title: Fast determination of ethambutol in pharmaceutical formulations using capillary electrophoresis with capacitively coupled contactless conductivity detection.
abstract: A method for the determination of ethambutol (EMB), a first-line drug against tuberculosis, based on CE with capacitively coupled contactless conductivity detection is proposed. The separation of EMB and its main product of degradation were achieved in less than 3 min with a resolution of 2.0 using a BGE composed of 50 mmol/L histidine and 30 mmol/L MES, pH 6.30. By raising the pH to 8.03, the analysis time was reduced to 1.0 min, but with a significant loss of resolution (0.7). Using the best separation conditions, linearity of 0.9976 (R(2), five data points), sensitivity of 1.26x10(-4) V min mumol(-1) L, and LOD and quantification of 23.5 and 78.3 mumol/L, respectively, were obtained. Recoveries at four levels of concentration ranged from 95 to 102% and the concentration range studied ranged from 100 to 500 mumol/L. The results obtained for the determination of EMB in pharmaceutical formulations were compared with those obtained by using CE with photometric detection.
authors.affiliation: Chemistry Institute, University of Campinas, Campinas, Brazil. fracassi@iqm.unicamp.br
authors.forename: José Alberto Fracassi
authors.initials: JA
authors.lastname: da Silva
authors.forename: Nathan Vitorazzi
authors.initials: NV
authors.lastname: de Castro
authors.forename: Dosil Pereira
authors.initials: DP
authors.lastname: de Jesus
authors.forename: Adriana F
authors.initials: AF
authors.lastname: Faria
authors.forename: Marcus V N
authors.initials: MV
authors.lastname: De Souza
authors.forename: Marcone Augusto Leal
authors.initials: MA
authors.lastname: de Oliveira
mesh_terms: D000995:Antitubercular Agents / Q000737:chemistry*; D004553:Electric Conductivity; D019075:Electrophoresis, Capillary / Q000379:methods*; D004977:Ethambutol / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D004364:Pharmaceutical Preparations / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013997:Time Factors
chemical_list: D000995:Antitubercular Agents; D004364:Pharmaceutical Preparations; D004977:Ethambutol