A new method of spectrophotometric determination of copper with N-heptyl-N’-(sodium p-aminaobenzenesulfonate) thiourea(HABST) has been reported. And the optimum conditions has been studied. In HAc-NaAc buffer solution at pH4.5～6.0, Cu 2+ HABST forms a 1:3 stable blue water soluble complex with an apparent molar absorptivity of ε 347.6 =4.5110 4L·mol -1 ·cm -1 . Beer’s law is applicable in the range of 5～μg/25ml Cu 2+ . It has been used to the determination of copper in biological samples with satisfactory results and ercoveries.
