Abstract
A square wave adsorptive stripping voltammetric (SWAdSV) method for the indirect determination of trace amounts of magnesium with thiopentone sodium (TPS) as an electroactive ligand, at carbon paste mercury film electrode (CP-MFE) is proposed. It is observed that the increase of the square wave voltammetric cathodic peak current of TPS, under alkaline conditions, is linear with the increase of Mg concentration. Under optimum experimental conditions viz.; pH 10.75, 3×10−5M TPS and 0.05M phosphate buffer (Na2HPO4–NaH2PO4), a linear relation in the range 6×10−9 to 9×10−8M Mg2+ (0.14–2.16ppb), at 60s deposition time, is obtained. The detection limit of Mg2+ is 0.14ppb for 60s deposition time with the relative standard deviation is 0.5% (n=5). The proposed method was successfully applied to the determination of magnesium in urine and tap water samples with satisfactory results. The data obtained are compared with the standard flame atomic absorption spectrophotometric method (FAAS).