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

3. 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)

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

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

6. Spray-and-Trap Device

8. Cleaning

9. Sampling

10. Mode A

11. Mode B

12. Injection

14. 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

15. Mode A VS. Mode B A

16. Purge-and-Trap Device

18. Analytical conditions for ST and PT

21. Recoveries of ST methods
Recovery =

22. DL, R.S.D, and R2 for BTEX

23. Chromatograms of ST-GC-ECD
Species
CHCl3
CCl4
CH2Br2
CHCl=CCl2
CHBrCl2
CCl2=CCl2

25. 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.