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Sample records for accuracy tandem mass

  1. MS Amanda, a Universal Identification Algorithm Optimized for High Accuracy Tandem Mass Spectra

    PubMed Central

    2014-01-01

    Today’s highly accurate spectra provided by modern tandem mass spectrometers offer considerable advantages for the analysis of proteomic samples of increased complexity. Among other factors, the quantity of reliably identified peptides is considerably influenced by the peptide identification algorithm. While most widely used search engines were developed when high-resolution mass spectrometry data were not readily available for fragment ion masses, we have designed a scoring algorithm particularly suitable for high mass accuracy. Our algorithm, MS Amanda, is generally applicable to HCD, ETD, and CID fragmentation type data. The algorithm confidently explains more spectra at the same false discovery rate than Mascot or SEQUEST on examined high mass accuracy data sets, with excellent overlap and identical peptide sequence identification for most spectra also explained by Mascot or SEQUEST. MS Amanda, available at http://ms.imp.ac.at/?goto=msamanda, is provided free of charge both as standalone version for integration into custom workflows and as a plugin for the Proteome Discoverer platform. PMID:24909410

  2. Tandem Mass Spectrometry with Ultrahigh Mass Accuracy Clarifies Peptide Identification by Database Retrieval

    PubMed Central

    Boyne, Michael T.; Garcia, Benjamin A.; Li, Mingxi; Zamdborg, Leonid; Wenger, Craig D.; Babai, Shannee; Kelleher, Neil L.

    2009-01-01

    A platform was developed to analyze MS/MS spectra from large peptides with low part-per-million mass accuracy, including a commercial-grade software suite. Termed Middle Down Proteomics, this platform identified 7454 peptides from 2–20 kDa (1472 unique) from 555 proteins after 23 LC-MS/MS injections of Lys-C digests of HeLa-S3 nuclear proteins. Along with greatly increased confidence for both peptide identification (expectation values from 10−89 to 10−4) and characterization (up to 18% of peptides were modified in some LC-MS/MS runs), fragmentation data with <2 ppm accuracy enabled error tolerant and routine multiplexed database searching–all clearly demonstrated in this study. PMID:19053528

  3. A tandem mass spectrometric study of the N-oxides, quinoline N-oxide, carbadox, and olaquindox, carried out at high mass accuracy using electrospray ionization

    NASA Astrophysics Data System (ADS)

    Miao, Xiu-Sheng; March, Raymond E.; Metcalfe, Chris D.

    2003-12-01

    A mass spectrometric study of three N-oxides, quinoline N-oxide, and the synthetic antibiotics carbadox and olaquindox, was carried out with a hybrid quadrupole/time-of-flight (TOF) mass spectrometer coupled with electrospray (ES) and atmospheric pressure chemical ionization (APCI) sources. The full scan mass spectra of the N-oxides obtained with ES are similar to those obtained with APCI, and the characteristic fragment ions corresponding to [M+H-O]+[radical sign] were observed in the full scan mass spectrum of each N-oxide examined. The protonated molecule of each N-oxide was subjected to collision-induced dissociation (CID) and accurate mass measurements were made of each fragment ion so as to determine its elemental composition. Fragment ions generated at enhanced cone voltages upstream of the first mass-resolving element were subjected to CID so as to identify the direct product ion-precursor ion relationship. Plausible structures have been proposed for most of the fragment ions observed. Elimination of OH[radical sign] radicals generated from the N-->O functional group is a characteristic fragmentation pathway of the N-oxides. The expulsion of radicals and small stable molecules is accompanied by formation and subsequent contraction of heterocyclic rings.

  4. DeconMSn: A Software Tool for accurate parent ion monoisotopic mass determination for tandem mass spectra

    SciTech Connect

    Mayampurath, Anoop M.; Jaitly, Navdeep; Purvine, Samuel O.; Monroe, Matthew E.; Auberry, Kenneth J.; Adkins, Joshua N.; Smith, Richard D.

    2008-04-01

    We present a new software tool for tandem MS analyses that: • accurately calculates the monoisotopic mass and charge of high–resolution parent ions • accurately operates regardless of the mass selected for fragmentation • performs independent of instrument settings • enables optimal selection of search mass tolerance for high mass accuracy experiments • is open source and thus can be tailored to individual needs • incorporates a SVM-based charge detection algorithm for analyzing low resolution tandem MS spectra • creates multiple output data formats (.dta, .MGF) • handles .RAW files and .mzXML formats • compatible with SEQUEST, MASCOT, X!Tandem

  5. Liquid chromatography-high resolution/ high accuracy (tandem) mass spectrometry-based identification of in vivo generated metabolites of the selective androgen receptor modulator ACP-105 for doping control purposes.

    PubMed

    Thevis, Mario; Thomas, Andreas; Piper, Thomas; Krug, Oliver; Delahaut, Philippe; Schänzer, Wilhelm

    2014-01-01

    Selective androgen receptor modulators (SARMs) represent an emerging class of therapeutics which have been prohibited in sport as anabolic agents according to the regulations of the World Anti-Doping Agency (WADA) since 2008. Within the past three years, numerous adverse analytical findings with SARMs in routine doping control samples have been reported despite missing clinical approval of these substances. Hence, preventive doping research concerning the metabolism and elimination of new therapeutic entities of the class of SARMs are vital for efficient and timely sports drug testing programs as banned compounds are most efficiently screened when viable targets (for example, characteristic metabolites) are identified. In the present study, the metabolism of ACP-105, a novel SARM drug candidate, was studied in vivo in rats. Following oral administration, urine samples were collected over a period of seven days and analyzed for metabolic products by Liquid chromatography-high resolution/high accuracy (tandem) mass spectrometry. Samples were subjected to enzymatic hydrolysis prior to liquid-liquid extraction and a total of seven major phase-I metabolites were detected, three of which were attributed to monohydroxylated and four to bishydroxylated ACP-105. The hydroxylation sites were assigned by means of diagnostic product ions and respective dissociation pathways of the analytes following positive or negative ionization and collisional activation as well as selective chemical derivatization. The identified metabolites were used as target compounds to investigate their traceability in a rat elimination urine samples study and monohydroxylated and bishydroxylated species were detectable for up to four and six days post-administration, respectively. PMID:24881457

  6. Electrospray and tandem mass spectrometry in biochemistry.

    PubMed Central

    Griffiths, W J; Jonsson, A P; Liu, S; Rai, D K; Wang, Y

    2001-01-01

    Over the last 20 years, biological MS has changed out of all recognition. This is primarily due to the development in the 1980s of 'soft ionization' methods that permit the ionization and vaporization of large, polar, and thermally labile biomolecules. These developments in ionization mode have driven the design and manufacture of smaller and cheaper mass analysers, making the mass spectrometer a routine instrument in the biochemistry laboratory today. In the present review the revolutionary 'soft ionization' methods will be discussed with particular reference to electrospray. The mass analysis of ions will be described, and the concept of tandem MS introduced. Where appropriate, examples of the application of MS in biochemistry will be provided. Although the present review will concentrate on the MS of peptides/proteins and lipids, all classes of biomolecules can be analysed, and much excellent work has been done in the fields of carbohydrate and nucleic acid biochemistry. PMID:11311115

  7. Tandem mass spectrometry for sequencing proanthocyanidins.

    PubMed

    Li, Hui-Jing; Deinzer, Max L

    2007-02-15

    Proanthocyanidins (PAs) are a group of bioflavonoids consisting of oligomers based on catechin monomeric units. These polyphenolic compounds are widely distributed in higher plants and are an integral part of the human diet. A sensitive LC-tandem mass spectrometric (LC/ESI-MS(n)) method in the positive ion mode for sequencing these ubiquitous and highly beneficial antioxidants is described. The hydroxylation patterns and interflavanoid linkage for A- and B-type PAs were determined by fragment ions derived from a retro-Diels-Alder (RDA) fission, heterocyclic ring fission (HRF), a novel benzofuran-forming (BFF) fission described here for the first time, and a quinone methide (QM) fission. The subunit sequence of the PAs was determined by diagnostic ions derived from HRF/RDA fission, HRF/BFF fission, and RDA/HRF fission together with QM fission. A total of 26 PAs were reliably sequenced by the newly established tandem mass spectrometric protocol. It is shown that the protocol based on a combination of these different fragmentation patterns allows for uniquely identifying PA oligomers. PMID:17297981

  8. High-sensitivity mass spectrometry with a tandem accelerator

    SciTech Connect

    Henning, W.

