Determination of Phosphorus in Calcium-Iron Cored Wire by Spectrophotometry with Ethyl Violet-Molybdovanadophosphoric Heteropoly Acid System

Ethyl violet with molybdovanadophosphoric heteropoly acid formed a blue ion-association complex in 0.7—1.0mol/L nitric acid medium in the non-ion(O/w) of microemulsion(OP/n-C5H11OH/n-C7H16/H2O).The association matter maximum absorption was at 612nm,and Beer's law was obeyed for 0.03—0.4μg/mL of phosphorus,and the molar absorptivity was1.58×l05L·mol-1·cm-1.The lowest detection limit was 0.008μg/mL,The method was applied to the determination of phosphorus in iron-calcium cored wire samples,the relative standard deviation was less than 5%,and the recovery was in the range of 97.5%—101.5% with a satisfaction results.