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Papers by María S. Aurora Prado
Journal of AOAC International, 2002
Two novel analytical methodologies using capillary electrophoresis (CE) and liquid chromatography... more Two novel analytical methodologies using capillary electrophoresis (CE) and liquid chromatography (LC) were developed and compared for the determination of diclofenac sodium in commercial and simulated tablet formulations. The CE analysis was performed in a bare fused-silica capillary with 75 microm id and total length of 50 cm (28 cm to the detector) with a buffer solution of 20 mM sodium tetraborate, pH 9.23. The applied voltage was 20 kV, and acetaminophen was used as the internal standard (IS). The LC analysis was performed with a LiChrospher 100 RP-18 (5 microm) column and a mobile phase of methanol-diluted glacial acetic acid (0.3 parts in 2500; 75 + 25) at a flow rate of 0.9 mL/min with propylparaben as the IS. In both analyses, detection was by ultraviolet absorption at 276 nm. Under optimized conditions, the CE migration times for the diclofenac sodium standard and acetaminophen (IS) were 2.07 and 1.59 min, respectively, and the LC retention times for the diclofenac sodium ...
A simple and efficient micellar capillary electrophoresis method for the analysis of cephalexin i... more A simple and efficient micellar capillary electrophoresis method for the analysis of cephalexin in oral suspensions is described. The analysis was carried out in a bare silica capillary with 75 microm i.d. and total length of 50 cm (28 cm to the detector) with a buffer solution containing 20 mM sodium tetraborate, 20 mM sodium dodecyl sulfate, and 0.1% laurylpolyoxiethylenic ether. The applied voltage was 15 kV. Detection was achieved by ultraviolet absorption at 210 nm. The calibration curve was linear within the concentration range from 40.0 to 120 microg/mL with a correlation coefficient of 0.9998. The percentage recovery was found to be 100.09 +/- 0.56. The method showed good selectivity and resolution of the drug impurities, and was found suitable to study cephalexin stability in pharmaceutical preparations.
RSC Adv., 2016
Dual drug encapsulation in biodegradable nanoparticles is always challenging and often requires s... more Dual drug encapsulation in biodegradable nanoparticles is always challenging and often requires strenuous optimization of the synthesis–encapsulation processes.
Journal of capillary electrophoresis and microchip technology, 2002
A simple and efficient micellar capillary electrophoresis method for the analysis of cephalexin i... more A simple and efficient micellar capillary electrophoresis method for the analysis of cephalexin in oral suspensions is described. The analysis was carried out in a bare silica capillary with 75 microm i.d. and total length of 50 cm (28 cm to the detector) with a buffer solution containing 20 mM sodium tetraborate, 20 mM sodium dodecyl sulfate, and 0.1% laurylpolyoxiethylenic ether. The applied voltage was 15 kV. Detection was achieved by ultraviolet absorption at 210 nm. The calibration curve was linear within the concentration range from 40.0 to 120 microg/mL with a correlation coefficient of 0.9998. The percentage recovery was found to be 100.09 +/- 0.56. The method showed good selectivity and resolution of the drug impurities, and was found suitable to study cephalexin stability in pharmaceutical preparations.
Journal of Pharmaceutical and Biomedical Analysis, 2005
Two novel analytical methodologies using capillary electrophoresis (CE) and reversed-phase high-p... more Two novel analytical methodologies using capillary electrophoresis (CE) and reversed-phase high-performance liquid chromatography (RP-HPLC) for the determination of diazepam in commercial and simulated tablet formulations were developed and compared. The CE analysis was carried out in a bare fused-silica capillary with 75 microm i.d. and total length of 50 cm (28 cm to the detector) with a buffer solution containing 20 mmol L(-1) sodium tetraborate and 20 mmolL(-1) sodium dodecylsulfate (SDS), pH 9.23. The applied voltage was 20 kV and bromazepam was used as internal standard (IS). The RP-HPLC analysis was carried out in a LiChrospher((R)) 100 RP-18 (5 microm) column with a mobile phase constituted of methanol, acetonitrile and water (45:25:30) with a flow rate of 0.8 mL/min, using acetaminophen as IS. In both cases, detection was carried out by ultraviolet (UV) absorption at 242 nm. Under the optimized conditions, the CE retention times for the standard diazepam and bromazepam (IS) were 4.08 and 3.43 min, respectively, and the retention times of the RP-HPLC analysis for the standard diazepam and acetaminophen (IS) were 4.86 and 1.58 min, respectively. The resolution and efficiency for CE were 7.4 and 1.18 x 10(5)plates/m and for RP-HPLC, 7.5 and 1.76 x 10(4) plates/m. Analytical curves of peak area versus concentration presented correlation coefficients of 0.9996 for CE and 0.9994 for RP-HPLC. The limits of detection (LOD) and quantitation (LOQ) were 4.24 and 12.85 microg/mL for CE and 1.44 and 4.36 microg/mL for RP-HPLC. Relative standard deviations (R.S.D.) were 1.62 and 0.98% for CE and RP-HPLC, respectively. The percentage recovery determined with CE was 100.27+/-1.25 and with RP-HPLC was 101.12+/-2.48. Although both methodologies were shown to be suitable for the determination of diazepam in tablets, performing in a similar manner with regards to several aspects (linearity, recovery and specificity), CE provided a faster analysis and column efficiency whereas RP-HPLC presented a superior repeatability and sensitivity.
