Sorption-catalytic testing of copper on a paper-based sorbent with attached alkylamino groups

Copper(II) was preconcentrated from aqueous solution on paper filters with chemically attached hexamethylenediamino (HMDA) groups and determined direc tly on the filters by its catalytic action in the oxidation of hydroquinone with H2O2 in the presence of 2,2'-dipyridyl; the reaction was monitored by measuring the absorbance of wet filters. The linear calibration graph of a bsorbance at 5 min versus log c(Cu) permits the semiquantitative determinat ion of Cu-II over the range 1 x 10(-6)-0.1 mg l(-1) for a sample volume of 10 ml. Tolerance ratios for foreign ions are 3-4 orders of magnitude more f avorable in the hybrid sorption-catalytic procedure than those for the cata lytic determination of copper in solution without preconcentration. The pro cedure is simple and does not require any expensive instrumentation. Sample s of tap and sea-water were analyzed.