Appendix C
(Normative Appendix)
Determination of benzene concentration in the air
(capillary gas chromatography)
1, method summary
1.1 Related Standards and Basis
This method is mainly based on the standard method for gas chromatography of benzene, toluene and xylene in the residential area of ​​GB 11737-89.
1.2 Principle: The benzene in the air is collected with an activated carbon tube and then extracted with carbon disulfide. The flame gas ionization detector was analyzed with a gas chromatograph to determine the retention time and quantify the peak height.
1.3 Disturbance and Exclusion: When the amount of water vapor or water mist in the air is too large, even when it condenses in carbon tubes, the penetrating capacity and sampling efficiency of activated carbon are seriously affected. When the air humidity is 90%, the sampling efficiency of activated carbon tubes still meets the requirements. Interference from other pollutants in the air, due to the use of gas chromatographic separation techniques, can be eliminated by selecting the appropriate chromatographic separation conditions.
2, the scope of application
2.1 Measurement range: When the sample volume is 20L, extract it with 1ml carbon disulfide and inject 1μl. The measurement range is 0.05 to 10 mg/m 3 .
2.2 Applicable places: This Law applies to the determination of benzene concentration in the air of indoor air and residential areas.
3, reagents and materials
3.1 Benzene: Chromatographic purity.
3.2 Carbon disulfide: Analytically pure, it needs to be purified to ensure that the chromatographic analysis has no miscellaneous peaks.
3.3 Coconut shell activated carbon: 20~40 mesh, used for loading activated carbon sampling tubes.
3.4 Pure nitrogen: 99.99%.
4, instruments and equipment
4.1 Activated carbon sampling tube: Use a glass tube with a length of 150mm, an inner diameter of 3.5 to 4.0mm, and an outer diameter of 6mm, and enclose 100mg of coconut shell activated carbon with both ends fixed with a small amount of glass wool. After the tube is installed, it is blown with pure nitrogen at a temperature of 300-350°C for 5 to 10 minutes, and then the plastic cap is put on both ends of the tube. This tube can be stored in a desiccator for 5 days. If the glass tube is melted, this tube can be stable for three months.
4.2 Air Sampler: Flow range 0.2~1L/min, stable flow. Use the soap film flowmeter to calibrate the sampling system's flow rate before and after sampling. The flow error should be less than 5%.
4.3 syringe: 1ml. The volume scale error should be corrected.
4.4 Microsyringe: 1μl, 10μl. The volume scale error should be corrected.
4.5 stoppered test tube: 2ml.
4.6 Gas chromatograph: With hydrogen flame ionization detector.
4.7 Column: 0.53mm × 30mm wide non-polar quartz capillary column.
5, sampling and sample preservation
Activate the activated charcoal tube at the sampling site, with a minimum of 2 mm at both ends, and connect it vertically to the inlet port of the air sampler. Take 20 L of air at 0.5 L/min. After sampling, put plastic caps on both ends of the tube and record the temperature and atmospheric pressure at the time of sampling. Samples can be stored for 5 days.
6, analysis steps
6.1 Chromatographic conditions: Since chromatographic conditions often vary depending on the experimental conditions, the optimal chromatographic conditions for analyzing benzene should be established based on the type and performance of the gas chromatograph used.
6.2 Draw the standard curve and determine the calculation factor: In the same conditions as the sample analysis, draw the standard curve and determine the calculation factor.
6.2.1 Use the standard solution to draw a standard curve: In a 5.0 ml volumetric flask, add a small amount of carbon disulfide first, and accurately take a certain amount of benzene (1 875 lb, 0.8787 mg at 20 °C) into the volumetric flask with 1 μl microsyringe, and add carbon disulfide. To the mark, with a certain concentration of stock solution. Before use, a certain amount of stock solution was diluted with carbon disulfide to a standard solution with benzene contents of 2.0, 5.0, 10.0, and 50.0 μg/ml, respectively. Take 1 μL of standard sample and measure the retention time and peak height. Each concentration was repeated 3 times and the peak height was averaged. The standard curve was plotted with 1 μL benzene content (μg/ml) as the abscissa (μg) and the average peak height as the ordinate (mm ). The slope of the regression line was calculated and the reciprocal slope Bs [μg/mm] was used as a calculation factor for the determination of the sample.
