Determination of biapenem in a medicinal product by micellar electrokinetic chromatography with sweeping in an enhanced electric field.

The elaborated method of micellar electrokinetic chromatography (MEKC) used to separate biapenem from its related substances was successfully implemented using sweeping under an enhanced electric field, followed by UV absorption detection at 200nm. The best results were obtained with formic buffer (22.5mM) pH 4.3 and sodium dodecyl sulfate (150mM) added to the electrolyte as the sweeping agent. Neutral capillary (60/50cm; 50µm ID) with reverse polarity and voltage values of 22kV, were used throughout the investigation. The optimized method of biapenem determination, validated in terms of linearity, accuracy and precision, provides a detection limit of 0.5µg/mL at S/N=3 for biapenem. The repeatability of the CE system, expressed by relative standard deviations (RSD) in the migration times, for biapenem and its degradation products varied from 0.14 to 1.48%, whereas for the corrected peak areas RSD were about 0.68-8.43%. Satisfactory separation was achieved within 20min of electrophoresis; moreover all carbapenems (imipenem, meropenem, ertapenem, doripenem and biapenem) were separated from each other during analysis. The evaluated MEKC method was applied to the analysis of a medicinal product containing biapenem - Omegacin(®) 0.3g for intravenous drip infusion.

Determination of doripenem and related substances in medicinal product using capillary electrophoresis.

Doripenem, the latest carbapenem antibiotic licensed in the United States (15 October 2007) and the European Union (25 July 2008), has been implemented into therapeutic use along with imipenem, meropenem and ertapenem. The described method of zone electrophoresis in a low pH buffer for the separation of doripenem from its impurities has been successfully performed using field-amplified sample stacking (FASS), followed by UV absorption detection at 214 nm. The best results were obtained with phosphate buffer (100 mM) pH 2.9 containing 10% (v/v) of methanol, as the background electrolyte. Uncoated fused-silica capillary (60/52 cm; 75 µm id) with normal polarity, and voltage values of 25 kV, was used throughout the investigation. The optimised method of doripenem determination was validated in terms of linearity, accuracy and precision, and provides a detection limit of 3.0 µg/mL of doripenem. The repeatability, expressed by relative standard deviation (RSD) of the migration time, for doripenem and its degradation products varied from 1.37 to 2.51%, whereas the corrected peak areas were about 0.91-9.87%. Satisfactory separation was achieved within 20 min of electrophoresis; moreover, all carbapenems (imipenem, meropenem, ertapenem and doripenem) were well separated from each other during this time. The evaluated CZE method was applied in the analysis of a medicinal product containing doripenem Doribax(®) powder for solution for infusion.

Different sample stacking strategies for the determination of ertapenem and its impurities by micellar electrokinetic chromatography in pharmaceutical formulation.

Ertapenem, a Group 1 carbapenem, is most recently introduced into the market. It is a beta-lactam antibiotic that possesses a broad antibacterial spectrum including common community-acquired Gram-positive and Gram-negative aerobic and anaerobic pathogens, but low activity against some nosocomial pathogens such as Pseudomonas aeruginosa, Acinetobacter spp., enterococci and methicillin-resistant staphylococci. The elaborated method of micellar electrokinetic chromatography (MEKC) of ertapenem separation from its impurities was successfully performed using normal stacking mode (NSM) and stacking with reverse migrating micelles (SRMM), followed by UV absorption detection at 214 nm. The best results were obtained with 60mM sodium dihydrogen phosphate and 20mM boric acid buffer pH 6.0, as background electrolyte. Uncoated fused-silica capillary and neutral-coated capillary with normal and reverse polarity, and voltage values of +18 and -12 kV, respectively, were used throughout the investigation. Sodium dodecyl sulfate was employed as the pseudostationary phase. A comparison of applied techniques, including sensitivity enhancement factors and limits of detection (LOD), is presented. The optimized method was validated in terms of linearity, accuracy and precision. Comparable LOD was obtained using both stacking methods (0.3 microg/mL) but better efficiency of ertapenem peak was obtained using NSM. Under the optimum stacking conditions, about 183-4.75-fold and 1289-4.07-fold improvements in peak areas were obtained for NSM and SRMM, respectively, compared to the usual hydrodynamic sample injection (10s). The reproducibility, expressed by relative standard deviations (RSD) of the migration times, for NSM was about 0.96-1.25 and for SRMM was 0.32-0.45. The RSD of corrected peak areas, for NSM was about 1.07-8.14 and for SRMM was 0.74-8.12. The difference in separation time between the two techniques was not obvious. Satisfactory separation was possible after less than 11min of electrophoresis. The evaluated MEKC method was applied in the analysis of medicinal product containing ertapenem: Invanz-ertapenem for injection.

