DETERMINATION OF COBALAMINS AND COBINAMIDES BY MICROBORE REVERSED-PHASE HPLC WITH SPECTROPHOTOMETRIC, ION-SPRAY IONIZATION MS AND INDUCTIVELY-COUPLED PLASMA MS DETECTION

Microbore reversed-phase HPLC was optimized for the separation of cyan ocobalamin, 5'-desoxyadenosylcobalamin (coenzyme Bit), methylcobalamin , hydroxocobalamin, aquocobalamin and cobinamide dicyanide isoforms. V arious detection modes: UV at 278 nm, ion-spray (IS)-MS and direct-inj ection nebulization ICP-MS were examined and compared. IS-MS allows on e to identify, unambiguously, the eluted compounds, whereas ICP MS was found to be more sensitive than any other on-line detection technique s described for the cobalamin analogues, so far allowing to achieve de tection limits down to ca. LO ng ml(-1). The usefulness of the methods developed was demonstrated for the determination of cobalamins presen t in pharmaceutical preparations. (C) 1998 Elsevier Science B.V.