Paper tests for the determination of heavy metals in waste and natural waters

Reactive papers are proposed for the semiquantitative determination of copper(II), iron(III), zinc, cadmium, mercury(II), silver, and lead based on the intensity of color that appears after pumping a certain volume of the test liquid through the paper. The test systems involve precipitates of lead diethyldithiocarbamate; copper hexacyanoferrate(II); copper, zinc, and cobalt dithizonates; and zinc sulfide immobilized in pores of paper filters and capable of exchanging test ions to give compounds with intense and contrast colors. A testing nozzle is proposed for pumping the test liquid through reactive papers. It consists of two frustums of circular cones inserted one into another through the intermediary test paper, base to base. Rapid test methods have been developed for determining 0.001-0.1 mg/L of copper(II), 0.01-1 mg/L of lead and iron(III), 0.001-1 mg/L zinc and mercury(II), and 0.005-1 mg/L of cadmium and silver in waste and natural waters. Analysis time was 10-15 min, the relative standard deviation of the results of analysis in the vicinity of the lower determination limit was no worse than 50%.