Flow-injection spectrophotometric determination of cobalt(II) at low mu g 1(-1) levels with 4-benzylpiperidinedithiocarbamate

A rapid, sensitive and reproducible flow-injection (FI) analysis method is described for the spectrophotometric determination of cobalt(II) using 4-be nzylpiperidinedithiocarbamate as a chromogenic reagent. The method involves the measurement of the absorbance of the colored cobalt(II)-(4-benzylpiper idinedithiocarbamate)(2) complex at 640 nm. In the system, a microcolumn (M C) containing strong cation-exchange resin was placed between injection man ifold and spectrophotometer to increase interactions between cobalt(II) and reagent, and for preconcentration of cobalt(II). The linear range of the p roposed Fl method was 0.6-100 mu gl(-1), and the limit of detection (signal /noise = 3) was 0.1 mu gl(-1) for a 10 mul injection of cobalt(II) ion solu tion at a sampling rate of 60 h(-1). The relative standard deviation (R.S.D .) for 0.6-100 mu gl(-1) cobalt(II) was <1.0% (n = 5). The precision and ac curacy of the method were checked by analysis of certified reference metals , and the method was applied to river, sea and hot spring water samples. (C ) 2001 Elsevier Science B.V. Allrights reserved.