Search result: HJ 639-2012
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Water quality. Determination of volatile organic compounds. Purge and trap/gas chromatography-mass spectrometer
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HJ 639-2012
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| Standard ID | HJ 639-2012 (HJ639-2012) | | Description (Translated English) | Water quality. Determination of volatile organic compounds. Purge and trap/gas chromatography-mass spectrometer | | Sector / Industry | Environmental Protection Industry Standard | | Word Count Estimation | 24,296 | | Quoted Standard | GB 17378.3; HJ/T 91; HJ/T 164; HJ 586 | | Summary | This standard specifies the determination of volatile organic compounds in a purge and trap gas chromatography mass spectrometry. This standard applies to water, groundwater, surface water, sewage and industrial waste water, 57 Determination of volatile o |
HJ 639-2012
Water quality.Determination of volatile organic compounds.Purge and trap/gas chromatography-mass spectrometer
National Environmental Protection Standard of the People's Republic
Determination of volatile organic compounds in water
Purge and trap/gas chromatography-mass spectrometry
Water quality-Determination of volatile organic compounds-
Purge and trap/gas chromatography-mass spectrometer
2 0 1 2 - 1 2 - 0 3 released
2 0 1 3 - 0 3 - 0 1 implementation
Release Ministry
Content
Preface II
1 Scope.1
2 Normative references.1
3 Terms and Definitions 1
4 principle of the method. 2
5 Reagents and materials 2
6 Instruments and equipment 2
7 sample 3
8 Analysis steps.3
9 Calculation and representation of results. 6
10 Precision and Accuracy.7
11 Quality Assurance and Quality Control 7
Appendix A (Normative) Quantitative ions, auxiliary ions, method detection limits and lower limit of determination of target compounds..9
Appendix B (informative) Total ion chromatogram of the target compound.11
Appendix C (informative) method precision and accuracy..12
Foreword
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, to protect the environment,
This standard is formulated to ensure human health and to regulate the determination of volatile organic compounds in water.
This standard specifies the purging of volatile organic compounds in seawater, groundwater, surface water, domestic sewage and industrial wastewater.
Capture/gas chromatography - mass spectrometry.
This standard is the first release.
Appendix A of this standard 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. Qingdao Environmental Monitoring Center Station and Qingdao Technological University.
This standard is verified by. National Urban Water Supply and Water Quality Testing Network Qingdao Monitoring Station, Qingdao Economic and Technological Development Zone Water Supply and Drainage Supervision
Station, Jinan Environmental Protection Monitoring Station, Weifang Environmental Monitoring Center Station, Dalian Environmental Monitoring Center and Anshan City Environment
Monitoring center station.
This standard was approved by the Ministry of Environmental Protection on December 3,.2012.
This standard has been implemented since March 1,.2013.
This standard is explained by the Ministry of Environmental Protection.
Water quality - Determination of volatile organic compounds - Purge and capture - Gas chromatography - mass spectrometry
Warning. The internal standard, substitutes and standard samples used in the experiment are volatile toxic compounds, and the solution should be prepared in
In the fume hood, the protective equipment should be worn as required to avoid contact with skin and clothing.
1 Scope of application
This standard specifies the purge and trap/gas chromatography-mass spectrometry for the determination of volatile organic compounds in water.
This standard applies to the determination of 57 volatile organic compounds in seawater, groundwater, surface water, domestic sewage and industrial wastewater.
This standard is also applicable to the determination of other volatile organic compounds if verified.
When the sample amount is 5ml, the detection limit of the target compound is 0.6-5.0μg/L by the full scan method.
The limit is 2.4～20.0μg/L; the detection limit of the target compound is 0.2～2.3μg/L by the selective ion method, and the lower limit of determination
It is 0.8 to 9.2 μg/L. See Appendix A for details.
2 Normative references
The contents of this standard refer to the following documents or their terms. For undated references, the valid version applies to
This standard.
GB 17378.3 Marine monitoring specification Part 3 Sample collection, storage and transportation
HJ/T 91 Surface Water and Wastewater Monitoring Technical Specifications
HJ/T 164 Technical Specifications for Groundwater Environmental Monitoring
HJ 586 - Determination of free chlorine and total chlorine - N,N-diethyl-1,4-phenylenediamine spectrophotometric method
3 Terms and definitions
The following terms and definitions apply to this standard.
3.1
Internal standard
Refers to a substance that is not contained in the sample but has similar physicochemical properties to the target compound to be tested. Usually added before sample analysis
In, used for quantification of the target compound.
