Effect of cyclodextrins on the stability of adriamycin, adriamycinol, adriamycinone and daunomycin

The stability of adriamycin (ADR), adriamycinol, adriamycinone (ADR-ONE) and daunomycin in the presence of alpha-, beta- and gamma-cyclodextrins (CDs) was studied using high-performance liquid chromatography. It was found that alpha-CD did not affect the degradation of tested compounds, beta-CD caused a little effect and gamma-CD resulted in pronounced stabilizing effect. The formation of complexes between ADR and ADR-ONE with CDs was monitored by fluorescence spectroscopy. The fluorescence spectrum of ADR-gamma-CD complex had an activation maximum at 460 nm, emission maximum at 555 nm and a shoulder at 585 nm. A similar finding was observed in case of alpha-CD. In case of beta-CD, the fluorescence intensity at 580 nm peak enhanced less than in case of gamma-CD. With ADR-ONE, alpha-CD did not cause any significant change compared with the spectrum of free molecule. On the other hand, it was noticed that, the fluorescence spectra of ADR-ONE with both beta- and gamma-CD were the same but showed a significant difference to the spectrum of free molecule, especially the molar fluorescence of the 585 nm emission peak.     

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

Summary A new high performance liquid chromatographic method was developed using a column-switching technique for the simultaneous determination of cephalexin, cefuroxime, cefoxitin and cephaloridine in plasma. The plasma samples were injected onto a precolumn packed with Corasil RP C₁₈ (37–50 m) after simple dilution with an internal standard solution in 0.01 M acetate buffer (pH 3.5). Polar plasma components were washed out using 0.01 M acetate buffer (pH 3.5). After valve switching, the concentrated drugs were desorbed in back-flush mode and separated on a Partisil ODS-3 column using acetonitrile in 0.02 M acetate buffer (pH 4.3) (1585, v/v) as the mobile phase. The method showed excellent precision with good sensitivity and speed with a detection limit of 0.5 g/ml. The total analysis time per sample was less than 25 min, and the mean coefficients of variation for intra- and inter-assay were both less than 4.9 %.This method has been successfully applied to plasma from rats after subcutaneous injection of cefuroxime.     

Reversed-phase liquid chromatographic determination of plasma levels of adriamycin and adriamycinol

A method is given for the determination of adriamycin and its main metabolite, adriamycinol in plasma from cancer patients after administration of adriamycin as the free drug or as a complex with DNA. Adriamycin and adriamycinol are extracted in a column from 1 ml of plasma (pH 8.6) using a mixture of chloroform--1-heptanol (8:2). After re-extraction into phosphate buffer pH 2.2, the separation is performed as reversed-phase liquid chromatography on a LiChrosorb RP-2 (5 micron) column with a mobile phase of acetonitrile-water, acidified with phosphoric acid. The precision by quantitation with photometric detection was better than 5% within the range 50-300 ng/ml. Plasma levels of adriamycin and adriamycinol in a cancer patient are presented in this paper.     

A highly sensitive method for the determination of adriamycin and adriamycinol in human plasma using HPLC with fluorimetric detection

Summary A simple and very sensitive HPLC method, for the simultaneous determination in human plasma of adriamycin and its metabolite adriamycinol, is described. Plasmas from patients were stored frozen. Thawed samples were extracted by absorption of anthracyclin onto a small C18 column. After evaporation of the eluate and reconstitution of the residue with methanol (100L), 30 to 40L of the mixture were injected into the chromatograph. Separation was obtained using an RP 8 column with a mobile phase of formate buffermethanol-acetonitrile (502327, v/v). A spectrofluorimeter was used as detector. The limit of sensitivity of the assay was 50 pcg/ml of plasma.     

High-performance liquid chromatographic method for the determination of alprazolam in plasma using the column-switching technique.

A reversed-phase high-performance liquid chromatographic method is described for the quantitative determination of alprazolam in the plasma of geriatric patients in the presence of 4-hydroxyalprazolam, alpha-hydroxyalprazolam, bromazepam, oxazepam, lorazepam, clobazam, desmethylclobazam, diazepam and desmethyldiazepam. The procedure is based on the enrichment of alprazolam on a PRP-1 pre-column, followed by the transfer of the compound in a forflush mode to the analytical column. Alprazolam can be quantified reliably down to a minimum concentration of 1 ng/ml of plasma.     

Simultaneous quantitation of loganin and sweroside in plasma using column-switching high-performance liquid chromatography

A column-switching high-performance liquid chromatography (HPLC) method is described for the simultaneous determination of loganin and sweroside, which are the active ingredients of purified herbal extract from Lonicera japonica (SKL JI), in rat plasma using column-switching and ultraviolet (UV) absorbance detection. Plasma was simply filtrated prior to injection to the HPLC system consisting of a clean-up column, a concentrating column, and an analytical column, which were connected with two six-port switching valves. Detection of loganin and sweroside was accurate and repeatable, with a limit of quantitation of 0.05 μg ml⁻¹ in plasma. The calibration curves for both loganin and sweroside were linear over the concentration ranges of 0.05-40.0 and 0.02-40.0 μg ml⁻¹ in rat plasma, respectively. The intra- and inter-day precision over the concentration range for loganin and sweroside were lower than 8.1 and 10.9% (relative standard deviation, R.S.D.), and accuracy was between 94.7 and 113.5 and 95.0 and 113.1%, respectively. This method has been successfully applied to determine the levels of loganin and sweroside in rat plasma samples from pharmacokinetics studies.     

