<title>REMPI detection of volatile aromatic hydrocarbons in ambient air</title>

Abstract

Volatile aromatic hydrocarbons such as benzene, toluene, ethylbenzene, and xylenes (BTEX), and styrene, aniline, and phenol can be directly and sensitively detected in ambient air by resonance-enhanced multiphoton ionization (REMPI) spectroscopy. The REMPI spectra closely resemble conventional absorbance spectra, but the REMPI technique is far more sensitive. Detection limits for directly focused tunable laser light into the ionization cell are less than 10 ppbv for BTEX and less than 1 ppbv for styrene, aniline, and phenol. Benzene in aqueous solution was remotely detected down to concentrations at the (mu) g/L level by a headspace analysis in which light was delivered to the ionization cell over a 20-meter long optical fiber.