    1983-01-01

    The characteristic features of accelerator mass spectrometry are discussed. A short overview is given of the current status of mass spectrometry with high-energy (MeV/nucleon) heavy-ion accelerators. Emphasis is placed on studies with tandem accelerators and on future mass spectrometry of heavier isotopes with the new generation of higher-voltage tandems.

  9. Protein Sequencing with Tandem Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Ziady, Assem G.; Kinter, Michael

    The recent introduction of electrospray ionization techniques that are suitable for peptides and whole proteins has allowed for the design of mass spectrometric protocols that provide accurate sequence information for proteins. The advantages gained by these approaches over traditional Edman Degradation sequencing include faster analysis and femtomole, sometimes attomole, sensitivity. The ability to efficiently identify proteins has allowed investigators to conduct studies on their differential expression or modification in response to various treatments or disease states. In this chapter, we discuss the use of electrospray tandem mass spectrometry, a technique whereby protein-derived peptides are subjected to fragmentation in the gas phase, revealing sequence information for the protein. This powerful technique has been instrumental for the study of proteins and markers associated with various disorders, including heart disease, cancer, and cystic fibrosis. We use the study of protein expression in cystic fibrosis as an example.

  10. Improved Isobaric Tandem Mass Tag Quantification by Ion Mobility-Mass Spectrometry

    PubMed Central

    Li, Lingjun

    2014-01-01

    Isobaric tandem mass tags are an attractive alternative to mass difference tags and label free approaches for quantitative proteomics due to the high degree of multiplexing that can be performed with their implementation. A drawback of tandem mass tags are that the co-isolation and co-fragmentation of labeled peptide precursors can result in chimeric MS/MS spectra that can underestimate the fold-change expression of each peptide. Two methods (QuantMode and MS3) have addressed this concern for ion trap and orbitrap instruments, but there is still a need to solve this problem for quadrupole time-of-flight (Q-TOF) instruments. Ion mobility (IM) separations coupled to Q-TOF instruments have the potential to mitigate MS/MS spectra chimeracy since IM-MS has the ability to separate ions based on charge, m/z, and collision cross section (CCS). This work presents results that showcase the power of IM-MS to improve tandem mass tag peptide quantitation accuracy by resolving co-isolated differently charged and same charged peptides prior to MS/MS fragmentation. PMID:24677527

  11. Tandem mass spectrometry: analysis of complex mixtures

    SciTech Connect

    Singleton, K.E.

    1985-01-01

    Applications of tandem mass spectrometry (MS/MS) for the analysis of complex mixtures results in increased specificity and selectivity by using a variety of reagent gases in both negative and positive ion modes. Natural isotopic abundance ratios were examined in both simple and complex mixtures using parent, daughter and neutral loss scans. MS/MS was also used to discover new compounds. Daughter scans were used to identify seven new alkaloids in a cactus species. Three of these alkaloids were novel compounds, and included the first simple, fully aromatic isoquinoline alkaloids reported in Cactaceae. MS/MS was used to characterize the chemical reaction products of coal in studies designed to probe its macromolecular structure. Negative ion chemical ionization was utilized to study reaction products resulting from the oxidation of coal. Possible structural units in the precursor coal were predicted based on the reaction products identified, aliphatic and aromatic acids and their anhydrides. The MS/MS method was also used to characterize reaction products resulting from coal liquefaction and/or extraction. These studies illustrate the types of problems for which MS/MS is useful. Emphasis has been placed on characterization of complex mixtures by selecting experimental parameters which enhance the information obtained. The value of using MS/MS in conjunction with other analytical techniques as well as the chemical pretreatment is demonstrated.

  12. Crux: rapid open source protein tandem mass spectrometry analysis.

    PubMed

    McIlwain, Sean; Tamura, Kaipo; Kertesz-Farkas, Attila; Grant, Charles E; Diament, Benjamin; Frewen, Barbara; Howbert, J Jeffry; Hoopmann, Michael R; Käll, Lukas; Eng, Jimmy K; MacCoss, Michael J; Noble, William Stafford

    2014-10-01

    Efficiently and accurately analyzing big protein tandem mass spectrometry data sets requires robust software that incorporates state-of-the-art computational, machine learning, and statistical methods. The Crux mass spectrometry analysis software toolkit ( http://cruxtoolkit.sourceforge.net ) is an open source project that aims to provide users with a cross-platform suite of analysis tools for interpreting protein mass spectrometry data. PMID:25182276

  13. On the Benefits of Acquiring Peptide Fragment Ions at High Measured Mass Accuracy

    PubMed Central

    Scherl, Alexander; Shaffer, Scott A.; Taylor, Gregory K.; Hernandez, Patricia; Appel, Ron D.; Binz, Pierre-Alain; Goodlett, David R.

    2008-01-01

    The advantages and disadvantages of acquiring tandem mass spectra by collision-induced dissociation (CID) of peptides in linear ion trap – Fourier-transform hybrid instruments are described. These instruments offer the possibility to transfer fragment ions from the linear ion trap to the FT-based analyzer for analysis with both high resolution and high mass accuracy. In addition, performing CID during the transfer of ions from the linear ion trap (LTQ) to the FT analyzer is also possible in instruments containing an additional collision cell (i.e., the “C-trap” in the LTQ-Orbitrap), resulting in tandem mass spectra over the full m/z range and not limited by the ejection q value of the LTQ. Our results show that these scan modes have lower duty cycles than tandem mass spectra acquired in the LTQ with nominal mass resolution, and typically result in fewer peptide identifications during data-dependent analysis of complex samples. However, the higher measured mass accuracy and resolution provides more specificity and hence provides a lower false positive ratio for the same number of true positives during database search of peptide tandem mass spectra. In addition, the search for modified and unexpected peptides is greatly facilitated with this data acquisition mode. It is therefore concluded that acquisition of tandem mass spectral data with high measured mass accuracy and resolution is a competitive alternative to “classical” data acquisition strategies, especially in situations of complex searches from large databases, searches for modified peptides, or for peptides resulting from unspecific cleavages. PMID:18417358

  14. High mass accuracy and high mass resolving power FT-ICR secondary ion mass spectrometry for biological tissue imaging.

