Quantification of Levosulpiride in Human Plasma by High‐Performance Liquid Chromatography

Abstract

An analytical procedure was developed and validated for the quantification of levosulpiride in human plasma. After subjecting a plasma sample to a two‐step extraction procedure, an aliquot of the aqueous phase was injected onto an high‐performance liquid chromatography system equipped with a fluorescence detector. The detector response was linear for levosulpiride concentrations in the range of 2.5 to 500 ng/ml. The intra‐ and inter‐day precision was below 15.4 and 10.1%, and the accuracy was in a range from 89.7 to 109.4%. The method is applicable for use in the pharmacokinetic characterization of levosulpiride after a 75‐mg oral dose in humans.     

High Pressure Liquid Chromatography Assay for Determination of 18-β-Glycyrrhetinic Acid in Plasma

Abstract

This report presents a useful high pressure chromatography assay for determination of the proposed chemopreventive agent 18-β-glycerrhetinic acid (GA) in murine and human plasma. Drug was released from plasma proteins through precipitation with a mixture of sodium bisulfate and sodium chloride after which it was extracted with acetonitrile. Standard calibration curves of GA covered the concentration range of 2.5 to 120 μg/ml. The lower limit of detection was 0.5 μg/ml. No endogenous plasma constituents from plasma were found to interfere with the determination of GA. Recover of GA from plasma was greater than 95% over a concentration range of 20 to 100 μg/ml. Linearity of the assay was excellent; within-run precision showed a C.V. of 4.2% at 25 μg/ml, 5.6% at 20 μg/ml and 3.4% at 120 μg/ml. Between-run assay precision and accuracy was also considered to be excellent. The specificity, sensitivity and reproducibility of the procedure are adequate for proposed clinical pharmacology studies of this agent.     

Simultaneous Determination of Epinephrine, Noradrenaline and Dopamine in Human Serum Samples by High Performance Liquid Chromatography with Chemiluminescence Detection

A simple, rapid and accurate high performance liquid chromatographic （HPLC） technique coupled with chemiluminescence （CL） detection was developed for the simultaneous determination of epinephrine （E）, noradrenaline （NA） and dopamine （DA）. It was based on the analyte enhancement effect on the CL reaction between luminol and potassium ferricyanide. The effects of various parameters, such as potassium ferricyanide concentration, luminol concentration, pH value and component of the mobile phase on chromatographic behaviors of the analytes （E, NA and DA） were investigated. The separation was carded out on C18 column using the mobile phase of 0.01 mol/L potassium hydrogen phthalate solution and methanol （92 ： 8, V/V）. Under the optimum condi- tions, E, NA and DA showed good linear relationships in the range of 1 × 10^-8 -5 × 10^-6, 5.0× 10^-9 -1.0× 10^-6 and 5.0×10^-9-1.0× 10^-6 g]mL respectively. The detection limits for E, NA and DA were 4.0×10^-9, 1.0× 10^-9 and 8.0 × 10^-10 g/mL. The proposed method has been applied successfully to the analysis of E, NA and DA in human serum samples.     

High‐Performance Liquid Chromatographic Determination of Parecoxib in Human Plasma and Pharmaceutical Formulations

Abstract

A simple and sensitive RP‐HPLC method for the determination of parecoxib (PXB) in human plasma and pharmaceutical formulations has been developed and validated. The separation of PXB and the internal standard, ibuprofen (IBF) was achieved on a CLC C₁₈ (5 μ, 25 cm×4.6 mm i.d.) column using UV detector at 200 nm. The mobile phase consisted of acetonitrile‐water (92:8 v/v). The linear range of detection was found to be 0.9–18.4 µg/ml (r=0.9985). Intra‐ and inter‐day assay relative standard deviations were observed to be less than 0.3%. The method has been applied successfully for the determination of PXB in spiked human plasma and pharmaceutical preparations. Analytical parameters were calculated and complete statistical evaluation is incorporated.     

