Abstract

ESPINOZA CASTELLON, Erick R.  and  ALVARADO GAMEZ, Ana L. Devolopment and validation of a voltamperometric method to determine total tin in water. Rev. Int. Contam. Ambient [online]. 2012, vol.28, n.1, pp.61-72. ISSN 0188-4999.

A sensitive analytical method to determine traces of tin in distilled water, deionized water, tap water, river water and sea water by adsorptive differential pulse cathodic stripping voltammetry, oxalic acid as a ligand and methylene blue as a catalytic reagent was developed, under optimal conditions: initial potential -300 mV, final potential -700 mV, preconcentration potential -350 mV, electrodeposition time 30 s, scan rate 20 mV/s, pulse amplitude 40 mV and pulse width 20 ms. Different peaks signals were studied by cyclic, differential pulse and square wave voltammetry, for oxidation and reduction processes and systems: Sn²⁺ / Sn⁰, Sn⁰ / Sn²⁺ and Sn²⁺ / Sn⁴⁺. The proposed methodology has a limit of detection 0.03 µg/L and a limit of quantification 0.11 µg/L, with an average sensitivity 24 nA/(µg/L) in a dynamic range between 0.1 and 20 µg/L. Recovery rates of spiked water samples of 109, 109 and 113 % were obtained for 0.50, 2.00 and 10.02 µg/L of tin in water, and variation coefficient of 7.5, 4.8 and 6.9 %, respectively. Total tin concentration found among different water samples vary between 0.5 and 5.4 µg/L.

Keywords : adsorptive voltammetry; tin; trace analysis; methylene blue; oxalic acid.

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