    PubMed

    Smith, Donald F; Kiss, Andras; Leach, Franklin E; Robinson, Errol W; Paša-Tolić, Ljiljana; Heeren, Ron M A

    2013-07-01

    Biological tissue imaging by secondary ion mass spectrometry has seen rapid development with the commercial availability of polyatomic primary ion sources. Endogenous lipids and other small bio-molecules can now be routinely mapped on the sub-micrometer scale. Such experiments are typically performed on time-of-flight mass spectrometers for high sensitivity and high repetition rate imaging. However, such mass analyzers lack the mass resolving power to ensure separation of isobaric ions and the mass accuracy for elemental formula assignment based on exact mass measurement. We have recently reported a secondary ion mass spectrometer with the combination of a C60 primary ion gun with a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS) for high mass resolving power, high mass measurement accuracy, and tandem mass spectrometry capabilities. In this work, high specificity and high sensitivity secondary ion FT-ICR MS was applied to chemical imaging of biological tissue. An entire rat brain tissue was measured with 150 μm spatial resolution (75 μm primary ion spot size) with mass resolving power (m/Δm(50%)) of 67,500 (at m/z 750) and root-mean-square measurement accuracy less than two parts-per-million for intact phospholipids, small molecules and fragments. For the first time, ultra-high mass resolving power SIMS has been demonstrated, with m/Δm(50%) > 3,000,000. Higher spatial resolution capabilities of the platform were tested at a spatial resolution of 20 μm. The results represent order of magnitude improvements in mass resolving power and mass measurement accuracy for SIMS imaging and the promise of the platform for ultra-high mass resolving power and high spatial resolution imaging. PMID:23685962

  15. High Mass Accuracy and High Mass Resolving Power FT-ICR Secondary Ion Mass Spectrometry for Biological Tissue Imaging

    SciTech Connect

    Smith, Donald F.; Kiss, Andras; Leach, Franklin E.; Robinson, Errol W.; Pasa-Tolic, Ljiljana; Heeren, Ronald M.

    2013-07-01

    Biological tissue imaging by secondary ion mass spectrometry has seen rapid development with the commercial availability of polyatomic primary ion sources. Endogenous lipids and other small bio-molecules can now be routinely mapped on the micrometer scale. Such experiments are typically performed on time-of-flight mass spectrometers for high sensitivity and high repetition rate imaging. However, such mass analyzers lack the mass resolving power to ensure separation of isobaric ions and the mass accuracy for exact mass elemental formula assignment. We have recently reported a secondary ion mass spectrometer with the combination of a C60 primary ion gun with a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS) for high mass resolving power, high mass measurement accuracy and tandem mass spectrometry capabilities. In this work, high specificity and high sensitivity secondary ion FT-ICR MS was applied to chemical imaging of biological tissue. An entire rat brain tissue was measured with 150 μm spatial resolution (75 μm primary ion spot size) with mass resolving power (m/Δm50%) of 67,500 (at m/z 750) and root-mean-square measurement accuracy less than two parts-per-million for intact phospholipids, small molecules and fragments. For the first time, ultra-high mass resolving power SIMS has been demonstrated, with m/Δm50% > 3,000,000. Higher spatial resolution capabilities of the platform were tested at a spatial resolution of 20 μm. The results represent order of magnitude improvements in mass resolving power and mass measurement accuracy for SIMS imaging and the promise of the platform for ultra-high mass resolving power and high spatial resolution imaging.

  16. Determination of dalcetrapib by liquid chromatography-tandem mass spectrometry.

    PubMed

    Heinig, Katja; Bucheli, Franz; Kuhlmann, Olaf; Zell, Manfred; Pähler, Axel; Zwanziger, Elke; Gross, Günter; Tardio, Joseph; Ishikawa, Tomohiro; Yamashita, Tomoko

    2012-07-01

    The cholesteryl ester transfer protein modulator dalcetrapib is currently under development for the prevention of dyslipidemia and cardiovascular disease. Dalcetrapib, a thioester, is rapidly hydrolyzed in vivo to the corresponding thiophenol which in turn is further oxidized to the dimer and mixed disulfides (where the thiophenol binds to peptides, proteins and other endogenous thiols). These forms co-exist in an oxidation-reduction equilibrium via the thiol and cannot be stabilized without influencing the equilibrium, hence specific determination of individual components, i.e., in order to distinguish between the free thiol, the disulfide dimer and mixed disulfide adducts, was not pursued for routine analysis. The individual forms were quantified collectively as dalcetrapib-thiol (dal-thiol) after reduction under basic conditions with dithiothreitol to break disulfide bonds and derivatization with N-ethylmaleimide to stabilize the free thiol. The S-methyl and S-glucuronide metabolites were determined simultaneously with dal-thiol with no effect from the derivatization procedure. Column-switching liquid chromatography-tandem mass spectrometry provided a simple, fast and robust method for analysis of human and animal plasma and human urine samples. Addition of the surfactant Tween 80 to urine prevented adsorptive compound loss. The lower limits of quantitation (LLOQ) were 5 ng/mL for dal-thiol, and 5 ng/mL for the S-methyl and 50 ng/mL for the S-glucuronide metabolites. Using stable isotope-labeled internal standards, inter- and intra-assay precisions were each <15% (<20% at LLOQ) and accuracy was between 85 and 115%. Recovery was close to 100%, and no significant matrix effect was observed. PMID:22541249

  17. Biological Matrix Effects in Quantitative Tandem Mass Spectrometry-Based Analytical Methods: Advancing Biomonitoring

    PubMed Central

    Panuwet, Parinya; Hunter, Ronald E.; D’Souza, Priya E.; Chen, Xianyu; Radford, Samantha A.; Cohen, Jordan R.; Marder, M. Elizabeth; Kartavenka, Kostya; Ryan, P. Barry; Barr, Dana Boyd

    2015-01-01

    The ability to quantify levels of target analytes in biological samples accurately and precisely, in biomonitoring, involves the use of highly sensitive and selective instrumentation such as tandem mass spectrometers and a thorough understanding of highly variable matrix effects. Typically, matrix effects are caused by co-eluting matrix components that alter the ionization of target analytes as well as the chromatographic response of target analytes, leading to reduced or increased sensitivity of the analysis. Thus, before the desired accuracy and precision standards of laboratory data are achieved, these effects must be characterized and controlled. Here we present our review and observations of matrix effects encountered during the validation and implementation of tandem mass spectrometry-based analytical methods. We also provide systematic, comprehensive laboratory strategies needed to control challenges posed by matrix effects in order to ensure delivery of the most accurate data for biomonitoring studies assessing exposure to environmental toxicants. PMID:25562585

  18. Development of an advanced spacecraft tandem mass spectrometer

    NASA Technical Reports Server (NTRS)

    Drew, Russell C.

    1992-01-01

    The purpose of this research was to apply current advanced technology in electronics and materials to the development of a miniaturized Tandem Mass Spectrometer that would have the potential for future development into a package suitable for spacecraft use. The mass spectrometer to be used as a basis for the tandem instrument would be a magnetic sector instrument, of Nier-Johnson configuration, as used on the Viking Mars Lander mission. This instrument configuration would then be matched with a suitable second stage MS to provide the benefits of tandem MS operation for rapid identification of unknown organic compounds. This tandem instrument is configured with a newly designed GC system to aid in separation of complex mixtures prior to MS analysis. A number of important results were achieved in the course of this project. Among them were the development of a miniaturized GC subsystem, with a unique desorber-injector, fully temperature feedback controlled oven with powered cooling for rapid reset to ambient conditions, a unique combination inlet system to the MS that provides for both membrane sampling and direct capillary column sample transfer, a compact and ruggedized alignment configuration for the MS, an improved ion source design for increased sensitivity, and a simple, rugged tandem MS configuration that is particularly adaptable to spacecraft use because of its low power and low vacuum pumping requirements. The potential applications of this research include use in manned spacecraft like the space station as a real-time detection and warning device for the presence of potentially harmful trace contaminants of the spacecraft atmosphere, use as an analytical device for evaluating samples collected on the Moon or a planetary surface, or even use in connection with monitoring potentially hazardous conditions that may exist in terrestrial locations such as launch pads, environmental test chambers or other sensitive areas. Commercial development of the technology

  19. Accelerator mass spectrometry with a coupled tandem-linac system

    SciTech Connect

    Kutschera, W.