3.2
Surrogate
Refers to a substance that is not contained in the sample but has similar physicochemical properties to the target compound to be tested. Generally in sample extraction or other
Before the pretreatment, the recovery rate can be used to evaluate the influence of the sample matrix and the sample processing process on the analysis results.
3.3
Matrix spiked spike
Refers to the addition of a known amount of the target compound to be tested in the sample for evaluation of the recovery rate of the target compound and the matrix effect of the sample.
should.
3.4
Transport blank strip blank
A blank reagent water is placed in the sample vial in the laboratory prior to sampling and brought to the sampling site. Cap 1 when sampling
Straight in sealed state, transported to the laboratory with the sample, processed and measured in the same analytical step as the sample, used to inspect the sample
Whether it is contaminated during transportation.
3.5
Full program blank whole program blank
A blank reagent water is placed in the sample vial in the laboratory prior to sampling and brought to the sampling site. Sample bottle with sample
Simultaneously open the lid and seal, transport it back to the laboratory, and process and measure it in the same analytical step as the sample.
Whether the entire process of analysis is contaminated.
4 Principle of the method
The volatile organic compounds in the sample are purged with high-purity helium (or nitrogen) and adsorbed in the trap tube. The trap tube is heated and high.
Pure helium backflushing, the components desorbed by heat are separated by gas chromatography and detected by a mass spectrometer. By combining with the target to be tested
The retention time of the material is compared with a standard mass spectrum or a characteristic ion, and the internal standard method is used for quantification.
5 reagents and materials
Unless otherwise stated, the analytical grades used in accordance with national standards were used for the analysis.
5.1 Blank reagent water. double distilled water or water prepared by pure water equipment.
A blank test is required before use to confirm that no interference peak appears or the target compound is concentrated in the retention time interval of the target compound.
The degree is below the method detection limit.
5.2 Methanol (CH3OH). Before use, it is necessary to pass the test to confirm that the concentration of the target compound or target compound is lower than the method detection limit.
5.3 Hydrochloric acid solution, 1 1.
5.4 Ascorbic acid (C6H8O6).
5.5 Standard stock solution. ρ=200～2000 μg/ml.
It can be purchased directly from a commercially available certified standard solution or prepared with a high concentration standard solution.
5.6 Standard intermediate solution. ρ=5～25 μg/ml.
The standard stock solution (5.5) was diluted with methanol (5.2) for one month.
5.7 Internal standard solution. ρ=25 μg/ml.
Fluorobenzene and 1,4-dichlorobenzene-d4 should be selected as internal standards, and commercially available certified standard solutions can be purchased directly or dissolved in high concentration standards.
Liquid preparation.
5.8 Alternative standard solution. ρ = 25 μg/ml.
Dibromofluoromethane, toluene-d8 and 4-bromofluorobenzene should be used as substitutes, and commercially available certified standard solutions can be purchased directly, or
Formulated in a high concentration standard solution.
5.9 4-bromofluorobenzene (BFB) solution. ρ = 25 μg/ml.
It can be purchased directly from a commercially available certified standard solution or a high concentration standard solution.
5.10 Helium. Purity ≥99.999%.
5.11 Nitrogen. purity ≥ 99.999%.
Note 1. All the above standard solutions are treated with methanol (5.2) as solvent, stored at 4 ° C in the dark or with reference to the manufacturer's product instructions. use
Before returning to room temperature, mix well.
6 Instruments and equipment
6.1 Gas Chromatography/Mass Spectrometer. The chromatographic section has a split/splitless inlet for temperature programming. Mass spectrometry with 70 eV electrons
Bombardment (EI) ionization source with at least 6 scans per peak, 7-10 scans recommended; mass spectrum of 4-bromofluorobenzene produced
The requirements of Table 1 must be met. NIST mass spectrometry library, manual/auto-tuning, data acquisition, quantitative analysis, and library search
can.
6.2 Purge and trap device
The purge unit can be connected directly to the chromatographic section and automatically initiates the chromatogram with a 5 ml purge tube. Capture tube use
1/3 Tenax, 1/3 silica gel, 1/3 activated carbon mixed adsorbent or other equivalent adsorbent, but must meet the relevant quality control requirements.
6.3 Capillary column. 30m × 0.25mm, 1.4μm film thickness (6% nitrile propyl phenyl/94% dimethyl polysiloxane fixative), or
Use other equivalent capillary columns.
