Sensitive high-performance liquid chromatographic method for the determination of a benzonaphthazepine antipsychotic agent, SCH 39166, and its active metabolite, SCH 40853, in human plasma and its cross-validation with a gas chromatographic method

A sensitive high-performance liquid chromatographic (HPLC) method was developed for the determination of a benzonaphthazepine antipsychotic agent, SCH 39166, and its active metabolite, SCH 40853. The HPLC method required a single-step organic extraction at alkali pH followed by HPLC analysis utilizing a CN column with UV detection at 205 nm. The limit of quantitation was 1 ng/ml for SCH 39166 and 0.5 ng/ml for SCH 40853. The HPLC method was cross-validated with a previously reported GC method by the analysis of 73 plasma samples spiked with various concentrations of SCH 39166 and SCH 40853. The correlation coefficient was 0.9969 for SCH 39166 and 0.9984 for SCH 40853. Both GC and HPLC methods were used for the determination of plasma concentrations and yielded similar pharmacokinetic parameters for SCH 39166 and SCH 40853 in man following oral administration of SCH 39166 (100 mg).     

Chromatographic and capillary electrophoretic methods for the analysis of nicotinic acid and its metabolites

Methods for the assay of nicotinic acid (NiAc) and its metabolites in biological fluids using high-performance liquid chromatography (HPLC) and capillary electrophoresis (CE) are reviewed. Most of the references cited in this review concern HPLC methods. A few CE methods that have been recently reported are also included. As these compounds are relatively polar and have a wide range of physico-chemical properties, the sample pre-treatment or clean-up process prior to analysis is included. Most HPLC methods using an isocratic elution system allow determination of a single or few metabolites, but gradient HPLC methods enable simultaneous determination of five to eight compounds. Simultaneous determination of NiAc including many metabolites in a single run can be achieved by CE. We also discuss the pharmacokinetics of NiAc and some of its metabolites.     

Enantiomerization of chiral 2,3,3a,4-tetrahydro-1H-pyrrolo[2,1-c][1,2,4] benzothiadiazine 5,5-dioxide by stopped-flow multidimensional HPLC

An on-column stopped-flow multidimensional HPLC (sfMDHPLC) procedure using two chiral stationary phases (CSPs) and one achiral C18 column was developed for the determination of rate constants and free energy barriers of enantiomerization of (+/-)(R,S)-2,3,3a,4-tetrahydro-1H-pyrrolo[2,1-c][1,2,4]benzothiadiazine 5,5-dioxide. Moreover, a stopped-flow HPLC (sfHPLC) method previously developed was applied to the determination of kinetic parameters of enantiomerization of the above compound in the presence of a CSP. The individual enantiomers of the studied compound were isolated in parallel by preparative HPLC and the rate constants and free energy barriers of enantiomerization were determined in different solvents (off-column method). The data obtained by sfMDHPLC, sfHPLC and off-column methods were compared. The (S) enantiomer of the studied compound (S18986) was prepared by asymmetric synthesis and subsequently purified by preparative HPLC, followed by the determination of rate constants and free energy barriers of enantiomerization in different buffer solutions at pH 2-9.3.     

Bestimmung von Deoxynivalenol in Brot und Bier

Analytical procedures for the determination of deoxynivalenol (DON) in bread and beer, using enzyme immunoassay (EIA) and HPLC methods, were developed. For determination of DON by EIA, aqueous raw extracts of bread or degassed beer were extracted by liquid-liquid partitioning with ethyl acetate, the organic solvent evaporated, and the residue redissolved in phosphate buffered saline (PBS) for analysis. For determination by HPLC (UV detection at 218 nm), DON in bread extracts or beer was purified on immunoaffinity chromatographic columns. In bread, detection limits for DON of 15 µg/kg (EIA) and 7 µg/kg (HPLC) were achieved, with mean recoveries of 81%. In beer, the detection limit for DON was 2 µg/l both in EIA and HPLC, with recoveries of 91–93%. Both methods showed good agreement of the results for naturally contaminated sample materials, with r²=0.993 for bread and r²=0.823 for beer, respectively.     

