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Positive Electrospray Ionization (positive + electrospray_ionization)
Selected AbstractsSimultaneous determination of morphine, codeine, 6-acetylmorphine, cocaine and benzoylecgonine in hair by liquid chromatography/electrospray ionization tandem mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 7 2009Da-Kong Huang A fast and sensitive liquid chromatography/triple quadrupole tandem mass spectrometry (LC/MS/MS) method was developed for the simultaneous determination of morphine, codeine, 6-acetylmorphine (6-AM), cocaine and benzoylecgonine (BE) in hair. Pulverized hair samples were extracted with methanol, and a 50,µL supernatant aliquot was injected into the LC/MS/MS system. Chromatography was performed with an XBridgeÔ phenyl column (3.5,µm particle size, 4.6,×,150,mm), and the mobile phase was composed of methanol and 10,mM ammonium acetate adjusted to pH 4.00 with 99% formic acid (95:5, v/v). A separation run with isocratic elution was completed in 10,min at a flow rate of 500,µL/min. Positive electrospray ionization and multiple reaction monitoring (MRM) with one precursor ion/product ion transition were used for the identification of each analyte. Deuterated analogues as internal standards were used for quantification and qualification. Linearity was established in the concentration range of 100,3000,pg/mg. The limits of detection were 10,pg/mg for morphine, codeine and 6-AM; and 1,pg/mg for cocaine and BE. The precision and accuracy were determined by spiking hair samples at six concentration levels. For all analytes, the relative standard deviations of intra- and inter-day precision were 0.1,6.3% and 1.5,10.6%, respectively. The accuracy ranged from 92.7 to 109.7%. The validated LC/MS/MS method was successfully applied to the analysis of 79 authentic hair samples. Copyright © 2009 John Wiley & Sons, Ltd. [source] A rapid screening LC-MS/MS method based on conventional HPLC pumps for the analysis of low molecular weight xenobiotics: application to doping control analysisDRUG TESTING AND ANALYSIS, Issue 7 2010Monica Mazzarino Abstract This study presents a fast multi-analyte screening method specifically developed for the detection of xenobiotics in urine. The proposed method allows the screening of several classes of substance in a single chromatographic method with a run-time of 11 min, inclusive of post-run and reconditioning times. Chromatographic separation is achieved in 7.2 min using a reversed-phase 2.7 µm fused-core particle column, generating a back-pressure not exceeding 400 bar and therefore enabling the use of traditional high performance liquid chromatography (HPLC) instruments. The effectiveness of this approach was evaluated, by liquid-chromatography tandem mass spectrometry (LC-MS/MS) in positive electrospray ionization, using 20 blank urine samples spiked with 45 compounds prohibited in sport: 11 diuretics, 16 glucocorticoids, 9 stimulants, 5 anti-oestrogens, as well as formoterol, carboxy-finasteride (previously prohibited by the World Anti-Doping Agency (WADA) in 2008), gestrinone and tetrahydrogestrinone. Qualitative validation shows the proposed method to be specific with no significant interference. All of the analytes considered in this study were clearly distinguishable in urine, with limits of detection ranging from 5 ng/mL to 350 ng/mL, significantly below the Minimum Required Performance Levels (MRPL) set by WADA for the accredited sports anti-doping laboratories. All compounds of interest were separated, including synthetic and endogenous glucocorticoids with similar retention times and fragmentation patterns. Copyright © 2010 John Wiley & Sons, Ltd. [source] Urtica dioica agglutinin: Separation, identification, and quantitation of individual isolectins by capillary electrophoresis and capillary electrophoresis,mass spectrometryELECTROPHORESIS, Issue 9 2005Markus Ganzera Abstract With benign prostatic hyperplasia (BPH) being a major health problem in ageing men, alternative therapeutic approaches (e.g., with phytopharmaceuticals) are of great interest. Based on pharmacological evidences, one of the most promising options in that respect are the lectins found in Urtica dioica (stinging