Simultaneous Determination of Cobalt (II) and Nickel (II) Ions by H-Point Standard Addition Method

Abstract

Simple, accurate and precise spectrophotometric method was developed for the simultaneous determination of Co (II) and Ni (II) in several synthetic mixtures. The calibration curves were linear over the concentration range of 5.0E-6 to 5.0E-5 μg/mL using xylenol orange (XO) as chromogenic reagent at pH 4.4. This method was successfully applied to the simultaneous determination of cobalt (II) and nickel (II) in synthetically spiked mixtures and cobalt (II) in vitamin B12 samples. The results of applying the H-point standard addition method (HPSAM) showed that the cobalt (II) and nickel (II) ions could be determined simultaneously with concentration ratio of 20:1 and 1:20 (wt/wt). The R.S.D for a solution containing cobalt (II) and nickel (II) both at 2.0E-6M were 3.612 % and 2.183 %, respectively.