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Interday Precision (interday + precision)
Selected AbstractsIntroduction of HPLC/orbitrap mass spectrometry as screening method for doping controlJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 7 2008E. D. Virus Abstract A new doping control screening method has been developed, for the analysis of doping agents in human urine, using HPLC/orbitrap with in-source collision-induced dissociation and atmospheric pressure chemical ionization. The developed method allows the detection of 29 compounds, including agents with antiestrogenic activity, ,2 agonists, exogenous anabolic steroids, and other anabolic agents. The mass accuracy of this method is better at 2 ppm using an external reference. The detection limit for all compounds tested was better than 100 pg/ml. The recoveries of most analytes were above 70%. The measured median repeatability values for doping agents included in the method at concentrations of 1 and 10 ng/ml were 21 and 17%, respectively. The relative standard deviation (RSD) of the intraday precision (n = 6) ranged from RSD = 16,22%, whereas the interday precision (n = 18), ranged from RSD = 17,26%, depending on the solute concentration investigated. Copyright © 2008 John Wiley & Sons, Ltd. [source] Enantiomeric separation of mirtazapine and its metabolites by nano-liquid chromatography with UV-absorption and mass spectrometric detectionJOURNAL OF SEPARATION SCIENCE, JSS, Issue 14 2005Salvatore Fanali Abstract Mirtazapine (MIR) and two of its main metabolites, namely, 8-hydroxymirtazapine and N -desmethylmirtazapine, were separated in totheir enantiomers by nanoLC in a laboratory-made fused-silica capillary column (75 ,m ID) packed with a vancomycin-modified silica stationary phase. The simultaneous separation of the three couples of the studied enantiomers was achieved in less than 33 min, using an experimentally optimized mobile phase delivered in the isocratic mode. Optimization of the mobile-phase composition was achieved by testing the influence of the buffer pH and concentration, the water concentration, the organic modifier type and concentration, and on the retention and resolution of the analytes. The optimum mobile-phase composition contained 500 mM ammonium acetate pH 4.5/water/MeOH/MeCN, 1 : 14 : 40 : 45 v/v/v/v. Using a UV detector at 205 nm, the method was validated studying several experimental parameters such as LOD and LOQ, intraday and interday repeatability, and linearity. Good results were achieved: LOD and LOQ were in the range 5,15 and 10,40 ,g/mL, respectively (the highest value was obtained for the DEMIR enantiomers); correlation coefficients, 0.9993,0.9999; the intraday and interday precision was acceptable (RSD < 2%) using an internal standard. The method was tested for the separation of the studied enantiomers in an extracted (solid-phase) serum sample spiked with standard racemic mixture of MIR and its two metabolites. Finally, the nanoLC system was connected to a mass spectrometer through a nanoelectrospray interface and the MS, MS2, and MS3 spectra were acquired showing the potential of the system used for characterization and identification of the separated analytes. [source] Development of a liquid chromatography/tandem mass spectrometry assay for the quantification of PM02734, a novel antineoplastic agent, in dog plasmaRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 18 2006Jianming Yin A rapid and sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS) assay was developed and validated to quantify a novel antineoplastic agent, PM02734, in dog plasma. The method was validated to demonstrate the specificity, limit of quantification (LOQ), accuracy, and precision of measurements. The calibration range for PM02734 was established using PM02734 standards from 0.05 to 100,ng/mL in blank plasma. The dominating ions were doubly charged molecular ions [M+2H]2+ at m/z 740.0 instead of singly charged ones at m/z 1478.4. The selected reaction monitoring (SRM), based on the m/z 740.0,,,212.2 transition, was specific for PM02734, and that based on the m/z 743.8,,,212.2 transition was specific for deuterated PM02734 (the internal standard, IS); no endogenous materials interfered with the analysis of PM02734 and IS from blank plasma. The assay was linear over the concentration range 0.05,100,ng/mL. In terms of sensitivity of assay 0.05,ng/mL is a very low LLOQ, especially considering PM02734 is a peptide. The correlation coefficients for the calibration curves ranged from 0.9990 to 0.9999. The mean intraday and interday accuracies for all calibration standards (n,=,9) ranged from 93 to 111% (,11% bias) in dog plasma, and the mean interday precision for all calibration standards was less than 6.4%. The mean intra- and interday assay accuracy for all quality control replicates in dog plasma (n,=,9), determined at each QC level throughout the validated runs, ranged from 85,111% (,15% bias) and from 99,109% (,9% bias), respectively. The mean intra- and interday assay precision was less than 12.1 and 13.3% for all QC levels, respectively. The assay