Linear Ion trap-Orbitrap Mass Spectrometry Research Articles

Neutral Fragment Filtering for Rapid Identification of New Diester-Diterpenoid Alkaloids in Roots of Aconitum carmichaeli by Ultra-High-Pressure Liquid Chromatography Coupled with Linear Ion Trap-Orbitrap Mass Spectrometry

A rapid and effective method was developed for separation and identification of diester-diterpenoid alkaloids (DDA) in the roots of Aconitum carmichaeli by ultra-high-pressure liquid chromatography coupled with high resolution LTQ-Orbitrap tandem mass spectrometry (UHPLC-LTQ-Orbitrap-MSn). According to accurate mass measurement and the characteristic neutral loss filtering strategy, a total of 42 diester-diterpenoid alkaloids (DDA) were rapidly detected and characterized or tentatively identified. Meanwhile, the proposed fragmentation pathways and the major diagnostic fragment ions of aconitine, mesaconitine and hypaconitine were investigated to trace DDA derivatives in crude plant extracts. 23 potential new compounds were successfully screened and characterized in Aconitum carmichaeli, including 16 short chain fatty acyls DDA, 4 N-dealkyl DDA and several isomers of aconitine, mesaconitine and hypaconitine.

Profiling of phenolic constituents in Polygonum multiflorum Thunb. by combination of ultra-high-pressure liquid chromatography with linear ion trap-Orbitrap mass spectrometry

A simple and effective method was developed for characterization of phenolic constituents in the roots of Polygonum multiflorum by combination of ultra-high-pressure liquid chromatography with linear ion trap-Orbitrap tandem mass spectrometry (UHPLC–LTQ-Orbitrap). Stilbenes, anthraquinones, tannins and naphthalenes were differentiated by diagnostic fragment ions with accurate mass measurements and characteristic fragmentation pathways. Based on the proposed strategy, fifty-nine constituents were characterized or tentatively identified, of which twenty-two constituents were the first to be reported in P. multiflorum and twelve compounds were characterized as potential new compounds. The identification and structure elucidation of these chemicals provided essential data for further phytochemical studies and quality control of P. multiflorum. The results also demonstrated that our novel method can be extended to screen and characterize other phenolic constituents and their metabolites in botanical extracts.

A critical evaluation of liquid chromatography with hybrid linear ion trap—Orbitrap mass spectrometry for the determination of acidic contaminants in wastewater effluents

Acidic pesticide and pharmaceutical contaminants were pre-concentrated and extracted from wastewater samples (500mL) using solid-phase extraction. Analyte recoveries were 79–96%, with % RSD values in the range, 1.7–7.4%. Analyte identification and quantification were carried out using liquid chromatography–mass spectrometry (LC–MS) with hybrid linear ion trap (LIT) Orbitrap instrumentation. Using a resolution setting of 30,000 FWHM, full-scan MS analysis was performed using heated electrospray ionization (HESI) in negative mode. The high mass resolution capabilities of the Orbitrap MS were exploited for the determination of trace contaminants allowing facile discrimination between analytes and matrix. The dependant scan functions of the Orbitrap MS using higher collisional dissociation (HCD) and LIT MS were evaluated for the confirmation of analytes at trace concentration levels. Mass accuracy for target contaminants using this method was less than 2ppm. The limits of quantitation (LOQs) were in the range, 2.1–27ng/L. The inter-day accuracy and precision were measured over a five-day period at two concentrations. The % relative errors were in the range, 0.30–7.7%, and the % RSD values were in the range, 1.5–5.5%. Using this method, 2,4-D, mecoprop, ibuprofen, naproxene and gemfibrozil were identified in several wastewater treatment plants in Ireland.

