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Electrospray Source (electrospray + source)
Selected AbstractsInternal energy distribution of peptides in electrospray ionization : ESI and collision-induced dissociation spectra calculationJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 4 2008Alireza Pak Abstract The internal energy of ions and the timescale play fundamental roles in mass spectrometry. The main objective of this study is to estimate and compare the internal energy distributions of different ions (different nature, degree of freedom ,DOF' and fragmentations) produced in an electrospray source (ESI) of a triple-quadrupole instrument (Quattro I Micromass). These measurements were performed using both the Survival Yield method (as proposed by De Pauw) and the MassKinetics software (kinetic model introduced by Vékey). The internal energy calibration is the preliminary step for ESI and collision-induced dissociation (CID) spectra calculation. meta -Methyl-benzylpyridinium ion and four protonated peptides (YGGFL, LDIFSDF, LDIFSDFR and RLDIFSDF) were produced using an electrospray source. These ions were used as thermometer probe compounds. Cone voltages (Vc) were linearly correlated with the mean internal energy values ( Nanoelectrospray emitters: Trends and perspectiveMASS SPECTROMETRY REVIEWS, Issue 6 2009Graham T.T. Gibson Abstract The benefits of electrospray ionization are many, including sensitivity, robustness, simplicity and the ability to couple continuous flow methods with mass spectrometry. The technique has seen further improvement by lowering flow rates to the nanoelectrospray regime (<1,000,nL/min), where sample consumption is minimized and sensitivity increases. The move to nanoelectrospray has required a shift in the design of the electrospray source which has mostly involved the emitter itself. The emitter has seen an evolution in architecture as the shape and geometry of the device have proved pivotal in the formation of sufficiently small droplets for sensitive MS detection at these flow rates. There is a clear movement toward the development of emitters that produce multiple Taylor cones. Such multielectrospray emitters have been shown to provide enhanced sensitivity and sample utilization. This article reviews the development of nanoelectrospray emitters, including factors such as geometry and the manner of applying voltage. Designs for emitters that take advantage of multielectrospray are emphasized. © 2009 Wiley Periodicals, Inc., Mass Spec Rev 28:918,936, 2009 [source] A new hybrid electrospray Fourier transform mass spectrometer: design and performance characteristicsRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 2 2006Peter B. O'Connor A new hybrid electrospray quadrupole Fourier transform mass spectrometry (FTMS) instrument design is shown and characterized. This instrument involves coupling an electrospray source and mass-resolving quadrupole, ion accumulation, and collision cell linear ion trap system developed by MDS Sciex with a home-built ion guide and ion cyclotron resonance (ICR) cell. The iterative progression of this design is shown. The final design involves a set of hexapole ion guides to transfer the ions from the accumulation/collision trap through the magnetic field gradient and into the cell. These hexapole ion guides are separated by a thin gate valve and two conduction limits to maintain the required <10,9,mbar vacuum for FTICR. Low-attomole detection limits for a pure peptide are shown, 220,000 resolving power in broadband mode and 820,000 resolving power in narrow-band mode are demonstrated, and mass accuracy in the <2,ppm range is routinely available provided the signal is abundant, cleanly resolved, and internally calibrated. This instrument design provides high experimental flexibility, allowing Q2 CAD, SORI-CAD, IRMPD, and ECD experiments with selected ion accumulation as well as experiments such as nozzle skimmer dissociation. Initial top-down mass spectrometry experiments on a protein is shown using ECD. Copyright © 2005 John Wiley & Sons, Ltd. [source] Characterization of ammonium chloride derivatives by salt clustering in electrospray mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 22 2003Laurence Charles Clustering of ammonium