Simultaneous determination of cefoxitin, cefuroxime, cephalexin and cephaloridine in plasma using HPLC and a column-switching technique

Analysis of cephalosporin antibiotics

A comprehensive review with 276 references for the analysis of members of an important class of drugs, cephalosporin antibiotics, is presented. The review covers most of the methods described for the analysis of these drugs in pure forms, in different pharmaceutical dosage forms and in biological fluids.

Determination of cefuroxime axetil in tablets and biological fluids using liquid chromatography and flow injection analysis

Cefuroxime axetil is the pro-drug of cephalosporin cefuroxime that is used in the treatment of common community-acquired infections. A simple and precise liquid chromatographic method for the determination of cefuroxime axetil in pharmaceutical tablets, human serum and urine has been developed and validated. Cefuroxime axetil and indapamide (internal standard) were separated by a reversed phase column (Supelco Hypersil 5 microm, 150 mm x 4.6 mm i.d., C18) using a mobile phase consisting of KH2PO4 (0.1 M) and acetonitrile (70:30 v/v) (at pH 4.0). The mobile phase was pumped at 1.0 mL min(-1) flow rate and cefuroxime axetil was detected by ultraviolet detection at 281 nm within an average analysis time of 11 min. Flow injection analysis was performed for pharmaceutical tablet analysis using a carrier stream of methanol:water (10:90v/v) with a flow rate of 1.0 mL min(-1). The LOD and LOQ concentrations of the HPLC method were 1.35 x 10(-7) and 4.08 x 10(-7)M for the HPLC analysis and 1.31 x 10(-7) and 4.00 x 10(-7)M for FIA. The results of the analysis of the tablet formulation obtained by using these methods were statistically comparable with each other and with an additional spectrophotometric method. There was no significant difference between all these methods.

Colourimetric and AAS determination of cephalosporins using Reineck's salt

Two simple, accurate, sensitive and selective procedures for the determination of eight cephalosporins are described. These procedures are based on the formation of ion-pair complexes between the drugs and ammonium reineckate, the formed precipitates are quantitatively determined either colourimetrically or by atomic absorption spectrometrically. The methods consist of reacting drugs with Reinecke's salt in an acidic medium at 25+/-2 degrees. The first colourimetric procedure (procedure I) is based on dissolving the formed precipitate with acetone, the volume was completed quantitatively and the absorbance of the solution was measured at 525 nm against pure solvent blank. Also, the formed precipitates on the atomic absorption spectrometric procedure (procedure II) are quantitatively determined directly or indirectly through the chromium precipitate formed or the residual unreacted chromium in the filtrate at 358.6 nm. The optimum conditions for precipitation have been carefully studied. Beer's law is obeyed for the studied drugs in the range 5-35 microg ml(-1) with correlation coefficients not less-than 0.9989. Both procedures I and II hold well accuracy and precision when applied to the analysis of the cited cephalosporins in different dosage forms with good recovery percent ranged from 98.7+/-0.90 to 100.1+/-0.74 without interference from additives.

New spectrophotometric procedure for determining cefotaxime based on derivatization with 1,2-naphthoquinone-4-sulphonate into solid-phase extraction cartridges--application to pharmaceutical and urine samples

Cefotaxime was derivatised with 1,2-naphthoquinone-4-sulphonate (NQS), extracted into solid-phase cartridges (C18) and detected using a UV-visible detection system. Optimum conditions for this new procedure were: hydrogencarbonate-carbonate buffer, pH 10.5, 5-min reaction time at 25 degrees C and an NQS concentration of 7.1x10(-3) mol l(-1). The accuracy and the precision of the liquid-solid procedure were tested. The procedure was used to measure cefotaxime in pharmaceutical and urine samples. The results obtained were contrasted with those reported for a HPLC method for urine samples. The generalized H-point standard additions method was used to measure cefotaxime in urine samples.

On-line sample preparation of paraquat in human serum samples using high-performance liquid chromatography with column switching

A new ion-pair high-performance liquid chromatographic method with column-switching has been developed for the determination of paraquat in human serum samples. The diluted serum sample was injected onto a precolumn packed with LiChroprep RP-8 (25-40 microm) and polar serum components were washed out by 3% acetonitrile in 0.05 M phosphate buffer (pH 2.0) containing 5 mM sodium octanesulfonate. After valve switching to inject position, concentrated compounds were eluted in the back-flush mode and separated on an Inertsil ODS-2 column with 17% acetonitrile in 0.05 M phosphate buffer (pH 2.0) containing 10 mM sodium octanesulfonate. The total analysis time per sample was about 30 min and mean recovery was 98.5+/-2.8% with a linear range of 0.1-100 microg/ml. This method has been successfully applied to serum samples from incidents by paraquat poisoning.

