[Simultaneous determination of iron, cobalt and nickel in oil by multiwavelength linear regression spectrophotometry]

A method for simultaneous determination of iron, cobalt and nickel, using multiwavelength linear regression spectrophotometry, is proposed. Since there were no interferences caused by cobolt and nickel complexes at the peak of iron complex compound formed with 5-Br-PADAP at 750 nm, the content of iron was determined by working-curve method at 750 nm. Cobalt and nickel were simultaneously determined by multiwavelength linear regression method over the range 550-600 nm. The method was applied to the analysis of iron, cobalt and nickel in synthetic mixtures and oil samples with satisfactory results. The recovery was 97.5%-104.3% and the RSD% was 1.4%-3.8%.