Determination of iron(III) and copper(II) by zeroth, first and second derivative spectrophotometry with 2-thiobarbituric acid (4,6-dihydroxy-2-mercaptopyrimidine) as reagent

Sensitive methods for the determination of iron(III) alone and of iron(III) and copper(II) in mixtures, using 4,6-dihydroxy-2-mercaptopyrimidine (2-thiobarbituric acid), by normal and derivative spectrophotometry have been studied and compared experimentally. Fundamental conditions for the determination and the composition of the iron(III)- 2-thiobarbituric acid complex are discussed. A statistical analysis of the results is reported.