01 Solution Summary
For volatile organic compound samples from surface water, groundwater, domestic sewage, and industrial wastewater, the volatile organic compounds in water specified by HJ 639-2012 are determined by purge and trap-GC-MS in accordance with HJ 639-2012. Volatile components are purged out by the purge gas, trapped on an adsorbent trap, thermally desorbed, and transferred after focusing into the GC-MS. Quantitation and quality control use the following arrangements: calibration is performed with standard solutions according to HJ 639-2012, and quality is controlled in combination with blanks, spikes, and calibration verification. In each analytical batch, blanks, calibration verification, and applicable quality control samples are also set up.
02 Standards and Method Basis
Chinese standard: English standard titles on this page are descriptive translations. The cited Chinese text is authoritative.
| Standard number | Standard name | Status | Source |
|---|---|---|---|
| HJ 639-2012 | Water Quality — Determination of Volatile Organic Compounds — Purge and Trap/Gas Chromatography-Mass Spectrometry | Formal standard | Official source |
03 Samples and Analytes
The specific samples areVolatile organic compound samples from surface water, groundwater, domestic sewage, and industrial wastewater, and the analytes areVolatile Organic Compounds in Water Specified by HJ 639-2012. Pretreatment, injection, and detection configurations are determined according to the sample state, target concentration, and the formal method adopted.
04 Method Principle
As the purge gas passes through the water sample, it continuously carries volatile target compounds from the aqueous phase into the gas phase. The target compounds are enriched on the adsorption trap, and then enter the GC through thermal desorption and an inert transfer path.
GC completes the separation of the target compounds; MS performs identification based on retention time and characteristic ions, and quantification according to the calibration method specified in HJ 639-2012.
05 Sample Collection and Pretreatment
Volatile organic compound samples from surface water, groundwater, domestic sewage, and industrial wastewater are added directly to the purge vessel, reducing volatilization losses caused by the transfer process. Water samples, blanks, standards, and QC samples use the same purge volume, trapping, and desorption procedures.
Sample vials remain sealed, and headspace and agitation are controlled during sampling; high-concentration samples and routine samples are processed in separate batches to reduce carryover effects from the trap and transfer flow path.
06 Separation and Detection
After desorption, the target compounds are focused into the GC through an inert transfer path, separated by a column suitable for volatile organic compounds, and then enter the MS to acquire the characteristic ions specified by the acquisition method.
07 Instrument System Configuration
| Module | Configuration | Role in This Solution |
|---|---|---|
| Sample module | Water sample purge vessel and inert purge gas line | Carry volatile components out of the aqueous phase |
| Trapping module | Volatile organic compound adsorption trap | Enrich the purged target compounds |
| Desorption and transfer | Thermal desorption, focusing, and inert transfer channel | Introduce target analytes into the GC |
| GC separation | Gas chromatograph main unit and volatile organic compound separation column | Separate the target compounds |
| Mass spectrometric detection | MS | Identification and detection using characteristic ions |
| Data system | Calibrate using standard solutions according to HJ 639-2012, and control quality with blanks, spikes, and calibration checks | Complete calibration, calculations, and batch review |
08 Huishi Instruments system configuration
This application requiresGC-MS hyphenated systemComplete the analysis of volatile organic compounds in water specified in HJ 639-2012. When selecting the configuration, the sample introduction interface, detector, and data system should be determined based on the sample state of volatile organic compound samples from surface water, groundwater, domestic sewage, and industrial wastewater, thermal desorption after purge-and-trap and transfer to the chromatographic system, and detection requirements.
09 Analysis workflow
10 Qualitative, Quantitative, and Quality Control
Calibrate using standard solutions according to HJ 639-2012, and control quality with blanks, spikes, and calibration checks. Method blanks check background from water, containers, and flow path; spiked samples evaluate purge-and-trap recovery; calibration checks monitor trap and detector response.
After high-concentration samples, arrange blanks to check carryover, and include trap status, transfer flow path, and water management conditions in the batch records.
11 Method and Configuration Selection
- The standard method is HJ 639-2012.
- The water sample directly enters the purge vessel, using a continuous sample introduction chain consisting of purge, trap, thermal desorption, and focusing transfer.
- The detection unit uses MS and performs qualitative and quantitative analysis as specified by the method.
12 Frequently Asked Questions
Why is purge and trap suitable for VOCs in water?
An inert gas carries volatile target compounds out of the aqueous phase and enriches them in a sorbent trap, which can reduce the water matrix burden caused by direct liquid injection.
Is purge and trap part of the sample introduction chain?
Yes. Purge, trap, thermal desorption, and transfer continuously complete sample preparation and introduction of target compounds into the GC.
Which detector does this route use?
HJ 639-2012 specifies purge and trap coupled with gas chromatography-mass spectrometry; this solution uses MS to complete identification and detection of target compounds.
How can sample carryover be reduced?
Arrange high-concentration samples in batches, and run blanks afterward to check the trap and transfer flow path.
Why do water samples need to be stored sealed?
VOCs readily escape from samples; sealed sampling and reduced transfer can lower volatilization losses.
Which items are included in quality control?
Method blank, spiked sample, calibration verification, duplicate sample, and carryover blank after high-concentration samples.
What information is required before configuration?
Water sample type, target VOC list, expected concentration, sample batch size, detection method, and existing GC detector configuration.
13 Related Solutions and Knowledge
14 References
Get Configuration and Technical Consultation
Please provide sample information for volatile organic compound samples in surface water, groundwater, domestic wastewater, and industrial wastewater, the concentration range of volatile organic compounds in water specified by HJ 639-2012, testing batch size, method basis, and existing equipment. Huishi Instruments will prepare a configuration list based on this.
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