Modified Square-Wave Cathodic Stripping Voltammetry for Determination of Se(IV) at Trace and Ultratrace Levels

✍ Scribed by Vladimir Sladkov; Andras Bolyos; François David

• Publisher: John Wiley and Sons
• Year: 2002
• Tongue: English
• Weight: 148 KB
• Volume: 14
• Category: Article
• ISSN: 1040-0397
• DOI: 10.1002/1521-4109(200201)14:2<128::aid-elan128>3.0.co;2-e

✦ Synopsis

A method for the improvement of the signal-to-noise ratio in square-wave (SW) voltammetry is proposed. It is based on the modification of a square-wave waveform. This method is applied to cathodic stripping voltammetric (CSV) determination of selenium(IV) in nitric acid solutions. Hanging mercury drop electrode (HMDE) was used in the presence of Cu(II) ions. The optimal conditions were chosen: square-wave waveform mode, pH, time and potential of electrodeposition. Kinetic processes of copper selenide reduction with the use of SWCSV, applying different squarewave waveforms, are studied. Quasi-reversible processes are observed. The standard reaction rate constants are evaluated for different square-wave waveforms. It is shown that the determination of Se(IV) by this modified SWCSV technique is possible with an excellent sensitivity (the detection limit 8 Â 10 À12 mol L À1 only for 5 min of electrodeposition) and good reproducibility (S r < 8%) in a wide range of concentration (1 Â 10 À11 À 1 Â 10 À6 mol L À1 ) of Se(IV). The presence of Mo(VI), Pb(II), Ni(II), Zn(II), Cr(VI) metal ions with molar excess around 1000 do not prevent the detection of Se(IV) signals.