A. C. Sahayam
Bhabha Atomic Research Centre, Hyderabad
Dr. A. C. Sahayam completed his PhD at the age of 37 years from Osmania University, Hyderabad (India) and Postdoctoral research work at National Sun-Yat Sen University, Kaoshiung (Taiwan). He is Head, Bulk Analysis Section at National Centre for Compositional Characterisation of Materials, Bhabha Atomic Research Centre, Hyderabad. His field of expertise is analytical atomic spectrometry using ICP-OES and ICP-MS coupled with different sample introduction techniques. He has published more than 50 papers in reputed journals and serving as a reviewer for reputed journals.
Speciation analysis of cobalt in nutritive supplements has been carried out using HPLC and ICP-MS equipped with a membrane desolvation sample introduction system as detector. In this study, cobalt containing compounds, namely Co(II), cyanocobalamin (CN-Cbl), hydroxylcobalamin (OH-Cb1), 5’-deoxyladenosylcobalamin (Ado-Cbl) and methylcobalamin (Me-Cbl), were well separated by reversed phase HPLC with a microbore C8-HPLC column as the stationary phase. Gradient elution using ammonium acetate and acetonitrile at pH 4 allowed the chromatographic separation of all species, including strongly adsorbed Ado-Cbl and Me-Cbl, in less than 14 minutes. Detection limit was in the range of 0.007-0.031 ng Co mL-1 for various Co species. We determined the concentrations of cobalt containing compounds in selected nutritive supplements and two functional drinks. Over 91% of the total cobalt species was extracted using a 0.5% v/v HNO3 solution in a microwave field at 70oC within a period of 10 min; and the spike recovery was in the range of 94-101% for various species. The HPLC-ICP-MS results showed a satisfactory agreement with the total cobalt concentrations obtained by ICP-MS analysis of functional drinks and dissolved nutritive supplements samples.