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

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 10 μg l−1 for FBZ and between 0.08 and 20 μg l−1 for TBZ with 3σ detection limits of 0.012 and 0.02 μg l−1, respectively. The relative standard deviation (n=10) was 0.3% for 1 μg l−1 of FBZ and 0.5% for 2 μg l−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.