nettle) roots. In this study the qualitative and quantitative analysis of individual isolectins in U. dioica extracts is described, which is the first report on using capillary electrophoresis (CE) for the analysis of lectins in plant material at all. By utilizing a 200 mM sodium acetate buffer (pH 3.75) a baseline separation and determination of four closely related isolectins was feasible within 20 min in the aqueous plant extracts. The individual compounds were identified based on reference compounds as well as data obtained from CE-mass spectrometry (MS) experiments. After modifying the optimized CE conditions to 100 mM ammonium formate buffer with pH 3.75 and a voltage of 15 kV, the isolectins were clearly assignable in positive electrospray ionization (ESI) mode. The quantitative results obtained by CE (the total lectin content varied from 0 to 0.42% in the samples) were accurate (recovery rates of spiked samples between 92.5 and 96.2%), precise (relative standard deviation < 5%) and in good agreement to those obtained by High-performance liquid chromatography (HPLC). As for peak resolution, assignable compounds and required separation time the newly developed CE method was clearly advantageous over the determination achieved by LC. [source] Identification of diphenhydramine metabolites in human urine by capillary electrophoresis-ion trap-mass spectrometryELECTROPHORESIS, Issue 10-11 2004Andrea Baldacci Abstract The identification of diphenhydramine (DH) metabolites that are frequently observed in the capillary zone electrophoresis (CZE) and micellar electrokinetic capillary chromatography (MEKC) analyses of alkaline liquid/liquid and solid-phase extracts of patient urines is demonstrated. Having standards for DH and diphenhydramine- N -oxide (DHNO), the presence of these two compounds could be confirmed in urines that were collected overnight after administration of 25 mg DH chloride. Using CZE coupled to ion-trap mass spectrometry (CE-MSn) with positive electrospray ionization and an acetate buffer at pH 5.6, the [M+H]+ ions of DH (m/z = 256), DHNO (m/z = 272), and nordiphenhydramine (NDH, m/z = 242) and their fragmentation to a common m/z 167 product ion (diphenylcarbinol moiety) was monitored. The data indicate that all three compounds are cations in an acidic environment, the migration order being NDH, DH, and DHNO. Data obtained under negative electrospray ionization conditions suggest the presence of diphenylmethoxyacetic acid-glycine amide ([M-H], ion of m/z 298 and fragmentation to m/z 254, loss of CO2), a metabolite that could tentatively be assigned to a characteristic peak observed in the MEKC electropherogram at alkaline pH. The data presented in this paper illustrate the value of using CE-MSn for identification of urinary drug metabolites for which no standards are available. [source] Analysis of S -adenosylmethionine and related sulfur metabolites in bacterial isolates of Pseudomonas aeruginosa (BAA-47) by liquid chromatography/electrospray ionization coupled to a hybrid linear quadrupole ion trap and Fourier transform ion cyclotron resonance mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 21 2009Tommaso R. I. Cataldi A comprehensive and highly selective method for detecting in bacterial supernatants a modified sulfur nucleoside, S -adenosyl-L-methionine (SAM), and its metabolites, i.e., S -adenosylhomocysteine (SAH), adenosine (Ado), 5,-deoxy-5,-methylthioadenosine (MTA), adenine (Ade), S -adenosyl-methioninamine (dcSAM), homocysteine (Hcy) and methionine (Met), was developed. The method is based on reversed-phase liquid chromatography with positive electrospray ionization (ESI+) coupled to a hybrid linear quadrupole ion trap (LTQ) and 7-T Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS). A gradient elution was employed with a binary solvent of 0.05,M ammonium formate at pH 4 and acetonitrile. The assay involves a simultaneous cleanup of cell-free bacterial broths by solid-phase extraction and trace enrichment of metabolites with a 50-fold concentration factor by using immobilized phenylboronic and anion-exchange cartridges. While the quantitative determination of SAM was performed using stable-isotope-labeled SAM-d3 as an internal standard, in