Intra-assay Precision (intra-assay + precision)

Distribution by Scientific Domains

Selected Abstracts

Development and validation of a liquid chromatographic/electrospray ionization mass spectrometric method for the quantitation of prazepam and its main metabolites in human plasma

Paraskevi Valavani
Abstract A method was developed and fully validated for the quantitation of prazepam and its major metabolites, oxazepam and nordiazepam, in human plasma. Sample pretreatment was achieved by solid-phase extraction using Oasis HLB cartridges. The extracts were analysed by high-performance liquid chromatography (HPLC) coupled with single-quadrupole mass spectrometry (MS) with an electrospray ionization interface. The MS system was operated in the selected ion monitoring mode. HPLC was performed isocratically on a reversed-phase XTerra MS C18 analytical column (150 3.0 mm i.d., particle size 5 m). Diazepam was used as the internal standard for quantitation. The assay was linear over a concentration range of 5.0,1000 ng ml,1 for all compounds analyzed. The limit of quantitation was 5 ng ml,1 for all compounds. Quality control samples (5, 10, 300 and 1000 ng ml,1) in five replicates from three different runs of analysis demonstrated an intra-assay precision (CV) of ,9.1%, an inter-assay precision of ,6.0% and an overall accuracy (relative error) of <4.6%. The method can be used to quantify prazepam and its metabolites in human plasma covering a variety of pharmacokinetic or bioequivalence studies. Copyright 2005 John Wiley & Sons, Ltd. [source]

Analysis of urinary aromatic acids by liquid chromatography tandem mass spectrometry

Brian Crow
Abstract The separation and detection of 11 urinary aromatic acids was developed using HPLC-MS/MS. The method features a simple sample preparation involving a single-step dilution with internal standard and a rapid 8 min chromatographic separation. The accuracy was evaluated by the recovery of known spikes between 87 and 110%. Inter- and intra-assay precision (CV) was below 11% in all cases and the analytes were observed to be stable for up to 8 weeks when stored at ,20C. The method was validated based upon linearity, accuracy, precision and stability and was used to establish reference intervals for children and adults. Copyright 2008 John Wiley & Sons, Ltd. [source]

Determination of secnidazole in human plasma by high-performance liquid chromatography with UV detection and its application to the bioequivalence studies

Xiaoyu Li
Abstract A simple, accurate, precise and sensitive HPLC-UV method was developed for the determination of secnidazole in human plasma. Secnidazole and tinidazole (IS) were extracted from 0.2 mL of human plasma by ethyl acetate. Secnidazole was then separated by HPLC on a Diamond C18 column and quantified by ultraviolet detection at 319 nm. The mobile phase consisted of acetonitrile,aqueous 5 mm sodium acetate (30:70, v/v) containing of 0.1% acetic acid adjusted to pH 4.0, and the flow rate was 1.0 mL/min. The low limit of quantification was 0.1 g/mL. The method was linear over the concentration range 0.1,25.0 g/mL (R2 = 1.000). The recovery of secnidazole from human plasma ranged from 76.5 to 89.1%. Inter- and intra-assay precision ranged from 3.3 to 10.7%. Secnidazole in plasma was stable when stored at ambient temperature for 8 h, at ,20C for 2 weeks and at ,20C for three freeze,thaw cycles. The developed method was successfully applied to the pharmacokinetic and bioequivalence studies between test and reference secnidazole tablets following a single 500 mg oral dosage to 20 healthy volunteers of both genders. Pharmacokinetics parameters Tmax, Cmax, AUC0,t, AUC0,,, T1/2 were determined of both preparations. The analysis of variance (ANOVA) did not show any significant difference between the two preparations and 90% confidence intervals fell within the acceptable range for bioequivalence. It was concluded that the two secnidazole preparations are bioequivalence and may be used interchangeably. Copyright 2007 John Wiley & Sons, Ltd. [source]

Determination of cocaine and cocaethylene in urine by solid-phase microextraction and gas chromatography,mass spectrometry

Mauricio Yonamine
Abstract In order to evaluate recent cocaine exposure or its coingestion with ethanol, a simple and sensitive solid-phase microextraction (SPME) procedure for determination of cocaine and cocaethylene in urine was developed and validated. A polydimethylsiloxane fibre (100 m) was submersed in the urine sample for 20 min under magnetic stirring after alkalinization with solid buffer (NaHCO3:K2CO3, 2:1). Gas chromatography,mass spectrometry (GC-MS) was used to identify and quantify the analytes in selected ion monitoring mode (SIM). The limits of quantification were 5.0 ng/mL for both analytes. Good inter- and intra-assay precision was also observed (coefficient of variation <9%). Copyright 2006 John Wiley & Sons, Ltd. [source]