    1984-01-01

    A coupled system provides higher energies, which allows one to extend AMS to hitherto untouched mass regions. Another important argument is that the complexity, although bothersome for the operation, increases the selectivity of detecting a particular isotope. The higher-energy argument holds for any heavy-ion accelerator which is capable of delivering higher energy than a tandem. The present use of tandem-linac combinations for AMS, rather than cyclotrons, linacs or combinations of these machines, has mainly to do with the fact that this technique was almost exclusively developed around tandem accelerators. Therefore the tandem-linac combination is a natural extension to higher energies. The use of negative ions has some particular advantages in suppressing background from unwanted elements that do not form stable negative ions (e.g., N, Mg, Ar). On the other hand, this limits the detection of isotopes to elements which do form negative ions. For particular problems it may therefore be advantageous to use a positive-ion machine. What really matters most for choosing one or the other machine is to what extent the entire accelerator system can be operated in a truly quantiative way from the ion source to the detection system. 20 references, 4 figures.

  20. A high-throughput de novo sequencing approach for shotgun proteomics using high-resolution tandem mass spectrometry

    SciTech Connect

    Pan, Chongle; Park, Byung H; McDonald, W Hayes; Carey, Patricia A; Banfield, Jillian F.; Verberkmoes, Nathan C; Hettich, Robert {Bob} L; Samatova, Nagiza F

    2010-01-01

    Background High-resolution tandem mass spectra can now be readily acquired with hybrid instruments, such as LTQ-Orbitrap and LTQ-FT, in high-throughput shotgun proteomics workflows. The improved spectral quality enables more accurate de novo sequencing for identification of post-translational modifications and amino acid polymorphisms. Results In this study, a new de novo sequencing algorithm, called Vonode, has been developed specifically for analysis of such high-resolution tandem mass spectra. To fully exploit the high mass accuracy of these spectra, a unique scoring system is proposed to evaluate sequence tags based primarily on mass accuracy information of fragment ions. Consensus sequence tags were inferred for 11,422 spectra with an average peptide length of 5.5 residues from a total of 40,297 input spectra acquired in a 24-hour proteomics measurement of Rhodopseudomonas palustris. The accuracy of inferred consensus sequence tags was 84%. According to our comparison, the performance of Vonode was shown to be superior to the PepNovo v2.0 algorithm, in terms of the number of de novo sequenced spectra and the sequencing accuracy. Conclusions Here, we improved de novo sequencing performance by developing a new algorithm specifically for high-resolution tandem mass spectral data. The Vonode algorithm is freely available for download at http://compbio.ornl.gov/Vonode.

  1. STRUCTURAL CHARACTERIZATION OF SULFONATED AZO DYES USING LIQUID SECONDARY ION MASS SPECTROMETRY/TANDEM MASS SPECTROMETRY

    EPA Science Inventory

    Eight monosulfonated and disulfonated azo dyes were analyzed using liquid secondary ion mass spectrometry/tandem mass spectrometry, in the negative ion mode, under low-energy conditions (110-150 eV). any structurally characteristic fragment ions were obtained, several of which ha...

  2. Interpretation of tandem mass spectra obtained from cyclic nonribosomal peptides.

    PubMed

    Liu, Wei-Ting; Ng, Julio; Meluzzi, Dario; Bandeira, Nuno; Gutierrez, Marcelino; Simmons, Thomas L; Schultz, Andrew W; Linington, Roger G; Moore, Bradley S; Gerwick, William H; Pevzner, Pavel A; Dorrestein, Pieter C

    2009-06-01

    Natural and non-natural cyclic peptides are a crucial component in drug discovery programs because of their considerable pharmaceutical properties. Cyclosporin, microcystins, and nodularins are all notable pharmacologically important cyclic peptides. Because these biologically active peptides are often biosynthesized nonribosomally, they often contain nonstandard amino acids, thus increasing the complexity of the resulting tandem mass spectrometry data. In addition, because of the cyclic nature, the fragmentation patterns of many of these peptides showed much higher complexity when compared to related counterparts. Therefore, at the present time it is still difficult to annotate cyclic peptides MS/MS spectra. In this current work, an annotation program was developed for the annotation and characterization of tandem mass spectra obtained from cyclic peptides. This program, which we call MS-CPA is available as a web tool (http://lol.ucsd.edu/ms-cpa_v1/Input.py). Using this program, we have successfully annotated the sequence of representative cyclic peptides, such as seglitide, tyrothricin, desmethoxymajusculamide C, dudawalamide A, and cyclomarins, in a rapid manner and also were able to provide the first-pass structure evidence of a newly discovered natural product based on predicted sequence. This compound is not available in sufficient quantities for structural elucidation by other means such as NMR. In addition to the development of this cyclic annotation program, it was observed that some cyclic peptides fragmented in unexpected ways resulting in the scrambling of sequences. In summary, MS-CPA not only provides a platform for rapid confirmation and annotation of tandem mass spectrometry data obtained with cyclic peptides but also enables quantitative analysis of the ion intensities. This program facilitates cyclic peptide analysis, sequencing, and also acts as a useful tool to investigate the uncommon fragmentation phenomena of cyclic peptides and aids the

  3. MS2Analyzer: A Software for Small Molecule Substructure Annotations from Accurate Tandem Mass Spectra

    PubMed Central

    2015-01-01

    Systematic analysis and interpretation of the large number of tandem mass spectra (MS/MS) obtained in metabolomics experiments is a bottleneck in discovery-driven research. MS/MS mass spectral libraries are small compared to all known small molecule structures and are often not freely available. MS2Analyzer was therefore developed to enable user-defined searches of thousands of spectra for mass spectral features such as neutral losses, m/z differences, and product and precursor ions from MS/MS spectra in MSP/MGF files. The software is freely available at http://fiehnlab.ucdavis.edu/projects/MS2Analyzer/. As the reference query set, 147 literature-reported neutral losses and their corresponding substructures were collected. This set was tested for accuracy of linking neutral loss analysis to substructure annotations using 19 329 accurate mass tandem mass spectra of structurally known compounds from the NIST11 MS/MS library. Validation studies showed that 92.1 ± 6.4% of 13 typical neutral losses such as acetylations, cysteine conjugates, or glycosylations are correct annotating the associated substructures, while the absence of mass spectra features does not necessarily imply the absence of such substructures. Use of this tool has been successfully demonstrated for complex lipids in microalgae. PMID:25263576

  4. RScore: a peptide randomicity score for evaluating tandem mass spectra.

    PubMed

    Li, Fuxin; Sun, Wei; Gao, Youhe; Wang, Jue

    2004-01-01

    RScore, a new criterion of randomicity for evaluating tandem mass (MS/MS) spectra, is described. RScore is defined as the relative quality in cross-correlation and matched intensity percentage of a potentially positive peptide to those of other possible candidates for the same spectrum. By utilizing RScore combined with less stringent SEQUEST score filters, the number of true positive peptides can be increased and the number of false positives in datasets from a known protein mixture can be reduced compared with current SEQUEST parameters used alone. This algorithm is simple and adds little overheads to SEQUEST computation. PMID:15282793

  5. Ion-molecule adduct formation in tandem mass spectrometry.

    PubMed

    Alechaga, Élida; Moyano, Encarnación; Galceran, Maria Teresa

    2016-02-01

    Nowadays most LC-MS methods rely on tandem mass spectrometry not only for quantitation and confirmation of compounds by multiple reaction monitoring (MRM), but also for the identification of unknowns from their product ion spectra. However, gas-phase reactions between charged and neutral species inside the mass analyzer can occur, yielding product ions at m/z values higher than that of the precursor ion, or at m/z values difficult to explain by logical losses, which complicate mass spectral interpretation. In this work, the formation of adduct ions in the mass analyzer was studied using several mass spectrometers with different mass analyzers (ion trap, triple quadrupole, and quadrupole-Orbitrap). Heterocyclic amines (AαC, MeAαC, Trp-P-1, and Trp-P-2), photo-initiators (BP and THBP), and pharmaceuticals (phenacetin and levamisole) were selected as model compounds and infused in LCQ Classic, TSQ Quantum Ultra AM, and Q-Exactive Orbitrap (ThermoFisher Scientific) mass spectrometers using electrospray as ionization method. The generation of ion-molecule adducts depended on the compound and also on the instrument employed. Adducts with neutral organic solvents (methanol and acetonitrile) were only observed in the ion trap instrument (LCQ Classic), because of the ionization source on-axis configuration and the lack of gas-phase barriers, which allowed inertial entrance of the neutrals into the analyzer. Adduct formation (only with water) in the triple quadrupole instruments was less abundant than in the ion trap and quadrupole-Orbitrap mass spectrometers, because of the lower residence time of the reactive product ions in the mass analyzer. The moisture level of the CID and/or damper gas had a great effect in beam-like mass analyzers such as triple quadrupole, but not in trap-like mass analyzers, probably because of the long residence time that allowed adduct formation even with very low concentrations of water inside the mass spectrometer. PMID:26700446