6.3 Sample Analysis: Pour the activated carbon in the sampling tube into a stoppered test tube, add 1.0 ml of carbon disulfide, and plug the plug. Place it for 1 hour and shake it from time to time. Take 1μl injection, use the retention time qualitative, peak height (mm) quantitative. Perform three analyses for each sample and average the peak height. At the same time, take an unsampling activated carbon tube and operate the sample tube at the same time to measure the average peak height (mm) of the blank tube.
7, the result of calculation
7.1 Convert the sample volume according to formula (1) to the sample volume in the standard state
Where c - the concentration of benzene or toluene, xylene in the air, mg / m 3;
h - the average of sample peak heights, mm ;
h '- blank tube height, mm;
B s - the calculated factor obtained from 6.2.1, μg/mm;
E s ― the efficiency of carbon disulfide extraction determined experimentally;
V 0 - sample volume in standard conditions, L .
8, method characteristics
8.1 Lower limit of detection: When the sampling volume is 20L, 1 ml of carbon disulfide is used for extraction, and 1 μl of sample is injected. The detection limit is 0.05 mg/m 3 .
8.2 Linear range: 10 6 .
8.3 Precision: Liquid samples with benzene concentrations of 8.78 and 21.9 μg/ml were repeatedly tested with relative standard deviations of 7% and 5%.
8.4 Accuracy: The recoveries for benzene levels of 0.5, 21.1, and 200 μg were 95%, 94%, and 91%, respectively.
Appendix D
(Normative Appendix)
Test Method for Total Volatile Organic Compounds (TVOC) in Indoor Air
(thermal desorption/capillary gas chromatography)
1, method summary
1.1 Related Standards and Basis
ISO 16017-1 “Indoor, ambiant and workplace air - Sampling and analysis of volatile organic compounds by sorbent tube/thermal desorption/capillary gas chromatography ― part 1 : pumped samplingâ€
1.2 Principle
Select the appropriate adsorbent (Tenax GC or Tenax TA) and use a sorbent tube to collect a volume of air sample. The volatile organic compounds in the air stream remain in the sorbent tube. After sampling, the adsorption tube is heated to desorb the volatile organic compounds. The sample to be tested enters the capillary gas chromatograph with an inert carrier gas. With retention time qualitative, peak height or peak area quantification.
1.3 Interference and Exclusion
Sampling pre-treatment and activation of the sampling tube and adsorbent minimize interference; selecting a suitable column and analysis conditions, the method can separate a variety of volatile organic compounds, so that the coexistence interference problem can be solved.
2, the scope of application
2.1 Measurement range: This method is applicable to the determination of VOCs in air with a concentration range of 0.5 mg/m 3 to 100 mg/m 3 .
2.2 Applicable places: This Law applies to indoor, environmental, and workplace air, and is also suitable for evaluating the release of small or large test chamber materials.
3, reagents and materials
The reagents used in the analysis should be chromatographically pure; if analytically pure, they must be purified to ensure that the chromatographic analysis has no miscellaneous peaks.
3.1 VOC S: In order to correct the concentration, it is necessary to use VOC S as the reference reagent, and prepare the standard solution or standard gas with the required concentration, and then use liquid external standard method or gas external standard method to quantitatively inject it into the adsorption tube.
3.2 Dilution solvent: The diluent solvent used in the external standard method of the liquid should be chromatographically pure and should be separated from the test compound in the chromatographic elution curve.
3.3 Adsorbent: The particle size of the adsorbent used is 0.18-0.25mm (60-80 mesh). The adsorbent should be heated and activated with an inert gas flow overnight at the highest temperature of application before loading. In order to prevent secondary pollution, the adsorbent should be cooled to room temperature in clean air, stored and loaded. The desorption temperature should be lower than the activation temperature. The adsorption tube installed by the manufacturer must also be activated before use.
3.4 Pure nitrogen: 99.99%.
4, instruments and equipment
4.1 Adsorption tube: It is a stainless steel tube with an outer diameter of 6.3mm, an inner diameter of 5mm and a length of 90mm. The stainless steel tube is polished on the inner wall. The sample inlet end of the adsorption tube is marked. The adsorber tube can be filled with one or more adsorbents and the adsorbent layer should be in the heating zone of the desorber. According to the density of the adsorbent, the adsorption tube can be filled with 200-1000 mg of adsorbent, and both ends of the tube are plugged with stainless steel mesh or fiberglass hair. If multiple adsorbents are used in a single adsorption tube, the adsorbents should be arranged in the order of increased adsorption capacity and separated by glass fiber wool, with the weakest adsorption capacity on the sampling population side of the adsorption tube.
