Determination of cobalt in animal feces by tungsten coil atomic absorption spectrophotometry

An alternative analytical procedure for cobalt determination by tungsten coil electrothermal atomic absorption spectrophotometry (TCAAS) was developed to determine the liquid ruminal passage rate (turnover) of Co-EDTA in sheep feces. A matrix-matching procedure and a selective extraction of Co in 1.0 mol l(-1) HCl were evaluated in order to correct and minimize the interference effects caused by sample matrices. As application, six sheep received at the same time one dose of the marker (Co-EDTA); thier fecal samples were collected in intervals of 6 h during 90 h. The Co amounts determined in the dry sheep feces by TCAAS were compared with those obtained by a flow injection catalytic spectrophotometric method. The characteristic mass and the detection limit, both based on peak height absorbance, were 23.1 and 19.1 pg, respectively, for 10 mi of sample volume in the samples of sheep feces. The rsd was 0.5% for 10 consecutive injections of 20.0 mg Co l(-1). The accuracy was assessed by employing the paired t-test at 95% confidence level; there was no significant difference for Co content determined by TCAAS and by flow injection spectrophotometry.