Determination of cobalamins using capillary electrophoresis inductively coupled plasma mass spectrometry

The determination of cobalamins using capillary electrophoresis inductively coupled plasma mass spectrometry (CE-ICP-MS) was investigated. Both capill ary zone electrophoresis (CZE) and micellar electrokinetic chromatography ( MEKC) modes of operation were studied. The optimal separation of four cobal amin species (cyanocobalamin, hydroxocobalamin, methylcobalamin, and 5'-deo xyadenosylcobalamin) and a potentially harmful corrinoid analogue (cobinami de dicyanide) was obtained using CZE at a pH of 2.5. Both 20 mM phosphate a nd 20 mM formate buffers were used with success, although the formate buffe r provided improved resolution. The CZE-ICP-MS method was used to quantify cyanocobalamin in a vitamin supplement and the analytical results were in g ood agreement (+/-5%) with values obtained by ICP-MS for total Co levels. T he solution detection limits for cobalamins using CZE-ICP-MS were approxima tely 50 ng/ml. MEKC was found to be useful for the screening of vitamin pre parations because it provided a rapid means of distinguishing cyanocobalami n (the form most commonly used in Vitamin preparations) from free cobalt. T he separation of free cobalt and cyanocobalamin using MEKC was achieved in less than 10 min. Published by Elsevier Science B.V.