Detection of aromatic pollutants in the environment by using UV-laser-induced fluorescence

We present a compact and mobile battery-operated laser induced fluorescence (LIF) system. It is based on a diode-pumped solid-state laser with UV frequency conversion and a 7-ns pulse duration. The third (355 nm) and fourth (266 nm) harmonics of the laser can be used alternately. The detection system consists of a polychromator, a gated image intensifier, and a CCD camera, which can acquire time-resolved spectra with nanosecond time resolution. Fluorescence spectra, decay times, and detection limits of the 16 US-EPA polycyclic aromatic hydrocarbons (PAH) have been measured and the results are discussed in terms of separability of single PAHs in a multicomponent mixture. The results of a mathematical analysis of a 16-component mixture is presented. Spectra from natural water samples contaminated with gasoline and tar are also presented and the potential and limits of the LIF technique are discussed.