Determination of linezolid and its achiral impurities using sweeping preconcentration by micellar capillary electrophoresis.

Linezolid is the first compound of a truly new class of antibiotics--the oxazolidinones. The elaborated method of capillary electrophoresis (CE) of linezolid separation from its achiral impurities was successfully performed using sweeping preconcentration, followed by UV absorption detection at 254nm. The best results were obtained with 125mM Tris buffer, pH 2.0, with addition of 20% (v/v) methanol as background electrolyte. Sodium dodecyl sulfate (150mM) was added to the electrolyte in the inlet vial as the sweeping agent. The separation was carried out at negative polarity. Then, the optimized method was validated in terms of linearity, accuracy and precision. Sweeping preconcentration of linezolid provides detection limit at 0.05microg/ml level. The evaluated CE method was applied in the analysis of medicinal product containing linezolid-linezolid solution for infusion.

Determination of enantiomeric impurity of linezolid by capillary electrophoresis using heptakis-(2,3-diacetyl-6-sulfato)-beta-cyclodextrin.

A method for the enantioseparation of linezolid, the first compound of a truly new class of antibiotics-the oxazolidinones, was developed. The elaborated method of linezolid enantiomers separation was successfully performed using an anionic single-isomer cyclodextrin-heptakis-(2,3-diacetyl-6-sulfato)-beta-cyclodextrin (HDAS-beta-CD) as a resolving agent with the help of the charged resolving agent migration model (CHARM model). The best results were obtained with 27.5mM HDAS-beta-CD dissolved in 50mM borate buffer, pH 9.0, 15 degrees C, normal polarity. The facile strategies for the reversal of the enantiomers elution order are also described. Afterwards, the optimized method was validated in terms of sensitivity, linearity, accuracy and precision.

Analysis of phenoxymethylpenicillin potassium by capillary electrophoresis.

The application of capillary electrophoresis for separation of penicillin V and its impurities was investigated. The phosphate-borate buffer supplemented with sodium dodecyl sulfate (SDS) 20.0 g/L (69 mM) and pentanesulfonic acid sodium salt (PS) 2.2 g/L (12.5 mM) adjusted to pH 6.3, and current voltage 15 kV seem to provide optimal conditions for this aim. The resolution between penicillin V and each impurity was very good. The statistical analysis of phenoxymethylpenicillin V assay showed no significant differences between the results obtained by CE and HPLC methods.

Determination of ciprofloxacin and its impurities by capillary zone electrophoresis.

Capillary zone electrophoresis (CZE) has been elaborated for separation, identification and determination of ciprofloxacin and its impurities. The separation, phosphate buffer pH 6.0 was supplemented with 0.075 M pentane-1-sulfonic acid sodium salt. The elaborated method was validated. The selectivity, linearity, limits of detection (LOD) and quantification (LOQ), precision, and accuracy of capillary zone electrophoresis were evaluated. The results obtained by CZE were also compared with those obtained by liquid chromatography. Regarding the validation results the CE method fulfils the current European Pharmacopoeia (Eur. Ph.) requirements. The evaluated CE method could be applicable to the analysis of different medicinal products containing ciprofloxacin.

Application of capillary electrophoresis to the determination of various benzylpenicillin salts.