  6. Non-target screening of veterinary drugs using tandem mass spectrometry on SmartMass.

    PubMed

    Xia, Bing; Liu, Xin; Gu, Yu-Cheng; Zhang, Zhao-Hui; Wang, Hai-Yan; Ding, Li-Sheng; Zhou, Yan

    2013-05-01

    Non-target screening of veterinary drugs using tandem mass spectrometric data was performed on the SmartMass platform. This newly developed software uses the characteristic fragmentation patterns (CFP) to identify chemicals, especially those containing particular substructures. A mixture of 17 sulfonamides was separated by ultra performance liquid chromatography (UPLC), and SmartMass was used to process the tandem mass spectrometry (MS/MS) data acquired on an Orbitrap mass spectrometer. The data were automatically extracted, and each sulfonamide was recognized and analyzed with a prebuilt analysis rule. By using this software, over 98% of the false candidate structures were eliminated, and all the correct structures were found within the top 10 of the ranking lists. Furthermore, SmartMass could also be used to identify slightly modified contraband drugs and metabolites with simple prebuilt rules. PMID:23532781

  7. Non-Target Screening of Veterinary Drugs Using Tandem Mass Spectrometry on SmartMass

    NASA Astrophysics Data System (ADS)

    Xia, Bing; Liu, Xin; Gu, Yu-Cheng; Zhang, Zhao-Hui; Wang, Hai-Yan; Ding, Li-Sheng; Zhou, Yan

    2013-05-01

    Non-target screening of veterinary drugs using tandem mass spectrometric data was performed on the SmartMass platform. This newly developed software uses the characteristic fragmentation patterns (CFP) to identify chemicals, especially those containing particular substructures. A mixture of 17 sulfonamides was separated by ultra performance liquid chromatography (UPLC), and SmartMass was used to process the tandem mass spectrometry (MS/MS) data acquired on an Orbitrap mass spectrometer. The data were automatically extracted, and each sulfonamide was recognized and analyzed with a prebuilt analysis rule. By using this software, over 98 % of the false candidate structures were eliminated, and all the correct structures were found within the top 10 of the ranking lists. Furthermore, SmartMass could also be used to identify slightly modified contraband drugs and metabolites with simple prebuilt rules. [Figure not available: see fulltext.

  8. Quantitative Comparison of Tandem Mass Spectra Obtained on Various Instruments

    NASA Astrophysics Data System (ADS)

    Bazsó, Fanni Laura; Ozohanics, Oliver; Schlosser, Gitta; Ludányi, Krisztina; Vékey, Károly; Drahos, László

    2016-05-01

    The similarity between two tandem mass spectra, which were measured on different instruments, was compared quantitatively using the similarity index (SI), defined as the dot product of the square root of peak intensities in the respective spectra. This function was found to be useful for comparing energy-dependent tandem mass spectra obtained on various instruments. Spectral comparisons show the similarity index in a 2D "heat map", indicating which collision energy combinations result in similar spectra, and how good this agreement is. The results and methodology can be used in the pharma industry to design experiments and equipment well suited for good reproducibility. We suggest that to get good long-term reproducibility, it is best to adjust the collision energy to yield a spectrum very similar to a reference spectrum. It is likely to yield better results than using the same tuning file, which, for example, does not take into account that contamination of the ion source due to extended use may influence instrument tuning. The methodology may be used to characterize energy dependence on various instrument types, to optimize instrumentation, and to study the influence or correlation between various experimental parameters.

  9. Quantitative Comparison of Tandem Mass Spectra Obtained on Various Instruments.

    PubMed

    Bazsó, Fanni Laura; Ozohanics, Oliver; Schlosser, Gitta; Ludányi, Krisztina; Vékey, Károly; Drahos, László

    2016-08-01

    The similarity between two tandem mass spectra, which were measured on different instruments, was compared quantitatively using the similarity index (SI), defined as the dot product of the square root of peak intensities in the respective spectra. This function was found to be useful for comparing energy-dependent tandem mass spectra obtained on various instruments. Spectral comparisons show the similarity index in a 2D "heat map", indicating which collision energy combinations result in similar spectra, and how good this agreement is. The results and methodology can be used in the pharma industry to design experiments and equipment well suited for good reproducibility. We suggest that to get good long-term reproducibility, it is best to adjust the collision energy to yield a spectrum very similar to a reference spectrum. It is likely to yield better results than using the same tuning file, which, for example, does not take into account that contamination of the ion source due to extended use may influence instrument tuning. The methodology may be used to characterize energy dependence on various instrument types, to optimize instrumentation, and to study the influence or correlation between various experimental parameters. Graphical Abstract ᅟ. PMID:27206510

  10. Quantitative Comparison of Tandem Mass Spectra Obtained on Various Instruments

    NASA Astrophysics Data System (ADS)

    Bazsó, Fanni Laura; Ozohanics, Oliver; Schlosser, Gitta; Ludányi, Krisztina; Vékey, Károly; Drahos, László

    2016-08-01

    The similarity between two tandem mass spectra, which were measured on different instruments, was compared quantitatively using the similarity index (SI), defined as the dot product of the square root of peak intensities in the respective spectra. This function was found to be useful for comparing energy-dependent tandem mass spectra obtained on various instruments. Spectral comparisons show the similarity index in a 2D "heat map", indicating which collision energy combinations result in similar spectra, and how good this agreement is. The results and methodology can be used in the pharma industry to design experiments and equipment well suited for good reproducibility. We suggest that to get good long-term reproducibility, it is best to adjust the collision energy to yield a spectrum very similar to a reference spectrum. It is likely to yield better results than using the same tuning file, which, for example, does not take into account that contamination of the ion source due to extended use may influence instrument tuning. The methodology may be used to characterize energy dependence on various instrument types, to optimize instrumentation, and to study the influence or correlation between various experimental parameters.

  11. Sequencing of Oligourea Foldamers by Tandem Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Bathany, Katell; Owens, Neil W.; Guichard, Gilles; Schmitter, Jean-Marie

    2013-03-01

    This study is focused on sequence analysis of peptidomimetic helical oligoureas by means of tandem mass spectrometry, to build a basis for de novo sequencing for future high-throughput combinatorial library screening of oligourea foldamers. After the evaluation of MS/MS spectra obtained for model compounds with either MALDI or ESI sources, we found that the MALDI-TOF-TOF instrument gave more satisfactory results. MS/MS spectra of oligoureas generated by decay of singly charged precursor ions show major ion series corresponding to fragmentation across both CO-NH and N'H-CO urea bonds. Oligourea backbones fragment to produce a pattern of a, x, b, and y type fragment ions. De novo decoding of spectral information is facilitated by the occurrence of low mass reporter ions, representative of constitutive monomers, in an analogous manner to the use of immonium ions for peptide sequencing.

  12. Desorption electrospray ionisation mass spectrometry and tandem mass spectrometry of low molecular weight synthetic polymers.

