CATALYTIC DETERMINATION OF COBALT BY FLOW-INJECTION SPECTROPHOTOMETRY- APPLICATION IN ANIMAL FECES ANALYSIS USING HYDROCHLORIC-ACID AS EXTRACTING SOLUTION

A flow injection system for cobalt determination in faeces of bovines and equines receiving Co-EDTA as a tracer in animal nutrition studies is proposed, using 1.0 mol HCl l(-1) as extracting medium, and detecti on by flow injection spectrophotometric procedure based on the catalyt ic effect of Co(II) on the oxidation of Tiron by hydrogen peroxide. Li nearity was observed up to 8.0 mu g Co l(-1), and the detection limit was 0.2 mu g Co l(-1) (3 s blank). The system requires 0.12 mg Tiron p er determination and handles 65 samples h(-1). No baseline drift was o bserved during extended operation periods (8 h) and precise results (r .s.d.<l%) were detected. Accuracy was confirmed by running several fae ces samples already analysed by flame atomic absorption spectrometry. Results related to the HCl extraction procedure were in close agreemen t with those obtained using the nitric-perchloric digestion (y=0.978x0.101, R-2=0.9848), suggesting that HCl extraction and flow injection determination can be used routinely for rapid analysis of cobalt in fa eces, (C) 1998 Elsevier Science B.V.