Micellar Electrokinetic Chromatography of Aminoglycosides.

The components of the aminoglycosides, e.g., gentamicin, sisomicin, netilmicin, kanamycin, amikacin, and tobramycin, and related impurities of these antibiotics can be separated by means of micellar electrokinetic chromatography (MEKC). Derivatization with o-phthaldialdehyde and thioglycolic acid is found to be appropriate for these antibiotics. The background electrolyte was composed of sodium tetraborate (100 mM), sodium deoxycholate (20 mM), and ß-cyclodextrin (15 mM) having a pH value of 10.0. This method is valid for evaluation of gentamicin, kanamycin, and tobramycin. It has to be adopted for amikacin, paromomycin, neomycin, and netilmicin.

Micellar electrokinetic chromatography of aminoglycosides.

The components of the aminoglycosides, e.g., gentamicin, sisomicin, netilmicin, kanamycin, amikacin, and tobramycin, and related impurities of these antibiotics can be separated by means of micellar electrokinetic chromatography (MEKC). Derivatization with o-phthaldialdehyde and thioglycolic acid is found to be appropriate for all antibiotics. The background electrolyte was composed of sodium tetraborate (100 mM), sodium deoxycholate (20 mM), and beta-cyclodextrin (15 mM) and has a pH value of 10.0. This method is valid for evaluation of gentamicin, kanamycin, and tobramycin. It has yet to be adopted for amikacin, paramomycin, neomycin, and netilmicin.

A new micellar electrokinetic capillary chromatography method for separation of the components of the aminoglycoside antibiotics.

Aminoglycoside antibiotics are always a mixture of structurally related amino sugars, which do not have a chromophore or fluorophore. The aim of the study was to find one method for evaluation of the components and impurities of the antibiotics. Derivatization with o-phthaldialdehyde and thioglycolic acid is found to be appropriate for all antibiotics. The components of gentamicin (GM), sisomicin, netilmicin, kanamycin, amikacin, and tobramycin were tried to separate by means of micellar electrokinetic chromatography. The background electrolyte was composed of sodium tetraborate (100 mM, pH 10.0), sodium deoxycholate (20 mM), and beta-cyclodextrin (15 mM). This method is valid for evaluation of GM, kanamycin, and tobramycin. It has to be improved for amikacin and netilmicin. In addition, 46 bulk samples of GM of different manufacturer or pharmaceutical companies were investigated. Many samples were found to contain many minor products and different amounts. Beside different patterns of the main compounds GM C1, GM C1a, GM C2a, and GM C2, many lots were found consisting of a substantial number of minor products. The appearance of a high number of minor products is always associated with the existence of sisomicin, which is not found in "pure" samples. However, almost all samples met the requirements of the European Pharmacopoeia (EP) and United States Pharmacopoeia (USP).

Determination of clotrimazole in mice plasma by capillary electrophoresis.

In addition to its antifungal activity, clotrimazole attracts interest as an anti-inflammatory drug. In order to correlate this effect with plasma concentrations in mice, a capillary electrophoretic method was developed. Sample preparation was carried out by protein precipitation using methanol. Quantification of clotrimazole was achieved by means of capillary electrophoresis using ketoconazole as an internal standard (IS). The background electrolyte (BGE) composed of a Tris buffer solution (100 mM, pH 3.0, adjusted with acetic acid) and methanol (8:2, v/v). Injection was carried out electrokinetically with 10 kV over a time period of 20 s. A special rinsing procedure utilizing a sequence of a SDS/methanol solution, a sodium hydroxide solution, water and BGE, was applied to enhance the reproducibility. With this procedure, an intermediate precision (day-to-day precision) of the area ratios of clotrimazole and IS of 5.0% for 0.5 microg ml(-1) and 2.6% for 10 microg ml(-1) was obtained. In summary, with the described capillary zone electrophoresis (CZE) method it is possible to handle small sample volumes of 60 microl, to detect clotrimazole concentrations of 0.3 microg ml(-1) (limit of detection), and to quantify clotrimazole down to concentrations of 0.5 microg ml(-1) (limit of quantification).