E. Bravo

Simultaneous determination of doxorubicin, daunorubicin, and idarubicin by capillary electrophoresis with laser-induced fluorescence detection.

The separation and simultaneous determination of doxorubicin, daunorubicin and ida‐rubicin was investigated using capillary electrophoresis with laser‐induced fluorescence detection. Because the three anthracycline antibiotics were similar in structure and mass, careful manipulation of the electroosmotic flow and electrophoretic mobilities was required. A buffer consisting of 100 mM borate, adjusted to pH 9.5, containing 30% acetonitrile was found to provide a very efficient and stable electrophoretic system for the analysis of the three anthracyclines. The method was applied to the determination of three anthracyclines in serum samples. Responses were linear in the range of 10 — 500 ng·mL−1 and the detection limits were lower than 0.9 ng·mL−1.

Direct determination of ranitidine and famotidine by CE in serum, urine and pharmaceutical formulations

A simple and sensitive capillary electrophoresis method using UV detection has been developed for the direct determination of ranitidine (RANT) and famotidine (FAMT) in serum, urine and pharmaceutical formulations. A buffer consisting of 60 mM phosphate buffer adjusted to pH 6.5 was found to provide a very efficient and stable electrophoretic system for the analysis of both drugs. The detection limits obtained were 0.088 microgram ml(-1) for RANT and 0.16 microgram ml(-1) for FAMT.

Determination of riboflavin, flavin mononucleotide and flavin adenine dinucleotide in biological tissues by capillary zone electrophoresis and laser‐induced fluorescence detection

The separation of riboflavin, flavin mononucleotide and flavin adenine dinucleotide was investigated by capillary zone electrophoresis using laser‐induced fluorescence detection. In the systematic approach developed, the differential electrophoretic mobilities were first maximized by adjusting the pH. Increasing the buffer concentration improved the separation at the expense of migration times. A buffer consisting of 50 mM phosphate adjusted to pH 8.5 was found to provide a very efficient and stable electrophoretic system. Responses were linear within the range 0.1—100 μmol L−1, and the detection limits of B2 vitamers were 0.23 nmol L−1 or less. The method was successfully applied to a variety of biological tissues from different animals.

Separation and simultaneous determination of quinolone antibiotics by capillary zone electrophoresis

SummaryThe potential of capillary zone electrophoresis has been investigated for the separation and quantitative determination of some quinolone antibiotics. The influence of different conditions, such as the nature and concentration of the electrophoretic electrolyte, on migration time, peak symmetry, efficiency and resolution was studied. A buffer consisting of 100mm HEPES adjusted to pH 8.5 containing 10% (v/v) acetonitrile was found to furnish a very efficient and stable electrophoretic system for the separation of exoxacin, ciprofloxacin, ofloxacin, oxolinic acid, nalidixic acid and pipemedic acid. A linear relationship between concentration and peak area for each compound was obtained in the concentration range 0.25–40 μg mL−1; detection limits were approximately 0.25 ng mL−1. It was demonstrated that the method can be used for the simultaneous determination of these six antibiotics in serum and urine samples.

Sensitive method for the determination of ambroxol in body fluids by capillary electrophoresis and fluorescence detection

A sensitive and rapid capillary electrophoretic method combined with laser-induced fluorescence detection has been developed for the determination of ambroxol. Samples were derivatized with 5 x 10(-4) M fluorescein isothiocyanate. A linear relationship between concentration and peak area was obtained in the concentration range 0.008-42 microg ml(-1) with a correlation coefficient of 0.9999. The applicability of the method to serum and urine samples was demonstrated. The method is also useful for the determination of ambroxol in pharmaceutical preparations.