An Automated Method for the Determination of Enoximone and Its Major Sulfoxide Metabolite in Plasma Using Robotic Technology–High Performance Liquid Chromatography

Abstract

An automated analytical procedure for the determination of enoximone, a new cardiotonic agent, and its major oxidative metabolite in plasma using robotic technology is described. A Zymark robot is used to perform all the operations of solid phase extraction including column pretreatment, internal standard addition, sample mixing, sample pipetting, column rinsing, drying and sample elution. The processed sample is injected directly into the high performance liquid chromatography system which is equipped with an ultraviolet absorption detector. The assay has good precision and accuracy, equivalent to the manual method it replaces, and yet provides higher throughput of sample.     

Determination of 2′,3′-Dideoxyinosine in Plasma by High Performance Liquid Chromatography

Abstract

A high performance liquid chromatography analysis method has been developed for the quantitation of 2′,3′-dideoxyinosine (DDI) in plasma. Proteins were precipitated from plasma samples with acetonitrile containing the internal standard, 6-methylaminopurine riboside. The treated samples were evaporated to dryness and reconstituted in mobile phase for the analysis. Separation of the components was achieved on a 5 μm octadecylsilane column with ultraviolet detection at 254 nm. The method was validated at nine concentrations between 0.015 and 150 μg/mL. Using 500 μL of human plasma, the limit of quantitation was 120 ng/mL and the limit of detection was 60 ng/mL. The mean intra-day precision of the method was 1.6%. The mean accuracy of the method was within 2% of the actual values. This method is currently being used for pharmacokinetic studies in the rat.     

A New Sensitive Reversed‐phase High‐performance Liquid Chromatography Method for the Quantitative Determination of Metoclopramide in Canine Plasma

Abstract

A specific and sensitive high‐performance liquid chromatographic method was developed for the determination of metoclopramide in canine plasma. The procedure involves fast liquid–liquid extraction and analysis on an octadecyl silane (ODS) column. A preliminary pharmacokinetic study was performed by applying the developed method to a single oral administration of metoclopramide (MCP) to a dog. The validation method yielded good results regarding linearity, precision, accuracy, and specificity. The procedure is suitable for separation and quantification of MCP in canine plasma, enough to quantify 0.2 ng/ml when 0.5 ml of plasma is used. This assay procedure might be useful for the pharmacokinetic study of MCP in dogs.     

Routine Determination of a New 1–4 Dihydropyridine,Oxodipine, in Human Plasma by High Performance Liquid Chromatography with Electrochemical Detection

Abstract

A rapid, specific and reproducible high-performance liquid chromatographic routine assay with electrochemical detection was developed for the determination of Oxodipine in human plasma.

After extraction at alkaline pH by cyclohexane, Oxodipine and its internal standard were chromatographied on a reversed-phase column.

Calibration curves were linear over a concentration range of 1–50 ng/ml with relative errors within-day or between-day not exceeding 8% at any level.

The limit of detection was 30 pg injected based on a signal-to- noise ratio of 7. However, the reliable limit of quantification was 1 ng/ml using 1 ml of human plasma.

A dual-electrode coulometric detector was operated in a screening mode of oxidation, providing a greater specificity and reducing background noise.

This method allowed the complete follow-up of clinical pharmacokinetic studies and drug monitoring in patients.     

Rapid Determination of Coumatetralyl in Human Serum by High‐Performance Liquid Chromatography Coupled with Electrospray Ionization Tandem Mass Spectrometry

