On-line submicellar enhanced fluorometric determination of Se(IV) with 2,3-diaminonaphthalene

The flow injection (FI) analytical determination of Se(IV) with 2,3-diaminonaphthalene (DAN) was assayed employing enhanced fluorometric detection. The different variables affecting the reaction rate between Se(IV) and DAN were studied in batch mode, and the best conditions for the 4,5-benzopiazselenol (Se–DAN complex) formation were found. On this basis, two different FI manifolds able to give optimal sensitivity were designed. Once established the optimal flow conditions for the product formation, a submicellar medium of sodium dodecylsulphate with the addition of (beta)-cyclodextrin was tested to perform enhanced fluorometric detection. A limit of detection of 0.3 (mu)g1^-1 of Se(IV), a linear dynamic range ranging between 1 and 500 (mu)g1^-1 of Se(IV) and a sampling throughput of 40 samples h^-1 were obtained. A full discussion on each stage of the optimisation procedure and the validation of the propose methodology is provided.