Fundamentals of Sample Preparation for Environmental Analysis - Fundamentals of Environmental Sampling and Analysis - page 187

effluents of hazardous waste incinerators. The VOST consists of mainly a sorbent
cartridge containing Tenax, an empty impinger for condensate removal, a second
water-cooled glass condenser, a second sorbent cartridge containing Tenax and
petroleum-based charcoal, a silica gel drying tube, a calibrated rotometer, a
sampling pump, and a dry gas meter. These sorbent tubes are then thermally
desorbed and purged with organic-free helium through pre-purged organic-free
reagent water and trapped on an analytical sorbent trap in a purge-and-trap unit
(Figure 7.14a). After desorption, the analytical sorbent trap is heated rapidly and the
gas flow from the analytical trap is directed to the head of a wide-bore column under
subambient conditions for GC analysis. Details of VOST and the analysis of
cartridge from VOST can be found in EPA 0030 and 5041.
REFERENCES
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C HRISTIAN GD (2004), Analytical Chemistry, 6th Edition, John Wiley & Sons Hoboken, NJ.
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D EAN JR (2003), Methods for Environmental Trace Analysis, John Wiley & Sons West Sussex, English.
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M ITRA S (2003), Sample Preparation Techniques in Analytical Chemistry, Wiley-Interscience Hoboken, NJ.
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Supelco (1998), Guide to Solid Phase Extraction, Supelco Bulletin 910 Bellefonte, PA.
Supelco (1998), Solid Phase Microextraction: Theory and Optimization of Conditions. Supelco Bulletin
923 Bellefonte, PA.
Supelco (2001), SPME Application Guide, 3rd Edition. Supelco Bulletin 925B Bellefonte, PA.
Supelco, Solid phase microextraction of semivolatile compounds in US EPA method 625, Supelco
6-Pub#394006 Bellefonte, PA.
Supelco, Solid phase microextraction of volatile compounds in US EPA method 524.4, Supelco
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T ESSIER A, C AMPBELL PGC, B ISSON M (1979). Sequential extraction procedure for the speciation of
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QUESTIONS AND PROBLEMS
1. Explain briefly: (a) why HNO 3 , rather than other acids is most commonly used for acid
digestion? (b) why HF digestion is used for samples containing silicates? (c) why or why
not acid-preserving samples is appropriate for dissolved metals analysis?
* Suggested Readings