POTENTIOMETRIC STRIPPING ANALYSIS AT MICROELECTRODES IN VARIOUS SOLVENTS AND SOME COMPARISONS WITH VOLTAMMETRIC STRIPPING ANALYSIS

Potentiometric stripping analysis (PSA) differs from the better known voltammetric stripping analysis (VSA) in that the electrochemically preconcentrated analyte is stripped chemically, rather than electrochemically. We present here comparisons of lower detection limits and other features of PSA and VSA at both macro- and microelectrodes consisting of thin films of mercury on glassy carbon, carbon fiber, and gold substrates. The possibility that certain amalgams and/or metals that undergo sluggish electrochemical oxidation would exhibit more facile chemical oxidation was investigated. It was found that in fact the PSA of manganese and nickel is analytically more favorable than the VSA of these metals. The applicability of PSA to such electropositive elements as sodium and potassium, described by us before, was further improved. Fair resolution of sodium from potassium was obtained by solvent optimization and the use of microelectrodes on gold substrates. The PSA of lithium is much less favorable than that of sodium or potassium.