Voltammetric detection of titanium(IV) on interdigitated microelectrode array utilising its catalytically enhanced current with hydroxylamine

A novel electroanalytical method for the determination of titanium(IV) in plastic bags was developed. It is based on its reduction on platinum interdigitated microelectrode array (IDA) in the presence of oxalate. The electrode response is substantially higher when excess of hydroxylamine is added to the solution causing catalytic enhancement of titanium cathodic current. The detection limit of this method can be decreased further by using a pair of shortly circuited comb shaped segments of IDA with overlapping diffusion layers of both segments. The array behaves as a macroelectrode with area equal to the sum of areas of both segments and the area of insulating gap between them, however the charging current is lower due to the low area of conducting platinum layers in the interdigitated microelectrode array. The detection limit of 2 × 10−7 mol dm−3 was obtained in 0.2 mol dm−3 oxalic acid with 0.08 mol dm−3 hydroxylamine as supporting electrolyte. The method was applied to the analysis of plastic bags from sugar, milk and tea containing dyes based on titanium(IV) dioxide.