HEXADECYLPYRIDINIUM CHLORIDE MICELLES FOR THE KINETIC DETERMINATION OF SULFUR-CONTAINING-COMPOUNDS BY THEIR INDUCTION OF THE IODINE-AZIDE REACTION

The potential use of the association formed by triiodide ion and hexad ecylpyridinium chloride (cetylpyridinium chloride, CPC) for the determ ination of sulphur-containing compounds, which act as inductors for th e iodine-azide reaction was investigated. Triiodide ion interacts with CPC cationic micelles, which results in maximum absorption at 500 nm in addition to a substantially increased absorptivity and stability co nstant of the triiodide complex. The micellar medium allows the determ ination of reduced glutathione, tetramethylthiuram disulphide and ethy lenebis-dithiocarbamic acid (zineb) in the ranges (2-10)x10(-7) M, (8- 63)x10(-9) M and 40-450 ng ml(-1), respectively, with detection limits (3 sigma) for the three inductors of 0.7x10(-7) M, 5.4x10(-9) M and 3 2 ng ml(-1), respectively. The presence of the surfactant allows one t o determine lower concentrations of tetramethylthiuram disulphide, red uced glutathione and zineb by factors of 51, 32 and 2.5 respectively, relative to the aqueous medium. The proposed method has been applied t o the determination of reduced glutathione in whole blood samples and to the fungicide tetramethylthiuram disulphide present in a commercial formulation used in agriculture.