Chromatographia, 2010
Page 1. Rapid Determination of Water-Soluble and Fat-Soluble Vitamins in Commercial Formulations ... more Page 1. Rapid Determination of Water-Soluble and Fat-Soluble Vitamins in Commercial Formulations by MEEKC Marıa S. Aurora-Prado1,&, Claudinei A. Silva2, Marina FM Tavares2, Kevin D. Altria3 1 Faculty of Pharmaceutical Sciences, University of Sao Paulo, Av. Prof. ...
Chromatographia, 2011
Page 1. FULL SHORT COMMUNICATION Separation of Steroids and the Determination of Estradiol Conten... more Page 1. FULL SHORT COMMUNICATION Separation of Steroids and the Determination of Estradiol Content in Transdermic Patches by Microemulsion Electrokinetic Chromatography Claudinei A. Silva Marıa S. Aurora-Prado Kevin D. Altria Marina FM Tavares ...
Journal of Chromatography A, 2004
A microemulsion electrokinetic chromatography (MEEKC) method has been developed and validated for... more A microemulsion electrokinetic chromatography (MEEKC) method has been developed and validated for the determination of folic acid, a water-soluble vitamin, in a commercial tablet formulation. The analysis was performed using a microemulsion containing 0.5% (w/w) ethyl acetate, 1.2% (w/w) butan-1-ol, 0.6% (w/w) sodium dodecyl sulfate, 15% (v/v) 2-propanol and 82.7% (w/w) 10 mmol L(-1) sodium tetraborate aqueous buffer at pH 9.2. Direct UV detection at 214nm led to an adequate sensitivity without interference from sample excipients. For quantitative purposes, niacin was used as internal standard. Acceptable precision (<1.2% relative standard deviation (R.S.D.)), linearity (r = 0.9992; range from 160.0 to 240.0 microg/mL), sensitivity (limit of detection (LOD) = 2.98 microg/mL; limit of quantification (LOQ) = 9.05 microg/mL) and recovery (99.8 +/- 1.8% at three concentration levels) were obtained. Based on the performance characteristics, the proposed methodology was found suitable for the determination of folic acid in tablet formulations.
Journal of AOAC International, 2002
Two novel analytical methodologies using capillary electrophoresis (CE) and liquid chromatography... more Two novel analytical methodologies using capillary electrophoresis (CE) and liquid chromatography (LC) were developed and compared for the determination of diclofenac sodium in commercial and simulated tablet formulations. The CE analysis was performed in a bare fused-silica capillary with 75 microm id and total length of 50 cm (28 cm to the detector) with a buffer solution of 20 mM sodium tetraborate, pH 9.23. The applied voltage was 20 kV, and acetaminophen was used as the internal standard (IS). The LC analysis was performed with a LiChrospher 100 RP-18 (5 microm) column and a mobile phase of methanol-diluted glacial acetic acid (0.3 parts in 2500; 75 + 25) at a flow rate of 0.9 mL/min with propylparaben as the IS. In both analyses, detection was by ultraviolet absorption at 276 nm. Under optimized conditions, the CE migration times for the diclofenac sodium standard and acetaminophen (IS) were 2.07 and 1.59 min, respectively, and the LC retention times for the diclofenac sodium ...
A simple and efficient micellar capillary electrophoresis method for the analysis of cephalexin i... more A simple and efficient micellar capillary electrophoresis method for the analysis of cephalexin in oral suspensions is described. The analysis was carried out in a bare silica capillary with 75 microm i.d. and total length of 50 cm (28 cm to the detector) with a buffer solution containing 20 mM sodium tetraborate, 20 mM sodium dodecyl sulfate, and 0.1% laurylpolyoxiethylenic ether. The applied voltage was 15 kV. Detection was achieved by ultraviolet absorption at 210 nm. The calibration curve was linear within the concentration range from 40.0 to 120 microg/mL with a correlation coefficient of 0.9998. The percentage recovery was found to be 100.09 +/- 0.56. The method showed good selectivity and resolution of the drug impurities, and was found suitable to study cephalexin stability in pharmaceutical preparations.
RSC Adv., 2016
Dual drug encapsulation in biodegradable nanoparticles is always challenging and often requires s... more Dual drug encapsulation in biodegradable nanoparticles is always challenging and often requires strenuous optimization of the synthesis–encapsulation processes.
