Anodic-stripping voltammetry of heavy metals in the presence of organic surfactants.
The efficacy of fumed silica for removal of sorption interferences by organic surfactants in the anodic-stripping voltammetry of heavy metals is demonstrated. Appropriate addition of silica to the sample solution rapidly "purifies" it from interfering surfactants during the nitrogen purge step. Up to at least 6 ppm of gelatin, Triton X-100, albumin or Liqui-Nox then does not affect the stripping response of cadmium, lead and zinc at the hanging mercury drop electrode. A relative standard deviation of 5.5% is obtained for 20 successive measurements of 1 x 10(-7)M lead in the presence of 2 ppm Triton X-100. Analogous improvements are observed at the mercury film electrode (in the presence of up to 60 ppm of these surfactants). The use of silica thus possesses the advantages of speed, efficiency, simplicity and low cost compared to other schemes for dealing with surfactant interferences in anodic-stripping voltammetry.