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Ionization Interface (ionization + interface)
Kinds of Ionization Interface Selected AbstractsDevelopment and validation of a liquid chromatographic/electrospray ionization mass spectrometric method for the quantitation of prazepam and its main metabolites in human plasmaJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 4 2005Paraskevi 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 µm). 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] In vivo absorption of steroidal hormones from smart polymer based delivery systemsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 8 2010Sibao Chen Abstract The purpose of this study was to develop smart polymer based controlled delivery systems to deliver steroidal hormones after single subcutaneous (s.c.) injection at predetermined rates over extended period of time. In vivo absorption and pharmacokinetics of levonorgestrel (LNG) and testosterone (TSN) were investigated from the thermosensitive and phase sensitive polymeric controlled delivery systems. A selective, reliable, and rapid method for determination of serum LNG concentration was developed using high-performance liquid chromatography,tandom mass spectrometry with atmospheric pressure chemical ionization interface (HPLC,MS,MS with APCI), while TSN in serum samples was detected and quantified by a competitive immunoassay. The delivery systems controlled the absorption of LNG in rabbits up to 6 weeks from thermosensitive and ,4 weeks from phase sensitive polymeric delivery systems. In vivo study of TSN delivery systems in castrated rabbits controlled the release of TSN for at least 2 months from both thermosensitive and phase sensitive polymers. Thermosensitive and phase sensitive polymer formulations significantly (p,<,0.05) increased relative bioavailability of steroidal hormones compared to control. In conclusion, thermosensitive and phase sensitive polymer based delivery systems controlled the release in vivo in rabbits for longer duration after single s.c. injection. © 2010 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99:3381,3388, 2010 [source] Simultaneous determination of carotenoids, tocopherols, and ,-oryzanol in crude rice bran oil by liquid chromatography coupled to diode array and mass spectrometric detection employing silica C30 stationary phasesJOURNAL OF SEPARATION SCIENCE, JSS, Issue 14 2005Wolfgang Stöggl Abstract Crude rice bran oil contains tocopherols (vitamin E), carotenoids (vitamin A), and phytosterols, which possess antioxidant activities and show promising effects as preventive and therapeutic agents. The aim of this work was to establish methods and to compare C18 and C30 silica stationary phases in order to separate and detect tocopherols, carotenoids, and ,-oryzanol in one single run. Comparing RP-LC on silica C18 and C30, higher resolution between all target compounds was obtained using the C30 stationary phase. Methanol was used as eluent and the elution strength was increased by the addition of tert -butyl methyl ether for highly hydrophobic analytes such as ,-oryzanol. Detection was accomplished by diode array detection from 200 to 500 nm. Absorbance maxima were found at 295 nm for tocopherols, 324 nm for ,-oryzanol, and 450 nm for carotenoids. Furthermore, compounds were characterized and identified on the basis of their UV-spectra. Both RP systems were coupled to MS (LC-MS) by using an atmospheric pressure chemical ionization interface. [source] The ion funnel: Theory, implementations, and applicationsMASS SPECTROMETRY REVIEWS, Issue 2 2010Ryan T. Kelly Abstract The electrodynamic ion funnel has enabled the manipulation and focusing of ions in a pressure regime (0.1,30 Torr) that has challenged traditional approaches, and provided the basis for much greater mass spectrometer ion transmission efficiencies. The initial ion funnel implementations aimed to efficiently capture ions in the expanding gas jet of an electrospray ionization interface and radially focus them for efficient transfer through a conductance limiting orifice. We review the improvements in fundamental understanding of ion motion in ion funnels, the evolution in its implementations that have brought the ion funnel