Abstract

A rapid, sensitive, and selective high‐performance liquid chromatography‐tandem mass spectrometric method (HPLC‐MS‐MS) for the determination of coumatetralyl in human serum using warfarin as an internal standard has been developed and validated. Coumatetralyl and the internal standard were extracted from the human serum samples by liquid‐liquid extraction with ethyl acetate, followed by separation on a XDB C₁₈ reversed‐phase column (150 mm×2.1 mm i.d., 5 µm) using a mobile phase consisting of acetic acid‐ammonium acetate (5 mmol/L, pH=4.5)/methanol (20:80, v/v) at a constant flow rate of 0.40 mL/min. Coumatetralyl and the internal standard were ionized by negative ion pneumatically assisted electrospray and detected in the multiple‐reaction monitoring mode using precursor→product ion combinations at m/z 291→247 and 307→161, respectively. The calibration curve was linear (r²=0.9945) in the concentration range of 0.5～100.0 ng/mL, with a lower limit of quantification of 0.5 ng/mL in human serum. Intra‐ and inter‐day relative standard deviations were less than 6.3 and 11.0%, respectively. The mean extraction recovery was 87.9% for coumatetralyl and 90.1% for the internal standard. This method is found to be able to determine trace coumatetralyl in human serum and can be used for the diagnosis of poisoned human beings.     

Determination of Vitamin C in Plasma and Dialysate from Uremia Patientsby High Performance Liquid Chromatography with Electrochemical Detection

 Abstract：Aconvenientandvalidmethodforthedeterminationofascorbicacid(AA)anddehydroascorbicacid(DHAA)inplasmaanddialysatefrompatientswithuremiabyhighperformanceliquidchromatographywithelectrochemicaldetectionisdescribedAmixtureof08g/Lmetaphosphoricacidand     

A Simple and Rapid Reversed Phase High Performance Liquid Chromatographic Method for Quantification of Alprazolam and α-Hydroxyalprazolam in Plasma

Abstract

A simple and rapid reversed-phase liquid chromatographic method for the determination of alprazolam and a-hydroxyalprazolam in plasma is described. Flunictrazepam was used as internal standard. Plasma samples were buffered with sodium borate and extracted with dichloromethane /n-pentane 4:6 v/v for 60 sec on a vortex apparatus. Extraction solvent was evaporated to dryness and extraction residues were reconstituted in the mobile phase. Samples were chromatographed on a 5μ Lichrospher RP-18 column (25cm × 4mm i. d) using acetonitrile/water 40:60 v/v as the mobile phase. The column effluent was monitored at 230nm. The lower limit of detection was 1ng/ml for alprazolam and a-hydroxyalprazolam while the lower limit of quantification was 2ng/ml for both compounds. Peak height and plasma     

Quantitation of Branched Chain α-Keto Acids in Sheep Plasma Using Reversed-Phase High Performance Liquid Chromatography and Quinoxalinol Derivatization

Abstract

The concentration of branched chain α-keto acids in sheep plasma was determined by reversed-phase high performance liquid chromatography using precolumn quinoxalinol formation and ion exchange chromatography for sample preparation. The clear resolution, high degree of precision and accuracy, and relatively simple sample cleanup and derivatization procedures render this technique suitable for the routine analysis of physiological fluids.     

The “On Line” Determination of Cefsulodin by High Performance Liquid Chromatography in CSF and Plasma of Rats

Abstract

After an intraveinous injection of 20 mg.kg^?1 of cefsulodin in anaesthetized rats, the cerebrospinal fluid (CSF) and plasma drug levels were determined on line by HPLC. The CSF was withdrawn from the IIIe venticle at a flow rate of I μl. minute and pushed with a peristaltic pump, via a teflon tube into a “micro vial” inside the WISP vial. At the end of fiveteen minutes, about 15 μ1 of CSF was collected and a small volume (7 μl) was injected by the WISP into the column, the excess of CSF was discarded by another teflon tube inside the “micro-vial”. After the injection, the continous flow of CSF filled the “micro vial”, an injection was running at fiveteen minutes and so on during three hours. Plasma samples were collected every thirty minutes, and after methanol extraction cefsulodin levels were determined by HPLC. Given the low drug levels found in the CSF, this method appeared very sensitive; it was a direct, rapid, automatic technique. Other biological molecules can be determined by this automatic dosage.     

