title: Electrochemical detection of cobalt in hair following on-column derivatization with 1-(2-pyridylazo)-2-naphthol-6-sulphonic acid and reversed-phase liquid chromatography.
abstract: A method for the specific determination of cobalt based on reversed-phase liquid chromatography with amperometric detection via on-column complex formation has been developed. A water-soluble chelating agent, 1-(2-pyridylazo)-2-naphthol-6-sulphonic acid (PAN-6S), is added to the mobile phase and aqueous cobalt solutions are injected directly into the column to form in situ the cobalt-PAN-6S chelate, which is then separated from other metal PAN-6S chelates and subjected to reductive amperometric detection at a moderate potential of -0.3 V. Because the procedure eliminates the interference of oxygen and depresses the electrochemical reduction of the mobile phase-containing ligand PAN-6S, by virtue of the quasi-reversible electrode process of the cobalt-PAN-6S complex, a low detection limit of 0.06 ng can be readily obtained. Interference effects were examined for sixteen common metal species, and at a 5- to 8000-fold excess by mass no obvious interference was observed. The feasibility of the method as an approach to the specific analysis of cobalt in a hair sample has been demonstrated.
authors.affiliation: Laboratory of Electroanalytical Chemistry, Chinese Academy of Sciences, Changchun, Jilin.
authors.forename: J
authors.initials: J
authors.lastname: Zhou
authors.forename: L
authors.initials: L
authors.lastname: Zhang
authors.forename: E
authors.initials: E
authors.lastname: Wang
mesh_terms: D002853:Chromatography, Liquid; D003035:Cobalt / Q000032:analysis*; D004563:Electrochemistry; D006197:Hair / Q000737:chemistry*; D006801:Humans; D007094:Imides; D007202:Indicators and Reagents; D009282:Naphthalenesulfonates; D013056:Spectrophotometry, Ultraviolet
chemical_list: D007094:Imides; D007202:Indicators and Reagents; D009282:Naphthalenesulfonates; D003035:Cobalt; C084535:1-(2-pyridylazo)-2-naphthol-6-sulfonic acid