Quantitative determination of semisynthetic cephamycins in human serum and urine by ion-exchange, reversed-phase and ion-pair chromatography

High-performance liquid chromatographic methods have been developed for the determination of semisynthetic cephamycins: cefoxitin, cefmetazole and cefminox in human serum and urine samples. Serum samples spiked with each cephamycin were combined with an equal volume of methanol to remove proteins and, after centrifugation, and aliquot of the supernatant was analysed by ion-exchange, reversed-phase and ion-pair chromatography with hexadecyltrimethylammonium bromide as the ion-pairing agent. Urine samples were diluted, filtered and analysed by same chromatographic procedure. The cephamycins were detected by their ultraviolet absorbance (265-272 nm). It was possible to determine concentrations of cephamycins to 0.2 micrograms/ml in serum 2 micrograms/ml in urine samples with a good level of reproducibility and accuracy.

HPTLC assay of cephalexin and cefaclor in pharmaceuticals

A simple and reliable HPTLC method for the simultaneous determination of cephalexin and cefaclor is developed and validated. The methanol-ethyl acetate-acetone-water (5:2.5:2.5:1.5 v/v/v/v) solvent system is used for the quantitative evaluation of chromatograms. The chromatographic zones, corresponding to the spots of cephalexin and cefaclor on the silica gel plates, are scanned in the reflectance/absorbance mode at 265 nm. The method is found to be reproducible and convenient for the quantitative analysis of cephalexin and cefaclor in its dosage forms.

Measurement of cefuroxime in human bronchoalveolar lavage fluid by high-performance liquid chromatography after solid-phase extraction

A sensitive and selective method for the determination of cefuroxime in bronchoalveolar lavage (BAL) fluid using high-performance liquid chromatography (HPLC) with UV detection at 280 nm after solid-phase extraction with C18 cartridges was developed. A Waters symmetry C18 column was used and the mobile phase was acetonitrile-0.05 M ammonium phosphate buffer (pH 3.2) (15:85, v/v). The method enabled the determination of cefuroxime at concentrations below 100 ng/ml, with a linear calibration curve at concentrations of 5-100 ng/ml for 400 microliters of BAL. The intra- and inter-assay coefficient of variations for 10, 40 and 80 ng/ml were between 5.3 and 8.9%. Analytical recoveries were between 92.7 and 106.2%. The detection limit was 1 ng/ml at a signal-to-noise ratio of 3:1 using 400 microliters of BAL. The method was successfully used for the analysis of BAL fluid from patients after oral administration of 500 mg cefuroxime axetil twice daily.

Simultaneous determination of ampicillin and metampicillin in biological fluids using high-performance liquid chromatography with column switching

A new high-performance liquid chromatographic method with column switching has been developed for the simultaneous determination of metampicillin and its metabolite ampicillin in biological fluids. The plasma, urine and bile samples were injected onto a precolumn packed with LiChrosorb RP-8 (25-40 microns) after simple dilution with an internal standard solution in 0.05 M phosphate buffer (pH 7.0). The polar plasma components were washed out using 0.05 M phosphate buffer (pH 7.0). After valve switching, the concentrated drugs were eluted in the back-flush mode and separated by an Ultracarb 5 ODS-30 column with a gradient system of acetonitrile-0.02 M phosphate buffer (pH 7.0) as the mobile phase. The method showed excellent precision, accuracy and speed with a detection limit of 0.1 microgram/ml. The total analysis time per sample was less than 40 min and the coefficients of variation for intra- and inter-assay were less than 5.1%. This method has been successfully applied to plasma, urine and bile samples from rats after intravenous injection of metampicillin.

High-performance liquid chromatographic determination of rifapentine in serum using column switching

A high-performance liquid chromatographic method with column switching has been developed for the determination of rifapentine in serum. The serum samples were injected onto a precolumn packed with Corasil RP C18 (37-50 microns) after simple dilution with an internal standard in a 1% ascorbic acid solution. Polar serum components were washed out using 0.05 M phosphate buffer. After valve switching, the concentrated drugs were eluted in the back-flush mode and separated by a mu Bondapak C18 column with acetonitrile-tetrahydrofuran-0.05 M phosphate buffer (pH 7.0) (42:5:53, v/v/v) as the mobile phase. The method showed excellent precision with good sensitivity and speed, and a detection limit of 0.1 microgram/ml. The total analysis time was less than 25 min and the mean coefficients of variation for intra- and inter-assay were less than 4.8%. The method has been successfully applied to serum samples from dogs after the oral administration of rifapentine.