    PubMed

    Jackson, Anthony T; Williams, Jonathan P; Scrivens, James H

    2006-01-01

    A range of low molecular weight synthetic polymers has been characterised by means of desorption electrospray ionisation (DESI) combined with both mass spectrometry (MS) and tandem mass spectrometry (MS/MS). Accurate mass experiments were used to aid the structural determination of some of the oligomeric materials. The polymers analysed were poly(ethylene glycol) (PEG), polypropylene glycol (PPG), poly(methyl methacrylate) (PMMA) and poly(alpha-methyl styrene). An application of the technique for characterisation of a polymer used as part of an active ingredient in a pharmaceutical tablet is described. The mass spectra and tandem mass spectra of all of the polymers were obtained in seconds, indicating the sensitivity of the technique. PMID:16912984

  13. Electrospray Ionization Tandem Mass Spectrometry of Ammonium Cationized Polyethers

    NASA Astrophysics Data System (ADS)

    Nasioudis, Andreas; Heeren, Ron M. A.; van Doormalen, Irene; de Wijs-Rot, Nicolette; van den Brink, Oscar F.

    2011-05-01

    Quaternary ammonium salts (Quats) and amines are known to facilitate the MS analysis of high molar mass polyethers by forming low charge state adduct ions. The formation, stability, and behavior upon collision-induced dissociation (CID) of adduct ions of polyethers with a variety of Quats and amines were studied by electrospray ionization quadrupole time-of-flight, quadrupole ion trap, and linear ion trap tandem mass spectrometry (MS/MS). The linear ion trap instrument was part of an Orbitrap hybrid mass spectrometer that allowed accurate mass MS/MS measurements. The Quats and amines studied were of different degree of substitution, structure, and size. The stability of the adduct ions was related to the structure of the cation, especially the amine's degree of substitution. CID of singly/doubly charged primary and tertiary ammonium cationized polymers resulted in the neutral loss of the amine followed by fragmentation of the protonated product ions. The latter reveals information about the monomer unit, polymer sequence, and endgroup structure. In addition, the detection of product ions retaining the ammonium ion was observed. The predominant process in the CID of singly charged quaternary ammonium cationized polymers was cation detachment, whereas their doubly charged adduct ions provided the same information as the primary and tertiary ammonium cationized adduct ions. This study shows the potential of specific amines as tools for the structural elucidation of high molar mass polyethers.

  14. Direct Analysis in Real Time (DART) of an Organothiophosphate at Ultrahigh Resolution by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry and Tandem Mass Spectrometry

    PubMed Central

    Prokai, Laszlo; Stevens, Stanley M.

    2016-01-01

    Direct analysis in real time (DART) is a recently developed ambient ionization technique for mass spectrometry to enable rapid and sensitive analyses with little or no sample preparation. After swab-based field sampling, the organothiophosphate malathion was analyzed using DART-Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry (MS) and tandem mass spectrometry (MS/MS). Mass resolution was documented to be over 800,000 in full-scan MS mode and over 1,000,000 for an MS/MS product ion produced by collision-induced dissociation of the protonated analyte. Mass measurement accuracy below 1 ppm was obtained for all DART-generated ions that belonged to the test compound in the mass spectra acquired using only external mass calibration. This high mass measurement accuracy, achievable at present only through FTMS, was required for unequivocal identification of the corresponding molecular formulae. PMID:26784186

  15. Direct Analysis in Real Time (DART) of an Organothiophosphate at Ultrahigh Resolution by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry and Tandem Mass Spectrometry.

    PubMed

    Prokai, Laszlo; Stevens, Stanley M

    2016-01-01

    Direct analysis in real time (DART) is a recently developed ambient ionization technique for mass spectrometry to enable rapid and sensitive analyses with little or no sample preparation. After swab-based field sampling, the organothiophosphate malathion was analyzed using DART-Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry (MS) and tandem mass spectrometry (MS/MS). Mass resolution was documented to be over 800,000 in full-scan MS mode and over 1,000,000 for an MS/MS product ion produced by collision-induced dissociation of the protonated analyte. Mass measurement accuracy below 1 ppm was obtained for all DART-generated ions that belonged to the test compound in the mass spectra acquired using only external mass calibration. This high mass measurement accuracy, achievable at present only through FTMS, was required for unequivocal identification of the corresponding molecular formulae. PMID:26784186

  16. An accurate and efficient algorithm for Peptide and ptm identification by tandem mass spectrometry.

    PubMed

    Ning, Kang; Ng, Hoong Kee; Leong, Hon Wai

    2007-01-01

    Peptide identification by tandem mass spectrometry (MS/MS) is one of the most important problems in proteomics. Recent advances in high throughput MS/MS experiments result in huge amount of spectra. Unfortunately, identification of these spectra is relatively slow, and the accuracies of current algorithms are not high with the presence of noises and post-translational modifications (PTMs). In this paper, we strive to achieve high accuracy and efficiency for peptide identification problem, with special concern on identification of peptides with PTMs. This paper expands our previous work on PepSOM with the introduction of two accurate modified scoring functions: Slambda for peptide identification and Slambda* for identification of peptides with PTMs. Experiments showed that our algorithm is both fast and accurate for peptide identification. Experiments on spectra with simulated and real PTMs confirmed that our algorithm is accurate for identifying PTMs. PMID:18546510

  17. N, N-Dimethyl Leucines as Novel Isobaric Tandem Mass Tags for Quantitative Proteomics and Peptidomics

    PubMed Central

    Xiang, Feng; Ye, Hui; Chen, Ruibing; Fu, Qiang; Li, Lingjun

    2010-01-01

    Herein we describe the development and application of a set of novel N, N-dimethyl leucine (DiLeu) 4-plex isobaric tandem mass (MS2) tagging reagents with high quantitation efficacy and greatly reduced cost for neuropeptide and protein analysis. DiLeu reagents serve as attractive alternatives for isobaric tag for relative and absolute quantitation (iTRAQ) and tandem mass tags (TMTs) due to their synthetic simplicity, labeling efficiency and improved fragmentation efficiency. DiLeu reagent resembles the general structure of a tandem mass tag in that it contains an amine reactive group (triazine ester) targeting the N-terminus and ε-amino group of the lysine side-chain of a peptide, a balance group, and a reporter group. A mass shift of m/z 145.1 is observed for each incorporated label. Intense a1 reporter ions at m/z 115.1, 116.1, 117.1, and 118.1 are observed for all pooled samples upon MS2. All labeling reagents are readily synthesized from commercially available chemicals with greatly reduced cost. Labels 117 and 118 can be synthesized in one step and labels 115 and 116 can be synthesized in two steps. Both DiLeu and iTRAQ reagents show comparable protein sequence coverage (~43%) and quantitation accuracy (<15%) for tryptically digested protein samples. Furthermore, enhanced fragmentation of DiLeu labeling reagents offers greater confidence in protein identification and neuropeptide sequencing from complex neuroendocrine tissue extracts from a marine model organism, Callinectes sapidus. PMID:20218596

  18. A tandem mass spectrometric method for singlet oxygen measurement.

    PubMed

    Karonen, Maarit; Mattila, Heta; Huang, Ping; Mamedov, Fikret; Styring, Stenbjörn; Tyystjärvi, Esa

    2014-01-01

    Singlet oxygen, a harmful reactive oxygen species, can be quantified with the substance 2,2,6,6-tetramethylpiperidine (TEMP) that reacts with singlet oxygen, forming a stable nitroxyl radical (TEMPO). TEMPO has earlier been quantified with electron paramagnetic resonance (EPR) spectroscopy. In this study, we designed an ultra-high-performance liquid chromatographic-tandem mass spectrometric (UHPLC-ESI-MS/MS) quantification method for TEMPO and showed that the method based on multiple reaction monitoring (MRM) can be used for the measurements of singlet oxygen from both nonbiological and biological samples. Results obtained with both UHPLC-ESI-MS/MS and EPR methods suggest that plant thylakoid membranes produce 3.7 × 10(-7) molecules of singlet oxygen per chlorophyll molecule in a second when illuminated with the photosynthetic photon flux density of 2000 μmol m(-2 ) s(-1). PMID:24849296

