Extracts of roots Phyllanthus acidus were examined by free zone capillary electrophoresis, micellar electrokinetic chromatography (MEKC), and MEKC using the sweeping technique which involves application of a negative potential to the inlet end of the capillary and very much longer than conventional injection times. The latter technique, using a buffer of 50 mM sodium dihydrogen phosphate (pH 2) containing 80 mM sodium dodecylsulphate and 30% methanol was found to allow complete resolution of the active constituents of P. acidus, phyllanthusols A and B, from each other and from other extracted components in under 30 min. Several other components could be detected when hydrodynamic injection times of 500 s were used. The separation, combined with an appropriate extraction procedure and using an internal standard of proguanil, permitted quantification of both phyllanthusols. Calibrations were linear over the range 2-8 micrograms/mL for phyllanthusol A, and 1-4 micrograms/mL for phyllanthusol B. Within-day and day-to-day repeatability RSDs were below 10%, and the precision of extraction RSD was around 14%. The limits of quantification and detection were 0.55 and 0.24 microgram/mL, respectively.

Benzofurans↗

PubMedDate not supplied

Multidrug assay method for antimalarials.

A general separation strategy, involving solid-phase extraction followed by reversed-phase ion-pairing HPLC with an organic counter ion for a set of 11 widely used antimalarial drugs and metabolites has been developed. The basis underlying the separation has been explored and work, including quantitative data, has been carried out on illustrative separations which form the basis of novel quantitative assays of groups of antimalarials which are relevant to current prophylaxis and treatment of malaria.

Antimalarials↗

PubMedDate not supplied

Analysis of basic antimalarial drugs by CZE and MEKC. Part 1--Critical factors affecting separation.

The separations of 11 antimalarial drugs and metabolites are shown by CZE at low pH and by MEKC at high pH. CZE is shown to be superior to MEKC in resolution capability for these compounds under the conditions examined. Both are shown to provide different selectivities to those obtained by ion-pair reversed-phase HPLC. The effect of sample injection solvent is examined in CZE and it is shown that field-amplified sample injection is effective for these compounds. In addition, it is shown that injection of sample in an organic solvent such as methanol augments the stacking of analytes resulting in lower detection limits. The limit of detection of some antimalarials in a urine matrix is reported.

Antimalarials↗

PubMedDate not supplied

Capillary electrophoresis and liquid chromatography in the analysis of some quaternary ammonium salts used in lozenges as antibacterial agents.

A comparison is made of the relative merits of high-performance liquid chromatography and capillary electrophoresis, both using direct UV detection, for the determination of three quaternary ammonium compounds used as the active antibacterial ingredient in lozenge formulations. While both techniques are capable of separating the compounds cetylpyridinium chloride, dequalinium chloride, and benzalkonium chlorides, the liquid chromatographic method involving ion pairing and using a 5-micron cyanopropyl stationary phase, was unable to resolve the benzalkonium chlorides from the lozenge excipients and quantitation was not possible. The capillary electrophoresis method using a 205-mm 50-micron-i.d. capillary with a running buffer of 50% vol/vol 50 mM phosphate buffer at pH 3 provided superior resolution of the three antibacterials in all lozenge formulations. This system was also capable of resolving impurities in the dequalinium chloride both in the standard and in lozenges containing this compound. On the basis of quantitative results previously published, both methods have adequate validation parameters since the relative insensitivity of capillary electrophoresis compared with liquid chromatography is not important at the concentration required to be determined following a single simple sample pretreatment.

Anti-Infective Agents↗

PubMedDate not supplied

Comparisons of the separations of some neutral analytes by LC, MEKC, and CEC.

The relative utility of high-performance liquid chromatography, micellar electrokinetic chromatography (MEKC), and capillary electrochromatography (CEC) is examined for the separation of essentially uncharged solute mixtures. Three model systems are used for which separations by reversed-phase liquid chromatography had been established. These consisted of a set of three substituted hydroxybenzoates; a mixture of six structurally closely related steroids; and the multicomponent aminoglycoside antibiotic, teicoplanin. These sets represented a range of difficulty in achieving separations by reversed-phase LC. It was found that equivalent or better separations for all systems could be established by MEKC and CEC. Both electrophoretic techniques offer much higher peak efficiencies than LC, and MEKC is found to be superior to CEC in terms of peak efficiencies and ruggedness of operation.

Chromatography↗