RESUMO
Objective To establish a new method for determination of trace cadmium in river water. Methods Cadmium in river water was separated and enriched with sulfhydryl cotton, in the presence of 4?10~3 % emulsifier OP and H3PO4-NaH2PO4 water solution, Victoria Pure Blue BO reacted with [CdI4]2- forming an ionic-associated complex and the color of the solution changed from yellow to pure blue, and the content of trace cadmium in river water was determined by spectrophotometry. Results When cadmium was enriched fifty times, the apparent molar absorptivity of the associated complex was ?=2.79?10_5 L/(mol?cm). Beer's law was obeyed in the range 2-100 ?g/L. The recovery rate and RSD of the method was 96.2%-98.6% and 2.5% respectively. Conclusion The method was accurate and sensitive,and was suitable for determination of trace cadmium in river water.