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HJ 621-2011 English PDF

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HJ 621-2011: Water quality. Determination of chlorobenzenes. Gas chromatography
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Basic data

Standard ID HJ 621-2011 (HJ621-2011)
Description (Translated English) Water quality. Determination of chlorobenzenes. Gas chromatography
Sector / Industry Environmental Protection Industry Standard
Classification of Chinese Standard Z16
Classification of International Standard 13.060
Word Count Estimation 17,166
Date of Issue 2011-09-01
Date of Implementation 2011-11-01
Older Standard (superseded by this standard) GB/T 17131-1997
Regulation (derived from) Department of Environmental Protection Notice No. 63 of 2011
Issuing agency(ies) Ministry of Ecology and Environment
Summary This standard specifies the determination of chlorobenzene compounds in water by gas chromatography. This standard applies to surface water, groundwater, drinking water, sea water, industrial wastewater and domestic sewage Determination of chlorobenzenes.

HJ 621-2011: Water quality. Determination of chlorobenzenes. Gas chromatography

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Water quality.Determination of chlorobenzenes.Gas chromatography National Environmental Protection Standard of the People's Republic Replace GB/T 17131-1997 Determination of water quality chlorobenzene compounds Gas chromatography Water quality –Determination of chlorobenzenes –gas chromatography Published on.2011-09-01 2011-11-01 Implementation release Ministry of Environmental Protection

Content

Foreword..II 1 Scope.1 2 Principles of the method.1 3 interference and elimination 1 4 reagents and materials 2 5 Instruments and equipment 2 6 sample 3 7 Analysis steps .4 8 Calculation and representation of results. 5 9 precision and accuracy.6 10 Quality Assurance and Quality Control 6 Appendix A (normative appendix) method of precision and accuracy..8 Appendix B (informative appendix) carbon disulfide purification method..10 Appendix C (informative) Interfering substances for the analysis of chlorobenzene compounds.11

Foreword

To protect the environment and protect the human body in order to implement the Environmental Protection Law of the People's Republic of China and the Law of the People's Republic of China on Water Pollution Prevention and Control This standard is established for the determination of healthy, standardized chlorinated compounds in water. This standard specifies gas chromatography for the determination of chlorobenzene compounds in water. This standard is for the determination of 1,2-dichlorobenzene, 1,4-dichlorobenzene, 1,2,4-trichlorobenzene by gas chromatography (GB 17131-1997) Revision. This standard was first published in.1997. The original drafting unit was the China Environmental Monitoring Center. This is the first revision. Major within the revision The capacity is as follows. -- Separating the packed column by capillary column separation; -- Increased target compound components. Gas chromatographic method for the determination of 1,2-dichlorobenzene, 1,4-dichlorobenzene and 1,2,4-trichlorobenzene from the date of implementation of this standard (GB/T 17131-1997) abolished. Appendix A is a normative appendix, and Appendix B and Appendix C are informative appendices. This standard was formulated by the Science and Technology Standards Department of the Ministry of Environmental Protection. This standard is mainly drafted by. China Environmental Monitoring Center, Liaoning Provincial Environmental Monitoring Experimental Center. This standard is verified by. Zhejiang Environmental Monitoring Center, Jilin Province Environmental Monitoring Center Station, Shenyang Environmental Monitoring Center Station, Dalian City Environmental Monitoring Center, Anshan Environmental Monitoring Center Station and Liaoyang Environmental Monitoring Station. This standard was approved by the Ministry of Environmental Protection on September 1,.2011. This standard has been implemented since November 1,.2011. This standard is explained by the Ministry of Environmental Protection. Water quality - Determination of chlorobenzene compounds - Gas chromatography Warning. The standard samples of chlorobenzene compounds used in this method, carbon disulfide, concentrated sulfuric acid, etc. are harmful to human health. Wear protective gear to avoid contact with skin and clothing.