Journal of capillary electrophoresis and microchip technology, 2002
A simple and efficient micellar capillary electrophoresis method for the analysis of cephalexin i... more A simple and efficient micellar capillary electrophoresis method for the analysis of cephalexin in oral suspensions is described. The analysis was carried out in a bare silica capillary with 75 microm i.d. and total length of 50 cm (28 cm to the detector) with a buffer solution containing 20 mM sodium tetraborate, 20 mM sodium dodecyl sulfate, and 0.1% laurylpolyoxiethylenic ether. The applied voltage was 15 kV. Detection was achieved by ultraviolet absorption at 210 nm. The calibration curve was linear within the concentration range from 40.0 to 120 microg/mL with a correlation coefficient of 0.9998. The percentage recovery was found to be 100.09 +/- 0.56. The method showed good selectivity and resolution of the drug impurities, and was found suitable to study cephalexin stability in pharmaceutical preparations.
Journal of Pharmaceutical and Biomedical Analysis, 2005
Two novel analytical methodologies using capillary electrophoresis (CE) and reversed-phase high-p... more Two novel analytical methodologies using capillary electrophoresis (CE) and reversed-phase high-performance liquid chromatography (RP-HPLC) for the determination of diazepam in commercial and simulated tablet formulations were developed and compared. The CE analysis was carried out in a bare fused-silica capillary with 75 microm i.d. and total length of 50 cm (28 cm to the detector) with a buffer solution containing 20 mmol L(-1) sodium tetraborate and 20 mmolL(-1) sodium dodecylsulfate (SDS), pH 9.23. The applied voltage was 20 kV and bromazepam was used as internal standard (IS). The RP-HPLC analysis was carried out in a LiChrospher((R)) 100 RP-18 (5 microm) column with a mobile phase constituted of methanol, acetonitrile and water (45:25:30) with a flow rate of 0.8 mL/min, using acetaminophen as IS. In both cases, detection was carried out by ultraviolet (UV) absorption at 242 nm. Under the optimized conditions, the CE retention times for the standard diazepam and bromazepam (IS) were 4.08 and 3.43 min, respectively, and the retention times of the RP-HPLC analysis for the standard diazepam and acetaminophen (IS) were 4.86 and 1.58 min, respectively. The resolution and efficiency for CE were 7.4 and 1.18 x 10(5)plates/m and for RP-HPLC, 7.5 and 1.76 x 10(4) plates/m. Analytical curves of peak area versus concentration presented correlation coefficients of 0.9996 for CE and 0.9994 for RP-HPLC. The limits of detection (LOD) and quantitation (LOQ) were 4.24 and 12.85 microg/mL for CE and 1.44 and 4.36 microg/mL for RP-HPLC. Relative standard deviations (R.S.D.) were 1.62 and 0.98% for CE and RP-HPLC, respectively. The percentage recovery determined with CE was 100.27+/-1.25 and with RP-HPLC was 101.12+/-2.48. Although both methodologies were shown to be suitable for the determination of diazepam in tablets, performing in a similar manner with regards to several aspects (linearity, recovery and specificity), CE provided a faster analysis and column efficiency whereas RP-HPLC presented a superior repeatability and sensitivity.
Chromatographia, 2010
Page 1. Rapid Determination of Water-Soluble and Fat-Soluble Vitamins in Commercial Formulations ... more Page 1. Rapid Determination of Water-Soluble and Fat-Soluble Vitamins in Commercial Formulations by MEEKC Marıa S. Aurora-Prado1,&, Claudinei A. Silva2, Marina FM Tavares2, Kevin D. Altria3 1 Faculty of Pharmaceutical Sciences, University of Sao Paulo, Av. Prof. ...
Chromatographia, 2011
Page 1. FULL SHORT COMMUNICATION Separation of Steroids and the Determination of Estradiol Conten... more Page 1. FULL SHORT COMMUNICATION Separation of Steroids and the Determination of Estradiol Content in Transdermic Patches by Microemulsion Electrokinetic Chromatography Claudinei A. Silva Marıa S. Aurora-Prado Kevin D. Altria Marina FM Tavares ...
Journal of Chromatography A, 2004
A microemulsion electrokinetic chromatography (MEEKC) method has been developed and validated for... more A microemulsion electrokinetic chromatography (MEEKC) method has been developed and validated for the determination of folic acid, a water-soluble vitamin, in a commercial tablet formulation. The analysis was performed using a microemulsion containing 0.5% (w/w) ethyl acetate, 1.2% (w/w) butan-1-ol, 0.6% (w/w) sodium dodecyl sulfate, 15% (v/v) 2-propanol and 82.7% (w/w) 10 mmol L(-1) sodium tetraborate aqueous buffer at pH 9.2. Direct UV detection at 214nm led to an adequate sensitivity without interference from sample excipients. For quantitative purposes, niacin was used as internal standard. Acceptable precision (<1.2% relative standard deviation (R.S.D.)), linearity (r = 0.9992; range from 160.0 to 240.0 microg/mL), sensitivity (limit of detection (LOD) = 2.98 microg/mL; limit of quantification (LOQ) = 9.05 microg/mL) and recovery (99.8 +/- 1.8% at three concentration levels) were obtained. Based on the performance characteristics, the proposed methodology was found suitable for the determination of folic acid in tablet formulations.