6.4 Hermetic syringe. 5ml.
6.5 Microinjectors. 5, 10, 25, 50, 250 and 500 μl.
6.6 Vial. 40 ml brown glass bottle with silicone rubber-polytetrafluoroethylene gasketed screw cap.
6.7 Brown glass bottle. 2ml with Teflon-silica liner and solid screw cap.
6.8 Volumetric flask. Class A, 25ml.
6.9 Common instruments and equipment used in general laboratories.
7 samples
7.1 Sample collection
Sample collection of seawater, groundwater, surface water and sewage is based on the relevant provisions of GB 17378.3, HJ/T 164 and HJ/T 91 respectively.
Regulations are enforced. All samples were collected in parallel and each sample should have a full program blank and a transport blank.
When collecting samples, the water sample should be allowed to overflow in the vial without leaving space. Try to avoid or reduce the sample in the air when sampling
Exposed.
Note 2. The sample vial should be cleaned with methanol (5.2) before sampling, and the sample should not be washed without sampling.
7.2 Preservation of samples
Ascorbic acid needs to be added to each vial prior to sampling, and 25 mg of ascorbic acid (5.4) is added per 40 ml of sample.
If the total amount of residual chlorine in the water sample exceeds 5 mg/L, the total residual chlorine should be determined according to the method of HJ 586 Appendix A before determining the ascorbic acid.
The amount of acid added. In a 40ml vial, each additional 5mg/L of residual chlorine requires an additional 25 mg of ascorbic acid (5.4). When sampling,
When the water sample is neutral, add 0.5ml hydrochloric acid solution (5.3) to each vial and tighten the cap; when the water sample is alkaline, add appropriate amount.
The hydrochloric acid solution (5.3) makes the sample pH ≤ 2. Once the water sample has been collected, the label should be immediately labeled.
When a large amount of bubbles are generated after the water sample is added with the hydrochloric acid solution, the sample should be discarded and the sample collected again. Re-acquired samples should not
Add hydrochloric acid solution, the sample label should be marked as unacidified, and the sample should be analyzed within 24 h.
The sample is collected and refrigerated. After being shipped back to the laboratory, it should be placed in the refrigerator immediately, stored at 4 ° C or less, and analyzed within 14 days.
The sample storage area should be free of organic interference.
8 Analysis steps
8.1 Instrument Reference Conditions
8.1.1 Purge and trap reference conditions
Purge temperature. room temperature or constant temperature; purge flow rate. 40 ml/min; purge time. 11 min; dry purge time. 1 min;
Desorption temperature. 180 ° C; desorption temperature. 190 ° C; desorption time. 2 min; baking temperature..200 ° C; baking time. 6 min.
The rest of the parameters are set according to the instruction manual of the instrument.
8.1.2 Gas Chromatography Reference Conditions
Inlet temperature. 220 ° C; injection method. split injection (split ratio 30.1); programmed temperature. 35 ° C (2 min)
→5°C/min→120°C→10°C/min→220°C (2min); carrier gas. helium (5.10), flow rate. 1.0ml/min.
8.1.3 Mass Spectrometry Reference Conditions
Ion source. EI source; ion source temperature. 230 ° C; ionization energy. 70 eV; scanning method. full scan or selected ion sweep
Description (SIM). Scanning range. m/z 35-270 amu; solvent delay. 2.0 min; electron multiplying voltage. consistent with tuning voltage;
Interface temperature. 280 ° C. The rest of the parameters are set according to the instruction manual of the instrument.
8.1.3.1 For the full scan mode, the mass spectrometer should collect all ions with m/z ≥ 35 or more per target compound, but with water or two
When the carbon oxide peak is present, the mass of the scan can start from m/z 45.
8.1.3.2 For the use of the SIM method, each target compound shall select one quantitative ion and at least one auxiliary ion, if
Yes, also choose a confirmation ion (such as a halogen isotope) to ensure that the quantitative ions are not affected by the same ions in the overlapping peaks.
Disturb.
8.1.4 Analysis of BFB solution reference conditions
8.1.4.1 Direct injection through the GC inlet
Injection method. manual or automatic; injection volume. 2μl; programmed temperature. 100 ° C (0.1 min) → 12/min → 160 ° C ° C;
For the rest of the conditions, see 8.1.2~8.1.3.
8.1.4.2 Injection through a purge trap
The analysis conditions are shown in 8.1.1~8.1.3.
