Resonance Rayleigh scattering for an indirect determination of trace amounts of selenium(IV) with iodide-basic triphenylmethane dye systems

The resonance Rayleigh scattering (RRS) spectra of selenium(IV)/iodide/basic triphenylmethane dye systems have been studied. Intense RRS appears when selenium(IV) reacts with iodide and a basic triphenylmethane dye, such as Crystal Violet (CV), Ethyl Violet (EV), Brilliant Green (BG), Malachite Green (MG) and Iodine Green (IG), to form an ion-association complex. The characteristics of the RRS spectra of the ion-association complexes and the suitable conditions for the reactions were investigated. The intensity of RRS is directly proportional to the concentration of selenium(IV) in the range 0 - 0.30 mu g/25 ml for the CV and EV systems, and 0 - 0.40 mu g/25 ml for other systems. The RRS methods have very high sensitivities for an indirect determination of selenium(IV); the detection limits are between 0.094 ng/ml and 0.86 ng/ml for different dye systems. A new way to determine trace amounts of selenium based on the RRS spectra of the ion-association complex has been developed.