4.2 Injector: A 10 m L liquid syringe can be accurately read out in 0.1 m L; a 10 m L gas injector can be accurately read out in 0.1 m L; a 0.01 mL 1 mL gas syringe can be precisely read out.
4.3 Sampling pump: constant current air individual sampling pump, flow range 0.02 ~ 0.5L/min, stable flow. Use the soap film flowmeter to calibrate the sampling system's flow rate before and after sampling. The flow error should be less than 5%.
4.4 Gas Chromatograph: Equipped with a hydrogen flame ionization detector, mass spectrometer detector or other suitable detector.
Column: Non-polar (less than 10 polar index) quartz capillary columns.
4.5 Thermal desorption instrument: It can perform secondary thermal desorption of the adsorption tube and carry the desorption gas into the gas chromatograph with inert gas. Desorption temperature, time and carrier gas flow rate are adjustable. The cold trap concentrates the desorption sample.
4.6 Liquid standard method Preparation of standard series of injection devices: conventional gas chromatographic injection port, can be used on-line or can be independently assembled, retain the inlet port connection, and the lower end of the injection port can be connected to the adsorption tube.
5, sampling and sample preservation
Connect the adsorption tube to the sampling pump with plastic or silicone rubber tubing. For individual sampling, the sampling tube is mounted vertically on the breathing belt; when sampling in a fixed position, select the appropriate sampling position. Turn on the sample pump and adjust the flow rate to ensure that the desired sample volume (1 to 10L) is obtained in a reasonable amount of time. If the total sample volume exceeds 1 mg, the sampling volume should be reduced accordingly. Record the time, sampling flow, temperature, and barometric pressure at the beginning and end of sampling.
After sampling, the tube is removed and either ends of the tube are sealed or placed in a sealable metal or glass tube. Samples can be stored for 5 days.
6, analysis steps
6.1 Desorption and Concentration of Samples
The adsorption tube is mounted on a thermal desorption instrument and heated to desorb the organic vapor from the adsorbent and is carried into the cold trap by the carrier gas stream for preconcentration. The direction of the carrier gas flow is opposite to the direction of the sample. It is then rapidly desorbed at a low flow rate and passed through a transmission line into a capillary gas chromatograph. The temperature of the transmission line should be high enough to prevent condensation of the component under test. Desorption conditions (see Table 1).
Table 1 Desorption conditions
Desorption temperature 250 °C ~325 °C
Desorption time 5~15min
Inspiratory flow 30~50ml/min
Cold trap cooling temperature +20 °C ~-180 °C
Cold trap heating temperature 250 °C ~350 °C
The adsorbent in the cold trap, if used, is generally the same as the adsorption tube, 40~100mg
Carrier gas helium or high purity nitrogen
The split ratio between the split ratio sample tube and the secondary cold trap and between the secondary cold trap and the analytical column should be selected based on the concentration in the air
6.2 Chromatographic conditions
A quartz column with a film thickness of 1 to 5 mm, 50 m x 0.22 mm can be selected. The stationary phase can be dimethyl siloxane or 7% cyanopropane, 7% phenyl, 86% methyl siloxane. Column operating conditions were programmed temperature ramp, initial temperature 50 °C for 10 min, and ramp up to 250 °C at 5 °C/min.
6.3 Standard Curve Drawing
Gas external standard method: Accurately pump 100 mg/m 3 standard gas 100ml, 200ml, 400ml, 1L, 2L, 4L, 10L through the adsorption tube and prepare the standard series.
Liquid external standard method: Use a 4.6 sample introduction device to take 1~5 ml of standard solution containing 100 mg/ml and 10 mg/ml liquid components into the adsorption tube, while passing 100 ml/min of inert gas through the adsorption tube, after 5 min Remove the sorbent tube seal and prepare the standard series.
The standard series of adsorption tubes were analyzed by thermal desorption gas chromatography. The logarithm of the area after the blank was subtracted was the ordinate, and the logarithm of the measured mass was the abscissa. The standard curve was plotted.
6.4 Sample Analysis
Each sample adsorption tube was analyzed according to the procedure for drawing a standard curve (ie, the same desorption and concentration conditions and chromatographic conditions). The retention time was used for qualitative analysis and the peak area was quantified.
