01 Solution Summary
Chlorinated hydrocarbons in groundwater samples are determined according to HJ 639-2012 using purge-and-trap-GC-MS. Volatile components are carried out by the purge gas and, after being trapped by the adsorbent trap, thermally desorbed, and focused/transferred, enter the GC-MS. The following arrangements are used for quantification and quality control: calibration relationships are established for chlorinated hydrocarbons in groundwater using reference materials matched to the detection channel; the identification basis, quantification method, and result units are all subject to the applicable method; blanks, calibration checks, parallel samples, and QC samples constitute batch quality control. Analytical batches are also set up with blanks, calibration checks, and applicable QC samples.
02 Standards and Method Basis
Chinese standard: English standard titles on this page are descriptive translations. The cited Chinese text is authoritative.
Method basis: application method. The laboratory may enter the name and version of the adopted formal method into the project file.
03 Samples and Analytes
The specific samples areGroundwater samples, and the analytes areChlorinated hydrocarbons in groundwater. 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
Add groundwater samples directly to the purge vessel to reduce volatilization losses caused by transfer. Water samples, blanks, standards, and quality control samples use the same purge volume, trapping, and desorption program.
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 | Calibration relationships are established for chlorinated hydrocarbons in groundwater using reference materials matched to the detection channel; the identification basis, quantification method, and result units are all subject to the applicable method; blanks, calibration checks, parallel samples, and QC samples constitute batch quality control | Complete calibration, calculations, and batch review |
08 Huishi Instruments system configuration
This application requiresGas chromatography (GC) analysis systemComplete the analysis of chlorinated hydrocarbons in groundwater. When selecting the configuration, the injection interface, detector, and data system should be determined based on the sample state of the groundwater samples, thermal desorption after purge-and-trap and transfer to the chromatographic system, and the detection requirements.
09 Analysis workflow
10 Qualitative, Quantitative, and Quality Control
Calibration relationships are established for chlorinated hydrocarbons in groundwater using reference materials matched to the detection channel; the identification basis, quantification method, and result units are all subject to the applicable method; blanks, calibration checks, parallel samples, and QC samples constitute batch quality control. Method blanks check the background of water, containers, and flow paths; spiked samples evaluate purge-and-trap recovery; calibration checks monitor the response of the trap and detector.
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
Get Configuration and Technical Consultation
Please provide the sample information for the groundwater samples, the concentration range of chlorinated hydrocarbons in groundwater, the testing batch size, the method basis, and the existing equipment. Huishi Instruments will use this to prepare the configuration list.
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