the case of Met and Ade, Met- 13C and Ade- 15N2 were employed as isotope-labeled internal standards, respectively. This method enabled the identification of SAM and its metabolites in cell-free culture of Pseudomonasaeruginosa grown in Davis minimal broth (formulation without sulphur organic compounds), with routine sub-ppm mass accuracies (,0.27,±,0.68,ppm). The resulting contents of SCSS -SAM, SS -dcSAM, MTA, Ado and Met in the free-cell supernatant of P. aeruginosa was 56.4,±,2.1,nM, 32.2,±,2.2,nM, 0.91,±,0.10,nM, 19.6,±,1.2,nM and 1.93,±,0.02,µM (mean,±,SD, n,=,4 extractions), respectively. We report also the baseline separation (Rs ,1.5) of both diastereoisomeric forms of SAM (SCSS and SCRS) and dcSAM (SS and RS), which can be very useful to establish the relationship between the biologically active versus the inactive species, SCSS/SCRS and SS/RS of SAM and dcSAM, respectively. An additional confirmation of SAM-related metabolites was accomplished by a systematic study of their MS/MS spectra. Copyright © 2009 John Wiley & Sons, Ltd. [source] Development of a multi-mycotoxin liquid chromatography/tandem mass spectrometry method for sweet pepper analysisRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 1 2009Sofie Monbaliu A multi-mycotoxin method was developed for the simultaneous determination of trichothecenes (nivalenol, deoxynivalenol, 3-acetyldeoxynivalenol, 15-acetyldeoxynivalenol, neosolaniol, fusarenon-X, diacetoxyscirpenol, HT-2 toxin, T-2 toxin), aflatoxins (aflatoxin-B1, aflatoxin-B2, aflatoxin-G1 and aflatoxin-G2), Alternaria toxins (alternariol, alternariol methyl ether and altenuene), fumonisins (fumonisin-B1, fumonisin-B2 and fumonisin-B3), ochratoxin A, zearalenone, beauvericin and sterigmatocystin in sweet pepper. Sweet pepper was extracted with ethyl acetate/formic acid (99:1, v/v). After splitting up the extract, two-thirds of the extract was cleaned up using an aminopropyl column followed by an octadecyl column. The remaining part was cleaned up using a strong anion-exchange column. After recombination of both cleaned parts of the sample extract, the combined solvents were evaporated and the residue was dissolved in mobile phase; 20,µL was injected into the chromatographic system, so only one run was used to separate and detect the mycotoxins in positive electrospray ionization using selected reaction monitoring. The samples were analyzed with a Micromass Quattro Micro triple quadrupole mass spectrometer (Waters, Milford, MA, USA). The mobile phase consisted of variable mixtures of water and methanol, 1% acetic acid and 5,mM ammonium acetate. The limits of detection of the multi-mycotoxin method varied from 0.32,µg.kg,1 to 42.48,µg.kg,1. The multi-mycotoxin liquid chromatography/tandem mass spectrometry (LC/MS/MS) method fulfilled the method performance criteria required by the Commission Regulation (EC) No 401/2006. Sweet peppers inoculated by Fusarium species were analyzed using the developed method. Beauvericin (9,484,µg.kg,1) and fumonisins (fumonisin-B1 up to 4330,µg.kg,1, fumonisin-B2 up to 4900,µg.kg,1, and fumonisin-B3 up to 299,µg.kg,1) were detected. Copyright © 2008 John Wiley & Sons, Ltd. [source] Structural characterization and identification of ecdysteroids from Sida rhombifolia L. in positive electrospray ionization by tandem mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 16 2008Yan-Hong Wang Seven ecdysteroids isolated from Sida rhombifolia L. were studied by electrospray ionization multi-stage tandem mass spectrometry (ESI-MSn) in the positive ion mode using an ion trap analyzer and high-performance liquid chromatography coupled with a diode-array detector (HPLC/DAD). The HPLC experiments were performed by means of a reversed-phase C18 column and a binary mobile phase system consisting of water (containing 0.05% formic acid) and acetonitrile (containing 0.05% formic acid) under gradient elution conditions. According to mass spectral features and the substitution at C-2, C-20, C-24 and C-25, ecdysteroids in S. rhombifolia were classified into three sub-groups. Structural identification of these three sub-groups of ecdysteroids was established by LC/multi-stage ion trap mass spectrometry on-line or off-line. The fragmentation