High-performance liquid chromatographic method for simultaneous determination of sophoridine and matrine in rat plasma

A high-performance liquid chromatographic (HPLC) method is described for the simultaneous determination of sophoridine and matrine in rat plasma. Sophoridine and matrine in the resulting supernatant of the plasma deproteinized with acetonitrile containing an internal standard (acetanilide) were directly determined by reversed-phase HPLC and ultraviolet detection. The result of limits of quantitation for matrine and sophoridine were 200 and 350 ng/mL in plasma, respectively, and recovery of both analytes was greater than 98%. The assay was linear from 250 to 4000 ng/mL for matrine and from 500 to 8000 ng/mL for sophoridine. Variation over the range of the standard curve was less than 15%. The method was used to determine the concentration-time profiles of matrine and sophoridine in the plasma following oral administration of Kexieling tablets, which is one of the preparations of Kudouzi at a dose equivalent to 30 and 60 mg/kg of matrine and sophoridine, respectively.     

High-performance liquid chromatographic method for simultaneous determination of honokiol and magnolol in rat plasma

A high-performance liquid chromatographic (HPLC) method is described for the simultaneous determination of honokiol and magnolol in rat plasma. The plasma was deproteinized with acetonitrile which contained an internal standard (diphenyl) and was separated from the aqueous layer by adding sodium chloride. Honokiol and magnolol are extracted into the acetonitrile layer with high yield, and determined by reversed-phase HPLC and ultraviolet detection. The limits of quantitation for honokiol and magnolol were 13 and 25 ng ml⁻¹ in plasma, respectively, and recovery of both analytes was greater than 93%. The assay was linear from 20 to 200 ng ml⁻¹ for honokiol and from 40 to 400 ng ml⁻¹ for magnolol. Variation over the range of the standard curve was less than 15%. The method was used to determine the concentration-time profiles of honokiol and magnolol in the plasma following rectal administration of Houpo extract at a dose of 245 mg kg⁻¹, equivalent to 13.5, 24.4 mg kg⁻¹ of honokiol and magnolol, respectively.     

High-performance liquid chromatographic method for the determination of spectinomycin in turkey plasma.

A selective high-performance liquid chromatographic (HPLC) method with ultraviolet-visible (UV-VIS) detection was developed to measure therapeutic concentrations of spectinomycin in turkey plasma. Treatment of plasma samples with 3% trifluoroacetic acid in acetonitrile facilitated spectinomycin extraction and protein precipitation. After centrifugation, the stable derivatization reagent, 2,4-dinitrophenyl-hydrazine, was added to an aliquot of the supernatant, and the mixture was incubated for 30 min at 70 degrees C. Excess reagent was quenched with acetone and additional heating. The resulting derivative, a proposed spectinomycin-hydrazone, was separated from other compounds by reversed-phase HPLC during a short gradient run. The absorbance of the effluent was monitored spectrophotometrically with the UV-VIS detector set at 205 nm. The detector response was linear through the range of interest, 2-100 micrograms/ml.     

High-performance liquid chromatographic determination of prostacyclin.

A high-performance liquid chromatographic method for the analysis of prostacyclin using a laboratory prepared reversed-phase column packing is described. A relative standard deviation of less than 1% was obtained for ten replicate injections. The system resolves prostacyclin from its hydrolysis product, 6-oxo-prostaglandin F1 alpha and from other prostaglandins present as impurities. These can be estimated to levels of approximately 0.5%. The separation of other unrelated prostaglandins by this method is briefly reported.     

High-performance liquid chromatographic determination of kanamycin.

A fast, selective, and precise liquid chromatographic method for simultaneous, independent determination of kanamycins A and B is described. Sample components are separated on a pellicular cation exchanger and monitored by fluorescence using post-column on-line derivatization. Less than 0.35 mug of kanamycin B can be detected in as much as 7 mug kanamycin A injected. The detection limit for kanamycin A is less than 20 ng injected. Reproducibility of the entire chromatographic system is about 1% (2 theta) based upon repeated injections of standards. Precision of repeated process sample preparation is about 6% (2 theta). Chromatographic analysis time is less than 15 min per sample.     

