Sequential injection analysis for the determination of fuberidazole and thiabendazole by variable-angle scanning fluorescence spectrometry

A study of the behaviour of fuberidazole (FBZ) (2-(2´-furyl)benzimidazole), and thiabendazole (TBZ) (2-(thiazol-4-yl)benzimidazole) in a sequential injection system with a fluorimetric detector has been performed. Several variables such as pH, composition of buffers, volumes of sample and reagents, addition order, geometry of mixing coil and spectrofluorimetric parameters have been optimised. A pH 2 buffer solution was found to be optimal for both FBZ and TBZ. The calibration graphs are linear between 0.04 and 10µgl-1 for FBZ and between 0.08 and 20µgl-1 for TBZ with 3sigma detection limits of 0.012 and 0.02µgl-1, respectively. The relative standard deviation (n=10) was 0.3% for 1µgl-1 of FBZ and 0.5% for 2µgl-1 of TBZ. Resolution of the system was carried out by applying a multiple linear regression (MLR) calibration model. The method was applied to the determination of both fungicides added to natural waters. Recoveries between 96 and 106% were achieved.