Simultaneous determination of iron and copper in pregnant liquid solutions

A new method for the determination of FeTotal and Cu is proposed. The method is based on the formation of the iron and copper complexes with 5-sulfosalicylic acid (SSA), the optimal conditions were found, using SSA 5.1 g L−1 in the presence of ammonia 7.5 g L−1 (pH = 10). Under these conditions the selected analytical wavelengths were 488.5 and 423.5 nm for the determination of iron and copper, respectively, by using the zero crossing approach. The detection and quantification limits were 0.02 mg L−1 and 0.07 mg L−1 for iron and 1.14 mg L−1 and 3.80 mg L−1 for copper. The proposed method was applied to the determination of both analytes in pregnant liquid solutions and the recovery was between 98% and 100% and in all cases the relative standard deviation was minor to 2%.