Some standard content:
9-1996
GB16249
This standard is first formulated based on root seeding toxicology experiments, on-site labor hygiene surveys, epidemiological survey data and reference to foreign occupational exposure limits. It is a hygienic standard used for workplace environmental monitoring and health supervision. This standard shall be implemented from September 1, 1996. Appendix A and Appendix B of this standard are both appendices to the standard. This standard is proposed and managed by the Ministry of Health of the People's Republic of China. The drafting unit of this standard: Henan Occupational Disease Prevention and Control Institute. The main drafter of this standard is Lin Mipan.
This standard is entrusted by the Ministry of Health to the Institute of Labor Hygiene and Occupational Diseases, Chinese Academy of Preventive Medicine, which is the technical management unit, to interpret it. 592
1 Scope
National Standard of the People's Republic of China
Health standard for cresol
in the air of workplace
GB 16249-1996
This standard specifies the maximum allowable concentration and time-weighted average allowable concentration of cresol in the air of workplaces and its monitoring and inspection methods. This standard is applicable to all types of enterprises that produce and use cresol. 2 Hygienic requirements
The maximum allowable concentration of cresol in the air of workplaces is 10mg/m3 (skin); the time-weighted average concentration is 5mg/m3 (skin). 3 Monitoring and inspection methods
The monitoring and inspection methods of this standard adopt gas chromatography, see Appendix A (Appendix to the standard). Approved by the State Administration of Technical Supervision on April 3, 1996, and implemented on September 1, 1996
A1 Principle
GB16249—1996
Appendix A
(Appendix to the standard)
Gas chromatography method for cresol in workshop air
Cresol in air is sampled with a silicone tube and desorbed with ether; separated by gas chromatography on a bis-(p-octyloxybenzoic acid) hydroquinone ester (PBOB) column and detected by a hydrogen flame ionization detector, with retention time as the qualitative and peak height as the quantitative. A2 Instrument
A2.1 Silicone tube, a glass tube with a length of 80 mm and an inner diameter of 3.5 to 4 mm, containing two sections of activated silica gel (A3.1), 150 mg for the front section and 75 mg for the rear section; separated and fixed in the middle and at both ends with glass wool, and covered with plastic caps at both ends; placed in a desiccator for later use. A2.2 Sampler, flow range 0~～1L/min. A2.3 Micro syringe, 10μL.
A2.4 Stoppered graduated test tube, 5mL.
A2.5 Gas chromatograph, hydrogen flame ionization detector; 1ng o-cresol gives a signal-to-noise ratio of at least 3:1. Chromatographic column: 2m long, 4mm inner diameter, glass column. PBOB: phosphoric acid: ChromosorbWAWDMCS=5:1,100; column temperature: 80℃;
vaporization chamber temperature: 160℃;
detection chamber temperature: 160℃;
carrier gas (N,) flow rate: 15mL/min.
A3 Reagents
A3.1 Activated silica gel, 20-40 mesh silica gel is soaked in 1+1 hydrochloric acid overnight, washed with water until there is no chloride ion; dried at 90-100℃, activated at 320℃ for 4h; placed in a dryer to cool, used to load silica gel tubes. A3.2 Cresol, ortho and meta isomers, chromatographically pure. A3.3 Ether, redistilled.
A3.4 PBOB, chromatographic stationary liquid.
A3.5 Phosphoric acid.
A3.6 ChromosorbWAWDMCS, chromatographic support, 60-80 mesh. A4 Sampling
At the sampling point, remove the plastic caps at both ends of the silica gel tube, install it upright, and collect 5L of air at a rate of 0.5L/min. After sampling, put the plastic caps on both ends of the tube tightly. Transport and store at room temperature. A5 Analysis steps
A5.1 Control test: Bring the silicone tube to the sampling point, do not collect air, and the rest of the operation is the same as A5.2, as a blank control A5.2 Sample processing: Pour the front and rear sections of the silicone into 5mL graduated stoppered test tubes, add 1.0mL of ether to each, plug the stopper tightly, desorb for 2 hours, and shake from time to time.
A5.3 Drawing of the standard curve: Accurately weigh a certain amount of o-cresol and m-cresol, dissolve them in ether, and prepare a standard stock solution of about 5mg/mL. Before use, dilute with ether to 50, 150 and 300μg/mL standard solutions. Adjust the gas chromatograph to the optimal measurement conditions, take 2u of the standard solution for injection, and measure each concentration 3 times. Qualitatively determine the peak height based on the retention time; use the mean peak height as the ordinate and 59.1
GB16249
cresol concentration (μg/ml.) as the abscissa to draw the standard curve. Phenol
Figure A1 Chromatogram of cresol
A5.4 Determination: Under the same conditions as the standard solution determination, take 2μL of sample desorption solution for injection, qualitatively determine by retention time, measure peak height, determine each sample 2 to 3 times, calculate the average, and find out the concentration of cresol (ug/mL) from the standard curve. A6 Calculation
A6.1 Convert the sampling volume into the volume under standard conditions according to formula (A1): 273
V. =V×
Where: V.
Sampling volume under standard conditions, L;
-sampling volume, L,
Atmospheric pressure at the sampling point, kPa;
t—air temperature at the sampling point, ℃.
