The effects of CopperZinc and CopperCadmium intermetallic compounds in different systems used for anodic stripping voltammetry

The CuZn intermetallic compound resulting from simultaneous deposition of copper and zinc at a hanging mercury drop electrode (HMDE) and at preformed mercury film electrodes (MFE) has been studied. Goals were to determine what conditions can be used to avoid intermetallic compound formation and to reduce errors that result from the method of standard additions. For Cu 2+ and Zn 2+ concentrations in the ng ml −1 range, the use of shortened preconcentration times in conjunction with a differential pulse stripping waveform and the HMDE show significant reduction in the extent of the interference. The CuCd interference was also characterized at performed MFE's and at MFE's deposited in situ from 5–300 μg ml −1 mercury(II) solutions. No significant interference with the cadmium stripping were was observed with preformed MFE's, but peak depression was observed when the electrodes were deposited in situ. The degree of interference was found to decrease with both increased mercury(II) concentrationa and decreased copper(II) concentration. Errors in the standard addition method are minimal when the copper(II) concentration is not significantly altered.