The spectrophotometric determination of microamount of zinc in yeast powder with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) in the presence of OP was studied. The sample were digested more effectively by HNO3 and H2O2 in a closed-vessel. The effects of digestion time , pressure were researched and analytical conditions optimized. The interferences of coexistent elements in yeast for the determination of Zinc were investigated. The results showed that the maximum absorption wavelength of the complex formed by Zn with 5-Br-PAD...