1 Scope of application

This standard specifies gas chromatography for the determination of chlorobenzene compounds in water. This standard applies to the determination of chlorobenzene compounds in surface water, groundwater, drinking water, seawater, industrial wastewater and domestic sewage. With The body components include. chlorobenzene, 1,4-dichlorobenzene, 1,3-dichlorobenzene, 1,2-dichlorobenzene, 1,3,5-trichlorobenzene, 1,2,4-trichloro Benzene, 1,2,3-trichlorobenzene, 12 kinds of 1,2,4,5-tetrachlorobenzene, 1,2,3,5-tetrachlorobenzene, 1,2,3,4-tetrachlorobenzene, pentachlorobenzene and hexachlorobenzene. When the water sample is 1L and the volume is set to 1.0mL, the method detection limit and the lower limit of measurement are shown in Table 1. Table 1 Detection limit and lower limit of determination of chlorobenzene compounds No. Compound name CAS Detection limit (μg/L) Lower limit of determination (μg/L) 1. Chlorobenzene 108-90-7 12 48 2. 1,4-Dichlorobenzene 106-46-7 0.23 0.92 3.1,3-Dichlorobenzene 541-73-1 0.35 1.4 4.1,2-dichlorobenzene 95-50-1 0.29 1.2 5.1,3,5-trichlorobenzene 108-70-3 0.11 0.44 6.1,2,4-trichlorobenzene 120-82-1 0.08 0.32 7.1,2,3-trichlorobenzene 87-61-6 0.08 0.32 8.1,2,4,5-tetrachlorobenzene 95-94-3 0.01 0.05 9.1,2,3,5-tetrachlorobenzene 634-90-2 0.02 0.06 10.1,2,3,4-tetrachlorobenzene 634-66-2 0.02 0.07 11. PeCB 608-93-5 0.003 0.012 12. Hexachlorobenzene 118-74-1 0.003 0.012

2 Principle of the method

The chlorobenzene compound in the water sample is extracted with carbon disulfide, and the extract is purified, concentrated, and made up to volume, and then used with an electron capture detector. (ECD) gas chromatograph was analyzed and characterized by retention time and quantified by external standard method.

3 interference and elimination

Under the analytical conditions, organochlorine pesticides commonly found in environmental waters can be separated from chlorobenzene compounds without interfering with the determination. Hexachlorobutadiene To interfere with the determination of 1,2-dichlorobenzene, non-polar column separation can be selected to eliminate interference. When organic halides or organic nitrations may be present When the compound (see Appendix C) interferes, it can be confirmed by gas chromatography-mass spectrometry or separated by different polar columns to eliminate interference.

4 reagents and materials

Reagents used in this standard use analytically pure reagents that meet national standards unless otherwise stated. Experimental water is not included in the new preparation Pure water of the organism. 4 .1 Chlorobenzene compound mixed standard solution. Chlorobenzene ρ = 100,000 μg/ml, 1,4-dichlorobenzene ρ = 1000 μg/ml, 1,3-dichlorobenzene ρ = 1000 μg/ml, 1,2-dichlorobenzene ρ = 1000 Gg/ml, 1,3,5-trichlorobenzene ρ =.200 μg/ml, 1,2,4-trichlorobenzene ρ =.200 μg/ml, 1,2,3-trichlorobenzene ρ =.200 μg/ Ml,1,2,4,5-four Chlorobenzene ρ = 50.0 μg/ml, 1,2,3,5-tetrachlorobenzene ρ = 50.0 μg/ml, 1,2,3,4-tetrachlorobenzene ρ = 50.0 μg/ml, pentachlorobenzene ρ = 20.0 μg/ml, Hexachlorobenzene ρ = 20.0 μg/ml. Purchase different concentrations of certified reference materials or standard solutions as needed. The opened standard solution is sealed under freezing and dark conditions save. 4.2 Sodium chloride Bake at 300 ° C for 4 h, cool to room temperature in a desiccator, and store in a ground glass bottle. 4.3 anhydrous sodium sulfate Bake at 300 ° C for 4 h, cool to room temperature in a desiccator, and store in a ground glass bottle. 4.4 Concentrated sulfuric acid. excellent grade, ρ 20=1.84 g/ml. 4.5 Carbon disulfide. chromatographically pure, 100 times concentrated and chromatographically detected without interference peaks. Analytically pure reagents can be purified according to Appendix B. 4.6 Methanol. pesticide residue level. 4.7 n-hexane. pesticide residue level. 4.8 Sodium sulfate solution. ρ(Na2SO4)=20 g/L. 20 g of anhydrous sodium sulfate (4.3) was weighed and dissolved in water containing no organic matter and diluted to 1000 ml. 4 .9 carrier gas. nitrogen, purity ≥ 99.999%. 4.10 Glass wool In the presence of interference, it can be soxed in n-hexane for 4 h and stored in a closed container.