to its current state of refinement, as well as applications of the ion funnel for purposes such as ion trapping, ion cooling, low pressure electrospray, and ion mobility spectrometry. © 2009 Wiley Periodicals, Inc., Mass Spec Rev 29:294,312, 2010 [source] Simultaneous determination of lamivudine, stavudine and nevirapine in human plasma by LC,MS/MS and its application to pharmacokinetic study in clinicBIOMEDICAL CHROMATOGRAPHY, Issue 9 2010Zhou Li Abstract A new high-throughput LC,MS/MS method for the simultaneous determination of lamivudine (3TC), stavudine (d4T) and nevirapine (NVP) in human plasma is presented, with zidovudine as an internal standard. The analytes were extracted from plasma by protein precipitation and only 150,,L plasma was needed. Chromatographic separation was achieved on a Shiseido C8 column (150 × 2.0,mm, 5,,m) with a total run time of 6,min. A tandem mass spectrometric detection was conducted using multiple reaction monitoring under positive ionization mode with an electrospray ionization interface. The method was developed and validated over the concentration range of 25,5000,ng/mL for 3TC and NVP and 20,4000,ng/mL for d4T. The method was validated in terms of intra- and inter-day precision (,8.6%), accuracy (within ± 8.4%), linearity and specificity. The method has been successfully applied to the pharmacokinetic study of a combination treatment of 300,mg lamivudine, 30,mg stavudine and 200,mg nevirapine in 22 healthy male volunteers under fasting conditions. Copyright © 2010 John Wiley & Sons, Ltd. [source] A sensitive liquid chromatography,electrospray ionization,mass spectrometry method for the simultaneous determination of pentoxyverine citrate and guaifenesin in human plasma,application to pharmacokinetic and bioequivalence studiesBIOMEDICAL CHROMATOGRAPHY, Issue 4 2010Jinhua Wen Abstract A sensitive and specific liquid chromatography,electrospray ionization,mass spectrometry method for the identification and quantification of pentoxyverine citrate and guaifenesin in human plasma has been developed. After extraction from plasma samples by ethyl acetate, the internal standard and analytes were separated by high-performance liquid chromatographic on a Shim-pack VP-ODS C18 column (150 × 2.0 mm) using a mobile phase consisting of A (methanol) and B (0.4% glacial acetic acid and 4 mmol/L ammonium acetate) (A:B, 43 : 57). Analysis was performed on a Shimadzu LC/MS-2010A in selected ion monitoring mode with a positive electrospray ionization interface. The method was linear in the concentration range of 1.0,640.0 ng/mL for pentoxyverine citrate and 0.025,6.4 ,g/mL for guaifenesin. The inter- and intra- precision were all within 12% and accuracy ranged from 85 to 115%. The lower limits of quantification were 1.0 ng/mL for pentoxyverine citrate and 25.0 ng/mL for guaifenesin. The extraction recovery was on average 81.95% for pentoxyverine citrate and 89.03% for guaifenesin. This is the first assay method reported for the simultaneous determination of pentoxyverine citrate and guaifenesin in plasma using one chromatographic run. Copyright © 2009 John Wiley & Sons, Ltd. [source] Determination of teniposide in rat plasma by ultra performance liquid chromatography electrospray ionization tandem mass spectrometry after intravenous administrationBIOMEDICAL CHROMATOGRAPHY, Issue 9 2009Jing Wang Abstract A novel, specific and rapid ultra performance liquid chromatography electrospray ionization tandem mass spectrometry method has been developed and validated for determination of teniposide in rat plasma. A one-step liquid,liquid extraction method was used and the separation was carried out on an Acquity UPLCTM BEH C18 column with gradient elution using a mobile phase composed of acetonitrile and water (containing 0.1% formic acid) at a flow rate of 0.20 mL/min. A triple quadrupole tandem mass spectrometer in multiple-reaction monitoring mode via an electrospray ionization interface was used for the detection of teniposide. The detection was complete within 3.0 min. A linear calibration curve was obtained over the concentration range 10,10,000 ng/mL for teniposide, with a lower limit of quantification of 10 ng/mL. The intra-day precision and inter-day precision (relative standard deviation) were less than 10.23 and 13.09%, respectively. The developed method was applied for the first time to the pharmacokinetic study of teniposide in rats following a single intravenous administration of 4.5 mg/kg teniposide. Copyright © 2009 John Wiley & Sons, Ltd. [source] Determination of huperzine A in human plasma by liquid chromatography,electrospray tandem mass spectrometry: application to a bioequivalence study on Chinese volunteersBIOMEDICAL CHROMATOGRAPHY, Issue 4 2008Wei Li Abstract A simple, sensitive and selective LC-MS-MS method has been developed for the quantification of huperzine A in human plasma. Huperzine A and pseudoephedrine hydrochloride (internal standard) were isolated from human plasma by extraction with ethyl acetate, chromatographed on a C18 column with a mobile phase consisting of 0.2% formic acid,methanol (15:85, v/v) and detected using a tandem mass spectrometer with an electrospray ionization interface. The lower limit of quantification was 0.0508 ng/mL, and the assay exhibited a linear range of 0.0508,5.08 ng/mL (r = 0.9998). The method was successfully applied to investigate the bioequivalence between two kinds of tablets (test vs reference product) in 18 healthy male Chinese volunteers. After a single 0.2 mg dose for the test and reference product, the resulting means of major pharmacokinetic parameters such as AUC0,24, AUC0,,, Cmax, Tmax and t1/2 of huperzine A were 16.35 ± 3.42 vs 16.38 ± 3.61 ng h/mL, 17.53 ± 3.80 vs 17.70 ± 3.97 ng h/mL, 2.47 ± 0.49 vs 2.51 ± 0.51 ng/mL, 1.3 ± 0.4 vs 1.2 ± 0.3 h and 5.92 ± 0.75 vs 6.18 ± 0.66 h, respectively, indicating that these two kinds of tablets were bioequivalent. Copyright © 2007 John Wiley & Sons, Ltd. [source] Simple determination of huperzine A in human plasma by liquid chromatographic,tandem mass spectrometric methodBIOMEDICAL CHROMATOGRAPHY, Issue 1 2007Yun-Xia Li Abstract Huperzine A is a potent, reversible acetylcholinesterase inhibitor. In the present work, a rapid and sensitive LC,MS,MS method for the determination of huperzine A in human plasma using codeine phosphate as internal standard has been developed and validated. The analyte and internal standard were extracted from plasma using ethyl acetate, chromatographed on a C18 column (5 µm, 150 × 4.6 mm i.d.) with a mobile phase consisting of 1% formic acid,methanol (40:60, v/v), and detected using a tandem mass spectrometer with a TurboIonSpray ionization interface. The run time was only 2 min. Good linearity was achieved in the range 0.126 -25.2 ng/mL and the limit of detection in plasma was 0.064 ng/mL. The average recovery for huperzine A was 83.4% from plasma. The analytical sensitivity and accuracy of this assay is adequate for characterization of huperzine A in human plasma. Copyright © 2006 John Wiley & Sons, Ltd. [source] Simultaneous determination of chlorpheniramine and pseudoephedrine in human plasma by liquid chromatography,tandem mass spectrometryBIOMEDICAL CHROMATOGRAPHY, Issue 4 2004Xiaoyan Chen Abstract A sensitive and speci,c procedure for simultaneous quantitation of chlorpheniramine and pseudoephedrine in human plasma has been developed and validated. Analytes were extracted from plasma samples by liquid,liquid extraction, separated on a Diamonsil C18 column (250 × 4.6 mm i.d.) and detected by tandem mass spectrometry with an atmospheric pressure chemical ionization interface. Diphenhydramine was used as the internal standard. The method has a lower limit of quantitation of 0.2 and 2.0 ng/mL for chlorpheniramine and pseudoephedrine, respectively. The intra- and inter-day relative standard deviation, calculated from quality control (QC) samples were below 4.3% for chlorpheniramine and below 9.5% for pseudoephedrine. The inter-day relative error as determined from QC samples was within 4.7% for each analyte. The overall extraction recoveries of chlorpheniramine and pseudoephedrine were 77 and 61% on average, respectively. The method was successfully applied to pharmaockinetic study of chlorpheniramine and pseudoephedrine in volunteers receiving formulations containing 4 mg of chlorpheniramine maleate and 60 mg of pseudoephedrine hydrochloride. Copyright © 2004 John Wiley & Sons, Ltd. [source] | ||||||||||