  19. Profiling oligosaccharidurias by electrospray tandem mass spectrometry: quantifying reducing oligosaccharides.

    PubMed

    Ramsay, Steven L; Meikle, Peter J; Hopwood, John J; Clements, Peter R

    2005-10-01

    A method to semiquantify urinary oligosaccharides from patients suffering from oligosaccharidurias is presented. 1-Phenyl-3-methyl-5-pyrazolone has been used to derivatize urinary oligosaccharides prior to analysis by electrospray ionization-tandem mass spectrometry (ESI-MS/MS). Disease-specific oligosaccharides were identified for several oligosaccharidurias, including GM1 gangliosidosis, GM2 gangliosidosis, sialic acid storage disease, sialidase/neuraminidase deficiency, galactosialidosis, I-cell disease, fucosidosis, Pompe and Gaucher diseases, and alpha-mannosidosis. The oligosaccharides were referenced against the internal standard, methyl lactose, to produce ratios for comparison with control samples. Elevations in specific urinary oligosaccharides were indicative of lysosomal disease and the defective catabolic enzyme. This method has been adapted to enable assay of large sample numbers and could readily be extended to other oligosaccharidurias and to monitor oligosaccharide levels in patients receiving treatment. It also has immediate potential for incorporation into a newborn screening program. PMID:16111643

  20. Synthesis and tandem mass spectrometry of chlorinated triacylglycerols.

    PubMed

    Lefsay, Abir M; Guy, Robert D; Chatt, Amares; White, Robert L

    2013-09-01

    The incorporation of 9,10-dichlorooctadecanoyl groups using enzyme-catalyzed acylation and protecting group strategies yielded specific regioisomers of di- and tetrachlorinated triacylglycerols. Hexachloro- and hexabromotriacylglycerols were synthesized by addition of chlorine or bromine to tri-(cis-9-octadecenoyl)glycerol. Upon electrospray ionization and tandem mass spectrometry, the sodium adduct ions of all compounds containing a 9,10-dichlorooctadecanoyl group readily lost two molecules of HCl when subjected to collision-induced dissociation. A mechanism describing sequential HCl losses and the formation of a conjugated diene is proposed for the loss of both vicinal chlorine atoms from an alkyl chain. This characteristic fragmentation behavior and the availability of characterized standards will facilitate the development of quantitative analytical methods for the determination of chlorinated triacylglycerols in lipid mixtures isolated from marine and other biological sources. PMID:23872189

  1. Assay for Glycosaminoglycans by Tandem Mass Spectrometry and its Applications

    PubMed Central

    Tomatsu, Shunji; Shimada, Tsutomu; Mason, Robert W; Kelly, Joan; LaMarr, William A; Yasuda, Eriko; Shibata, Yuniko; Futatsumori, Hideyuki; Montaño, Adriana M; Yamaguchi, Seiji; Suzuki, Yasuyuki; Orii, Tadao

    2014-01-01

    Glycosaminoglycans (GAGs) are distributed in the whole body and play a variety of important physiological roles associated with inflammation, growth, coagulation, fibrinolysis, lipolysis, and cell-matrix biology. Accumulation of undegraded GAGs in lysosomes gives rise to a distinct clinical syndrome, mucopolysaccharidoses. Measurement of each specific GAG in a variety of specimens is urgently required to understand GAG interaction with other molecules, physiological status of patients, and prognosis and pathogenesis of the disease. We established a highly sensitive and accurate tandem mass spectrometry (LC-MS/MS) method for measurements of disaccharides derived from four specific GAGs [dermatan sulfate (DS), heparan sulfate (HS), keratan sulfate (KS), and chondroitin sulfate (CS)]. Disaccharides were produced by specific enzyme digestion of each GAG, and quantified by negative ion mode of multiple reaction monitoring. Subclasses of HS and GAGs with identical molecular weights can be separated using a Hypercarbcolumn (2.0 mm×50 mm, 5 μm) with an aectonitrile gradient in ammonium acetate (pH 11.0). We also developed a GAG assay by RapidFire with tandem mass spectrometry (RF-MS/MS). The RF system consists of an integrated solid phase extraction robot that binds and de-salts samples from assay plates and directly injects them into a MS/MS detector, reducing sample processing time to ten seconds. RF-MS/MS consequently yields much faster throughput than conventional LC-MS/MS-based methods. However, the RF system does not have a chromatographic step, and therefore, cannot distinguish GAGs that have identical molecular weights. Both methods can be applied to analysis of dried blood spots, blood, and urine specimens. In this article, we compare the assay methods for GAGs and describe their potential applications. PMID:25068074

  2. Simulation of Two Dimensional Electrophoresis and Tandem Mass Spectrometry for Teaching Proteomics

    ERIC Educational Resources Information Center

    Fisher, Amanda; Sekera, Emily; Payne, Jill; Craig, Paul

    2012-01-01

    In proteomics, complex mixtures of proteins are separated (usually by chromatography or electrophoresis) and identified by mass spectrometry. We have created 2DE Tandem MS, a computer program designed for use in the biochemistry, proteomics, or bioinformatics classroom. It contains two simulations--2D electrophoresis and tandem mass spectrometry.…

  3. Scandium analysis in silicon-containing minerals by inductively coupled plasma tandem mass spectrometry

    NASA Astrophysics Data System (ADS)

    Whitty-Léveillé, Laurence; Drouin, Elisabeth; Constantin, Marc; Bazin, Claude; Larivière, Dominic

    2016-04-01

    This article reports on the development of a new method for the accurate and precise determination of the amount of scandium, Sc, in silicon-containing minerals, based on the use of tandem quadrupole inductively coupled plasma mass spectrometry (ICP-MS/MS). The tandem quadrupole instrument enables new mass filtering configurations, which can reduce polyatomic interferences during the determination of Sc in mineral matrices. He and O2 were used and compared as collision and reaction gases for the removal of interferences at m/z 45 and 61. Using helium gas was ineffective to overcome all of the spectral interferences observed at m/z 45 and particularly for Si-based interferences. However, conversion of Sc+ ions into ScO+ ions (after bombardment with O2 in the octopole reaction system coupled with the use of the instrument in MS/MS mass-shift mode) provided interference-free conditions and sufficiently low limits of detection, down to 3 ng L- 1, to accurately detect Sc. The accuracy of the proposed methodology was assessed by analyzing five different reference materials (BX-N, OKA-2, NIM-L, SY-3 and GH).

  4. Fast atom bombardment tandem mass spectrometry of carotenoids

    SciTech Connect

    van Breeman, R.B.; Schmitz, H.H.; Schwartz, S.J.

    1995-02-01

    Positive ion fast atom bombardment (FAB) tandem mass spectrometry (MS-MS) using a double-focusing mass spectrometer with linked scanning at constant B/E and high-energy collisionally activated dissociation (CAD) was used to differentiate 17 different cartenoids, including {beta}-apo-8{prime}- carotenal, astaxanthin, {alpha}-carotene, {beta}-carotene, {gamma}-carotene, {zeta}-carotene, canthaxanthin, {beta}-cryptoxanthin, isozeaxanthin bis (pelargonate), neoxanthin, neurosporene, nonaprene, lutein, lycopene, phytoene, phytofluene, and zeaxanthin. The carotenoids were either synthetic or isolated from plant tissues. The use of FAB ionization minimized degradation or rearrangement of the carotenoid structures due to the inherent thermal instability generally ascribed to these compounds. Instead of protonated molecules, both polar xanthophylls and nonpolar carotenes formed molecular ions, M{sup {center_dot}+}, during FAB ionization. Following collisionally activated dissociation, fragment ions of selected molecular ion precursors showed structural features indicative of the presence of hydroxyl groups, ring systems, ester groups, and aldehyde groups and the extent of aliphatic polyene conjugation. The fragmentation patterns observed in the mass spectra herein may be used as a reference for the structural determination of carotenoids isolated from plant and animal tissues. 18 refs., 4 figs.

