Development and validation of a capillary electrophoresis method for the determination of sulfate in indinavir sulfate raw material

In this work, a simple and fast capillary electrophoresis method using indirect UV detection (230 nm) for the quantitative determination of sulfate in the indinavir sulfate raw material was described. A running electrolyte consisting of 10 mmol L-1 ammonium molybdate containing 0.15 mmol L-1 cetyltrimethylammonium bromide (pH 7.5) was used. Samples were injected hydrodynamically by applying 5000 Pa pressure during 3 s. The response was linear from 10.1 µg mL-1 to 79.8 mg µL-1. Limits of detection and quantification were 0.34 and 1.13 mg µL-1, respectively. The intra-day precision expressed as relative standard deviation was 2.8% for 10 independent sample preparations. Recoveries varying from 96.9 to 102.4% at three concentration levels were obtained. The methodology was successfully applied for real samples. The concentration of sulfate in indinavir sulfate raw material varied from 13.3 to 13.5% (m/m calculated as anhydrous base)

Development and validation of a capillary electrophoresis method for the determination of sulfate in indinavir sulfate raw material

In this work, a simple and fast capillary electrophoresis method using indirect UV detection (230 nm) for the quantitative determination of sulfate in the indinavir sulfate raw material was described. A running electrolyte consisting of 10 mmol L-1 ammonium molybdate containing 0.15 mmol L-1 cetyltrimethylammonium bromide (pH 7.5) was used. Samples were injected hydrodynamically by applying 5000 Pa pressure during 3 s. The response was linear from 10.1 µg mL-1 to 79.8 mg µL-1. Limits of detection and quantification were 0.34 and 1.13 mg µL-1, respectively. The intra-day precision expressed as relative standard deviation was 2.8% for 10 independent sample preparations. Recoveries varying from 96.9 to 102.4% at three concentration levels were obtained. The methodology was successfully applied for real samples. The concentration of sulfate in indinavir sulfate raw material varied from 13.3 to 13.5% (m/m calculated as anhydrous base)

Multivariant optimization, validation, and application of capillary electrophoresis for simultaneous determination of polyphenols and phenolic acids in brazilian wines

A method for the simultaneous determination of the stilbene resveratrol, four phenolic acids (syringic, coumaric, caffeic, and gallic acids), and five flavonoids (catechin, rutin, kaempferol, myricetin, and quercetin) in wine by CE was developed and validated. The CE electrolyte composition and instrumental conditions were optimized using 27‐3 factorial design and response surface analysis, showing sodium tetraborate, MeOH, and their interaction as the most influential variables. The optimal electrophoretic conditions, minimizing the chromatographic resolution statistic values, consisted of 17 mmol/L sodium tetraborate with 20% methanol as electrolyte, constant voltage of 25 kV, hydrodynamic injection at 50 mbar for 3 s, and temperature of 25°C. The R 2 values for linearity varied from 0.994 to 0.999; LOD and LOQ were 0.1 to 0.3 mg/L and 0.4 to 0.8 mg/L, respectively. The RSDs for migration time and peak area obtained from ten consecutive injections were less than 2% and recoveries varied from 97 to 102%. The method was applied to 23 samples of inexpensive Brazilian wines, showing wide compositional variation323822382

Multivariant optimization, validation, and application of capillary electrophoresis for simultaneous determination of polyphenols and phenolic acids in Brazilian wines

A method for the simultaneous determination of the stilbene resveratrol, four phenolic acids (syringic, coumaric, caffeic, and gallic acids), and five flavonoids (catechin, rutin, kaempferol, myricetin, and quercetin) in wine by CE was developed and validated. The CE electrolyte composition and instrumental conditions were optimized using 2(7-3) factorial design and response surface analysis, showing sodium tetraborate, MeOH, and their interaction as the most influential variables. The optimal electrophoretic conditions, minimizing the chromatographic resolution statistic values, consisted of 17 mmol/L sodium tetraborate with 20% methanol as electrolyte, constant voltage of 25 kV, hydrodynamic injection at 50 mbar for 3 s, and temperature of 25 degrees C. The R(2) values for linearity varied from 0.994 to 0.999; LOD and LOQ were 0.1 to 0.3 mg/L and 0.4 to 0.8 mg/L, respectively. The RSDs for migration time and peak area obtained from ten consecutive injections were less than 2% and recoveries varied from 97 to 102%. The method was applied to 23 samples of inexpensive Brazilian wines, showing wide compositional variation

A Systematic Procedure to Develop a Capillary Electrophoresis Method Using a Minimal Experimental Data

The choice of an appropriate background electrolyte (BGE) and its components for capillary electrophoresis analysis is the main step in capillary electrophoresis method development. The use of an inadequate co-ion component could lead to asymmetrical peaks and selecting an inappropriate counter-ion could affect the buffer capacity and the pH of the BGE, leading to unreliable analysis. In this paper, we describe a systematic procedure for the development of a capillary electrophoresis method, based on the effect of varying pH on the ion effective mobility, to optimize the BGE composition. The method was applied to the separation of L-ascorbic acid in different samples. The optimized background electrolyte composition was 40 mmol L-1 tris(hydroxymethyl)aminomethane and 20 mmol L-1 2-morpholinoethanesulfonic acid, at pH 8.1. Sorbic acid was used as the internal standard and separation was carried out in a fused-silica capillary (32 cm total length and 8.5 cm effective length, 50 µm inner diameter), with a short-end-injection configuration and direct ultraviolet (UV) detection at 266 nm. The separation was performed in 26 s. The method shows good linearity (R2 > 0.999), excellent values for inter-day and intra-day precision and good recovery (in the range of 94-107%). The values obtained for limit of detection (LOD) and limit of quantification (LOQ) were 0.14 and 41 mg L-1, respectively. The systematic procedure applied shows to be a very useful tool for the first step method development for capillary electrophoresis

High-Throughput Analysis of Lidocaine in Pharmaceutical Formulation by Capillary Zone Electrophoresis Using Multiple Injections in a Single Run

This paper reports the development of a subminute separation method by capillary zone electrophoresis in an uncoated capillary using multiple injection procedure for the determination of lidocaine in samples of pharmaceutical formulations. The separation was performed in less than a minute leading to doing four injections in a single run. The cathodic electroosmotic flow contributed to reducing the analyses time. The background electrolyte was composed of 20 mmol L−1 2-amino-2-(hydroxymethyl)-1,3-propanediol and 40 mmol L−1 2-(N-morpholino)ethanesulfonic acid at pH 6.1. The internal standard used was benzylamine. Separations were performed in a fused uncoated silica capillary (32 cm total length, 23.5 cm effective length, and 50 μm internal diameter) with direct UV detection at 200 nm. Samples and standards were injected hydrodynamically using 40 mbar/3 s interspersed with spacer electrolyte using 40 mbar/7 s. The electrophoretic system was operated under constant voltage of 30 kV with positive polarity on the injection side. The evaluation of some analytical parameters of the method showed good linearity (r2>0.999), a limit of detection 0.92 mg L−1, intermediate precision better than 3.2% (peak area), and recovery in the range of 92–102%