HJ 903-2017Ambient air. Determination of polychlorinated biphenyls. Gas chromatography (English PDF)

5.19 Composite silica gel column

The bottom of the column filled with glass wool (5.24), from bottom to top were filled with anhydrous sodium sulfate 4 g, silica gel 0.9 g, 2% KOH Silica gel 3 g, silica gel 0.9 g, 44% silica gel 4.5 g, 22% silica gel 6 g, silica gel 0.9 g, 10% silver nitrate silica gel 3 g,

3 The top layer is anhydrous sodium sulfate 6 g. Can also be purchased directly commodity column.

5.20 Magnesium silicate. 150 µm to 250 µm (100 mesh to 60 mesh), activated at 130 ° C for at least 18 h before use, After cooling in the desiccator, transfer to a glass bottle and seal it for preservation.

5.21 quartz/glass fiber filter. According to the sampling head to select the appropriate specifications, the filter on the 0.3 µ m standard particle retention efficiency not less than 99%. Before use in the muffle furnace 400 °C heating 5 h above, after cooling, stored in the filter box, to ensure that the filter at Sampling before and after not contaminated, and in the sample before the flat state.

5.22 Polyurethane Foam (PUF). polyether type, with a density of 22 mg/cm3 ~ 25 mg/cm3, cut to grow 70 mm, straight Cylindrical diameter of 45 mm to 65 mm (length, diameter as determined by the specifications of the glass sampling cartridge). Use heat before use Water scald, and then repeatedly rub into warm water, drained, with acetone (5.1) three times, into the Soxhlet extractor (6.4), followed by reflux extraction with acetone (5.1), ether-n-hexane mixed solvent (5.8) for 16 h, Times fresh diethyl ether - n-hexane mixed solvent (5.8) reflux extraction, removed after the nitrogen (5.23) flow drying (also available Vacuum dried at room temperature 2 h ~ 3 h). Place in a glass sample holder (6.3.2) and seal in a suitable container.

5.23 Nitrogen. Purity >=99.999%.

5.24 glass wool. before use dichloromethane (5.4) reflux extraction 2 h ~ 4 h, dried and sealed.

6.3 Sampling device

6.3.1 Large flow sampler. to meet the HJ 691 requirements, with automatic accumulation of sampling volume, automatically convert the standard sampling volume Function, and automatic timing, power and then restart the function and automatically compensate for voltage fluctuations, changes in resistance caused by the flow changes Features. In the presence of filters and sorbents, for large flow rates, the sampler load flow should be up to

250 L/min, the working point of the flow rate of 225 L/min; for large flow sampling, the sampler load flow should be able to achieve

900 L/min, working point flow is 800 L/min.

6.3.2 Sampling head. to meet the HJ 691 requirements, by the filter holder and the sampling sleeve of two parts, as shown in Figure 1. Sampling head the material selection of PTFE or stainless steel and other non-adsorption of organic materials. Filter clip includes filter ring, filter and filter Film stent. Sampling tube Sleeve equipped with a glass sampling cylinder, the bottom of the sampling cylinder supported by a stainless steel mesh, the adsorption cartridge the material is PUF (5.22). Sampling tube sealed with a silicone rubber seal between the filter holder and the suction pump.

Soxhlet extractor. 500 ml or 1000 ml. Other performance extraction devices may also be used.

6.5 Glass Column. 350 mm long, 20 mm id, glass column with Teflon piston on the bottom.

6.6 Concentration device. Rotary evaporator, nitrogen blowing concentrator and other performance-equivalent equipment.

6.7 solid phase extraction device.

6.8 separatory funnel. 60 ml.

6.9 General laboratory equipment commonly used.

41-airflow inlet; 2-filter holder; 3-sampling sleeve Barrel; 4-gas outlet; 5-filter ring; 6-Silicone rubber ring; 7-filter; 8- stainless steel mesh;

9-filter holder; 10-glass sampling cartridge.

Figure 1 sampling head schematic

7.1 Sample Collection

7.1.1 Ambient air samples

According to HJ 194 and HJ 691, sampling points should be laid for the determination of meteorological parameters and sample collection.

