Stripping Voltammetric Determination of Selenium in Biological Materials by Direct Calibration

Specific and accurate determination of selenium in biological materials can be made by stripping voltammetric techniques following ion-exchange separation of the element from the bulk of the acid-digest matrix. The use of an anion-exchange method enables direct quantitation of selenium in the sample from calibration curves rather than by the normally recommended time-consuming standard addition method. The separation method described removes interferences usually encountered from other metal Ions and also enables preconcentration of the analyte. Differential pulse anodic stripping voltammetry at a rotating gold disk electrode and differential pulse cathodic stripping voltammetry at a hanging mercury drop electrode gave comparable limits of detection for selenium. However the latter approach was adopted because of its inherently greater reproducibility. Application of the method to a range of biological standard reference materials proved to be very satisfactory and it is currently being used for biomedical studies. Selenium concentrations less than 1 ng/mL can be determined by this method.