title: Synthesis and application of a new thiazolylazo reagent for cloud point extraction and determination of cobalt in pharmaceutical preparations.
abstract: The synthesis and characterization of the reagent 2-(5-bromothiazolylazo)-4-chlorophenol and its application in the development of a preconcentration procedure for cobalt determination using flame atomic absorption spectrometry after cloud point extraction is presented. This procedure is based on cobalt complexing and entrapment of the metal chelates into micelles of a surfactant-rich phase of Triton X-114. The preconcentration procedure was optimized by using a response surface methodology through the application of the Box-Behnken matrix. Under optimum conditions, the procedure determined the presence of cobalt with an LOD of 2.8 microg/L and LOQ of 9.3 microg/L. The enrichment factor obtained was 25. The precision was evaluated as the RSD, which was 5.5% for 10 microg/L cobalt and 6.9% for 30 microg/L. The accuracy of the procedure was assessed by comparing the results with those found using inductively coupled plasma-optical emission spectrometry. After validation, the procedure was applied to the determination of cobalt in pharmaceutical preparation samples containing cobalamin (vitamin B12).
authors.affiliation: Universidade Estadual do Sudoeste da Bahia, Laboratório de Química Analítica, 45206-190, Jequié, Bahia, Brazil. reginayamaki@terra.com.br
authors.forename: Regina Terumi
authors.initials: RT
authors.lastname: Yamaki
authors.forename: Luana Sena
authors.initials: LS
authors.lastname: Nunes
authors.forename: Hygor Rodrigues
authors.initials: HR
authors.lastname: de Oliveira
authors.forename: André S
authors.initials: AS
authors.lastname: Araújo
authors.forename: Marcos Almeida
authors.initials: MA
authors.lastname: Bezerra
authors.forename: Valfredo Azevedo
authors.initials: VA
authors.lastname: Lemos
mesh_terms: D001391:Azo Compounds / Q000737:chemistry*; D003035:Cobalt / Q000737:chemistry*; D005410:Flame Ionization / Q000379:methods; D006846:Hydrocarbons, Halogenated / Q000737:chemistry*; D015394:Molecular Structure; D004364:Pharmaceutical Preparations / Q000737:chemistry*; D015203:Reproducibility of Results; D013054:Spectrophotometry, Atomic / Q000379:methods*; D014805:Vitamin B 12 / Q000737:chemistry
chemical_list: C561841:2-(5-bromothiazolylazo)-4-chlorophenol; D001391:Azo Compounds; D006846:Hydrocarbons, Halogenated; D004364:Pharmaceutical Preparations; D003035:Cobalt; D014805:Vitamin B 12