5 Instruments and equipment

5.1 Gas chromatograph with electron capture detector (ECD). 5.2 Column. Quartz capillary column, 30m (length) × 0.25mm (inside diameter) × 0.25μm (film thickness), the stationary phase is nitro pair Phthalic acid modified polyethylene glycol or other equivalent stationary phase. 5.3 Separating funnel. 125ml,.2000ml, several. 5.4 Round bottom flask. 100 ml, several. 5.5 Volumetric flask. 50ml, several. 5.6 Rotate the evaporator. 5.7 Nitrogen blowing instrument. 5.8 Measuring cylinder. 1000ml. 5.9 Oscillator, 300 times/minute. 5.10 Brown threaded bottle. 1ml with push-on bonnet. 5.11 Vial. 2ml. 5.12 Microinjector. 10.0 μl, 50.0 μl. 5.13 Other instruments and equipment commonly used in laboratories.

6 samples

6.1 Sample Collection Samples were taken in brown glass bottles to fill the sample bottles. Sealed with a cap lined with a Teflon silicone pad (or aluminum foil pad), Prevent bubbles. 6.2 Sample storage Samples collected should be analyzed as soon as possible. If it cannot be analyzed on the day, add 1.0ml concentrated sulfuric acid (4.4) per liter of water sample at the time of sampling, at 2~ Store at 5 ° C and complete sample analysis within 7 days. 6.3 Sample preparation 6.3.1 Extraction Take 1000ml water sample from the measuring cylinder, place in.2000ml separatory funnel, add 30g sodium chloride (4.2), use 20ml, 10mL respectively Carbon disulfide (4.5) was extracted twice. Start shaking gently, and pay attention to deflation. After deflation is complete, fully oscillate on the oscillator. 5min. After extraction, the mixture was allowed to stand for separation, and the lower carbon disulfide was dried over anhydrous sodium sulfate, collected and combined into a 100 ml round bottom flask, and then used in small amounts. The carbon disulfide was rinsed with a layer of anhydrous sodium sulfate, and the eluent was also collected in a 100 ml round bottom flask. Note 1. Other solvents such as petroleum ether can also be used as extraction solvent after laboratory method verification. Note 2. High-concentration samples should be appropriately reduced in sample volume or de-concentration step, and directly or after purification, use a volumetric flask to make up to 50ml. 6.3.2 Purification The surface water, industrial wastewater and domestic sewage with serious pollution are extracted and purified by concentrated sulfuric acid. The extract was collected using a 125 ml separatory funnel. Add 5ml concentrated sulfuric acid (4.4) and gently shake (prevent heat and pay attention to deflation), leave the layer and discard the sulfuric acid layer, repeat the operation until sulfur The acid layer is colorless. Add 25 ml of sodium sulfate solution (4.8), shake off the residual sulfuric acid, stratify at rest, and discard the aqueous phase. Carbon disulfide Dehydrated and dried with anhydrous sodium sulfate, collected in a 100 ml round bottom flask, and then rinsed with anhydrous sodium sulfate with a small amount of carbon disulfide. The eluent was also collected. Collected in a 100 ml round bottom flask. 6.3.3 Concentrated and fixed volume The extract or the purified extract is concentrated to 1.0 ml with a rotary evaporator (25 ° C water bath) and a nitrogen gas blower, and then transferred to the sample. In the bottle. High-concentration samples can be volumeed in a 50ml volumetric flask and transferred to a vial.