Determination of flufenamic, meclofenamic and mefenamic acids by capillary electrophoresis using β-cyclodextrin

The possibility of separating flufenamic, meclofenamic and mefenamic acids by capillary electrophoresis was studied. The best approach involved combining a suitable pH of the carrier electrolyte (pH 12.0) with the host-guest complexation effects of beta-cyclodextrin. A running buffer consisting of 30 mM phosphate buffer (pH 12.0), 2 mM beta-CD and 10% (v/v) acetonitrile was found to provide a very efficient and stable electrophoresis system for the analysis of fenamic acids by capillary zone electrophoresis. Responses were linear from 0.4 to 40 microg/ml for the three drugs with detection limits of about 0.3 ng/ml. Intra- and inter-day precision values of about 1-2% R.S.D. (n = 11) and 3-4% R.S.D. (n = 30), respectively, were obtained. The method is highly robust and no breakdowns of the current or capillary blockings were observed for several weeks. The general applicability of this rapid CZE procedure (migration times less than 12 min) is demonstrated for several practical samples, including serum, urine and pharmaceuticals.

Determination of bromhexine and ambroxol in pharmaceutical dosage forms, urine and blood serum.

Data presented in this paper show that bromhexine and its pharmacologically active metabolite can easily be determined by capillary zone electrophoresis. The composition of the running buffer had a significant effect on the reproducibility of the migration time for which a carrier solution containing 30 mM phosphate buffer (pH 3.0), 5 M urea and 10% (v/v) acetonitrile was used. The method was validated with respect to its response linearity and reproducibility. The method is suitable for the determination of bromhexine and ambroxol in several samples such as pharmaceuticals, urine and serum. Photodiode-array detection permitted the rapid identification of both drugs in the sample analyzed.

Development and validation of a capillary electrophoretic method for the determination of amiodarone and desethylamiodarone

SummaryA simple, sensitive and rapid capillary electrophoretic method has been developed for the separation and quantification of amiodarone and its metabolite, desethylamiodarone. The compounds were separated in a capillary of 45 cm effective length and 75 μm i.d., by use of an applied voltage of 25 kV and an electrolyte containing 15mm ADA buffer (pH 7.5), 10mm SDS, and 70% (v/v) acetonitrile. The selectivity, precision, linearity, range, sensitivity, and robustness of the method were good. The applicability of the assay was demonstrated by analyzing these drugs in serum. Electrokinetic injection with field-amplified sample-stacking was used to increase sensitivity. The limit of detection of the serum assay was 6.46 ng mL−1 and the precision 3.7%.

Separation of fluorescein dyes by capillary electrophoresis using β-cyclodextrin

SummaryA capillary electrophoresis method for the separation and determination of five synthetic dyes used in pharmaceutical preparations, cosmetics and as food additives is described. The dyes, fluorescein, dichlorofluorescein, Rose Bengal erythrosine and eosine are well separated in less than 12 min using an electrolyte of 50 mM phosphate buffer (pH 7.5), 10 mM β-cyclodextrin and 5% (v/v) methanol. A linear relationship between concentration and peak area for each dye was obtained in the concentration range 0.3–500 μg mL−1, with a correlation coefficient greater than 0.999. Intra- and inter-day precision of about 0.2–2.6% RSD (n=11) and 4.9–9.7% RSD (n=30), respectively, were obtained. The method has been used for determining the purity of fluorescein and erythrosine in practical samples.

Analysis of glutamate in beverages and foodstuffs by capillary electrophoresis with laser-induced fluorescence detection

SummaryA simple, sensitive, and robust method has been developed for the separation and quantification of glutamate in beverages and foodstuffs. Samples were derivatized with 5 × 10−4 M fluorescein isothiocyanate. Glutamate was separated by capillary electrophoresis and detected by laser-induced fluorescence with 488-nm radiation from an argon ion laser. Response was linearly dependent on concentration between 10−7 and 10−4 M. The limit of mass detection was 16 amol and the limit of concentration detection was 5.4×10−10 M. Intra- and interday precision were 3.3%RSD (n=11) and 4.8%RSD (n=7), respectively. The method has been applied to beverages and other foods.