Spectrophotometric determination for chromium (III) and cobalt (II) with 4-(nitro phenyl azo imidazole) (NPAI) as organic reagent

Sh. M. Eassa

Abstract

A sensitive and selective spectrophotometric method is proposed for the rapid determination of Chromium (III) and Cobalt (II) using (NPAI), as spectrophotometeric reagent. The maximum absorbance observed at 582 nm, and 556 nm for Cr(III) and Co(II) respectively. The molar absorptivity for Chromium (III) and Cobalt (II) complexes is (1.1497x104 and 1.0162x104) L.mol-1.cm-1 respectively. The Mole ratio [M: L] was 1:1 for the Cr (III) complex and1:2 for Co (II) complexe. The linear range of (1-19) and (1-21) respectively along with limit of detection 0.132 and 0.12 μg mL-1. Relative standard deviation for seven replication measurements (0.29% Cr and 0.27% Co),and the recovery range of (98.79) and( 99) were obtained for Cr(III) and Co(II) ions ,and Erel= -1.22 , -1 for Cr(III) and Co(II) respectively. The most important interference were due to Ni2+, Ag1+, Cu2+ and Hg2+, suitable masking agents were used.