7 Analysis steps

7.1 Chromatographic Analysis Reference Conditions Injection volume. 1.0μl Vaporization chamber temperature. 220 ° C Detector temperature. 300 ° C Carrier gas flow rate. 1.0ml/min Injection method. no split injection, split after 0.5min injection, split ratio 60.1. Heating program. ) (hold) (maintain min5220min/10min440 CCC D D ⎯⎯⎯⎯⎯ →⎯ 7.2 Drawing of working curves Add 1000 ml of pure water to each of the 5.2000 ml separatory funnels, and then add 1.0 μl with 10 μl and 50 μl syringes. Mix 10.0 μl, 20.0 μl, 30.0 μl, 50.0 μl of the standard mixed solution (4.1). The concentration of chlorobenzene compounds in water is shown in Table 2. Prepared according to 6.3 Standard series. The peak height or peak area of a standard solution of a series of chlorobenzene compounds is measured by gas chromatography to contain various chlorobenzene compounds. The amount (μg/L) plots a calibration curve corresponding to its peak height or peak area. Table 2 Chlorobenzene compounds standard series solution concentration (in water) Unit. μg/L Compound concentration 1 concentration 2 concentration 3 concentration 4 concentration 5 Chlorobenzene 1.00×102 1.00×103 2.00×103 3.00×103 5.00×103 Dichlorobenzene 1.00 10.0 20.0 30.0 50.0 Trichlorobenzene 0.20 2.00 4.00 6.00 10.0 Tetrachlorobenzene 0.05 0.50 1.00 1.50 2.50 Pentachlorobenzene Hexachlorobenzene 0.02 0.20 0.40 0.60 1.0 1-chlorobenzene, 2-1,4-dichlorobenzene, 3-1,3-dichlorobenzene, 4-1,2-dichlorobenzene, 5-1,3,5-trichlorobenzene, 6-1 , 2,4-trichlorobenzene, 7-1,2,3-trichlorobenzene, 8-1,2,3,5-tetrachlorobenzene, 9-1,2,4,5-tetrachlorobenzene, 10-1,2,3,4- Tetrachlorobenzene, 11-pentachlorobenzene, 12-hexachlorobenzene Figure 1 Standard chromatogram of 12 chlorobenzene compounds 7.3 Sample determination 7.3.1 Qualitative analysis Qualitative according to the retention time of each component of the standard chromatogram. 7.3.2 Quantitative analysis The concentration of the analyte in the sample solution is obtained from the working curve according to the peak area of the analyte. 7.4 Blank test Replace the water sample with pure water and prepare the assay according to step 6.3.

8 Calculation and representation of results

8.1 Calculation of results The concentration of chlorobenzene compounds in the water sample is calculated according to the following formula. Ow Sii VV 11000 ××= ρρ Where. iρ -- the mass concentration of component i in the water sample, μg/L; Siρ -- the mass concentration of component i derived from the working curve, μg/L; Vw -- sampling volume, ml; Vo -- volume to volume, ml. 8.2 Results representation When the result is greater than or equal to 1.00 μg/L, the result retains three significant digits; when less than 1.00 μg/L, the result remains after the decimal point Two digits (pentachlorobenzene, hexachlorobenzene retained to three decimal places).

