Stability of reconstituted solutions of ceftazidime for injections: an HPLC and CE approach.

The stability of aqueous reconstituted ceftazidime injection vials containing ceftazidime pentahydrate blended with anhydrous sodium carbonate was investigated in different storage conditions (4 degrees C and 10 degrees C for 7 days in a refrigerator, 20 and 30 degrees C for 24 h) with validated HPLC and (micellar) CE methods. Stability indicating data were obtained for ceftazidime and two degradation products: pyridine and the delta2-ceftazidime isomer. Other degradation products were also identified (the complementarity of the two used experimental procedures was useful in such exercise) and characterized by their UV spectra and retention times. Stability data (7 days at 4 degrees C in a refrigerator and 18 h at room temperature) resulted in agreements with the manufacturers prescription and point out the need of a strict temperature control of the refrigerator's compartment used to store the reconstituted solution.

The indirect UV detection in the analysis of ursodeoxycholic acid and related compounds by HPCE.

A high-performance capillary zone electrophoretic (HPCE) assay has been developed for the determination of ursodeoxycholic acid (UDCA) and its usual impurities. Considering the low molecular absorptivity of UDCA and its related compounds indirect UV detection was used. The electrophoretic capillary was filled with a background electrolyte (BGE) containing an UV absorbing ion: benzoic acid (BA) or 5,5-diethylbarbituric acid (DBA). To enhance the selectivity of the assay diimethyl-beta-cyclodextrines (D-beta-CDs) or trimethyl-beta-cyclodextrines (T-beta-CDs) have been added to the running buffer together with methylcellulose or urea. All considered impurities were well resolved with two buffers studied, with the exception of methylursodehoxycholate, a neutral compound.

HPTLC and reflectance mode densitometry of anthocyanins in Malva silvestris L.: a comparison with gradient-elution reversed-phase HPLC.

Aqueous alcoholic mallow flower extracts were analyzed both by HPTLC-densitometry in the reflectance mode at 530 nm and by reversed-phase HPLC with gradient elution. For the mallow flower anthocyanins the best chromatographic resolution was obtained by HPLC, which revealed only two main compounds, confirmed by FAB-MS: malvidin 3,5-O-diglucoside (malvin) and malvidin 3-O-(6"-O-malonylglucoside)-5-O-glucoside. The HPTLC densitometric method on cellulose plates provides accuracy, reproducibility and selectivity for the quantitative analysis of the anthocyanins and this method was shown to be much more sensitive than the HPLC-DAD system, at 530 nm. Both methods give comparable quantitative results for total anthocyanins when applied to mallow flowers from two different sources: Italy and Albania.

Analysis of FCE 23762 (methoxymorpholinodoxorubicin hydrochloride), a new antitumour agent, by HPTLC and scanning densitometry.

A simple, rapid and reproducible high-performance thin-layer chromatographic (HPTLC) method using UV or fluorescence scanning densitometry has been developed for the assay and purity control of methoxymorpholinodoxorubicin hydrochloride (FCE 23762). With a mobile phase of chloroform-methanol-acetic acid (93:6:1, v/v/v) and a silica gel plate, all potential impurities were separated from the main component and from each other. Detection limits at a signal-to-noise ratio of 2:1 were a few nanograms for UV detection and < 1 ng for fluorescence emission. The RSD values for the examined compounds were all < 3%.

Analysis of new serotonergic anxiolytics by liquid chromatography.

A simple isocratic procedure was developed for the analysis of new serotonergic anxiolytics and the related compounds in bulk materials, pharmaceutical formulations and in biological samples. The system may be applied for the assay of other serotonergic anxiolytics of related structure such as buspirone. The liquid chromatographic assay utilizes a reversed-phase C18 column, a mobile phase consisting of a mixture (55:45, v/v) of (A) buffer potassium dihydrogen phosphate (0.05 M) containing sodium lauryl sulphate (0.005 M) and (B) acetonitrile. A fluorescence detection is used with lambda ex 237 nm; lambda cm 374 nm. The accuracy, precision and sensitivity of the proposed method are established. Standard curves are linear with respect to concentration in the range 0.05-7.5 micrograms ml-1. The method also allows the separation and identification of related compounds at concentrations below 0.01%.

Quantitative analysis of beta-adrenergic blocking agents by NMR spectroscopy.

The quantitative analysis by (1)H NMR of labetalol, oxprenolol and four other beta-adrenergic blocking agents is described. The method depends on the integration of selected resonances of the analyte and an internal reference which do not overlap. Procedures for the extraction of the analyte from tablets are given and corrections due to the NMR features of excipients outlined in some cases. The NMR method is reasonably precise and rapid, and the assay results compare favourably with those obtained by a UV procedure.