GBZ/T 300.68-2017 English PDF (GBZT300.68-2017)

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GBZ/T 300.68-2017: Determination of toxic substances in workplace air -- Part 68: Styrene, methylstyrene and divinyl benzene
GBZ/T 300.68-2017
GBZ
NATIONAL OCCUPATIONAL HEALTH STANDARD
OF THE PEOPLE'S REPUBLIC OF CHINA
ICS 13.100
C 52
Partially replacing GBZ/T 160.42-2007
Determination of toxic substances in workplace air - Part 68.
Styrene, methylstyrene and divinyl benzene
ISSUED ON. NOVEMBER 9, 2017
IMPLEMENTED ON. MAY 1, 2018
Issued by. National Health and Family Planning Commission of PRC
Table of Contents
Foreword... 3
1 Scope... 4
2 Normative references... 4
3 Basic information on styrene, methylstyrene and divinylbenzene... 4
4 Solvent desorption-gas chromatography of styrene and methylstyrene... 5
5 Thermal desorption-gas chromatography of styrene... 8
6 Solvent desorption-gas chromatography of divinylbenzene... 11
Determination of toxic substances in workplace air - Part 68.
Styrene, methylstyrene and divinyl benzene
1 Scope
This part of GB/T 300 specifies the solvent desorption-gas chromatography method for
the determination of styrene, methylstyrene and divinylbenzene in the air of the
workplace and the thermal desorption-gas chromatography method for the
determination of styrene.
This part applies to the determination of the concentrations of vaporous styrene, methyl
styrene and divinylbenzene in the air of the workplace.
2 Normative references
The following documents are essential for the application of this document. For any
referenced document with a date, only the version with the date is applicable to this
document. For any referenced document without a date, the latest version (including all
amendments) is applicable to this document.
GBZ 159 Specifications of air sampling for hazardous substances monitoring in
the workplace
GBZ/T 210.4 Guide for establishing occupational health standards - Part 4.
Determination methods of air chemicals in workplace
3 Basic information on styrene, methylstyrene and
divinylbenzene
The basic information on styrene, methylstyrene and divinylbenzene is shown in Table
1.
a) Chromatographic column. 30 m×0.32 mm×0.5 μm, FFAP;
b) Column temperature. 80 °C;
c) Vaporization chamber temperature. 150 °C;
d) Testing room temperature. 150 °C;
e) Carrier gas (nitrogen) flow rate. 1 mL/min;
f) Split ratio. 10.1.
4.3 Reagents
4.3.1 Carbon disulfide. No interfering peaks are found in chromatographic
identification.
4.3.2 Standard solution. Add carbon disulfide to a volumetric flask, weigh it accurately,
then add a certain amount of styrene and/or methyl styrene, weigh it accurately again,
and make up the volume with carbon disulfide. Calculate the concentration of the
solution from the difference in weight, which is the styrene and/or methyl styrene
standard solution. Or prepare it with a nationally recognized standard solution.
4.4 Sample collection, transportation and storage
4.4.1 On-site sampling shall be carried out in accordance with GBZ 159.
4.4.2 Short-time sampling. At the sampling point, use an activated carbon tube to collect
air samples at a flow rate of 100 mL/min for 15 minutes.
4.4.3 Long-term sampling. At the sampling point, use an activated carbon tube to collect
air samples at a flow rate of 50 mL/min for 2~8 hours.
4.4.4 After sampling, immediately seal both ends of the activated carbon tube and place
it in a clean container for transportation and storage. The sample can be stored in a
refrigerator for 14 days.
4.4.5 Sample blank. At the sampling point, open both ends of the activated carbon tube
and seal them immediately, then transport, store and measure together with the sample.
Each batch of samples shall have no less than 2 sample blanks.
4.5 Analysis steps
4.5.1 Sample treatment. Place the front and rear section activated carbon into two
solvent desorption bottles respectively, add 1.0 mL of carbon disulfide to each, seal,
and desorb for 30 minutes, shaking occasionally. The sample solution is for
determination.
4.6.3 The time-weighted average exposure concentration (CTWA) in the air shall be
calculated in accordance with the provisions of GBZ 159.
4.7 Description
4.7.1 This method is developed in accordance with the method and requirements of
GBZ/T 210.4.The detection limit of this method is 2.5 μg/mL, the lower limit of
quantification is 8.3 μg/mL, and the quantitative determination range is 8.3 μg/mL~900
μg/mL; based on the collection of 1.5 L air sample, the minimum detection
concentration is 1.7 mg/m3, and the minimum quantitative concentration is 5.5 mg/m3;
the relative standard deviation is 4.2%~5.3%, the penetration capacity (100 mg of
activated carbon) is 6.9 mg, and the desorption efficiency is 79.5%. The desorption
efficiency of each batch of activated carbon tubes shall be measured.
4.7.2 This method can also be used with other equivalent gas chromatographic columns.
Constant temperature measurement or programmed temperature measurement can be
selected according to the measurement requirements.
5 Thermal desorption-gas chromatography of styrene
5.1 Principle
The vaporous styrene in the air is collected by activated carbon, injected after thermal
desorption, separated by a gas chromatography column, and detected by a hydrogen
flame ionization detector. The retention time is used for qualitative analysis and the
peak height or peak area is used for quantitative analysis.
5.2 Instruments
5.2.1 Activated carbon tube. thermal desorption type, containing 100 mg of activated
carbon.
5.2.2 Air sampler. with a flow range of 0 mL/min～500 mL/min.
5.2.3 Thermal desorber.
5.2.4 Syringe. 1 mL, 100 mL.
5.2.5 Gas chromatograph with a hydrogen flame ionization detector. Reference
operating conditions.
a) Chromatographic column. 30 m×0.32 mm×0.5 μm, FFAP;
b) Column temperature. 80 °C;
c) Vaporization chamber temperature. 150 °C;
d) Testing room temperature. 150 °C;
e) Carrier gas (nitrogen) flow rate. 1 mL/min;
f) Split ratio. 10.1.
5.3 Reagents
5.3.1 Styrene. At 20 °C, the mass of 1.0 μL of gas is 0.9060 mg.
5.3.2 Standard gas. Use a microsyringe to accurately extract 1.0 μL of styrene, inject it
into a 100 mL airtight glass syringe, dilute it to 100.0 mL with clean air, and prepare
9.06 μg/mL standard gas. Or use a nationally recognized standard gas to prepare.
5.4 Sample collection, transportation and storage
5.4.1 On-site sampling shall be carried out in accordance with GBZ 159.
5.4.2 Short-time sampling. At the sampling point, use an activated carbon tube to collect
air samples at a flow rate of 100 mL/min for 15 minutes.
5.4.3 Long-term sampling. At the sampling point, use an activated carbon tube to collect
air samples at a flow rate of 50 mL/min for 2~8 hours.
5.4.4 After sampling, immediately seal both ends of the activated carbon tube and place
it in a clean container for transportation and storage. The sample can be stored in a
refrigerator for 14 days.
5.4.5 Sample blank. At the sampling point, open both ends of the activated carbon tube
and seal them immediately, then transport, store and measure together with the sample.
Each batch of samples shall have no less than 2 sample blanks.
5.5 Analysis steps
5.5.1 Sample treatment. Place the activated carbon tube in a thermal desorber, connect
the gas inlet to a 100 mL syringe and the other end to a carrier gas (nitrogen), and desorb
to 100.0 mL at 350 °C at a flow rate of 50 mL/min. The sample gas is used for
determination.
5.5.2 Preparation of the standard curve. Take 4~7 100 mL airtight glass syringes, inject
0.0 mL~10.0...