Detection of Flow Injection Analysis by Acousto-Optic Tunable Filter-Based Fluorimetry and its Application in the Determination of Solvent Polarity

Abstract

The instrumentation development of a fluorescence detector for flow injection analysis (FIA) based on an acousto-optic tunable filter (AOTF) is reported. The unique features of the AOTF—namely, its all-solid-state, compact, fast-scanning, and high-resolution characteristics—make it possible to develop the first fluorescence detector for FIA which is capable of recording the whole fluorescence spectrum with fine vibronic structure of the compound as it is flowing through the FIA detector. This capability, in turn, makes it possible to use this detector for the determination of the polarity of any sample by doping it with a small amount of pyrene and measuring the ratio of fluorescence intensities of band 1 and band 3. Because the sample in this case is flowing through the FIA instrument, it can be a mixture of two different solvents or surfactants by operating the FIA instrument under gradient condition. Polarity of any mixtures of solvents and surfactants can be simply, rapidly, and economically (in terms of the amount of samples and the time needed for measurements) determined.