Glutathione S-transferase pi trapping method for generation and characterization of drug–protein adducts in human liver microsomes using liquid chromatography–tandem mass spectrometry

Covalent binding of reactive metabolites (RMs) to proteins is thought to play an important role in the processes leading to adverse drug reactions. Therefore, there is great interest in methodologies that enable the characterization of covalent binding of drugs to proteins. To facilitate the study of drug-protein adducts, we have developed a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for characterizing RM-modified proteins formed through drug bioactivation in human liver microsomes (HLMs), which are commonly used for the in vitro drug bioactivation studies. The technique was illustrated by the trapping of RMs of acetaminophen (APAP) and raloxifene with human glutathione S-transferase pi (hGSTP) as a model target protein. After hGSTP-supplemented HLM incubations, the modified/unmodified hGSTP fractions were collected by high-performance liquid chromatography. hGSTP fractions were digested with trypsin, and then analyzed by linear ion trap-orbitrap mass spectrometry followed by a SEQUEST database search. Characteristic MS/MS fragment ions of RM-modified peptides were identified by searching for possible adducted-mass shifts. The method successfully revealed that RMs of both drugs adducted to Cys-47 of hGSTP and the mass shifts corresponded to modification by the N-acetyl-p-benzoquinone imine form of APAP and diquinone methide form of raloxifene, respectively. The developed method would be a possible tool for widespread use for the generation and characterization of drug-protein adducts in HLMs and has the potential to assess the risk of covalent binding of drugs to proteins.

Simultaneous determination of triazine herbicides in rice by high-performance liquid chromatography coupled with high resolution and high mass accuracy hybrid linear ion trap-orbitrap mass spectrometry

A method was developed for the simultaneous determination of 10 triazine herbicides (cyanazine, simazine, simetryn, metribuzin, atrazine, ametryn, terbuthylazine, prometryn, terbutryn, and dimethametryn) in rice samples by high resolution and high mass accuracy hybrid linear ion trap-Orbitrap mass spectrometer. After extraction with acetonitrile and evaporation, the herbicides were redissolved in n-hexane and purified on a Florisil solid-phase extraction column. All compounds were separated within 12 min, producing more than 11 data points for each herbicide and high mass accuracy quantified ions which the mass errors of absolute value were less than 1.9 ppm in pure solution and 2.1 ppm in the matrix-matched standards solution. The method was validated in terms of the limits of detection and the limits of quantification. The linearity was satisfactory, with a correlation coefficient of >0.9975. Precision and recovery studies were evaluated at three concentration levels for Japonica, Indica, and G lutinous rice matrix. The mean recoveries obtained for all analytes in spiked Xiushui 03, Liangyoupeijiu, and Taihunuo rice samples were 83.3–99.0%, 82.0–99.7%, and 84.2–99.4%, respectively, with relative standard deviation in range 1.7–10.6%, 1.2–10.7%, and 1.9–11.6% for spiked rice samples, respectively. The intra-day precision ( n = 5) for the 10 herbicides in rice samples spiked at an intermediate level was between 2.8% and 7.9%, and the inter-day precision over 10 days ( n = 10) was between 5.5% and 15.9%.

High-Throughput Identification of Microbial Transformation Products of Organic Micropollutants

During wastewater treatment, many organic micropollutants undergo microbially mediated reactions resulting in the formation of transformation products (TPs). Little is known on the reaction pathways that govern these transformations or on the occurrence of microbial TPs in surface waters. Large sets of biotransformation data for organic micropollutants would be useful for assessing the exposure potential of these TPs and for enabling the development of structure-based biotransformation prediction tools. The objective of this work was to develop an efficient procedure to allow for high-throughput elucidation of TP structures for a broad and diverse set of xenobiotics undergoing microbially mediated transformation reactions. Six pharmaceuticals and six pesticides were spiked individually into batch reactors seeded with activated sludge. Samples from the reactors were separated with HPLC and analyzed by linear ion trap-orbitrap mass spectrometry. Candidate TPs were preliminarily identified with an innovative post-acquisition data processing method based on target and non-target screenings of the full-scan MS data. Structures were proposed following interpretation of MS spectra and MS/MS fragments. Previously unreported microbial TPs were identified for the pharmaceuticals bezafibrate, diazepam, levetiracetam, oseltamivir, and valsartan. A variety of previously reported and unreported TPs were identified for the pesticides. The results showed that the complementary use of the target and non-target screening methods allowed for a more comprehensive interpretation of the TPs generated than either would have provided individually.

