Determination of ultra-trace concentrations of tin by adsorptive cathodic stripping voltammetry on a glassy carbon mercury film electrode

✍ Scribed by Samuel B.O. Adeloju; Fleurdelis Pablo

• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 666 KB
• Volume: 270
• Category: Article
• ISSN: 0003-2670
• DOI: 10.1016/0003-2670(92)80101-c

✦ Synopsis

A sensitive and selective method is described for the determination of ultra-trace concentrations of tin by adsorptive cathodic stripping voltammetry on a glassy carbon mercury film electrode. The method involves a controlled preconcentration by accumulation of tin-catechol complexes on the electrode followed by stripping voltammetric measurement in the cathodic direction. The optimum conditions for the determination of tin by this method include the use of a rotated electrode at 1920 rpm, 0.10 M acetate buffer electrolyte (pH 4.2-4,7), 5 x 10 -4 M catechol and an accumulation potential of -0.20 V vs. Ag/AgCI. A linear concentration range is obtained from 0 to 35/xg 1-1 and the limit of detection is 0.5/zg 1-i for an accumulation period of 300 s. An interference study with~ various metal ions indicated that these substances generally do not interfere with the tin determination, except for Cu, Cd and Cr. The interference of Cu and Cd is eliminated by the addition of 1 x 10 -6 M EDTA into the solution. The interference of surface-active organic substances, e.g., Triton X-100, is overcome by UV irradiation of the sample for at least 2 h. The method was successfully employed for the determination of tin in fruit juices. Comparison of the results obtained for the juices demonstrated reasonable agreement with those obtained by atomic absorption spectrometry.

Keywords." Stripping voltammetry; Fruit juices; Tin

Tin is one of the essential trace elements which are involved in various metabolic processes in plants, animals and man [1]. Besides ingestion from food, it is introduced into the human environment both as inorganic tin and as organotin compounds, through their use in food packaging, as fungicides in crops, in some veterinary formulations, in wood preservation, in marine anti-fouling paints, as stabilizer for poly(vinyl chloride