Monitoring airborne reactive chemicals by derivatization and high performance thin layer chromatography--anhydrides, acid halides, isocyanates.

A versatile reagent-coated solid sorbent tube has been developed for monitoring airborne reactive chemicals--including acetic anhydride (AcAn), chloroacetyl chloride (CAC), and isocyanatoethyl methacrylate (IEM). The monitoring procedures involve simultaneous collection and derivatization of these chemicals using the reagent 1-(2-pyridyl)piperazine. Following tube/pump sampling, the derivatives are solvent desorbed and analyzed by high performance thin layer chromatography (HPTLC). HPTLC offers high sample throughout chromatographic analyses. The methods are designed to provide accurate time-weighted-average (TWA) and short-term excursion measurements. The reactivity of anhydrides, acid halides, and isocyanates preclude long-term collection without derivatization. Formation of the derivative immediately stabilizes the molecules allowing retention on the solid sorbent. In addition, the derivative allows good chromatography and provides high detection sensitivity. The recoveries for acetic anhydride, chloracetyl chloride and isocyanatoethyl methacrylate are 97.5, 95.2 and 85.0%, respectively. Validation also included the evaluation of humidity effects, storage effects, and potential interferences.