EVALUATION OF A FIELD-TEST KIT FOR MONITORING LEAD IN DRINKING-WATER

This article describes a conceptual framework for designing evaluation studies of test kits for the analysis of significant drinking water c onstituents. A commercial test kit for the analysis of lead in tap wat ers was evaluated and compared with a standard graphite furnace atomic absorption spectrophotometry (GFAAS) technique. The kit was relativel y free of operator bias and had a detection limit of 4 mug/L in spiked deionized water. Above the detection limit of the kit, accuracy was c omparable to that of GFAAS when samples were analyzed in triplicate. T he relative precision of the kit varied with concentration. The absolu te precision of the kit was about +/-3 mug/L from 10 to 100 mug/L. Sig nificant interferences were found for certain concentration thresholds of zinc, iron [Fe(II)], polyphosphate species, and orthophosphate. Hi gh concentrations of aluminum and chloride reduced method precision. S everal operational changes are presented that improve precision and ac curacy of the test kit for field and laboratory use.