has been used to support preclinical pharmacokinetic (PK) and toxicokinetic studies. The results showed that preclinical samples could be monitored for PM02734 up to 168,h after dosing, which allowed us to identify multiple elimination phases and accurately estimate PK information. Copyright © 2006 John Wiley & Sons, Ltd. [source] Analysis of aromatic amines in cigarette smoke,RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 18 2003Regina Stabbert A method for the analysis of o -toluidine, o -anisidine, 2-naphthylamine, and 4-aminobiphenyl in cigarette mainstream smoke has been developed, which combines the sensitivity of their pentafluoropropionyl (PFP) derivatives in negative ion chemical ionization (NICI) mode with the selectivity of the gas chromatography/tandem mass spectrometry (GC/MS/MS) technique. The use of four deuterated analogues as internal standards along with the application of the standard addition method results in accurate and precise results; the interday precision for the aromatic amines was 3,10% and the accuracy ranged from 97,100%. This method was applied to two American-blend University of Kentucky reference cigarettes, eight American-blend market cigarettes, a bright (flue-cured) tobacco cigarette, and an electrically heated cigarette smoking system (EHCSS). For the American-blend cigarettes there was a linear correlation between aromatic amine yields and mainstream smoke ,tar' (,tar',=,total particulate matter , (nicotine,+,water)), whereas the bright tobacco cigarette and the EHCSS demonstrated significantly lower aromatic amine yields on an equal ,tar' basis. The results support the hypothesis that the nitrogen content of the tobacco, and above all the cigarette combustion temperature, are determining factors for the yields of aromatic amines in smoke. Copyright © 2003 John Wiley & Sons, Ltd. [source] Enantioselective analysis of primaquine and its impurity quinocide by capillary electrophoresisBIOMEDICAL CHROMATOGRAPHY, Issue 3 2009Abdalla A. Elbashir Abstract A capillary electrophoretic (CE) method for the baseline separation of the enantiomers of primaquine diphosphate (PQ) and quinocide (QC) (a major contaminant) in pharmaceutical formulations is proposed. Both components were separated under the following conditions: 50 mm tris phosphate buffer (pH 3.0) containing 15 mm hydroxypropyl- , -cyclodextrin (HP- , -CD) as background electrolyte; applied voltage, 16 kV; capillary temperature, 25°C; detection wavelength, 254 nm; hydrostatic injection, 10 s. The separations were conducted using a 35 cm length and 50 µm i.d. uncoated fused silica capillary column. Under the optimized conditions, the components were successfully separated in about 5 min. Intraday precision of migration time and corrected peak areas when expressed as relative standard deviation ranged from 0.17 to 0.45 and 2.60 to 3.94%, respectively, while the interday precision ranged from 2.59 to 4.20 and 3.15 to 4.21%, respectively. After the validation exercise, the proposed method was applied for the determination of QC impurity in PQ formulations. Copyright © 2008 John Wiley & Sons, Ltd. [source] An isocratic fluorescence HPLC assay for the monitoring of l -asparaginase activity and l -asparagine depletion in children receiving E. colil -asparaginase for the treatment of acute lymphoblastic leukaemiaBIOMEDICAL CHROMATOGRAPHY, Issue 2 2009Christa E. Nath Abstract A novel assay for the determination of l -asparaginase activity in human plasma is described that is based on the HPLC quantitation of l -aspartic acid produced during enzyme incubation. Methods for monitoring l -asparagine depletion are also described. Chromatography of l -aspartic acid, l -asparagine and l -homoserine (the internal standard) involved derivatization with o -pthaldialdehyde, then separation from other amino acids on a Phenomenex Luna C18 column using a 1 mL/min flow rate and a mobile phase consisting of di-potassium hydrogen orthophosphate propionate buffer, pH 6, with 10% methanol and 10% acetonitrile. Fluoresence detection was at excitation/emission wavelengths of 357/455 nm. Under these conditions l -aspartic acid, l -asparagine and l -homoserine had retention times of 3.5, 9.8 and 17.7 min, respectively. The l -asparaginase assay was linear from 0.1 to 10 U/mL activity and interday precision and accuracy were less than 13%. The limit of quantitation was approximately 0.03 U/mL. The assay utility was established in 12 children who received E. colil -asparaginase as treatment for acute lymphoblastic leukaemia. Copyright © 2008 John Wiley & Sons, Ltd. [source] Enantioselective HPLC-UV method for determination of eslicarbazepine acetate (BIA 2-093) and its metabolites in human plasmaBIOMEDICAL CHROMATOGRAPHY, Issue 11 2007Gilberto Alves Abstract Eslicarbazepine acetate (BIA 2-093) is a novel central nervous system drug undergoing clinical phase III trials for epilepsy and phase II trials for bipolar disorder. A simple and reliable chiral reversed-phase HPLC-UV method was developed and validated for the simultaneous determination of eslicarbazepine acetate, oxcarbazepine, S- licarbazepine