patterns of ecdysteroids yielded ions of successive loss of 1,4 water molecules. Furthermore, ions corresponding to the complete loss of the side chain at C-17 will help to identify the sub-groups of ecdysteroids in addition to containing a hydroxyl moiety at one of the above-mentioned positions. Based on the HPLC retention behavior, the diagnostic UV spectra and the molecular structural information provided by ESI-MSn spectra, a total of nine naturally occurring ecdysteroids were identified, of these two are identified for the first time in S. rhombifolia. Copyright © 2008 John Wiley & Sons, Ltd. [source] Direct determination of endogenous melatonin in human saliva by column-switching semi-microcolumn liquid chromatography/mass spectrometry with on-line analyte enrichmentRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 12 2004Akira Motoyama An analytical method that enables direct and sensitive determination of endogenous melatonin (MLT) in human saliva was developed by means of column-switching semi-microcolumn liquid chromatography (i.d.: 1,2,mm)/mass spectrometry (LC/MS). The system allows direct injection analysis of a 400-,L aliquot of saliva with minimal sample pretreatment (internal standard (IS) addition and vortex mixing) and a relatively short run-time (10,min). The system consists of three columns to attain large volume injection and on-line analyte enrichment. A pre-column packed with a silica-based mixed-functional C8 (4.0,mm i.d.,×,20,mm) was used for on-line sample cleanup. MLT and an IS, the d7 isomer of MLT (d7-MLT), were heart-cut by valve switching and enriched at the top of the intermediate trapping column packed with a silica-based C18 (4.0,mm i.d.,×,10,mm). Subsequently, the analytes were backflushed into a semi-micro C18 silica column (2.0,mm i.d.,×,150 mm) for the final separation. MLT and IS were ascertained by positive electrospray ionization and selected ion monitoring (SIM). MLT was monitored based on its fragment ion at m/z 174.1 by in-source collision-induced dissociation (CID). The validation of this method revealed a detection limit of 2.5,pg,mL,1 at a signal-to-noise (S/N) ratio of 5. The linearity of the method was established in the ranges 5,250 and 100,2500,pg,mL,1 with a coefficient of determination of greater than 0.998. Accuracies, evaluated at five levels in the range 5,1000,pg,mL,1, were between 81 and 108% with a relative standard deviation (RSD) ranging from 1.3,20%. The method was successfully applied for the endogenous saliva MLT monitoring of two healthy subjects. Copyright © 2004 John Wiley & Sons, Ltd. [source] Development of a method for the direct analysis of peptide AM336 in monkey cerebrospinal fluid using liquid chromatography/electrospray ionization mass spectrometry with a mixed-function columnRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 21 2003Wei Bu A liquid chromatography/mass spectrometry (LC/MS) analytical procedure, using a single column for sample clean-up, enrichment and separation, has been developed for the determination of the peptide AM336 in monkey cerebrospinal fluid (CSF). CSF samples were injected and analyzed using a polymer-coated mixed-function high-performance liquid chromatography (HPLC) column with gradient elution and application of a timed valve-switching event. The mass spectrometer was operated in the positive electrospray ionization (ESI+) mode with single ion recording (SIR) at m/z 920. The method was validated, yielding calibration curves with correlation coefficients greater than 0.9892. Assay precision and accuracy were evaluated by direct injection of AM336-fortified CSF samples at three concentration levels. Analyzed concentrations ranged from 99.93 to 113.1% of their respective theoretical concentrations with coefficients of variation below 9.0%. An evaluation of the signal-to-noise (S/N) ratio for a 200 ng/mL calibration standard, considered to be the lower limit of quantitation (LLOQ), resulted in an estimated limit of detection (LOD) of 31.2,ng/mL. Preliminary data suggest the possibility of using this method to analyze AM336 also in plasma samples, pending the successful outcome of additional investigations. Copyright © 2003 John Wiley & Sons, Ltd. [source] | ||||||||||