High-performance liquid chromatographic determination of bleomycins.

A rapid and specific ion-pair reversed-phase high-performance liquid chromatographic method was developed for the determination of bleomycins. The use of 5-microns particles of less adsorptive reversed-phase packings and sodium perchlorate as ion-pairing reagent permitted a short analysis time and the transferability of the separations on different batches of the reversed-phase materials. The detection sensitivity and precision of the method demonstrated that the system is suitable for routine analysis.     

High-performance liquid chromatographic method for the determination of RGH-5702 in plasma samples.

A quick and selective high-performance liquid chromatographic method has been developed for the determination of RGH-5702 in plasma samples. A simple one-step extraction is used followed by reversed-phase chromatography and UV detection. This method allowed the separation of the compound and internal standard within 7 minutes. Validation of the method was performed prior to the assay of samples and continued throughout the study. Acceptable accuracy and precision was achieved at all concentrations investigated. The quantitation limit was 20 ng/ml using 1 ml of plasma. The method has been applied to the analysis of plasma samples from toxicokinetic studies in dogs.     

High-performance liquid chromatographic method for the determination of free gossypol in chicken liver.

A high-performance liquid chromatographic method for the determination of free gossypol in chicken liver at levels down to 0.5 ppm has been developed. Tissue was deproteinized with acetonitrile in presence of ascorbic acid and the filtrate was subjected to hydrolysis with hydrochloric acid. The liberated pure gossypol was partitioned into chloroform and analysed by gradient elution on a 10-microns C18 column. The overall recovery was 83.5 +/- 2.6%, with an overall relative standard deviation of 9%.     

High-performance liquid chromatographic method for the simultaneous estimation of the key intermediates of duloxetine

A simple reversed-phase high-performance liquid chromatographic method employing C-18 column has been developed for simultaneous analysis of three intermediates in the synthesis of S-duloxetine, the antidepressant drug, viz., 2-acetyl thiophene (AT), N,N-dimethyl-3-keto-(2-thienyl)-propanamine (DKTP) and (S)-N,N-dimethyl-3-hydroxy-(2-thienyl)-propanamine (DHTP). Good separations were achieved by employing an isocratic system using acetonitrile and 0.05 M phosphate buffer (pH 7.0) containing 0.02% diethylamine. The detection was carried out at 241 nm. The method was validated for linearity, range, accuracy and precision. The developed method was applied for monitoring the progress of chemical synthesis of DKTP from AT followed by the biocatalytic reduction of DKTP to DHTP as the disappearance of the substrate and formation of the product can be monitored simultaneously by the present method.     

High-performance liquid chromatographic method for the simultaneous determination of cyclosporine A and its four major metabolites in whole blood

This study aimed to develop a simple and efficient optimized high-performance liquid chromatograph (HPLC) method for simultaneous determination of cyclosporine A (CyA) and its major, partly active metabolites AM1, AM9, AM4N, and AM19 in whole blood from transplant patients using cyclosporine D (CyD) as internal standard. The method used a CN analytical column maintained at 60 °C with hexan-isopropanol (93:7, v/v) as mobile phase; detection was at 212 nm. Linearity for all five compounds was tested in the range of 31-1500 ng ml⁻¹ for CyA and of 31-1000 ng ml⁻¹ for metabolites. The limit of detection was found to be 15 ng ml⁻¹ for all compounds.This modified, inexpensive method is also suitable for measuring cyclosporine A and metabolite concentrations in routine monitoring of patients undergoing treatment with CyA.     

High-performance liquid chromatographic method for determination of ciprofloxacin in biological fluids

A simple and precise high-performance liquid chromatographic procedure has been developed for the determination in biological fluids of ciprofloxacin, a new, with extended antibacterial spectrum, quinoline carboxylic acid. The work-up procedure involves a chemical extraction step followed by isocratic chromatography on a reversed-phase analytical column, with ultraviolet detection. The detection limit for blood levels is 10 ng/ml. The calibration curve is linear from this detection limit to 10 microgram/ml. The statistical analysis of the correlation made between this assay and an agar diffusion procedure during a pharmacokinetic study suggests the existence of one or more active metabolites which could be mainly excreted in the bile.