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Published byTimothy Crawford Modified over 9 years ago
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Extraction Methods Static Headspace (HS) Dynamic Headspace
Spray-and-Trap (ST) SPME Membrane Inlet Purge-and-Trap
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Purge-and-Trap Method
Advantage : More sensitive than HS Drawback : Foaming and slowness of the purging step 2. Large sample volume and long purging time (10~30 min)
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Experimental Aim To construct an automated ST-GC system for on-line determination of dissolved VOCs in water.
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Micro-sorbent Trap Carboxen 1000 Carboxen 1003 1/16”
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Spray-and-Trap Device
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Cleaning
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Sampling
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Mode A
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Mode B
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Injection
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Sensitivity of Mode A Sensitivity of Mode A 1. Sprying condition
A. Size of droplet 2. Amount of sample B. Extraction gas flow rate C. Design of nozzle 3. Amount of extraction gas that is sampled. D. Introducing a limited amount of sample and extraction gas
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Mode A VS. Mode B A
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Purge-and-Trap Device
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Analytical conditions for ST and PT
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Recoveries of ST methods
Recovery =
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DL, R.S.D, and R2 for BTEX
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Chromatograms of ST-GC-ECD
Species CHCl3 CCl4 CH2Br2 CHCl=CCl2 CHBrCl2 CCl2=CCl2
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Conclusion An automated spray-and-trap device
was built in the laboratory. The studied ST method was validated in comparison with classic PT: recoveries precision, and linearity. The ST method shows a fast response to abrupt changes in sample quality, which makes it suitable for on-site monitoring of a water body.
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