Selective extraction of quercetrin in vegetable drugs and urine by off-line coupling of boronic acid affinity chromatography and high-performance liquid chromatography

Quercetrin, quercetin and chlorogenic acid were measured in urine or in drugs by combination of boronic acid affinity chromatography and HPLC. Simple reversed-phase HPLC with UV detection was used to determine quercetrin in five different Solidago virgaurea drugs. For determination of quercetrin in human urine immobilized boronic acid was applied for sample pretreatment. This procedure leads to a determination limit of 0.01 μg/ml with a recovery rate of 95.3%. The first results using this method for quercetrin pharmacokinetics are presented.     

Liquid chromatographic determination including simultaneous "on-cartridge" separation of ranitidine cisapride drug combinations from paediatric plasma samples using an automated solid-phase extraction procedure

HPLC methodology was investigated for the simultaneous determination of cisapride and ranitidine in small volume paediatric plasma samples. Such a simultaneous determination proved difficult due to the small sample volumes, the low concentrations of the drugs and the different log P values of the two compounds. The two drugs and their respective internal standards were separated "on-cartridge" using HLB Solid Phase Extraction cartridges and the samples quantified by individual HPLC methodologies. The technique has been applied successfully to 60 paediatric plasma samples containing both cisapride and ranitidine.     

Application of HPLC for the determination of phospholipid hydroperoxides in food and biological systems

Hydroperoxides derived from phospholipids of biological source could be analyzed quantitatively by using reverse phase high performance liquid chromatography (HPLC). The combination of reverse phase HPLC and normal phase HPLC, which is used for the separation of lipid classes, seems to be a powerful technique for the determination of peroxidized phospholipids in food and biological systems. The development of the detector specific to the hydroperoxy group is desired for increasing the effectiveness of this method.     

有机溶剂对HPLC测定头孢菌素C含量的影响

考察了10种水溶性有机溶剂对HPLC测定头孢菌素C含量的影响,采用C_(18)色谱柱,流动相为磷酸二氢钠-甲醇(90:10),波长254 nm。发现不同的有机溶剂有不同程度的影响,其中乙醇的影响最大;乙醇浓度越高,峰面积就越小。将含有乙醇的头孢菌素C溶液稀释到一定程度,能够有效消除乙醇的影响。稀释法具有较好的精密度、重复性和回收率,为在工业生产中准确测定头孢菌素C的含量提供了依据。     

Rapid and simple micro-determination of carvedilol in rat plasma by high-performance liquid chromatography

We studied the use of high-performance liquid chromatography (HPLC) with spectrofluorometric detection, using a solid-phase extraction for a simple, rapid and sensitive determination of plasma carvedilol levels in rats. Extracted aliquots were analyzed by HPLC, using a reversed-phase octadecyl silica column. The analytical mean recovery of carvedilol added to the blank plasma was 94.2%. The detection limit was 3.6 ng/ml in the plasma. The reproducibilities (C.V.) were 2.7–7.5% for the within-day assay, and 2.6–7.4% for the between-day assay, indicating that the method was effective for the determination of carvedilol plasma levels.     

HPLC法测定低pH静脉注射用人血丙种球蛋白麦芽糖含量

本文采用HPLC法测定低pH静脉注射用血丙种球蛋白中麦芽糖含量,所用色谱柱为氨基柱。首先用磺基水杨酸沉淀蛋白并离心分离,上清液上样分析。通过外标法建立三级校正曲线来测定样品中麦芽糖含量,该法准确快速较化学方法好。     

Analysis of the stereochemistry of lipoxygenase-derived hydroxypolyenoic fatty acids by means of chiral phase high-pressure liquid chromatography

