A method is described for the specific and accurate determination of Se in samples by anodic stripping voltammetry following separation of the Se with pentyl alcohol. The separation procedure removes Cu(II) ions with a single extraction. After the extraction, the acidic solution can be used for the determination of Cu(II) because most of these ions remain in the solution. The height of the anodic stripping peak and the standard additions method were used as a quantitative measurement. Following the extraction, 1 x 10(-9) mol dm-3 Se can be determined; the relative standard deviation is 1% (n = 4).