In situ sampling followed by the installation of membrane clamps, sampling tube sleeve, connected to the sampler, adjusting the sampling flow, began sampling. Mining After the sample was taken off the filter, the sample dust inside the fold, remove the glass sampling tube, wrapped with aluminum foil, into the storage box in the close Save sealed.

7.1.2 Site blank samples

Will seal the preservation of the blank glass sampling cartridge and filter to the sampling site, installed in the sampling head without sampling, after Remove the cartridge and filter, store it in the same way as the sample, and ship it back to the lab with the sample.

57.2 Sample Storage

Samples were stored at room temperature protected from light, extracted within 24 h; otherwise, they should be stored in the dark below 4 °C and extracted within 7 d.

The sample extract is refrigerated at below 4 ° C and analyzed within 40 days.

7.3 Sample Preparation

7.3.1 Sample Extraction Filter and glass sampling cartridges were transferred to a Soxhlet extractor (6.4),.200 µL of replacement fluid (5.13) was added to the PUF, Add 300 ml ~ 500 ml ether - n-hexane mixed solvent (5.8) reflux extraction 16 h or more, refluxed three times per hour ~ 4 Times. After the extraction is completed and cooled to room temperature, the bottom bottle is taken out, the extraction cup interface is washed, and the cleaning liquid is transferred to the bottom bottle together. Add nothing Sodium sulphate (5.5) to sodium sulphate granules are free-flowing and are allowed to dry for 30 min.

Note. If using automatic Soxhlet extraction, with ether - n-hexane mixed solvent (5.8) reflux extraction of not less than 40 cycles. As long as you can achieve this Standard requirements of quality control, but also the use of other sample extraction methods.

7.3.2 Sample concentration the sample extract was transferred to a concentration apparatus, concentrated at below 45 °C, the solvent was replaced by n-hexane, concentrated to 1 ml about. If using sulfuric acid purification (7.3.3.1), concentrated to about 10 ml.

7.3.3 Sample Purification 7.3.3.1 sulfuric acid purification the sample extract concentrate (7.3.2) was transferred to a separatory funnel (6.8), add 5 ml sulfuric acid (5.7), gently Shake and deflate, shaking 1 min, after standing layered layer of sulfuric acid removed. Repeat the above procedure until the sulfuric acid layer is colorless. Add 5 ml of organic phase Sodium chloride solution (5.10), mix well, leave the aqueous layer after standing stratification, add anhydrous sodium sulfate (5.5) in the organic phase off Water, according to 7.3.2 concentrated below 1 ml, to be purified. If no further purification is required, dilute to 1.0 ml if internal standard is used the amount of law, adding 10.0 µl of internal standard solution (5.16), transferred to the vial to be analyzed.

7.3.3.2 Magnesium silicate column purification the bottom of the glass column (6.5) is filled with glass wool (5.24) and 20 g of magnesium silicate (5.20) is wet-filled with n-hexane (5.2) Exhaust air bubbles, add 1 cm ~ 2 cm anhydrous sodium sulfate (5.5) on the top. Pre-rinse with 60 ml of n-hexane (5.2) and keep the liquid level is slightly above the column bed and the sample extract concentrate (7.3.2) or sulfuric acid-concentrated concentrate (7.3.3.1) is transferred to a chromatographic the column was washed twice with 1 ml of n-hexane and transferred to the column. The eluate was discarded.

The column was eluted with.200 ml of ether-n-hexane mixed solvent (5.9) at an elution rate of 2 ml/min to 5 ml/min Receive eluate. Eluate according to 7.3.2 concentrated to 1.0 ml or less, constant volume to 1.0 ml, if using internal standard method, adding 10.0 µl internal standard solution (5.16), transfer to the vial for analysis.

7.3.3.3 Compound silica gel column purification Take a complex silica gel column (5.19), pre-rinse with 100 ml of n-hexane (5.2), keeping the liquid level just above the bed, concentrate to 1.0 ml of sample extract concentrate (7.3.2) was transferred to the column and the vial was washed twice with 1 ml of n-hexane (5.2) Transferred to the column together, discard the effluent.