The application of capillary electrophoresis for separation of benzylpenicillin, procaine, benzathine and clemizole was investigated. Phosphate-borate buffer supplemented with sodium dodecyl sulphate 14.4 g/l and electrophoresis voltage 18 kV seem to provide optimal conditions for micellar electrokinetic chromatographic assay of penicillin salts. This method is selective and precise. The results obtained from CE method recovery assay (above 98% for all but procaine-97% substances) and from determination of benzylpenicillin by CE compared with HPLC results, confirmed good accuracy.

Capillary electrophoresis method for simultaneous determination of penicillin G, procaine and dihydrostreptomycin in veterinary drugs.

Capillary electrophoresis method for identification and simultaneous determination of procaine, dihydrostreptomycin and penicillin G, present in multiantibiotic veterinary preparations, was elaborated. The influence of pH (5.0-9.75) and concentration of disodium tetraborate decahydrate in running buffers (0.02-0.1 M) as well as temperatures (25-40 degrees C) on separation efficacy were analyzed. For quantitative analysis, 0.08 M borate buffer (pH 8.0) at 35 degrees C and 15 kV were chosen. Method was validated, selectivity, precision, linearity, LOD, LOQ, accuracy and specificity of capillary zone electrophoresis (CZE) were evaluated.

Application of MEKC for determination of ticarcillin and clavulanic acid in Timentin intravenous preparation.

A micellar electrokinetic chromatography method for simultaneous assay of ticarcillin and clavulanic acid in Timentin i.v. injection preparation was developed. This method ensures excellent separation of both components of Timentin preparation. The validation of the method was performed, and specificity, reproducibility, precision and accuracy were confirmed. The detection and quantitative limits for Timentin were established in the concentrations 0.04 and 0.08 mg/ml, respectively. The elaborated technique was compared with two methods routinely used-UV and high performance liquid chromatography (HPLC). The obtained results and their statistical analysis proved the same precision of all methods, however, no significant differences were observed between CE and HPLC.

Application of micellar electrokinetic chromatography to the determination of sultamicillin in oral pharmaceutical preparations.

A micellar electrokinetic capillary electrophoretic method for determination of sultamicillin in Unasyn oral preparations--tablets and suspension--was evaluated. Phosphate-borate buffer at pH 7.0 containing 1.0% sodium dodecylsulfate was used as a mobile phase. The elaborated method ensures separation of sultamicillin from p-toluenesulfonic acid and the impurities, ampicillin, sulbactam and penicillamine. The method was validated for specificity, reproducibility, precision, accuracy and assay linearity (in a concentration range of sultamicillin of 0.05-1.5 mg/ml). Statistical analysis by Student's t-test showed no significant differences between the results obtained by micellar electrokinetic chromatography and HPLC, t(calculated) 0.519 for suspension assays and 0.284 for tablets assays were smaller then t(tabulated).

CE versus LC for simultaneous determination of amoxicillin/clavulanic acid and ampicillin/sulbactam in pharmaceutical formulations for injections.

A rapid, capillary electrophoresis method was evaluated for determination of amoxicillin and clavulanic acid in Augmentin as well as ampicillin and sulbactam in Unasyn preparations for injections. Phosphate-borate buffer at pH 8.66 containing 14.4% sodium dodecyl sulfate was used as a mobile phase. The method was validated. Reproducibility, precision, accuracy and assay linearity in concentration of amoxicillin 0.05-3.03 mg/ml and ampicillin 0.05-3.08 mg/ml, as well as clavulanic acid 0.02-2.02 mg/ml and sulbactam 0.05-2.08 mg/ml were established. This new method is fast, inexpensive and limits consumption of organic solvents when compared with alternative high performance liquid chromatography (HPLC) method, used for drug analysis. Statistical analysis by Student's t-test showed no significant differences between the results obtained by the two methods t(calculated) 0.32 and 1.69 for amoxicillin and clavulanic acid and 0.67 and 1.93 for ampicillin and sulbactam were smaller than t(tabulated).