GBZ/T 210.4. The detection limit of this method is 0.4µg/mL, and the lower limit of quantification is 1.4.

Gg/mL, the quantitative measurement range is from 1.4µg/mL to 500µg/mL; the minimum detection concentration is 0.1mg/m3, the highest detection concentration is 3L air sample.

The low quantitative concentration is 0.33 mg/m3; the relative standard deviation is 3.0% to 4.3%, and the breakthrough capacity (100 mg activated carbon) is 18.8 mg.

The rate is 99.8% to 100%, and the desorption efficiency is 94.3% to 97.6%. The desorption efficiency of each batch of activated carbon tubes should be determined.

5.7.2 methacrylic acid, acrylic acid, ethyl acrylate, methyl methacrylate and n-butyl acrylate may coexist in the air Carboxylic acids and their ester compounds do not interfere with the assay.

5.7.3 This method can also be measured using equivalent other GC columns. Constant temperature measurement or temperature programmed measurement can be selected according to the measurement requirements.

5.7.4 The chromatographic separation of this method is shown in Figure 2.

Figure 2 chromatogram

6.1 Principle

The vaporized glycidyl methacrylate in the air is collected by a large bubble absorption tube containing cyclohexane, directly injected, and subjected to gas chromatography.

The column is separated and detected by a hydrogen flame ionization detector, which is characterized by retention time, peak height or peak area.

6.2 Instruments

6.2.1 Large bubble absorption tube.

6.2.2 Air sampler, flow range from 0L/min to 1L/min.

6.2.3 Curling.

6.2.4 Test tube with plug scale, 10mL.

6.2.5 Micro syringes.

6.2.6 Gas chromatograph with hydrogen flame ionization detector, instrument operation reference conditions.

a) Column. 20m × 0.2mm × 0.2µm, OV-101;

b) column temperature. 90 ° C;

c) gasification chamber temperature..200 ° C;

d) detection chamber temperature..200 ° C;

e) carrier gas (nitrogen) flow rate. 5mL/min;

f) Blowing. 60 mL/min.

6.3 Reagents

6.3.1 Cyclohexane, chromatographic identification of interference-free peaks.

6.3.2 Standard solution. Add cyclohexane to the volumetric flask. After weighing accurately, add a certain amount of glycidyl methacrylate (if necessary) Refining is required, and then accurately weighed, diluted to the mark with cyclohexane; the concentration of the solution is calculated from the difference between the two weighings, which is the standard stock solution. Temporary Previously, it was diluted with cyclohexane to a standard solution of 500.0 µg/mL glycidyl methacrylate. Or formulated with a nationally recognized standard solution.

6.4 Sample collection, transportation and storage

6.4.1 On-site sampling shall be performed in accordance with GBZ 159.

6.4.2 Short-time sampling. At the sampling point, use a large bubble absorption tube (placed in a curling pot) containing 5.0 mL of cyclohexane at 500 mL/min.

Flow collection <= 15min air sample. Immediately after sampling, the inlet and outlet of the large bubble absorption tube are closed and transported and stored in a clean container.

The sample should be measured within 24 hours.

6.4.3 Sample blank. At the sampling point, open the inlet and outlet of a large bubble absorption tube containing 5.0 mL of cyclohexane, and immediately close it, then the same product is transported, stored and measured together. Not less than 2 sample blanks per batch.

6.5 Analysis steps

6.5.1 Sample treatment. After washing the inner wall of the inlet pipe 3 times with the sample solution in the large bubble absorption tube, pour the sample solution into the stopper test.

In the tube, the absorption tube was washed with a small amount of cyclohexane, and the washing solution was incorporated into a stoppered test tube, and then diluted to 5.0 mL for measurement.

6.5.2 Preparation of standard curve. Take 4 to 7 volumetric flasks and dilute the standard solution with cyclohexane to a concentration of 0.0µg/mL to 500.0µg/mL.

A range of standard glycidyl methacrylates. Adjust the gas chromatograph to the best measurement state according to the operating conditions of the instrument.

A sample of 2.0 µL was used to measure the peak height or peak area of each concentration of the standard series. Decrease the corresponding methacrylic acid with the measured peak height or peak area the glyceride concentration (µg/mL) is plotted as a standard curve or a regression equation is calculated, and the correlation coefficient should be >=0.999.

6.5.3 Sample determination. The peak height or peak area value measured by measuring the sample solution and the sample blank solution using the operating conditions of the standard series.

The concentration (µg/mL) of glycidyl methacrylate in the sample solution was obtained from a standard curve or a regression equation. If the concentration of the analyte in the sample solution Exceeding the measurement range, it is measured by diluting with cyclohexane, and the calculation is multiplied by the dilution factor.

6.6 Calculation

6.6.1 Convert the sample volume to the standard sample volume according to the method and requirements of GBZ 159.

6.6.2 Calculate the concentration of glycidyl methacrylate in air according to formula (3).

In the formula.

C--the concentration of glycidyl methacrylate in air, in milligrams per cubic meter (mg/m3);

C0--measurement of the concentration of glycidyl methacrylate in the sample solution (minus the sample blank) in micrograms per milliliter (µg/mL);

V--the volume of the sample solution in milliliters (mL);

V0 - the standard sampling volume in liters (L).

6.7 Description

6.7.1 This method is developed in accordance with the methods and requirements of GBZ/T 210.4. The detection limit of this method is 1.6µg/mL, and the lower limit of quantification is 5.3.

Gg/mL, the quantitative determination range is 5.3µg/mL~500µg/mL; the minimum detection concentration is 1mg/m3, the highest detection concentration is 7.5L air sample.

The low quantitative concentration was 3.5 mg/m3.

6.7.2 Cyclohexane is volatile, the sampling flow rate cannot be large, and the sampling time cannot be long.

6.7.3 This method can also be measured using equivalent other GC columns. Constant temperature measurement or temperature programmed measurement can be selected according to the measurement requirements.