Extraction Methods Static Headspace HS Dynamic Headspace Spray-and-Trap

Extraction Methods Static Headspace (HS) Dynamic Headspace Spray-and-Trap (ST) SPME Membrane Inlet Purge-and-Trap

Purge-and-Trap Method Advantage : More sensitive than HS Drawback : 1. Foaming and slowness of the purging step 2. Large sample volume and long purging time (10~30 min)

Experimental Aim To construct an automated ST-GC system for on-line determination of dissolved VOCs in water.

Micro-sorbent Trap Carboxen 1000 Carboxen 1003 1/16”

Spray-and-Trap Device

Cleaning

Sampling

Mode A

Mode B

Injection

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

Mode A VS. Mode B A

Purge-and-Trap Device

Analytical conditions for ST and PT

Recoveries of ST methods Recovery =

DL, R. S. D, and R 2 for BTEX

Chromatograms of ST-GC-ECD Species 1. CHCl 3 2. CCl 4 3. CH 2 Br 2 4. CHCl=CCl 2 5. CHBr. Cl 2 6. CCl 2=CCl 2

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.