Laser-induced fluorescence with an OPO system. Part I. Optimisation of the analytical system by use of experimental design methodology. Application to the direct quantification of traces of benzo[a]pyrene

Abstract : This study deals with the optimisation and application of a method for direct analysis of trace pollutants in water by laser-induced fluorescence. The arrangement used consisted of an Nd:YAG Laser coupled with an optical parametric oscillator (LYOPO) and connected to a spectrophotometer and a high-sensitivity camera. Optimisation was achieved by developing an experimental design methodology to maximise the signal-to-noise ratio and reduce the limit of detection. The technique was then applied to the detection of benzo[a]pyrene in water. The experimental results were evidence of its high sensitivity and time-resolution potential. The detection limit for benzo[a]pyrene was 0.7 ng L-1 in drinking water and 4 ng L-1 in raw water containing 1 mg L-1 humic acids.