Comparison of laser-excited fluorescence and photoacoustic limits of detection of polynuclear aromatic hydrocarbons

Abstract

An extremely simple and sensitive system that employs both fluorescence and photoacoustic detection modes simultaneously has been used to obtain limits of detection rapidly for 30 polynuclear aromatic hydrocarbons. The sensitivities of the two techniques are compared with both fixed and tunable laser excitation and a “levelling” effect is demonstrated by the photoacoustic results. High-energy pulse excitation demonstrates that the photoacoustic signal does not increase indefinitely with incident pulse energy. Application of the simultaneous detection scheme to the measurement of fluorophor quantum efficiencies in solutions and to antifluorochrome stains is suggested.