8.2 Calibration
8.2.1 Instrument performance check
The GC/MS system must perform an instrument performance check before daily analysis. Pipette 2μl of BFB solution (5.9) through GC
Inject directly into the inlet or add to 5 ml of blank reagent water (5.1), then inject through the purge trap and use GC/MS
Line analysis. The critical ion abundance of BFB obtained by GC/MS system should meet the standards specified in Table 1, otherwise one of the mass spectrometers is required.
These parameters are used to adjust or clean the ion source.
Table 1 4-bromofluorobenzene ion abundance standard
Mass-to-charge ratio ion abundance standard mass-to-charge ratio abundance standard
95 base peak, 100% relative abundance 175 mass 174 5% to 9%
96% 95% 5% to 9% 176 Quality 95% to 105% 174
173 is less than 25% of mass 174 177 is 5% to 10% of mass 176
174 is greater than 50% of mass 95
8.2.2 Drawing of the calibration curve
8.2.2.1 Use full scan mode. separately transfer a certain amount of standard intermediate solution (5.6) and substitute standard solution (5.8) to add quickly.
Go to the volumetric flask (6.8) with the blank reagent water (5.1) and bring the volume to the mark. Shake the volumetric flask three times vertically.
Evenly, the standard compounds of the target compounds and substitutes were prepared at a concentration of 5.00, 20.0, 50.0, 100, and.200 μg/L, respectively. then
Aspirate 5.0 ml of the standard solution with a 5 ml airtight syringe, and add 10.0 μl of the internal standard solution (5.7) according to the instrument reference strip.
(8.1), measured from low concentration to high concentration, recording the retention time of the standard series of target compounds and corresponding internal standards,
The response value of the ion.
8.2.2.2 Using SIM method. separately add a certain amount of standard intermediate solution (5.6) and substitute standard solution (5.8) to quickly add
In a volumetric flask (6.8) filled with blank reagent water (5.1), and set to volume, shake the volumetric flask three times vertically and mix well.
The concentrations of the target compounds and surrogates were formulated to be 1.0, 4.0, 10.0, 20.0, 40.0 μg/L standard series, respectively. Then use 5ml
The airtight syringe draws 5.0 ml of the standard solution and adds 2.0 μl of the internal standard solution (5.7) according to the instrument reference conditions (8.1).
From the low concentration to the high concentration, record the retention time of the standard series of target compounds and corresponding internal standards, and quantify the ion
Should be worth.
Note 3. If a purging and trapping instrument with an autosampler is used, the above procedure can be performed according to the instrument instructions.
Note 4. The standard solution prepared with blank reagent water is unstable, so it needs to be used now.
Note 5. For highly volatile target compounds (such as vinyl chloride, etc.), a gas-tight syringe should be used for solution formulation. Move a certain amount of labels separately
The quasi-intermediate solution (5.6) and the substitute standard solution (5.8) are directly added to the airtight syringe (6.4) containing 5 ml of blank reagent water (5.1), plus
Enter 2.0 μl of the internal standard solution (5.7) to the desired concentration.
Note 6. The purging device should be baked after each turn-on and before shutdown to ensure that the system is free from contamination.
The total ion chromatogram of the target compound is shown in Appendix B under the chromatographic conditions specified in this standard.
8.2.3 Calculation method of average relative response factor
The relative response factor (RRFi) of the target compound in point i of the standard series is calculated according to formula (1).
ISi
ISi
i A
ARRF ρ
ρ×=
(1)
In the formula.
RRFi--the relative response factor of the target compound at point i in the standard series;
Ai--the response value of the target ion of the target compound at the i-th point in the standard series;
AISi--the response point of the internal standard quantitative ion corresponding to the target compound in the i-th point of the standard series;
ρISi--the mass concentration of the internal standard in the standard series, μg/L;
Ρi--the mass concentration of the target compound at the i-th point in the standard series, μg/L.
The average relative response factor RRF of the target compound is calculated according to formula (2).
RRF
RRF
I∑
== 1 (2)
In the formula.
RRF - the average relative response factor of the target compound;
RRFi--the relative response factor of the target compound at point i in the standard series;
n--Standard series points.
The standard deviation (SD) of RRF is calculated according to formula (3).
)( 2
RRFRRF
SD
(3)
The relative standard deviation (RSD) of RRF is calculated according to formula (4).
0×=
RRF
SDRSD (4)
Relative standard deviation (RSD) of relative response factor (RRF) for a standard series of target compounds when calculated using relative response factors
Should be less than or equal to 20%.
