Optimization of an electrolyte system for analysis of ethambutol in pharmaceutical formulations by capillary zone electrophoresis using complexation with copper(II)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)An alternative methodology for the determination of ethambutol by capillary zone electrophoresis (CZE) under direct UV detection at 262 nm, using acetic acid/sodium acetate buffer solution (pH 4.6) containing copper(II) sulphate to form the ethambutol-copper(II) complex, within analysis time of 2.5 min is proposed. The optimum CE conditions for the background electrolyte were established performing experiments of a 32 factorial design. Complex formation was evidenced by the UV batochromic shift and the [CuETB](0) and [CuETB](2+) chemical structures were indicated by LC-MS analysis. After some validation parameters have been performed, such as linearity (r=0.999), selectivity (comparison between slope of the calibration curve of the external standard and calibration curve of the standard addition), area precision(RSD%: <2.13 for ETB and <1.94 for 2A1B), recovery mean (101.7% for ETB and 99.95% for 2A1B) and quantification limit (mg L-1: 10.17 for ETB and 19.70 for 2A1B), the method was successfully applied to ETB analysis in pharmaceutical formulation samples. It is possible to determine the presence of the 2A1B impurity at concentrations of less than 1% ETB content. (C) 2008 Elsevier B.V. All rights reserved.12022224228Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)CNPq [CNPq-400618/2004-4, 154931/2006-3, 476386/2007-1]Fundacao de Amparo A Pesquisa do Estado de Minas Gerais of Brazil [FAPEMIG-CEX-APQ 1906-5.02-07

Simultaneous determination of first-line anti-tuberculosis drugs by capillary zone electrophoresis using direct UV detection

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)An alternative methodology for simultaneous analysis of ethambutol, isoniazid, rifampicin and pyrazinamide in pharmaceutical formulations by capillary zone electrophoresis under UV direct detection with an analysis time of 8.0 min is proposed. Background running was based on the effective mobility curve of the analytes and an optimum separation condition was achieved using a 3(3) Box-Behnken design, with Brij 35, Cu(2+) and acetic acid/sodium acetate buffer as factors. An electrolyte consisting of 50.0 mmol L(-1) of acetic acid/sodium acetate buffer:12.5 mmol L(-1) of CuSO(4), and standard and sample solutions prepared in 2.00 mmol L(-1) of Brij 35 and 12.5 mmol L(-1) of CuSO(4) were optimized. After evaluating validation parameters, the method was successfully applied to the analysis of samples in the form of tablets and sachets. (C) 2010 Elsevier By. All rights reserved.821333339Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)CNPq [476386/2007-1, 300593/2008-2]Fundacao de Amparo a Pesquisa do Estado de Minas Gerais of Brazil [FAPEMIG-CEX-APQ 1906-502/07, CEX APQ 01837/08

Fast determination of ethambutol in pharmaceutical formulations using capillary electrophoresis with capacitively coupled contactless conductivity detection

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)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 2 conditions, linearity of 0.9976 (R(2) five data points), sensitivity of 1.26 x 10(-4) V min mu mol(-1) L, and LOD and quantification of 23.5 and 78.3 mu mol/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 mu mol/L. The results obtained for the determination of EMB in pharmaceutical formulations were compared with those obtained by using CE with photometric detection.313570574Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAPESP [04/09079-0, 06/07309-3

Simultaneous analysis of first-line anti-tuberculosis drugs in tablets by UV spectrophotometry compared to capillary zone electrophoresis

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)The development and optimization of a novel UV spectrophotometric methodology was proposed for simultaneous analysis of ethambutol (ETB), isoniazid (ISO), rifampicin (RIF) and pyrazinamide (PYR), using multivariate calibration based on the partial least squares method (PLS). The methodology was successfully applied for analysis of four-drug fixed dose combination (4-FDC) tablets used for tuberculosis treatment. A 3(4) Box-Behnken design, with triplicate in central point, was used for sample preparation in the calibration step. In the present case, nine latent variables were chosen for the model development that presented the smallest RMSECV and explain 98.76% of data variance in Y block (concentrations of ETB ISO, RIF and PYR) and 99.93% of data variance in X block (spectral data). PLS models for ETB, ISO, RIF and PYR presented RMSEP and R-2 values of 0.23 mg L-1 and 0.971; 0.14 mg L-1 and 0.731; 0.11 mg L-1 and 0.990 and 0.57 mg L-1 and 0.972, respectively. A validation step was performed based on the comparison between the UV spectrophotometric proposed methodology and capillary zone electrophoresis (CZE) in 4-FDC real samples and no significant difference was found between two methodologies at 95% of confidence level.10618081816Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)CNPq [CNPq - 300593/2008-2]Fundacao de Amparo a Pesquisa do Estado de Minas Gerais of Brazil [FAPEMIG - CEX - APQ-02420-11, CEX - PPM-00205-11