Add.200 ml of n-hexane (5.2) for elution, control the flow rate of 2.5 ml/min or so and collect the eluent. Eluent according to 7.3.2 Concentrate to 1.0 ml or less and dilute to 1.0 ml. If using internal standard method, add 10.0 µl internal standard solution (5.16)

6 Transfer to vial for analysis.

Note. by the column size, the amount of adsorbent and other effects, the amount of eluent may be different, the laboratory before the need to carry out the conditions of the real Inspection; as long as the quality control requirements of this standard can be achieved, you can also use other sample purification methods.

7.4 Preparation of blank samples

7.4.1 Site blank

On-site blank samples (7.1.2) In-situ blank samples were prepared according to the same procedure as Preparation of samples (7.3).

7.4.2 Laboratory blank the same batch of sampling cartridges and filters according to the preparation of the sample (7.3) the same procedure for the preparation of laboratory blank samples.

8 Analysis steps

8.1 Instrument reference conditions Use 6.2 in the two different polarity of the column, one for the analytical column, one for the verification column.

Inlet. 250 ° C; splitless injection, split at 0.75 min, split ratio 60.1; injection volume. 2.0 µl; column Temperature. maintained at 50 °C for 1 min, heated to 180 °C at 25 °C/min, maintained for 2 min, heated to 280 °C at 5 °C/min, Hold for 5 min; carrier gas. nitrogen (5.23), flow rate. 1.0 ml/min; electron capture detector (ECD). 300 ° C.

8.2 standard curve drawing Pipette a certain amount of standard solution (5.18), diluted with n-hexane (5.2) to prepare standard series, standard solution the concentrations were 20.0 µg/L, 50.0 µg/L, 100 µg/L,.200 µg/L and 300 µg/L respectively. If using internal standard method, Add 10.0 µl of internal standard solution (5.16) per 1.0 ml standard solution. According to the instrument reference conditions (8.1) analysis, record Target Compound, Internal Standard, and Substitute Peak Retention Time, Peak Area (or Peak Height).

Taking the concentration of the target compound (or the ratio of the concentration of the internal standard) as the abscissa, the peak area or height of the target compound (or Internal standard peak area or peak height ratio) for the vertical axis, using the least squares method to draw the standard curve. Figure 2 shows the standard PCBs Figure

8.3 Determination of the sample According to the standard curve drawing the same instrument reference conditions (8.1) for the determination of the sample, record the peak retention time, Peak area (or peak height).

8.4 Blank test

The blank sample (7.4) was measured according to the same instrument conditions as the sample.

7min10 15 20 25 30

24,23

min10 15 20 25 30

20,21

2-TCX (Alternative); 3-PCB 8; 4-PCB 18; 5-PCB 28; 6-PCB 52; 7-PCB 44;

8-PCB 66, 9-PCB 101, 10-PCB 81, 11-PCB 77, 12-PCB 123, 13-PCB 118, 14-PCB 114, 15-PCB 153, 16-PCB 105, 17-PCB 138, 18-PCB 126, 19-PCB 187, 20-PCB 128, 21-22-PCB 156, 23-PCB 157, 24-PCB 180, 25-PCB 169, 26-PCB 170, 27-PCB 189, 28-29-PCB 206; 30-DCBP (surrogate).

Note. The column chromatographic column fixative is 14% cyanopropyl phenyl 86% dimethylpolysiloxane, the column chromatographic column fixative is 5% phenyl 95% dimethyl Polysiloxane.

Figure 2 PCBs standard chromatogram

9 results calculated and expressed

9.1 Qualitative method Qualified according to retention time.

When the target compound is detected on the analytical column, verify it with a verification column. If the test column is also detected, as the group Points were detected; if the column was not detected in the verification, as the component was not detected.

Chromatographic conditions can be changed or verified using GC-MS if necessary.

9.2 Quantitative method According to the peak area (or peak height), the internal standard method or external standard method. When the sample in the internal standard interference peak area (or Peak height) abnormal, you must use the external standard method. Quantitative Results Report Analyze column results.

9.3 Results Calculation the concentration of PCBs in ambient air () is calculated according to equation (1).

FV xx= (1)

Where.

8 - mass concentration of target compound in ambient air, ng/m3;

i - The mass concentration of the target compound in the sample, µg/L, from the standard curve;

V - sample volume constant volume, ml;

F - the dilution of the sample;

Vs - Sampling volume at standard conditions (101.325 kPa, 273 K), m3.