How do sphingolipids and lipid rafts relate to pathology?

European Journal of Lipid Science and TechnologyVolume 108, Issue 10 p. 799-801 EditorialFree Access How do sphingolipids and lipid rafts relate to pathology? Gerrit van Meer, Gerrit van Meer Bijvoet Center and Institute of Biomembranes, Utrecht University, Utrecht, The NetherlandsSearch for more papers by this author Gerrit van Meer, Gerrit van Meer Bijvoet Center and Institute of Biomembranes, Utrecht University, Utrecht, The NetherlandsSearch for more papers by this author First published: 09 October 2006 https://doi.org/10.1002/ejlt.200600184Citations: 1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article. References 1 S. Hakomori: Glycosphingolipids in cellular interaction, differentiation, and oncogenesis. Annu Rev Biochem. 1981, 50, 733– 764. 2 K. Powell: Lipid raft idea is floated. J Cell Biol. 2006, 172, 166– 167. 3 A. H. Futerman, Y. A. Hannun: The complex life of simple sphingolipids. EMBO Rep. 2004, 5, 777– 782. 4 C. S. Ejsing, T. Moehring, U. Bahr, E. Duchoslav, M. Karas, K. Simons, A. Shevchenko: Collision-induced dissociation pathways of yeast sphingolipids and their molecular profiling in total lipid extracts: a study by quadrupole TOF and linear ion trap-orbitrap mass spectrometry. J Mass Spectrom. 2006, 41, 372– 389. 5 B. Brügger, B. Glass, P. Haberkant, I. Leibrecht, F. T. Wieland, H. G. Krausslich: The HIV lipidome: a raft with an unusual composition. Proc Natl Acad Sci U S A. 2006, 103, 2641– 2646. 6 K. I. Willig, S. O. Rizzoli, V. Westphal, R. Jahn, S. W. Hell: STED microscopy reveals that synaptotagmin remains clustered after synaptic vesicle exocytosis. Nature. 2006, 440, 935– 939. 7 F. Spener, S. D. Kohlwein, G. Schmitz: Lipid droplets and lamellar bodies – from innocent bystanders to prime targets of lipid research for combating human diseases. Eur J Lipid Sci Technol. 2006, 108, 541– 543. 8 F. Spener, R. Zechner, J. Borlak: Is lipotoxicity an oxymoron? Eur J Lipid Sci Technol. 2006, 108, 625– 627. 9 W. J. Griffiths: Why steroidomics in brain? Eur J Lipid Sci Technol. 2006, 108, 707– 708. Citing Literature Volume108, Issue10No. 10 October 2006Pages 799-801 ReferencesRelatedInformation

Collision‐induced dissociation pathways of yeast sphingolipids and their molecular profiling in total lipid extracts: a study by quadrupole TOF and linear ion trap–orbitrap mass spectrometry

The yeast Saccharomyces cerevisiae synthesizes three classes of sphingolipids: inositolphosphoceramides (IPCs), mannosyl-inositolphosphoceramides (MIPCs), and mannosyl-diinositolphosphoceramides (M(IP)2C). Tandem mass spectrometry of their molecular anions on a hybrid quadrupole time-of-flight (QqTOF) instrument produced fragments of inositol-containing head groups, which were specific for each lipid class. MS(n) analysis performed on a hybrid linear ion trap-orbitrap (LTQ Orbitrap) mass spectrometer with better than 3 ppm mass accuracy identified fragment ions specific for the amide-linked fatty acid and the long chain base moieties in individual molecular species. By selecting m/z of class-specific fragment ions for multiple precursor ion scanning, we profiled yeast sphingolipids in total lipid extracts on a QqTOF mass spectrometer. Thus, a combination of QqTOF and LTQ Orbitrap mass spectrometry lends itself to rapid, comprehensive and structure-specific profiling of the molecular composition of sphingolipids and glycerophospholipids in important model organisms, such as fungi and plants.