9 Precision and accuracy

9.1 precision Six laboratories tested three different concentrations of laboratory blanks and standardized samples. See Appendix A for details. The relative standard deviation range of the experimental room is. 0.17~12.6%; The relative standard deviation between laboratories ranges from 1.26 to 18.4%; The repeatability limit range is. 0.002 ~ 37.2 μg/L; The reproducibility limit range is. 0.004 to 38.3 μg/L. 9.2 Accuracy Six laboratories measured surface water, industrial wastewater and domestic sewage samples with different concentrations of chlorobenzene compounds. detailed See Appendix A. The recoveries of surface water, industrial wastewater and domestic sewage were. 72.2%~100.7%, 72.3%~96.2%, 69.5%~96.4%. The final recoveries of surface water, industrial wastewater and domestic sewage were. 79±6.9%~94±8.3%, 78±12.0%~93±4.7%, 78±11.4%~94±3.9%. 10 Quality Assurance and Quality Control 10.1 Blank sample At least one full program blank should be analyzed for each batch of samples, and the full program blank should be below the detection limit. 10.2 Parallel samples At least 10% of the parallel samples were determined for each batch (20 samples) of the analysis, and the relative deviation of the parallel samples was within 30%. 10.3 Intermediate concentration test One intermediate concentration test is added every 10 samples, and the relative deviation between the measured value of the intermediate concentration and the value of the curve should be less than 20%. Otherwise a new working curve should be established. 10.4 Matrix addition Each batch of samples should be filled with at least one matrix spiked sample. The scalar amount is equivalent to the content of the sample in the sample, and the recovery rate should be 65% to 120%. between. 10.5 Qualitative analysis A retention time window of t ± 3S should be established prior to sample analysis. t is the average retention time of the reference material at each concentration level of the curve, S The relative standard deviation of the retention time of the reference material for each concentration level of the curve. When the sample is analyzed, the retention time of the analyte should be retained. Within the time window. 10.6 Standard Curves and Calibration When the linear range of the instrument is narrow, the concentration point interval can be reduced, and no less than 5 equal interval concentration point curves can be made; when the instrument linear range When it is wider, the concentration point interval can be increased, and no less than 5 equal interval concentration point curves can be made. The linear regression coefficient of the curve is at least 0.995.

