Submitted to: Analytical Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/4/2005
Publication Date: 12/1/2005
Citation: Dungan, R.S. 2005. Headspace solid-phase microextraction for the determination of benzene, toluene, ethylbenzenes, and xylenes in foundry molding sand. Analytical Letters. 38:2393-2405.
Interpretive Summary: A headspace sampling technique, that uses a fused-silica fiber coated with a polymeric phase, was utilized to determine volatile organic compounds (VOCs) in foundry molding sand. The technique is known as headspace solid-phase microextraction (HS-SPME) and is very attractive because it is rapid, can be fully automated, and no organic solvents are required. Parameters that influence the sorption of the VOCs to the SPME fiber were tested. Overall, it was found that the technique is very sensitive for low levels of VOCs. However, because foundry molding sands often contain bentonite clay, this will effect the amount of VOC detected.
Technical Abstract: The use of headspace solid-phase microextraction (HS-SPME) to determine benzene, toluene, ethylbenzene, and xylenes (BTEX) in foundry molding sand, specifically a 'green sand' (clay-bonded sand) was investigated. BTEX extraction was conducted using a 75'M Carboxen-polydimethylsiloxane (CAR-PDMS) fiber which was suspended above 10 g of sample. The SPME fiber was desorbed in a gas chromatograph injector port (280oC for 1 min) and the analytes were characterized by mass spectrometry. The effect of extraction time and temperature, water content, and clay percentage on HS-SPME of BTEX were investigated. Because green sands contain bentonite clay, a matrix effect was observed and, therefore, extraction was conducted under non-equilibrium conditions. The detection limits for BTEX were determined to be ' 0.18 ng g-1 of green sand.