9.4 results indicated when the concentration of PCBs in ambient air is greater than or equal to 1.00 ng/m3, the result retains three significant digits; less than at 1.00 ng/m3, the result is retained until the second decimal place.

10 precision and accuracy

10.1 Precision

Six laboratories repeated the spiked (n = 6) spiked samples, respectively, at 25.0 ng, 100 ng and 300 ng (Equivalent to 0.07 ng/m3, 0.29 ng/m3 and 0.86 ng/m3 for air samples). The relative standard deviations in the laboratory were 2.7% ~ 20%, 1.1% ~ 23% and 1.3% ~ 13%, and the relative standard deviations were 3.4% ~ 16% and 1.8% 8.5% and 2.3% ~ 9.7% respectively. The repeatability limits were 0.01 ng/m3 ~ 0.02 ng/m3, 0.02 ng/m3 ~ 0.07 ng/m3 and 0.09 ng/m3 ~ 0.16 ng/m3, reproducibility limits of 0.01 ng/m3 ~ 0.03 ng/m3, 0.03 ng/m3 ~ 0.10 ng/m3 and 0.10 ng/m3 ~ 0.20 ng/m3. See Table D.1 for details.

10.2 Accuracy

Repeated determination (n = 6) of the five laboratories were ambient air samples spiked recoveries, the standard addition of 100 ng and 300 ng (equivalent to 0.29 ng/m3 air sample and 0.86 ng/m3 air sample), the recovery rates were 62.5% ~ 119% and 62.3% -108% .The final values of standard addition recoveries were 72.5% ± 22.4% ~ 104% ± 14% and 70.1% ± 10.4% ~ 97.2% ± 15.6%. See Table D.2 for details.

11 Quality Assurance and Quality Control 11.1 blank at least 1 field blank and 1 lab blank are determined for each batch of samples, and the blank value must not exceed the method detection limit.

11.2 Calibration

11.2.1 Initial calibration the correlation coefficient of the standard curve is >=0.995, otherwise, a new standard curve is drawn.

11.2.2 Continuous calibration the standard solution of the midpoint concentration of the curve is measured at least once every 24 h during the measurement of the sample, and the measurement of the target compound the relative error between the fruit and the standard value is within ± 20%.

11.3 Internal standard Sample internal standard, continuous calibration of the internal standard curve and the midpoint of the internal standard comparison, the peak area (or peak height) should be within ± 50% Within.

911.4 Recovery of alternatives After extraction, purification, concentration, analysis process, 2,4,5,6-tetrachloro-m-xylene and decablol recovery control range Respectively, 40% to 110% and 60% to 120%.

11.5 sampling efficiency in accordance with the requirements of HJ 691 sampling efficiency, the sampling efficiency of dynamic retention efficiency control in 50% to 150%.

11.6 parallel samples with two instruments at the same time collecting the same gas to obtain a parallel sample, when the measurement is greater than or equal to the lower limit of determination, the phase the deviation does not exceed 30%.

11.7 The standard flowmeter used to calibrate the sampler should be checked regularly. Before and after the sampler should be used for flow calibration, flow Fluctuation should not exceed ± 10%.

12 Waste treatment

The wastes and waste produced in the experiment shall be stored in categories, centrally stored and entrusted to qualified units for disposal.

Appendix A.

(Normative)

Method detection limit and determination of the lower limit when the sampling volume is 350 m3 (standard state), Soxhlet extraction or automatic Soxhlet extraction and sulfuric acid purification, concentration the volume of 1.0 ml, the method detection limit and the lower limit of determination in Table A.1.

Table A.1 method detection limit, lower limit of determination results table

No. Compound Name IUPAC number Method detection limit (Ng/m3) Method for determining the lower limit (Ng/m3) 1 2,4'-Dichlorobiphenyl PCB 8 0.02 0.08 2 2,2 ', 5-Trichlorobiphenyl PCB 18 0.02 0.08 3 2,4,4'-trichlorobiphenyl PCB 28 0.02 0.08 4 2,2 ', 5,5'-tetrachlorobiphenyl PCB 52 0.04 0.16 5 2,2 ', 3,5'-tetrachlorobiphenyl PCB 44 0.02 0.08 6 2,3 ', ...