Application of derivative spectrophotometry to simultaneous determination of lead and nickel with MEDTA

The application of derivative spectrophotometry to the simultaneous determination of lead(II) and nickel(II) with methylethylenediaminetetraacetic acid (MEDTA) is described. The procedure does not require equations to be solved, and is suitable for concentrations of 0.04-0.30 mg mL(-1) of lead and 0.20-2.60 mg mL(-1) of nickel. The main interferences, both anionic and cationic, are easily eliminated. The method was applied to different aqueous matrices and compared with an atomic absorption (AA) method. Good results were obtained.