title: Combined use of HPLC-ICP-MS and microwave-assisted extraction for the determination of cobalt compounds in nutritive supplements.
abstract: 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) and hydroxylcobalamin (OH-Cbl), were well separated by reversed phase HPLC with a C8-HPLC column as the stationary phase and 8 mmol L(-1) ammonium acetate in 22%v/v methanol solution (pH 4) as the mobile phase using isocratic elution. Detection limit was in the range of 0.008-0.014 μg CoL(-1) for various Co species. Over 98% of the total cobalt species was extracted in nutritive supplements using a 0.5%v/v HNO3 solution in a microwave field; and the spike recovery was in the range of 92-108% for various species. The HPLC-ICP-MS results showed a satisfactory agreement with the total cobalt concentrations obtained by ICP-MS analysis of completely dissolved samples.
authors.affiliation: Department of Chemistry, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan.
authors.forename: Fang-Yu
authors.initials: FY
authors.lastname: Yang
authors.forename: Shiuh-Jen
authors.initials: SJ
authors.lastname: Jiang
authors.forename: A C
authors.initials: AC
authors.lastname: Sahayam
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003035:Cobalt / Q000032:analysis* / Q000302:isolation & purification; D019587:Dietary Supplements / Q000032:analysis*; D059625:Liquid-Liquid Extraction / Q000379:methods*; D013058:Mass Spectrometry / Q000379:methods*; D008872:Microwaves
chemical_list: D003035:Cobalt
keywords: Cobalt speciation analysis; Electrospray ionisation-mass spectrometer; Inductively coupled plasma mass spectrometry; Nutritive supplements; Reversed-phase chromatography