High-performance liquid chromatographic determination of meropenem in rat plasma using column-switching

Summary The purpose of this study was to develop a columnswitching HPLC method for the determination of meropenem in plasma. This method showed excellent precision and accuracy with good sensitivity and speed. The total analysis time per sample was less than 20 min and the mean coefficients of variation for intra- and inter-assay were less than 4.0%. The method has been successfully applied to plasma samples from rats receiving an intraperitoneal injection of meropenem.     

Determination of nifedipine in human plasma by high performance liquid chromatography using column-switching technique

A highly sensitive reversed-phase HPLC method has been developed for the determination of nifedipine in human plasma with electrochemical detection. A liquid-liquid extraction procedure is used in sample preparation with an average extraction recovery of 75%. Removing the highly lipophilic plasma components using a special column switching technique reduced the duration of the HPLC measurement from 30 to 9 min. The method is applicable for the pharmacokinetic characterization and bioavailability study of a sustained-release (retard) formulation of nifedipine and for human drug monitoring as it is indicated by the validation of the analysis method. The assay gave a linear response over the concentration range 2.5–50 ng/ml. All the validation parameters are within the internationally required limits.     

Routine determination of hydroxyphenytoin in urine by high-performance liquid chromatography using an automatic column-switching technique

A high-performance liquid chromatographic method for the determination of the main phenytoin metabolite, hydroxyphenytoin, in the urine of epileptic patients is described. The use of an automated column-switching technique greatly simplifies the pretreatment steps. Thereby, both time and chemicals are saved. The possibility of error arising during the several pretreatment steps is considerably reduced. Following acid hydrolysis of the hydroxyphenytoin glucuronic acid conjugate the sample is diluted with water and after centrifugation is injected onto the pre-column. After washing for a short time with water, the substances which were absorbed on the head of the pre-column were backflushed with water--acetonitrile as eluent onto the analytical column. Separation is achieved by gradient elution using an ODS reversed-phase column with a particle size of 5 microns.     

Simultaneous determination of D- and L-serine in rat brain microdialysis sample using a column-switching HPLC with fluorimetric detection

Both D- and L-serine in rat brain microdialysis sample were simultaneously determined by pre-column fluorescence derivatization with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F), separation of the derivatives on ODS column, TSKgel ODS-80TsQA, followed by Pirkle type chiral columns, Sumichiral OA-2500 (S), which gave a sufficient enantiomeric separation of NBD-D-serine and NBD-L-serine, and fluorimetric detection at a wavelength of 540 nm with an excitation wavelength of 470 nm. The peaks of NBD-D-serine and NBD-L-serine in the rat brain microdialysis sample were clearly found, and the validation study showed satisfactory results; the precision and accuracy were within 5.14 and 109%, respectively. Using the proposed HPLC method, the time-course profile of D-serine concentration in rat prefrontal cortex following intraperitoneal administration of D-serine was investigated. As a consequence, D-serine appeared to be rapidly distributed in the brain, and then decreased gradually with time in the extracellular fluid of the rat prefrontal cortex. The proposed HPLC method will be useful for in vivo studies on D-serine, which acts as a coagonist for N-methyl-D-aspartate receptor, to the extracellular fluid of rat brain.     

离子色谱-柱切换技术同步测定饮料中的三氯蔗糖、葡萄糖、果糖和蔗糖

建立了一种离子色谱-柱切换-安培检测技术同步测定饮料中三氯蔗糖、葡萄糖、果糖和蔗糖的方法。以CarboPac PA10阴离子交换保护柱和分析柱进行分离,用水和250 mmol/L NaOH梯度淋洗,脉冲安培检测。弱保留糖类在25 mmol/L NaOH流动相淋洗下分离检测,通过柱切换将保护柱切换至分析柱后,同时切换至250 mmol/L NaOH淋洗,三氯蔗糖仅通过较短的保护柱分离,4种糖类能够得到同步检测。4种糖类在0.01~20 mg/L范围内有良好的线性关系和较低的检出限,重复性好,样品测定的回收率分别为90.38%~102.88%（三氯蔗糖）、95.56%~102.75%（葡萄糖）、101.66%~114.33%（果糖）和105.03%~106.49%（蔗糖）。该方法可广泛应用于食品中强保留物质的测定。     

Simultaneous determination of ten anticoagulant rodenticides in tissues by column-switching UHPLC-ESI-MS/MS

