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Determination of toxic substances in workplace air -- Part 161: Tribromomethane
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GBZ/T 300.161-2018
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Basic data Standard ID | GBZ/T 300.161-2018 (GBZ/T300.161-2018) | Description (Translated English) | Determination of toxic substances in workplace air -- Part 161: Tribromomethane | Sector / Industry | National Standard (Recommended) | Classification of Chinese Standard | C60 | Word Count Estimation | 7,789 | Date of Issue | 2018-07-16 | Date of Implementation | 2019-07-01 | Regulation (derived from) | State-Health-Communication (2018) No.13 | Issuing agency(ies) | National Health and Family Planning Commission |
GBZ/T 300.161-2018: Determination of toxic substances in workplace air -- Part 161: Tribromomethane---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
Determination of toxic substances in workplace air - Part 161. Tribromomethane
ICS 13.100
C 52
National Occupational Health Standards
Determination of toxic substances in workplace air
Part 161. Tribromomethane
Determination of toxic substances in workplace air-
Part 161. Tribromomethane
Published on.2018 - 07 - 16
2019 - 07 - 01 implementation
National Health and Wellness Committee of the People's Republic of China
Foreword
This part is part 161 of GBZ /T 300 "Determination of Toxic Substances in Workplace Air".
This part is drafted in accordance with the rules given in GB/T 1.1-2009.
This section is mainly drafted by. Jiangsu Provincial Center for Disease Control and Prevention, Nanjing Center for Disease Control and Prevention, Jiangsu Province, Safety Production Science
Research Institute, Nanjing Gulou District Center for Disease Control and Prevention.
The main drafters of this section. Zhu Baoli, Li Xiaojuan, Gong Wei, Wu Jian, Zhou Changmei, Cha Hexia, Zhao Hao, Zhang Rongrong, Chen Yu, Mei Tang
Lin, Fang Yan.
Determination of toxic substances in the workplace - Part 161. Tribromomethane
1 Scope
This part of GBZ /T 300 specifies solvent desorption-gas chromatography for the determination of tribromomethane in the workplace air.
This section applies to the determination of the concentration of tribromomethane in the workplace air.
2 Normative references
The following documents are indispensable for the application of this document. For dated references, only the dated version applies to this document.
For undated references, the latest edition (including all amendments) applies to this document.
GBZ 159 Sampling specification for monitoring of hazardous substances in the workplace air
3 Basic information on tribromomethane
See Table 1 for basic information on tribromomethane.
Table 1 Basic information of tribromomethane
Chemical material
Chemical Abstracts
(CAS number)
Molecular formula relative molecular mass
Tribromomethane
(Tribromomethane)
75-25-2 CHBr3 252.7
4 solvent desorption of tribromomethane - gas chromatography
4.1 Principle
The tribromomethane in the air is collected by an activated carbon tube, and the carbon disulfide is desorbed and injected, separated by a chromatographic column, and the hydrogen flame ionization detector is inspected.
Measured, characterized by retention time, peak area or peak height.
4.2 Instrument
4.2.1 Activated carbon tube, solvent desorption type, containing 100 mg/50 mg activated carbon.
4.2.2 Air sampler, flow 0 mL/min ~ 500 mL/min.
4.2.3 Solvent desorption bottle, 2 mL.
4.2.4 Microinjector, 10 μL, 1 μL.
4.2.5 Gas chromatograph, hydrogen flame ionization detector.
Instrument operation reference conditions.
a) Column. 30 m × 0.32 mm × 0.25 μm, FFAP;
b) Column temperature. initial temperature 60 °C, hold for 1 min, increase to 135 °C at 20 °C/min for 5 min;
c) vaporization chamber temperature. 220 °C;
d) detector temperature. 250 °C;
e) no splitting;
f) Carrier gas (nitrogen) flow. 3.0 mL/min.
4.3 Reagents
4.3.1 Tribromomethane. chromatographically pure.
4.3.2 Carbon disulfide, chromatographic identification without interference peaks.
4.3.3 Standard solution. Add a small amount of carbon disulfide in a 5 mL volumetric flask, weigh or measure a certain amount of tribromomethane (at 20 ° C, three
The methyl bromide density of 2.89 g/mL was added to a volumetric flask, diluted with carbon disulfide to the mark; the concentration of this solution was calculated as a standard stock solution.
Or formulated with a nationally recognized standard solution.
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, open both ends of the activated carbon tube and collect 15 minutes of air sample at a flow rate of.200 mL/min.
4.4.3 Long-time sampling. At the sampling point, open both ends of the activated carbon tube and collect the air sample for 2h~8h at a flow rate of 50 mL/min.