8.2.4 Establishing a calibration curve using least squares
The ratio of the response of the target compound to the corresponding internal standard is plotted on the ordinate, the concentration ratio is plotted on the abscissa, and the calibration is established by least squares method.
curve. If the correlation coefficient of the established linear calibration curve is less than 0.990, the nonlinear fitting curve can also be used for calibration.
The curve correlation coefficient needs to be greater than or equal to 0.990. When using a non-linear calibration curve, at least 6 concentration points should be used for calibration.
8.3 Determination
8.3.1 Determination by full scan. After returning the vial to room temperature, draw a 5.0 ml sample with a gas-tight syringe.
Add 10.0μl of internal standard solution (5.7) and substitute standard solution (5.8) to make the internal standard and substitute in the sample thick.
The degree is 50μg/L, and the sample is quickly injected into the purge tube. According to the instrument reference condition (8.1), the calibration curve of 8.2.2.1 is used.
Line measurement. A purge trap with an autosampler can be operated with reference to the instrument instructions.
8.3.2 Determination by SIM. After returning the vial to room temperature, draw a 5.0ml sample with a gas-tight syringe.
Add 2.0μl of internal standard solution (5.7) and substitute standard solution (5.8) to make the internal standard and substitute in the sample thick.
The degree is 10μg/L, and the sample is quickly injected into the purge tube. According to the instrument reference condition (8.1), the calibration curve of 8.2.2.2 is used.
Line measurement. A purge trap with an autosampler can be operated with reference to the instrument instructions.
Note 7. The SIM method is only suitable for low-level clean water or samples that do not meet the requirements of the corresponding standards with full-scan sensitivity.
Note 8. If the concentration of the analyte in the sample exceeds the highest point of the curve, it is necessary to take an appropriate amount of the sample and dilute it in a volumetric flask and measure it immediately.
Note 9. When analyzing a high concentration sample, one or more blank samples should be analyzed to check for cross contamination. Applying blank water after analysis of seawater samples
Wash the purge system to avoid salt residue in the purge line and block the line.
8.4 Blank test
Pipette 5.0ml of blank reagent water with a gas-tight syringe, and add 10.0μl of internal standard solution to the blank reagent water.
(5.7) and the alternative standard solution (5.8), so that the concentration of the internal standard and the substitute in the blank reagent water is 50 μg/L (using the SIM side)
In the formula, the internal standard and the substitute concentration should be 10μg/L), and the blank reagent water is quickly injected into the purge tube according to the instrument reference conditions (8.1).
The measurement was carried out. A purge trap with an autosampler can be operated with reference to the instrument instructions.
9 Calculation and representation of results
9.1 Qualitative analysis of target compounds
9.1.1 For each target compound, a retention time window should be established using standard solutions or multiple injections through a calibration curve.
The retention time window is ±3 times the retention time standard deviation. The retention time of the target compound in the sample should be at the retention time.
Inside the window.
9.1.2 For the full scan mode, all ions of the target compound with abundance above 30% in the standard mass spectrum should be in the sample mass spectrum.
Present in, and the relative abundance in the sample mass spectrum should be less than 20% of the absolute value of the relative abundance in the standard mass spectrum. example
For example, when the relative abundance of an ion in a standard mass spectrum is 30%, the abundance of the ion in the mass spectrum of the sample should be
Between 10% and 50%. For some compounds, some special ions such as molecular ion peaks, if their relative abundance is less than 30%,
Should be used as a basis for discriminating compounds. If there is significant background interference in the actual sample, the background effect should be subtracted from the comparison.
9.1.3 For the SIM method, the confirming ions of the target compound should be present in the sample. For each of the falling time windows
Compounds, the relative abundance of ions relative to quantified ions in the sample and the relative abundance obtained by recent calibration standards
The value deviation should be less than 20%.
9.2 Quantitative analysis of target compounds
After qualitative identification, the target compound is calculated by internal standard method according to the peak area or peak height of the quantitative ion. Targeting in the sample
When the quantitative ions of the compound interfere, the auxiliary ion quantification is allowed. See Appendix A for specific internal and quantitative ions.
9.2.1 Quantification by mean relative response factor
When the target compound is calculated using the average relative response factor, the mass concentration ρx of the target compound in the sample is given by equation (5).
Calculation.
RRFA
fA
IS
ISx
x ×
××= ρρ (5)
In the formula.
Ρx--the mass concentration of the target compound in the sample, μg/L;
Ax--the response value of the target compound quantitative ion;
AIS--the response value of the internal standard quant......
......
Similar standards: HJ 511 HJ 945.3 HJ 943
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