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A critical comparison of phase-selective fundamental harmonic a.c. anodic stripping voltammetry and differential pulse anodic stripping voltammetry for the determination of Pb, Cd, Cu and Zn in sea-water is reported. Differential pulse anodic stripping voltammetry was found to be slightly more sensitive than the a.c. technique, but the effect of the charging current could be more effectively eliminated by the latter, especially in the determination of zinc(II) and copper(II). The detection limits for both techniques were found to be about 10-10 M for all four elements. The precision, expressed as relative standard deviation, was of the order of 2-5% for the fundamental harmonic a.c. method and 5-8% for differential pulse voltammetry. The accuracy (expressed as recovery) was 95-105% for the former and 90-110% for the latter. [ABSTRACT FROM AUTHOR]

Alternating current (ACV) and differential pulse voltammetry (DPV) are employed for the determination of Cr(VI) in dialysis fluids, using 0.1 mol/1 dibasic ammonium citrate as supporting electrolyte (pH 5.9). A three-electrode cell was used: The working electrode was a long-lasting sessile-drop mercury electrode (LLSDME) with a drop time of 240 to 300 s. Precision, expressed as relative standard deviation ( s%), and accuracy, expressed as relative recovery ( R%) are also reported. [ABSTRACT FROM AUTHOR]