Determination of cobalamin in nutritive supplements and chlorella foods by capillary electrophoresis-inductively coupled plasma mass spectrometry.
A capillary electrophoresis-inductively coupled plasma mass spectrometric (CE-ICP-MS) method for the determination of cobalamin is described. Samples of cobalt-containing compounds were subjected to electrophoretic separation before injection into the microconcentric nebulizer (CEI-100) of ICP-MS. The Co-containing compounds studied include cyanocobalamin (CN-Cbl, vitamin B12), hydroxocobalamin (OH-Cbl), and Co(II). The species studied were well separated using a 70 cm lengthx75 microm i.d. fused silica capillary with the applied voltage set at +20 kV. A 25 mM Tris buffer (pH 9.0) containing 15 mM sodium dodecyl sulfate (SDS) was used as the electrophoretic buffer. The CE-ICP-MS detection limits were 0.3, 0.2, and 1.7 ng of Co mL(-1) for CN-Cbl, OH-Cbl, and Co(II), respectively. The concentrations of cobalamin compounds were determined in selected nutritive supplements and chlorella samples. A microwave-assisted extraction method was used for the extraction of these compounds. Over 92% of the total cobalt species was extracted using a 5% v/v HNO3 solution in a focused microwave field within a period of 10 min; spike recovery was in the range of 94-105% for various species. The major cobalt species in nutritive supplements and chlorella samples was cyanocobalamin.
Chen
Jing-Huan
JH
Department of Chemistry, National Sun Yat-sen University, Kaohsiung, Taiwan.
Jiang
Shiuh-Jen
SJ
D002708:Chlorella / Q000737:chemistry*; D019587:Dietary Supplements / Q000032:analysis*; D019075:Electrophoresis, Capillary / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012967:Sodium Dodecyl Sulfate; D053719:Tandem Mass Spectrometry / Q000379:methods*; D014805:Vitamin B 12 / Q000032:analysis*
D012967:Sodium Dodecyl Sulfate; D014805:Vitamin B 12