Determination of Metformin in Human Plasma by Liquid Chromatography-tandem Mass Spectrometric Assay

Metformin (1,1-dimethylbiguanide) (Fig. 1) i san oral anti-hyperglycemic agent used in the treatment of non-insulin-dependent diabetes mellitus(type Ⅱ ). Owing to its weight-decreasing and serum lipid-normalizing effects, it is especially recommended for obese patients. Various analytical methods have been described for the measurement of metformin in biological fluids,     

Liquid Chromatography‐Electrospray Ionization Mass Spectrometric Method for Determination of Gliclazide in Human Plasma

Abstract

A rapid, sensitive, and specific liquid chromatography‐electrospray ionization mass spectrometric (LC‐ESI‐MS) method has been developed for quantification of gliclazide in human plasma. The analyte and tolbutamide (internal standard, I.S.) were extracted from plasma samples with n‐hexane–dichloromethane (1:1, v/v) and analyzed on a C₁₈ column. The chromatographic separation was achieved within 4.0 min by using methanol–0.5% formic acid (80:20, v/v) as mobile phase and the flow rate was 1.0 mL/min. Ion signals m/z 324.0 and 271.0 for gliclazide and internal standard were measured in the positive mode, respectively. The method was linear within the range of 2.5–2000 ng/mL. The lower limit of quantification (LLOQ) was 2.5 ng/mL. The intra‐ and inter‐day precisions were lower than 2.8% in terms of relative standard deviation (RSD). The inter‐day relative error (RE) as determined from quality control samples (QCs) ranged from ?1.93% to 1.85%. This validated method was successfully applied for the evaluation of pharmacokinetic profiles of gliclazide modified‐release tablets in 20 healthy volunteers.     

Development and Validation of High‐Performance Liquid Chromatographic Method for Estimation of Lercanidipine in Rabbit Serum

Abstract

A new, simple, and sensitive reverse‐phase liquid chromatographic method was developed and validated for the estimation of Lercanidipine hydrochloride in rabbit serum using UV detector under isocratic conditions. After subjecting serum to simple and efficient one‐step extraction procedure, 100 µl of sample was injected onto high‐performance liquid chromatography system. The detector response was linear in the concentration range of 25–1000 ng/ml. The developed method was validated as per standard guidelines. Validation demonstrated accuracy, precision, and selectivity of the proposed method. The drug was found to be stable under various processing and storage conditions.     

Determination of Organotin Compounds in Wine by Microwave-Assisted Extraction and High Performance Liquid Chromatography–Inductively Coupled Plasma Mass Spectrometry

A new analytical procedure for the determination of five organotin compounds in several matrix wine samples is reported. The organotin compounds were extracted by microwave-assisted extraction with n-hexane. Extraction conditions, such as volume of n-hexane required, extraction temperature, and extraction time, were investigated and optimized by an orthogonal array experimental design. The determination of organotin compounds in the final extracts was carried out by liquid chromatography–inductively coupled plasma mass spectrometry. The procedure showed limits of detection between 0.029–0.049 µg · L^?1. The linearity was in the range of 0.5 to 100 µg · L^?1. The precision expressed as relative standard deviation (RSD) was below 9.43%. The developed method was successfully employed to analyze different matrix wine samples, and some analytes were detected at the level of 0.053 to 1.14 µg · L^?1.     

Determination of Fluoxetine in Human Plasma by Liquid Chromatography–Mass Spectrometry and Its Application

Abstract

A rapid, simple, and specific liquid chromatography–electrospray ionization–mass spectrometric method has been developed and validated for the determination of fluoxetine in human plasma. The method was validated with a linear range of 0.5–100 ng mL^?1, and the lowest limits of quantification were 0.5 ng mL^?1 for fluoxetine. The extraction efficiencies were about 65% and recoveries of method were in the range of 94.0–97.5%. The intraday relative standard deviation (RSD) was less than 11% and interday RSD was within 12%. The method has been successfully applied to the evaluation of pharmacokinetics and bioequivalence of fluoxetine.