4.4.4 Individual sampling. At the sampling point, open both ends of the activated carbon tube, and wear it on the upper part of the chest of the sampled object. The air inlet is as close as possible to the breathing.
Take a 2h~8h air sample at a flow rate of 50 mL/min.
4.4.5 Sample blank. Bring the activated carbon tube to the sampling point, except that the air sampler is not connected to the air sample, the rest of the operation is the same as the sample.
Not less than 2 sample blanks per batch.
4.4.6 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 7 days at room temperature.
4.5 Analysis steps
4.5.1 Sample treatment. Pour the activated carbon from the front and back sections into the solvent desorption bottle, add 1.0 mL of carbon disulfide, and close.
After that, shake it from time to time and desorb for 30 min. Shake well and desorb the solution for measurement.
4.5.2 Preparation and determination of the standard series. Prepare at least 4 concentrations from 0 g/mL to 150 g/mL with dilute carbon disulfide standard solution.
The standard series of tribromomethane. Refer to the operating conditions of the instrument, adjust the gas chromatograph to the optimal measurement conditions, and inject 1.0 μL, respectively.
Standard series, repeated 3 times for each concentration. Draw a standard for the concentration of tribromomethane (μg/mL) based on the measured peak area or peak height mean
Curve or calculate regression equations.
4.5.3 Sample determination. Determine the peak area or peak of the sample by measuring the sample and sample blank desorption solution using the operating conditions of the standard series.
After the high value, the concentration of tribromomethane (μg/mL) was obtained from a standard curve or a regression equation. If the concentration of tribromomethane in the desorbent exceeds the measurement range,
It can be determined by diluting with carbon disulfide and multiplied by the dilution factor when calculating.
4.6 Calculation
4.6.1 Convert the sample volume to the standard sample volume according to equation (1).
273 101 3.
VV
.(1)
In the formula.
V0--standard sampling volume in liters (L);
V -- sampling volume in liters (L);
t -- the temperature of the sampling point in degrees Celsius (°C);
p -- the atmospheric pressure at the sampling point in kilopascals (kPa).
4.6.2 Calculate the concentration of tribromomethane in air according to formula (2).
DV
Vcc
21)( .(2)
In the formula.
C - the concentration of tribromomethane in air, in milligrams per cubic meter (mg/m3);
C1, c2-- measured the concentration of tribromomethane in the activated carbon desorption solution before and after (minus the sample blank), the unit is microgram per ml
(g/mL);
v -- the volume of the desorbent in milliliters (mL);
V0 -- standard sampling volume in liters (L);
D -- desorption efficiency, %.
4.6.3 The time-weighted average contact concentration (CTWA) of tribromomethane in air is calculated in accordance with the provisions of GBZ 159.
4.7 Description
4.7.1 The detection limit of this method is 0.17 μg/mL, and the lower limit of quantification is 0.57 μg/mL. When 3.0 L air sample is collected, the volume of desorbed solution is
At 1.0 mL, the minimum detectable concentration was 0.06 mg/m3 and the lowest quantitative concentration was 0.19 mg/m3. The measurement range is from 0.57μg/mL to 150 μg
/mL. The relative standard deviation ranges from 1.5% to 2.9%.
4.7.2 The penetration capacity of this method is >0.61 mg (100 mg activated carbon), the average sampling efficiency is 100.0%, and the desorption efficiency range is 93.6 %.
96.2%.
4.7.3 Sample desorption measurement method. firstly decompose the front activated carbon of the activated carbon tube into the desorption bottle and measure it, if the measurement result shows
When the penetration capacity of the adsorbent is not exceeded, the latter stage may not be desorbed and measured; when the measurement result indicates that the penetration capacity of the adsorbent is exceeded,
The latter adsorbent is poured into a desorption bottle for desorption and determination, and the results of the previous and subsequent stages are added together and the corresponding treatment is performed. As in the latter paragraph
When the amount of the object to be tested is greater than 20% of the previous stage, it means that the activated carbon tube is overloaded and the sampling result cannot be used.
4.7.4 This method can also be carried out by using well-separated columns of similar polarity.
4.7.5 Under the conditions of this method, the on-site coexistence of acetone, ethanol, chloroform, monobromodichloromethane and dibromochloromethane is not dry.
Disturbance determination of tribromomethane. The chromatographic separation is shown in Figure 1.
Description.
1--carbon disulfide, acetone;
2--ethanol;
3-trichloromethane;
4--monobromodichloromethane;
5--dibromochloromethane;
6--tribromomethane.
Figure 1 Separation diagram of tribromomethane and coexisting materials
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