chloride salts was studied using an electrospray source to characterize the form, mono- vs. dihydrochloride, of organic compounds by mass spectrometry. This new way of taking advantage of cluster formation is applied to aminomethylacridines as their storage requires the synthesis of such derivatives. Both positive and negative cluster mass spectra were obtained and allowed the determination of the nature of the hydrochloride forms as the salt mass is straightforwardly derived from the mass of the cluster monomer, calculated from singly and multiply charged ion distributions. The identity of the counterion is confirmed from the mass of the ionic moieties in the clusters. Copyright © 2003 John Wiley & Sons, Ltd. [source] Quanti,cation of raf antisense oligonucleotide (rafAON) in biological matrices by LC-MS/MS to support pharmacokinetics of a liposome-entrapped rafAON formulationBIOMEDICAL CHROMATOGRAPHY, Issue 4 2005Jenifer L. Johnson Abstract An LC-MS/MS method was developed to quantify an antisense oligonucleotide against Raf-1 expression (rafAON) in monkey and mouse plasma and in mouse tissue homogenates from animals dosed with a liposome-entrapped rafAON easy-to-use formulation (LErafAON-ETU) intended for use as an antineoplastic agent. RafAON was extracted from mouse and monkey plasma using solid-phase extraction. Tissues were homogenized and sample cleanup was achieved by protein precipitation. RafAON and the internal standard (IS) were separated on a Hamilton PRP-1 column and quanti,ed by tandem mass spectrometry using an electrospray source in negative ion mode. The total run time was 4.0 min. The peak areas of two rafAON transitions were summed and plotted against the peak area of an IS transition to generate the standard curve. In monkey plasma the linear range was 50,10,000 ng/mL, and in mouse plasma it was 25,5000 ng/mL. The lower limit of quanti,cation was 500 ng/mL (10 µg/g tissue) in heart, kidney, liver, lung and spleen homogenates, and the standard curve was linear up to 10,000 ng/mL. Accuracy, precision and stability were evaluated and found to be acceptable in all three matrices. The assay was used to support pharmacokinetics and tissue distribution studies of LErafAON-ETU in mice and monkeys. Copyright © 2004 John Wiley & Sons, Ltd. [source] An HPLC-MS method for simultaneous estimation of ,,, -arteether and its metabolite dihydroartemisinin, in rat plasma for application to pharmacokinetic studyBIOMEDICAL CHROMATOGRAPHY, Issue 7 2003M. Rajanikanth Abstract This manuscript reports, the development and validation of a sensitive and selective assay method for simultaneous determination of ,,, -arteether and its metabolite dihydroartemisinin (DHA) in rat plasma by liquid chromatography,mass spectrometry. Chromatographic separations were achieved by gradient elution of the analytes with an initial composition of methanol,potassium acetate buffer (pH 4; 73:27, v/v) to 100% methanol in 3 min and maintained for 5 min on a Spheri-10, RP18 (100 × 4.6 mm i.d.) column following an RP18 (30 × 4.6 mm i.d.) guard column. The total ef,uent from the column was split so that one-tenth was injected into the electrospray LC/MS interface. ESI-MS analysis was performed using a Micromass Quattro II Triple Quadrupole Mass Spectrometer equipped with an electrospray source. The MS analysis was carried out at cone voltage of 22 V with a scan range of 200,500 Da. The analytes were quanti,ed from the [M+ K]+ ion chromatograms of ,,, -arteether at m/z 352, DHA at m/z 323, artemisinin at m/z 321 and propyl ether analogue of arteether at m/z 365. Liquid,liquid extractions with a combination of n -hexane and hexane,ethyl acetate (8:2) were used to isolate ,,, -arteether and DHA from rat plasma. The method was validated and gave good accuracy and precision for the studied domain. Linearity in serum was observed over the range 4.375,70 ng/mL for a -arteether and 10,160 ng/mL for , -arteether and DHA. Percentage bias (accuracy) and within- and between-assay precision were well within the acceptable range. This method was applied to study the pharmacokinetics following oral administration of ,,, -arteether (30 mg/kg) in rats. Copyright © 2003 John Wiley & Sons, Ltd. [source]
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