This paper describes the development of a method for the simultaneous determination of ten anticoagulant rodenticides (coumafuryl, warfarin, pindone, coumatetralyl, coumachlor, difenacoum, bromadiolone, brodifacoum, chlorophacinone and flocoumafen) in the liver and kidney based on column-switching liquid chromatography coupled with heated electrospray ionization tandem mass spectrometry. The simple sample preparation includes extraction with methanol. A C₁₈ trapping column was used for online solid-phase extraction before analytical separation with the mobile phase comprising a mixture of 0.1 % formic acid in water, methanol and acetonitrile. Chromatographic separation was achieved using a Thermo Hypersil ultra high-performance liquid chromatography (UHPLC) C₁₈ column with the mobile phase consisting of 5 mM ammonium formate buffer (pH?=?9) and methanol. The column-switching procedure ensured no matrix effects during electrospray ionization (ESI). Extraction recoveries ranged between 91 and 100 % for liver and between 89 and 97 % for kidney. The method showed good linearity up to 750 ng g^?1. The limit of detection ranged between 0.001 and 0.022 ng g^?1 for liver and between 0.001 and 0.028 ng g^?1 for kidney. The developed method was successfully used in several animal poisoning cases.     

HPLC-MS法同时测定5种抗癫痫药的血药浓度

癫痫是神经系统的一种常见病,不少患者需长期同时服用两种或两种以上抗癫痫药物.本研究采用高效液相色谱-电喷雾离子化质谱法同时测定5种常用抗癫痫药物卡马西平、氯硝西泮、阿普唑仑、艾司唑仑和苯妥英钠的血药浓度,色谱条件为以地西泮作为内标,Zorbax SB-C18(30mm×2.1mm,3.5μm)为色谱柱,甲醇-25mM的乙酸铵水溶液梯度洗脱,样品采用无水乙醚萃取.样品分析以离子阱质谱作为检测器,采用多重反应监测模式(MRM),选择MS2离子提高方法的专属性,5种抗癫痫药物在50～5000ng/mL浓度范围内均具有良好的线性关系,其日内、日间精密度均小于10%,方法回收率均大于90%.研究表明,本方法专属性强,灵敏度高,线性关系良好,适用于这5种抗癫痫药物的血药浓度监测、个体化给药方案的制定、药物滥用监测以及药代动力学研究.关键词高效液相色谱质谱抗癫痫药血药浓度药物分析     

HPLC column-switching technique for sample preparation and fluorescence determination of propranolol in urine using fused-core columns in both dimensions

A new and fast high-performance liquid chromatography (HPLC) column-switching method using fused-core columns in both dimensions for sample preconcentration and determination of propranolol in human urine has been developed. On-line sample pretreatment and propranolol preconcentration were performed on an Ascentis Express RP-C-18 guard column (5?×?4.6 mm), particle size, 2.7 μm, with mobile phase acetonitrile/water (5:95, v/v) at a flow rate of 2.0 mL min^?1 and at a temperature of 50 °C. Valve switch from pretreatment column to analytical column was set at 4.0 min in a back-flush mode. Separation of propranolol from other endogenous urine compounds was achieved on the fused-core column Ascentis Express RP-Amide (100?×?4.6 mm), particle size, 2.7 μm, with mobile phase acetonitrile/water solution of 0.5 % triethylamine, pH adjusted to 4.5 by means of glacial acetic acid (25:75, v/v), at a flow rate of 1.0 mL min^?1 and at a temperature of 50 °C. Fluorescence excitation/emission detection wavelengths were set at 229/338 nm. A volume of 1,500 μL of filtered urine sample solution was injected directly into the column-switching HPLC system. The total analysis time including on-line sample pretreatment was less than 8 min. The experimentally determined limit of detection of the method was found to be 0.015 ng mL^?1.

Simple determination of azasetron in rat plasma by column-switching high-performance liquid chromatography

For the quantification of azasetron in rat plasma samples, a column-switching HPLC method was developed and validated. Following dilution of plasma samples with mobile phase A (17?mM potassium phosphate buffer (pH 3.0)) and simple protein precipitation by addition of perchloric acid (60%), the mixture was directly injected onto the pre-column. After endogenous plasma substances were eluted to waste, the analyte was transferred to the trap column by switching the system. Then, the analyte was back-flushed to the analytical column for separation with mobile phase B (a 22:78 v/v mixture of acetonitrile and 17?mM potassium phosphate buffer (pH 3.0)) and detected at 250?nm using a photodiode array detector. A linear standard curve was obtained in the concentration range of 10-800?ng/mL with the correlation coefficient (r) of 0.9998. The intra- and inter-day precision and accuracy values for azasetron were in the ranges of 0.3-12.9% and 89.7-101.4%, respectively. The method was valid in terms of specificity, precision, and accuracy. In addition, this efficient analytical method was successfully applied to determine plasma concentrations of azasetron following oral administration of azasetron at a dose of 4.0?mg/kg to rats.