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Gas injection membrane extraction for fast on-line analysis using GC detection
1Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark 07102, USA.
Analytical Chemistry
|January 31, 2002
Summary
Gas injection of aqueous samples significantly speeds up membrane extraction for analyzing volatile organics. This method simplifies instrumentation and operational procedures, improving diffusion and reducing analysis time.
Area of Science:
- Analytical Chemistry
- Separation Science
Background:
- Membrane extraction coupled with gas chromatography (GC) and mass spectroscopy (MS) is used for volatile organic analysis in water.
- Analysis time is prolonged by slow analyte permeation due to carrier gas pressure and mass transfer resistance from aqueous boundary layers.
- Analyte dispersion in aqueous streams also broadens the input pulse, increasing overall analysis time.
Purpose of the Study:
- To introduce and evaluate gas injection of aqueous samples for membrane extraction.
- To overcome limitations of traditional liquid injection methods in GC-MS analysis.
- To enhance the speed and efficiency of volatile organic compound (VOC) analysis in aqueous matrices.
Main Methods:
- Developed a gas injection technique for aqueous samples in a membrane extraction setup.
- Utilized gas chromatography (GC) and mass spectroscopy (MS) for analysis.
- Compared performance against conventional liquid injection methods.
Main Results:
- Gas injection reduced aqueous boundary layer formation, increasing the overall diffusion coefficient sevenfold.
- Minimized axial mixing of the sample with the gaseous eluent, eliminating permeation profile tailing.
- Achieved significantly faster membrane extraction and analysis times compared to liquid injection.
Conclusions:
- Gas injection of aqueous samples is a more efficient method for membrane extraction in GC-MS analysis.
- This technique simplifies instrumentation and operational procedures.
- The method offers a faster and simpler approach for analyzing volatile organics in water.
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