7, the result of calculation
7.1 Convert the sample volume according to formula (1) to the sample volume in the standard state
Where V 0 - is converted into a sample volume under standard conditions, L;
V - sample volume, L;
T 0 - the absolute temperature of the standard state, 273K;
T - the sum of the sample site temperature (t) and the absolute temperature of the standard state at the time of sampling, (t + 273) K;
P 0 - atmospheric pressure under standard conditions, 101.3kPa;
P - Atmospheric pressure at the sampling point during sampling, kPa.
7.2 Calculation of TVOC
(1) All compounds between n-hexane and n-hexadecane should be analyzed for retention time.
(2) Calculate TVOC, including all compounds from n-hexane to n-hexadecane in the chromatogram.
(3) According to a single calibration curve, quantify as many VOCs as possible, quantify at least ten highest peaks, and finally list the names and concentrations of these compounds together with TVOC.
(4) Calculate the identified and quantified volatile organic compound concentration S id .
(5) Calculate the concentration of unidentifiable volatile organic compounds Sun using the response coefficient of toluene.
(6) The sum of S id and S un is the TVOC concentration or TVOC value.
(7) If the detected compound exceeds the range of VOC defined in (2), then this information should be added to the TVOC value.
7.3 The concentration of the component to be measured in the air sample is calculated according to formula (2)
Where: c - the concentration of the component to be tested in the air sample, mg / m 3;
F - the mass of the components in the sample tube, mg;
B - the mass of the components in the blank tube, mg;
V 0 - sample volume in the standard state, L .
8, method characteristics
8.1 Detection lower limit: When the sampling volume is 10L, the detection limit is 0.5 mg/m 3 .
8.2 Linear range: 10 6 .
8.3 Precision: Add 10μg of the mixed standard solution to the adsorption tube. The relative standard deviation of Tenax TA is 0.4% to 2.8%.
8.4 Accuracy: The total uncertainty of 10mg/ml n-hexane, Tenax TA and Tenax GR (average of 5 determinations) was added to the adsorption tube at 20 °C and relative humidity of 50%.
Appendix E
(Normative Appendix)
Test method for total bacteria in indoor air
1, the scope of application
This method is applicable to the determination of total bacteria in indoor air.
2. Definition
The impacting method is sampling with a percussive airborne microbiological sampler. Through the action of aerodynamic forces, air is passed through slits or small holes to create a high-speed air flow, so that the bacteria particles suspended in the air hit the nutrient agar plate. After cultivation at 37 °C for 48 h, a sampling method for determining the number of bacterial colonies per cubic meter of air was calculated.
3, instruments and equipment
3.1 High pressure steam sterilizer.
3.2 Dry heat sterilizer.
3.3 constant temperature incubator.
3.4 Refrigerator.
3.5 Petri dishes (diameter 9cm).
3.6 Prepare the medium using general equipment: graduated cylinder, conical flask, pH meter or precision pH test paper.
3.7 Impact Air Microbial Sampler.
Sampler basic requirements:
(1) The capture rate of bacteria in the air is 95%.
(2) Easy to operate, easy to carry, stable in performance, easy to disinfect.
4 nutrient agar medium
4.1. Ingredients:
Peptone 20g
Beef extract 3g
Sodium chloride 5g
Agar 15~20g
Distilled water 1000ml
4.2 Preparation of the above ingredients are mixed, dissolved by heating, corrected to pH 7.4, filtered and packed, 121 °C, 20min autoclave. Crush method reference sampler instructions for preparing nutrient agar plates.
5 Operation steps
5.1 Select a representative room and location to set sampling points. Disinfect the sampler and sample according to the instrument's instructions.
5.2 After the sample is collected, the nutrient agar plate containing the bacteria is placed in a 36 ± 1°C incubator and incubated for 48 hours. The number of colonies is counted and converted into the number of colonies per m 3 of air according to the sampler flow rate and sampling time. The results are reported in cfu/m 3 .
Appendix F
(Normative Appendix)
Thermal environment parameters inspection method
Requirements, Methods, and Instruments for Thermal Environmental Parameter Testing*
Test Item Test Range Accuracy Test Method and Instrument
Temperature -10~50 °C ± 0.3 °C Glass thermometer (including wet and dry bulb thermometer)
Digital thermometer (thermocouple, RTD, semiconductor including digital hygrometer or thermometer attached to the anemometer)
Relative humidity 12%~99% ±3% wet and dry bulb thermometer
Lithium chloride dew point hygrometer
Capacitive digital hygrometer
Air flow rate 0.01~20m/s ± 5% hot ball type electric anemometer
Hot-wire anemometer