and R -licarbazepine in human plasma. The analytes and internal standard were extracted from plasma by a solid-phase extraction using Waters Oasis® HLB cartridges. Chromatographic separation was achieved by isocratic elution with water,methanol (88:12, v/v), at a flow rate of 0.7 mL/min, on a LichroCART 250-4 ChiraDex (, -cyclodextrin, 5 µm) column at 30°C. All compounds were detected at 225 nm. Calibration curves were linear over the range 0.4,8 µg/mL for eslicarbazepine acetate and oxcarbazepine, and 0.4,80 µg/mL for each licarbazepine enantiomer. The overall intra- and interday precision and accuracy did not exceed 15%. Mean relative recoveries varied from 94.00 to 102.23% and the limit of quantification of the assay was 0.4 µg/mL for all compounds. This method seems to be a useful tool for clinical research and therapeutic drug monitoring of eslicarbazepine acetate and its metabolites S- licarbazepine, R -licarbazepine and oxcarbazepine. Copyright © 2007 John Wiley & Sons, Ltd. [source] Determination of antiviral nucleoside analogues AM365 and AM188 in perfusate and bile of the isolated perfused rat liver using HPLCBIOMEDICAL CHROMATOGRAPHY, Issue 3 2006Jiping Wang Abstract Development, validation and application of an HPLC assay for new antiviral nucleoside analogues AM365 and AM188 in isolated perfused rat liver perfusate and bile were performed. An analytical column (Phenosphere-NEXT, 250 × 4.6 mm, C18, 4 µm, Phenomenex) was used in tandem with a guard column (4 × 3 mm, C18, Phenomenex) and operated at 25°C. The mobile phase [methanol:10 mmol/L sodium orthophosphate buffer (pH 7.0), 15:85, v/v] was pumped at 1 mL/min. The signal from a diode array detector was collected from 190 to 300 nm. The chromatogram was processed at 220 and 252 nm for AM365 and AM188, respectively. The HPLC method was validated by six intraday and seven interday runs. Standard curves were linear in the range 0.125,8.00 µg/mL for AM365 and AM188, and the lower limit of quantification for AM365 and AM188 was 0.125 µg/mL. Mean interday precision and accuracy of IPL perfusate quality control samples were within 8.8%, and mean intraday precision and accuracy were within 13.1%. The assay has been successfully used in the study of metabolism and disposition of AM365 in the isolated perfused rat liver. Copyright © 2005 John Wiley & Sons, Ltd. [source] Arbutin determination in medicinal plants and creamsINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 2 2009W. Thongchai Synopsis A simple flow injection (FI) manifold with spectrophotometric detection was fabricated and tested for arbutin determination. It is based on the measurement of a red-coloured product at 514 nm formed by the complexation reaction between arbutin and 4-aminoantipyrine (4-AP) in the presence of hexacyanoferrate (III) in an alkaline medium. On injecting 300 ,L standard solutions at various concentrations of arbutin into the FI system under optimum conditions, a linear calibration graph over the range of 1.0,30.0 ,g mL,1 arbutin was established. It is expressed by the regression equation y = 0.2188 ± 0.0036x + 0.1019 ± 0.0366 (r2 = 0.9990, n = 5). The detection limit (3,) and the limit of quantitation (10,) were 0.04 ,g mL,1 and 0.13 ,g mL,1, respectively. The RSD of intraday and interday precisions were found to be 1.2,1.4% and 1.7,2.7%, respectively. The method was successfully applied in the determination of arbutin in four selected fruits and three commercial whitening cream extracts with the mean recoveries of the added arbutin over the range of 96.2,99.0%. No interference effects from some common excipients used in commercial whitening creams were observed. The method is simple, rapid, selective, accurate, reproducible and relatively inexpensive. Résumé Un collecteur simple pour injection en flux (FI) avec détection spectrométrique a été fabriqué et testé pour le dosage de l'arbutine. Son principe repose sur la mesure à 514 nm du produit rouge formé par la réaction de complexation entre l'arbutine et le 4-aminoantipyrine (4-AP) en présence d'hexacyanoferrate (III) en milieu alcalin. On procède à une injection de 300 ,L des solutions standards à diverses concentrations d'arbutine dans le système FI aux conditions optimales, puis on réalise un graphe de calibration linéaire dans l'intervalle de 1,0 à 30,0 ,g mL,1 d'arbutine. Le graphe correspond à l'équation de régression y = 0.2188 ± 0.0036x + 0.1019 ± 0.0366 (r2 = 0.9990, n = 5). La limite de détection (3,) et la limite de quantification (10,) sont respectivement de 0.04 ,g mL,1 et 0.13 ,g mL,1. La RSD des précisions intra et inter jours sont respectivement de 1.2,1.4% et 1.7,2.7%. La méthode a été appliquée avec succès à la mesure de l'arbutine dans 4 fruits sélectionnés et 3 extraits de crèmes de blanchiment commercialisées avec une recouvrance moyenne de l'arbutine ajoutée de 96.2 à 99%. Aucune interférence avec les excipients communément utilisés dans les crèmes de blanchiment commerciales n'a été observée. La méthode est simple, rapide, sélective, précise, reproductible et relativement bon marché. [source] | ||||||||||