A chiral phase HPLC method was developed for the simultaneous determination of the positional and optical isomers of the lipoxygenase-derived hydroxypolyenoic fatty acids. With a Bakerbond chiral phase HPLC column (dinitrobenzoyl phenylglycine as chiral phase) the positional and optical isomers of the reduced dioxygenation products (by triphenylphosphine or borohydride) of linoleic acid and arachidonic acid were separated after methylation of the carboxylic groups. No cumbersome chemical derivatization such as conversion to a diastereomer was necessary. As compared with the methods used up till now chiral phase HPLC proved to be simpler and more sensitive. About 10 pmol of hydroxy fatty acids suffice for an analysis. The chiral phase HPLC can be used for the preparative separation of the optical antipodes of the lipoxygenase products. An optical purity of more than 90% can be reached in one preparative run. The method was applied to the determination of the stereochemistry of the dioxygenation products of polyenoic fatty acids formed by the lipoxygenases from soybeans, reticulocytes, pea seeds (isoenzyme I and II), tomato fruits, by the quasilipoxygenase activity of hemoglobin, and by the methylene blue-mediated photooxidation of arachidonic acid.     

Comparison of HPLC method and commercial ELISA assay for asymmetric dimethylarginine (ADMA) determination in human serum

The performance of a new ELISA assay kit (DLD Diagnostika GmbH, Hamburg, Germany) for the determination of asymmetric dimethylarginine (ADMA) was evaluated against a reversed phase HPLC method. ADMA concentrations of 55 serum samples were measured with both methods. The intra-assay CV for ADMA-ELISA was 19% (n=10). Inter-assay CVs for ADMA-ELISA were 9% for kit control 1 (0.410+/-0.037 microM) and 14% for kit control 2 (1.174+/-0.165 microM). The intra- and inter-assay CVs for HPLC assay for ADMA were 2.5% (0.586+/-0.015 microM) and 4.2% (0.664+/-0.028 microM), respectively. There was no correlation between these two methods (R(2)=0.0972). The effect of storage conditions of the samples on ADMA concentrations was investigated by HPLC. ADMA concentration was stable after four freezing and thawing cycles. Overall, the HPLC method offered better sensitivity, selectivity and, very importantly, simultaneous determination of ADMA, SDMA, l-homoarginine and l-arginine.     

Determination of Relative Response Factors of Cefazolin Impurities by Quantitative NMR

The relative response factors (RRFs) of ten cefazolin impurities were determined by quantitative nuclear magnetic resonance (qNMR) and high-performance liquid chromatography (HPLC) equipped with an ultraviolet (UV) detector. The purities of these ten cefazolin impurities were successfully measured by qNMR for the purpose of RRFs determination by HPLC. The RRF values and their uncertainties determined by the two approaches are comparable. While the qNMR approach is effective and makes it easier to determine the RRFs for impurities, it also has the advantage of allowing the universal detection of protons without the limitations of common mass detectors. The use of qNMR provides a reliable and universal method for the RRF determination of impurities.     

Automated method for determination of glutardialdehyde residues in flexible endoscopes after disinfection

Glutardialdehyde (GDA) is the most commonly used disinfectant for flexible endoscopes. After inappropriate rinsing of endoscopes residual GDA in the narrow endoscope channels may lead to toxic effects in patients. Common methods for determination of aldehydes in water involve derivatization with 2,4-dinitrophenylhydrazine (DNPH), liquid-liquid or solid-phase extraction and HPLC determination. Since derivatization and extraction is both time-consuming and labor-intensive only a small number of samples can be measured. Thus, we developed a fully automated method which includes a conventional HPLC system, a programmable autosampler, and UV detection. After GDA derivatization using DNPH the samples remain in the aqueous phase and no preconcentration of the analyte is necessary. The samples are automatically derivatized through the autosampler. While derivatization in one sample takes place the previous sample is injected and measured by HPLC. Our method is well suited for screening residual GDA in endoscopes as it is both time- and labor-saving.     