A6.2 Calculate the concentration of cresol in the air according to formula (A2): C+C2
Wherein: X-
Concentration of cresol in the air, mg/m;
-Concentration of cresol measured in the samples before and after, ug/mL; CC2-
V. —-Sampling volume under standard conditions, L. A7 Explanation
·（Al）
.....(A2 )
A7.1 The detection limit of this method is 1×10-μg (2μL injection), the minimum detection concentration is 0.1mg/m (sampling volume is 5L); the linear range is 0.5~500μg/mL. Relative standard deviation: o-cresol is 4.9%, 3.2% and 2.6% (concentrations are 14, 28 and 281ug/mL respectively), and m-cresol is 5.6%, 3.9% and 1.5% (concentrations are 14, 28 and 283μg/mL respectively). A7.2 The sampling efficiency of this method is close to 100%. The penetration capacity is 9.4mg (relative humidity during measurement is 80%). After sampling with the silicone tube, the two ends of the tube are tightly capped with plastic caps and can be stored at room temperature for at least 10 days. A7.3 The desorption efficiency is related to factors such as the properties of the silica gel used, so it must be measured before the test and corrected during calculation. A7.4 Phenol coexisting with cresol does not interfere with this method. A7.5 When preparing the chromatographic column, the support is first coated with 1% phosphoric acid (methanol as solvent), and after evaporating the solvent, it is coated with 5% PBOB liquid crystal stationary liquid (dichloromethane as solvent). After loading the column, it is aged at 150℃ with low-flow nitrogen. 595
B1 Principle
GB16249-1996
Appendix BbzxZ.net
(Appendix of the standard)
FFAP capillary column gas chromatography method for cresol in workshop air Cresol in air is sampled with a silicone tube and desorbed with acetone; separated by a FFAP capillary column and detected by a gas chromatography-hydrogen flame ionization detector, with retention time as the qualitative and peak height as the quantitative. B2 Instruments
B2.1 Silicone tube, 100 mm long, 3.5~4 mm inner diameter glass tube, containing two sections of activated silica gel (B3.1), 250 mg in the front section and 100 mg in the back section, separated and fixed in the middle and at both ends with glass wool, and plastic caps on both ends; placed in a desiccator for later use. B2.2 Sampler, flow range 0~1L/min. B2.3 Micro syringe, 1μL.
B2.4 Stoppered graduated test tube, 5mL.
B2.5 Gas chromatograph, hydrogen flame ionization detector; 1ng o-cresol gives a signal-to-noise ratio of at least 3:1. Chromatographic column: 3.5m×0.22mmFFAP elastic quartz capillary column; column temperature: initial temperature 70℃, 15min; final temperature 190℃, 15min, heating rate 12℃/min Vaporization chamber temperature: 220℃;
Detection chamber temperature: 300℃;
Carrier gas (Nz) pressure: 1.75kg/cm2.
B3 Reagents
B3.1 Activated silica gel, 20-40 mesh silica gel is soaked in 1+1 hydrochloric acid for day and night, washed with water until there is no chloride ion, dried at 90～~100℃, and then activated at 320℃ for 4h; placed in a desiccator to cool, used to install silica gel tubes. B3.2 Cresol, o-, m-, and p-isomers, chromatographically pure. B3.3 Acetone.
B4 Sampling
Remove the plastic caps at both ends of the silicone tube at the sampling point, install it upright, and use 0.Collect 5L of air at a rate of 5L/min. After sampling, put plastic caps on both ends of the tube. Transport and store at room temperature. B5 Analysis steps
B5.1 Control test: Bring the silicone tube to the sampling point, do not collect air, and perform the other operations the same as B5.2 as a blank control. B5.2 Sample treatment: Pour the front and back sections of silicone into 5mL graduated stoppered test tubes, add 2.0mL acetone to each, plug the stopper tightly, desorb for 2 hours, and shake from time to time.
B5.3 Drawing of standard curve: Accurately weigh a certain amount of o-, p-, and m-cresol, dissolve them in methanol, and prepare a standard stock solution of about 1mg/mL. Before use, dilute with acetone to 10, 20, 30, 40, and 50ug/mL standard solutions. Adjust the gas chromatograph to the optimal measurement conditions, take 1ul of standard solution for injection, and measure each concentration 3 times. Use retention time for qualitative analysis and measure peak height; use the mean peak height as the ordinate and the cresol content (ug) as the abscissa to draw a standard curve. 596
GB16249-1996
Figure B1 Cresol chromatogram
B5.4 Determination: Under the same conditions as the standard solution determination, take 1μL of sample desorption solution for injection, use retention time for qualitative analysis, measure peak height, measure each sample 2 to 3 times, calculate the mean, and find out the cresol content (ug) from the standard curve. B6 Calculation
B6.1 Convert the sampling volume into the volume under standard conditions according to formula (B1): 273
V. = V× 273+ × 101. 3
Where: V. ——Sampling volume under standard conditions, L; V-sampling volume, L;
p-atmospheric pressure at the sampling point, kPa;
t———air temperature at the sampling point, ℃.
B6.2 Calculate the concentration of cresol in the air according to formula (B2): X = 2×(Gi+C2)
Where: X——the concentration of cresol in the air, mg/m; are the cresol contents measured in the samples before and after, ug, CC,
V. ———converted to the sampling volume under standard conditions, L. B7 Explanation
·(B1)
....(B2)
B7.1The minimum detection concentration of this method is 0.2mg/m (sampling volume is 10L) and the relative standard deviation is 2.3%~2.6% (the concentration range of cresol is 10~50 μg/mL).
B7.2 The sampling efficiency of this method is close to 100%. The penetration capacity is 9.4 mg (the relative humidity during the measurement is 80%). After sampling with the silicone tube, cover both ends of the tube with plastic caps and store it at room temperature for at least 10 days. B7.3 The desorption efficiency is related to factors such as the properties of the silica gel used, so it must be measured before the test and corrected during calculation. It is usually greater than 90%.
B7.4 Phenol coexisting with cresol does not interfere with this method. 597
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