Determination of copper by its catalytic effect on the oxidation of hydroquinone by hydrogen peroxide on supports

The reaction of oxidation of hydroquinone by hydrogen peroxide catalyzed by copper(II) in the presence of 2,2'-dipyridyl is activated by hexamethylene diamino groups that are bonded to the surface of filter paper; additional a ctivating effect is produced by 2,2'-dipyridyl. The introduction of malonic acid dinitrile into the indicator reaction improves the sensitivity of the determination of copper and the contrast of the reaction in solution becau se of the formation of a blue product. Differently colored compounds are fo rmed on a paper support at different concentrations of copper, which makes it possible to visually distinguish the quantities of copper that differ by an order of magnitude in the range 1 x 10(-5)-0.5 mu g. Quantitative detec tion is possible in the range 5 x 10(-6)-0.1 mu g (c(min) = 3 x 10(-6) mu g ). The concentration of copper (0.2-1.5 mu g/mL) is determined in blood ser um; the consumption of the sample per one determination is 3 mu L.