Bis-[2,6-(2´-hydroxy-4´-sulpho-1´-napthylazo)]pyridine disodium salt (HSNP), a new heterocyclic azo dye is proposed as a sensitive spectrophotometric reagent for zinc. A selective spectrophotometric method is presented for the trace determination of zinc in blood serum using HSNP as spectrophotometric reagent (λmax = 565 nm) in basic aqueous solution (pH range = 7.5 to 9.1). The HSNP forms a 1:1 purple coloured complex. The Sandell’s Sensitivity is 1.37× 10-3 dm3 mol-1 cm-2 with molar absorptivity 4.6 ×104 mol L-1 cm-1. The proposed method has been successfully applied to the determination of zinc in blood samples of diabetic patients. The precision and the accuracy obtained were satisfactory.