Simple and sensitive high-performance liquid chromatographic method for the determination of an everninomycin,SCH 27899, in rat plasma

A simple and sensitive high-performance liquid chromatographic (HPLC) method was developed for the determination of SCH 27899, an everninomycin antibiotic, in rat plasma. The method involved plasma protein precipation with acetonitrile, followed by reversed-phase HPLC analysis using a polymeric column and a mobile phase containing acetonitrile and ammonium phosphate, pH 7.8. The linear relationship between detector response and concentration was demonstrated with a correlation coefficient of larger than 0.996 at concentrations ranging from 0.2 to 100 μg/ml. The results showed that the HPLC method was accurate (bias ≤6%) and precise (coefficient of variation, C.V.≤6%). The limit of quantitation was 0.2 μg/ml with a C.V. of 2.6% and bias of 5%. SCH 27899 was stable in rat plasma at −20°C for at least 40 days. The HPLC method has been utilized for the determination of SCH 27899 in plasma samples from rats following single intravenous administration (3 mg/kg).     

Laccase assay by means of high-performance liquid chromatography

Spectrophotometric determination of laccase activity may be affected by the formation of quinoid chromophores arising from nonenzymatic oxidations interfering with enzymatic reactions. Km values for guaiacol obtained by spectrophotometric and HPLC methods confirm the above hypothesis. HPLC results are particularly useful for the assay of laccase activity on natural phenolic extracts.     

Determination of deracoxib in feline plasma samples using high performance liquid chromatography

A new HPLC procedure for the determination of deracoxib, a selective cyclooxygenase-2 inhibitor, has been developed and validated. Following a liquid-liquid extraction using isopropyl alcohol and chloroform, samples were separated by isocratic reversed-phase HPLC on an Atlantis C18 column and quantified using UV detection at 252 nm. The mobile phase was a mixture of 10 mM potassium phosphate (pH 4.5) and acetonitrile, with a flow-rate of 1.0 ml/min. The procedure produced a linear curve over the concentration range 10-1500 ng/ml. The development of the assay allowed the determination of pharmacokinetic parameters after oral administration of deracoxib in cats and would be suitable for other pharmacokinetic studies.     

Application of high-performance liquid chromatography to the determination of vinblastine in Catharanthus roseus

A method for the determination of vinblastine in Catharanthus roseus by HPLC is described. A crude alkaloid extract, obtained by extraction of leaves with toluene, 2% citric or tartaric acid and benzene, was separated by TLC. The vinblastine fraction was cut out and vinblastine was eluted from the sorbent. The amount of vinblastine was determined by HPLC with peak-height measurement. The standard deviation is 0.2 μg/ml. The detection limit is 0.05 ng of vinblastine in a sample applied to the HPLC column.     

蝮蛇肌肉中次黄嘌呤的鉴定与含量测定

目的建立一种高效液相色谱法测定蝮蛇肌肉中次黄嘌呤的新方法。方法采用Venusil MP-C18柱分离和LC—MS技术联用鉴定蝮蛇肌肉中存在次黄嘌呤,并测定蝮蛇肌肉中次黄嘌呤的含量。姑果该法适合于蝮蛇肌肉中次黄嘌呤含量的测定。操作简便,样品稳定。结论该法操作简便,结果准确可靠,为蝮蛇药材的质量控制提供了有效的方法。     

The development and validation of liquid chromatography method for the simultaneous determination of metformin and glipizide, gliclazide, glibenclamide or glimperide in plasma

This article describes the development of SPE and HPLC methods for the simultaneous determination of metformin and glipizide, gliclazide, glibenclamide or glimperide in plasma. Several extraction and HPLC methods have been described previously for the determination of each of these analytes in plasma separately. The simultaneous determination of these analytes is important for the routine monitoring of diabetic patients who take combination medications and for studying the pharmacokinetics of the combined dosage forms. In addition this developed method can serve as a standard method for the plasma determination of these analytes therefore saving time, effort and money. The recoveries of the developed methods were found to be between 76.3% and 101.9%. The limits of quantification were between 5 and 22.5 ng/ml. The intraday and interday precision (measured by coefficient of variation, CV%) was always less than 9%. The accuracy (measured by relative error %) was always less than 12%. Stability analysis showed that all analytes are stable for at least 3 months when stored at -70 degrees C.