Appendix A

(informative appendix) Method precision and accuracy Tables A.1 and A.2 give the precision and accuracy indicators for method repeatability, reproducibility, and spike recovery. Table A.1 Precision measurement results of chlorobenzene compounds The actual value of the compound name is measured (μg/L) Experimental room relative standard deviation(%) Interlaboratory standard deviation(%) Repeatability limit r (μg/L) Reproducibility limit R (μg/L) 47.8 5.9-9.9 13.0 0.932 1.93 2.52×103 0.80-1.2 3.10 7.13 22.8 Chlorobenzene 5.00×103 1.7-3.4 1.26 37.2 38.3 0.90 3.3-8.5 7.68 0.152 0.239 55.3 1.5-4.7 11.9 5.90 19.2 1,4-dichlorobenzene 96.2 1.4-3.3 2.97 7.23 10.4 0.97 7.3-11.5 6.17 0.253 0.285 55.0 2.2-4.7 11.8 5.37 18.8 1,3-dichlorobenzene 97.3 3.0-3.6 2.72 9.03 11.1 1.00 5.2-9.2 7.21 0.217 0.283 55.4 1.5-4.1 11.9 4.79 19.0 1,2-dichlorobenzene 96.0 2.1-3.7 3.03 7.42 10.6 0.22 7.6-12.6 18.4 0.063 0.127 5.20 0.17-0.30 12.4 0.033 1.81 1,3,5-trichlorobenzene 9.61 1.6-3.3 2.34 0.735 0.921 0.23 4.9-10.2 11.7 0.050 0.087 5.20 0.20-0.39 12.4 0.043 1.80 1,2,4-trichlorobenzene 9.62 1.8-3.5 3.40 0.683 1.11 0.23 5.6-11.6 14.9 0.055 0.109 5.20 0.23-0.47 12.5 0.045 1.81 1,2,3-trichlorobenzene 9.54 1.9-3.0 3.35 0.650 1.08 0.04 5.1-12.2 7.32 0.011 0.014 0.90 0.36-0.57 10.9 0.012 0.274 1,2,4,5-tetrachlorobenzene 2.07 2.8-5.7 7.21 0.255 0.478 0.23 5.6-11.6 14.9 0.055 0.109 0.90 0.36-0.55 10.8 0.011 0.271 1,2,3,5-tetrachlorobenzene 2.05 3.8-4.8 7.79 0.248 0.503 0.06 5.1-12.1 13.8 0.013 0.025 0.90 0.37-0.49 10.9 0.011 0.276 1,2,3,4-tetrachlorobenzene 2.07 3.1-4.5 7.50 0.238 0.486 0.009 4.8-10.7 11.1 0.002 0.004 0.487 2.7-5.3 12.1 0.060 0.174 pentachlorobenzene 0.978 3.2-5.3 9.51 0.123 0.284 0.010 4.7-10.5 10.0 0.002 0.004 0.477 2.2-6.4 10.1 0.059 0.144 Hexachlorobenzene 0.959 1.3-5.6 11.4 0.115 0.322 Table A.2 Determination of the recovery rate of surface water, industrial wastewater and domestic sewage by chlorobenzene compounds Spike recovery rate (%) Compound spiked concentration (μg/L) Matrix Laboratory 1 Laboratory 2 Laboratory 3 Laboratory 4 Laboratory 5 Laboratory 6 Spike recovery Final value (%) Surface water 75.2 80.4 84.1 78.7 74.8 79.1 79±7 Industrial wastewater 84.0 81.4 72.6 82.3 74.9 76.7 79±9 chlorobenzene 50.0 Domestic sewage 88.3 85.9 85.3 76.0 84.4 78.5 83±10 Surface water 78.6 85.5 92.8 72.2 80.5 86.1 83±14 Industrial wastewater 82.4 89.7 77.5 83.2 74.8 85.1 82±11 1,4-dichlorobenzene Domestic sewage 70.6 94.2 82.5 76.2 80.0 86.5 82±16 Surface water 77.4 85.8 81.7 84.6 92.2 78.2 83±11 Industrial wastewater 72.3 90.1 88.7 82.2 82.1 75.9 82±14 1,3-dichlorobenzene Domestic sewage 77.4 84.1 73.8 69.5 80.1 83.5 78±11 Surface water 90.3 88.7 79.1 90.1 89.0 81.7 86±10 Industrial wastewater 77.8 75.0 73.6 78.4 72.8 89.2 78±12 1,2-dichlorobenzene 1.00 Domestic sewage 76.9 86.1 76.3 83.5 87.6 81.3 82±9 Surface water 77.9 85.0 84.4 81.7 86.9 83.7 83±6 Industrial wastewater 87.7 83.3 79.8 86.2 92.3 88.7 86±9 1,3,5-trichlorobenzene Domestic sewage 89.9 84.3 91.9 86.3 87.2 83.4 87±7 Surface water 81.4 82.9 87.2 92.7 84.1 85.7 86±8 Industrial wastewater 81.3 86.5 87.4 82.0 83.5 90.5 85±7 1,2,4-trichlorobenzene Domestic sewage 85.1 79.8 85.6 90.0 88.2 90.5 86±8 Surface water 82.1 88.4 81.1 81.8 85.0 85.6 84±6 Industrial wastewater 85.9 88.4 85.4 89.7 83.5 90.1 87±5 1,2,3-trichlorobenzene 0.10 Domestic sewage 90.8 88.8 81.4 81.4 83.8 85.5 85±8 Surface water 92.8 94.0 97.4 87.0 89.2 95.3 93±8 Industrial wastewater 93.1 95.1 89.3 93.9 96.2 93.2 93±5 1,2,4,5-tetrachlorobenzene Domestic sewage 96.4 93.9 95.0 91.2 95.8 93.0 94±4 Surface water 99.1 93.7 97.0 96.7 92.3 87.5 94±8 Industrial wastewater 92.9 90.1 90.0 92.8 91.9 89.5 91±3 1,2,3,5-tetrachlorobenzene Domestic sewage 86.9 93.3 92.8 92.7 90.8 87.4 91±6 Surface water 91.5 95.8 94.3 89.4 93.4 86.2 92±7 Industrial wastewater 91.7 90.7 90.6 92.0 87.3 88.9 90±4 1,2,3,4-tetrachlorobenzene 0.02 Domestic sewage 89.0 94.3 87.0 94.8 93.0 89.7 90±6 Surface water 89.7 89.4 100.7 91.5 92.3 89.2 92±9 Industrial wastewater 90.0 92.1 87.7 89.9 91.9 92.3 91±4 pentachlorobenzene Domestic sewage 94.3 93.7 89.0 86.4 91.9 89.7 92±5 Surface water 92.6 87.8 91.6 89.8 93.1 92.9 92±4 Industrial wastewater 92.1 83.8 95.8 91.1 95.7 85.8 91±10 hexachlorobenzene 0.01 Domestic sewage 93.9 94.6 91.2 93.3 88.7 90.5 92±5 SP 2±

