01 Solution Summary
Methyl tert-butyl ether (MTBE) in groundwater samples is determined by purge and trap-GC-MS according to HJ 639-2012. Volatile components are carried out by the purge gas and, after capture by the sorbent trap, thermal desorption, and focusing transfer, enter the GC-MS. Quantification and quality control use the following arrangements: identification is based on the retention behavior of target components and reference materials; calibration is performed using reference materials corresponding to methyl tert-butyl ether (MTBE), with external standard or internal standard calibration according to the applicable method; injection blanks, calibration verification, and duplicate determinations are used to monitor contamination and response stability. The analytical batch also includes blanks, calibration verification, 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 areMethyl tert-butyl ether (MTBE). 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 | Identify by the retention behavior of target components and reference materials; use reference materials corresponding to methyl tert-butyl ether (MTBE) and perform external standard or internal standard calibration according to the applicable method; injection blanks, calibration checks, and duplicate determinations are used to monitor contamination and response stability | Complete calibration, calculations, and batch review |
08 Huishi Instruments system configuration
This application requiresGas chromatography (GC) analysis systemComplete the analysis of methyl tert-butyl ether (MTBE). When selecting a configuration, determine the sample introduction interface, detector, and data system based on the sample state of groundwater samples, thermal desorption after purge-and-trap and transfer to the chromatographic system, and detection requirements.
09 Analysis workflow
10 Qualitative, Quantitative, and Quality Control
Identify by the retention behavior of target components and reference materials; use reference materials corresponding to methyl tert-butyl ether (MTBE) and perform external standard or internal standard calibration according to the applicable method; injection blanks, calibration checks, and duplicate determinations are used to monitor contamination and response stability. Method blanks check water, container, and flow path background; 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
Get Configuration and Technical Consultation
Please provide sample information for the groundwater samples, the concentration range of methyl tert-butyl ether (MTBE), testing batch size, method basis, and existing equipment. Huishi Instruments will prepare a configuration list based on this.
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