Potassium fluoride as a selective moisture trapping agent for SPE-TD-GC-FID determination of volatile organic compounds in air

Abstract

Anhydrous potassium fluoride has been proposed as a novel selective moisture trapping agent for gas chromatography to remove water vapor during adsorption concentration of low molecular weight volatile organic compounds (VOCs) from moist air. Unlike the traditional desiccants, potassium fluoride does not adsorb alcohols and ketones. To improve the adsorption efficiency, the analyzed air stream was purged through two sequential traps. The first trap was filled with a desiccant based on potassium fluoride and the second trap contained a sorbent to retain low molecular weight VOCs such as methanol and acetone. The adsorption of VOCs was followed by a thermal desorption from the second trap into the gas chromatographic column for analysis with a flame ionization detector. The proposed moisture trapping and preconcentration assembly allows determination of low molecular weight VOCs at the levels of μg m⁻³ with RSD not exceeding 5% after 4–8 minutes of preconcentration.