Appendix B

(informative appendix) Carbon disulfide purification method B.1 Method 1 Add.200ml of carbon disulfide in a 500ml separatory funnel, add 20ml of 1.100 formaldehyde-sulfuric acid solution, and extract multiple times until the sulfate layer It is colorless. To the purified carbon disulfide, 20 ml of a 20% aqueous sodium sulfate solution was added to wash to neutrality. The carbon disulfide is dried over anhydrous sodium sulfate. Re-steam and reserve. B.2 Method 2 Add.200ml of carbon disulfide to be purified to a 1000ml filter bottle, add 50ml of concentrated sulfuric acid, and add 50ml of concentrated nitric acid. The separatory funnel is placed above the suction filter bottle, and the above-mentioned suction filter bottle is tightly connected to the heating electromagnetic stirrer, and the electromagnetic stirrer is turned on to increase the temperature. The nitrification temperature was controlled to be vigorously stirred at 45.2 ° C for 5 min, and the nitric acid was added dropwise to the suction filter bottle for 5 min while stirring. Repeated co-reaction half In the hour, transfer the solution to a 500 ml separatory funnel, leave the acid layer for about half an hour, wash with water and add 10% potassium carbonate solution for neutralization. The pH is 6~8, then washed to neutral, the aqueous phase is discarded, and the carbon disulfide is dried with anhydrous sodium sulfate to remove water.

Appendix C

(informative appendix) Interfering substances determined by analysis of chlorobenzene compounds Table C may interfere with the determination of halogenated compounds and organic nitro compounds Compound boiling point (°C) polarity (octanol water partition coefficient Log Kow ) Chlorobenzene 131.7 2.89 1,1,1,2-tetrachloroethane 130.5 2.66 1,2-dibromoethane 131～132 1.96 1,3-dichloro-2-butene 131 - 1-nitropropane 131.6 0.87 2-chloro-2-nitropropane 134 - 1,2-dichlorobenzene 180.1 3.43 2-bromotoluene o-bromotoluene 181.7 3.5 Diiodomethane 181 - Benzyl chloride 179 2.3 Chlorooctane 181.5 4.73 1,3-dichlorobenzene 173 3.53 1,4-dichlorobenzene 174 3.44 3,4-dichlorobenzotrifluoride 173～174 - N-nitrosodiethylamine 175～177 0.48 Tribromomethane 149.5 2.4 1,2,3-trichlorobenzene 218.5 4.05 1,4-dibromobenzene 220.4 3.79 4-methylbromobenzyl 218～220 - ,,α,α-trichlorotoluene 220.8 2.92 1,2,4-trichlorobenzene 213.5 4.02 M-methyl bromide 212 ~ 215 - Hexachlorobutadiene 215 4.78 2-hydroxymethyl-2-nitro-1,3-propanediol 214 Nitrobenzene 210.8 1.85 1,3,5-trichlorobenzene 208 4.19 Αα-dichlorotoluene 205 3.22 Perchloropropene 209.5 - 4-nitrofluorobenzene 206～207 - 1,2,3,4-tetrachlorobenzene 254 4.64 2-chloronaphthalene 256 3.9 1,2-dimethyl-4-nitrobenzene 254 - 3,4-dichloronitrobenzene 255～256 3.12 1,2,3,5-tetrachlorobenzene 246 4.66 1,2,4,5-tetrachlorobenzene 244.5 4.6 1,1,2,2-tetrabromoethane 243.5 - 4-chlorotrichlorotoluene 245 - --bromobenzonitrile 242 - Dichlorobenzyl 245~252 - 1-chloro-2-nitrobenzene 246 2.52 1-chloro-4-nitrobenzene 242 2.39 PeCB 277 5.18 2-nitroanisole 277 1.73 Hexachlorobenzene 325 5.73 Hexabromobenzene 326～327 5.18 Pentachloronaphthalene 327～371 - Pentachloronitrobenzene 328 4.22

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