RESUMO
Recently, cobalt (Co) is reported to be taken as a supplement by athletes for improving anaerobic performance. For the diagnosis of abuse, the limit of detection (LOD) of Co in the analysis should be lower than the concentrations of Co in plasma and urine of normal persons. A simple, rapid and sensitive method has been developed for the determination of Co in urine. Co was complexed with diethyldithiocarbamate (DDC) and extracted with isoamyl alcohol in the presence of citric acid. The detection of Co was achieved by injecting a 1-microL aliquot of isoamyl alcohol containing Co-DDC complex directly into an electrospray ionization tandem mass spectrometric (ESI-MS-MS) instrument without chromatographic separation. The quantification was performed using selected reaction monitoring at m/z 291 of the product ion Co(C(4)H(10)NCS)(2)(+) which was produced by collision-induced dissociation from the precursor ion Co(DDC)(2)(+) at m/z 355. ESI-MS-MS data were obtained in less than 10 min with an LOD of 0.05 microg L(-1) and a linear calibration range of 0.1-100 microg L(-1) using 10 microL of urine. The procedure was validated with certified reference materials (SRM 2670a and SRM 1643e). This method is suitable for the analysis of Co in the laboratories already equipped with an ESI-MS-MS instrument.