title: [Determination of trace cobalt in water samples by graphite furnace atomic absorption spectrometry after cloud point].
abstract: In buffer solution of citric acid monohydrate-disodium hydrogen phosphate at pH 5-7.5, cobalt water samples were chelated by 1-(2-pyridylazo)-2-naphthol (PAN) to form Co-PAN. After water-bath at 66 degrees C for two hours, Co-PAN is extracted into Triton X-100 nonionic surfactant phase and separated from bulk water. Extracted cobalt content was measured by graphite furnace atomic absorption spectrometry. The surfactant phase separated was treated with 0.5% HNO3-0.1% Pd(NO3)2 to remove background interference at 1200 degrees C temperature. The pre-concentration of cobalt in water samples permitted the detection of 0.003 microg x L(-1) (10sigma) with the enhancement factor of 100. The recoveries were 90.5%-106%. The proposed method was applied to the determination of cobalt in water samples and satisfactory results were obtained.
authors.affiliation: Shantou University Medical College Central Laboratory, Shantou 515041, China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Wen-hong
authors.initials: WH
authors.lastname: Luo
authors.forename: Hui
authors.initials: H
authors.lastname: Li
mesh_terms: D003035:Cobalt / Q000032:analysis*; D005618:Fresh Water / Q000032:analysis / Q000737:chemistry; D006108:Graphite; D006863:Hydrogen-Ion Concentration; D008900:Mineral Waters / Q000032:analysis; D009284:Naphthols / Q000737:chemistry; D017942:Nitric Acid / Q000737:chemistry; D017830:Octoxynol / Q000737:chemistry; D015203:Reproducibility of Results; D045483:Rivers / Q000737:chemistry; D012623:Seawater / Q000032:analysis / Q000737:chemistry; D013054:Spectrophotometry, Atomic / Q000379:methods*; D013696:Temperature; D014867:Water / Q000032:analysis* / Q000737:chemistry; D014881:Water Supply / Q000032:analysis
chemical_list: D008900:Mineral Waters; D009284:Naphthols; D014867:Water; C041728:1-(2-pyridylazo)-2-naphthol; D003035:Cobalt; D017942:Nitric Acid; D006108:Graphite; D017830:Octoxynol