Suppression of surfactant interferences in anodic stripping voltammetry by sodium dodecyl sulfate

Abstract

It was investigated whether interferences from surfactants in anodic stripping voltammetry (ASV) could be remedied by the anionic surfactant sodium dodecyl sulfate (SDS) which causes little or no interference in itself. Cadmium and lead were used as test analytes, and measurements were performed in acetate buffer as well as in 0.1 M HNO 3. One hundred parts per million of the interfering surfactant was added. SDS eliminated severe interference from the non-ionic surfactants Triton © X-100 and dodecyl octaethylene glycol ether as well as from the polymer polyethylene glycol 6000 and from the cationic surfactant cetyl trimethyl ammonium bromide. SDS could not remedy the extraordinarily severe interference from the cationic surfactant cetyl pyridinium chloride. Two anionic surfactants were also tested as interferents but they had little detrimental effect on the ASV signals. The effect of SDS was explained by the formation of mixed micelles which scavenge the interferent in the bulk solution and by competitive displacement of the interferent at the electrode surface.