  5. Tandem-in-space and tandem-in-time mass spectrometry: Triple quadrupoles and quadrupole ion traps

    SciTech Connect

    Johnson, J.V.; Yost, R.A. ); Kelley, P.E.; Bradford, D.C. )

    1990-10-15

    Tandem-in-time and tandem-in-space MS/MS on quadrupole ion trap (ITMS) and triple quadrupole (TQMS) tandem mass spectrometers, respectively, were compared by evaluating the MS/MS daughter spectra, efficiencies of collision-induced dissociation (CID), limits of detection, and dynamic ranges obtained for the methane positive chemical ionization (PCI)-CID of two alkylphosphonates. Although the yield of daughter ions is dependent upon a number of instrumental parameters on both instruments, with judicious selection of parameters the ITMS and TQMS both yielded daughter ions of similar relative abundances. The ITMS had greater efficiencies of fragmentation, collection, and mass selection and transmission of the daughter ions to the detector. With PCI-MS/MS analysis of diisopropyl methylphosphonate standards introduced via capillary gas chromatography, full daughter spectra could be obtained for as little as 15 pg and 1.5 ng injected for the ITMS and the TQMS, respectively.

  6. iPE-MMR: An integrated approach to accurately assign monoisotopic precursor masses to tandem mass spectrometric data

    PubMed Central

    Jung, Hee-Jung; Purvine, Samuel O.; Kim, Hokeun; Petyuk, Vladislav A.; Hyung, Seok-Won; Monroe, Matthew E.; Mun, Dong-Gi; Kim, Kyong-Chul; Park, Jong-Moon; Kim, Su-Jin; Tolic, Nikola; Slysz, Gordon W.; Moore, Ronald J.; Zhao, Rui; Adkins, Joshua N.; Anderson, Gordon A.; Lee, Hookeun; Camp, David G.; Yu, Myeong-Hee; Smith, Richard D.; Lee, Sang-Won

    2010-01-01

    Accurate assignment of monoisotopic precursor masses to tandem mass spectrometric (MS/MS) data is a fundamental and critically important step for successful peptide identifications in mass spectrometry based proteomics. Here we describe an integrated approach that combines three previously reported methods of treating MS/MS data for precursor mass refinement. This combined method, “integrated Post-Experiment Monoisotopic Mass Refinement” (iPE-MMR), integrates steps: 1) generation of refined MS/MS data by DeconMSn; 2) additional refinement of the resultant MS/MS data by a modified version of PE-MMR; 3) elimination of systematic errors of precursor masses using DtaRefinery. iPE-MMR is the first method that utilizes all MS information from multiple MS scans of a precursor ion including multiple charge states, in an MS scan, to determine precursor mass. By combining these methods, iPE-MMR increases sensitivity in peptide identification and provides increased accuracy when applied to complex high-throughput proteomics data. PMID:20863060

  7. Sequence analysis of styrenic copolymers by tandem mass spectrometry.

    PubMed

    Yol, Aleer M; Janoski, Jonathan; Quirk, Roderic P; Wesdemiotis, Chrys

    2014-10-01

    Styrene and smaller molar amounts of either m-dimethylsilylstyrene (m-DMSS) or p-dimethylsilylstyrene (p-DMSS) were copolymerized under living anionic polymerization conditions, and the compositions, architectures, and sequences of the resulting copolymers were characterized by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and tandem mass spectrometry (MS(2)). MS analysis revealed that linear copolymer chains containing phenyl-Si(CH3)2H pendants were the major product for both DMSS comonomers. In addition, two-armed architectures with phenyl-Si(CH3)2-benzyl branches were detected as minor products. The comonomer sequence in the linear chains was established by MS(2) experiments on lithiated oligomers, based on the DMSS content of fragments generated by backbone C-C bond scissions and with the help of reference MS(2) spectra obtained from a polystyrene homopolymer and polystyrene end-capped with a p-DMSS block. The MS(2) data provided conclusive evidence that copolymerization of styrene/DMSS mixtures leads to chains with a rather random distribution of the silylated comonomer when m-DMSS is used, but to chains with tapered block structures, with the silylated units near the initiator, when p-DMSS is used. Hence, MS(2) fragmentation patterns permit not only differentiation of the sequences generated in the synthesis, but also the determination of specific comonomer locations along the polymer chain. PMID:25181590

  8. Identification of degradation products of indigoids by tandem mass spectrometry.

    PubMed

    Witkoś, Katarzyna; Lech, Katarzyna; Jarosz, Maciej

    2015-11-01

    The study concerns identification of photodegradation products of indigotin, indirubin and isoindigo. Experimental methodology consists of degradation of standard solutions of indigoids in a solar box and analysis of samples taken at different aging time by using capillary high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometric and spectrophotometric detectors. Identification of the formed compounds was based on careful interpretation of the electrospray ionization MS/MS spectra. Apart from the well-known degradation products of indigoids: isatin, isatoic anhydride and anthranilic acid, another seven species were also identified, and their proposed structures were confirmed by high-resolution molecular masses measurements; according to the best knowledge of authors, they have not been reported so far. The obtained results formed the basis for postulating mechanism of the process. Moreover, the MRM (Multiple Reaction Monitoring) method was developed for the identification of natural dyes and their degradation products in textiles of historical value. Apart from such colorants as indigotin and flavonoids, also presence of degradation products of indigoids was confirmed. PMID:26505769

  9. Determination of parabens in serum by liquid chromatography-tandem mass spectrometry: Correlation with lipstick use.

    PubMed

    Tahan, Gabriella Padovani; Santos, Nayara de Kássia Souza; Albuquerque, Ana Carolina; Martins, Isarita

    2016-08-01

    Parabens are the most widely used preservative and are considered to be relatively safe compounds. However, studies have demonstrated that they may have estrogenic activity, and there is ongoing debate regarding the safety and potential cancer risk of using products containing these compounds. In the present work, liquid chromatography-tandem mass spectrometry was applied to determine methylparaben and propylparaben concentrations in serum, and the results were correlated with lipstick application. Samples were analyzed using liquid-liquid extraction, followed by liquid chromatography-tandem mass spectrometry. The validation results demonstrated the linearity of the method over a range of 1-20 ng/mL, in addition to the method's precision and accuracy. A statistically significant difference was demonstrated between serum parabens in women who used lipstick containing these substances compared with those not using this cosmetic (p = 0.0005 and 0.0016, respectively), and a strong association was observed between serum parabens and lipstick use (Spearman correlation = 0.7202). PMID:27154569

  10. Quantitative analysis of tivantinib in rat plasma using ultra performance liquid chromatography with tandem mass spectrometry.

    PubMed

    Bai, Yan-Li; Yuan, Hong-Chang; Zhang, Dong-Tao; Liu, Yuan; Zhang, Yin

    2016-07-15

    In this work, a simple, sensitive and fast ultra performance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for the quantitative determination of tivantinib in rat plasma. Plasma samples were processed with a protein precipitation. The separation was achieved by an Acquity UPLC BEH C18 (2.1mm×50mm, 1.7μm) column with a gradient mobile phase consisting of 0.1% formic acid in water and acetonitrile. Detection was carried out using positive-ion electrospray tandem mass spectrometry via multiple reaction monitoring (MRM). The validated method had an excellent linearity in the range of 1.0-100ng/mL (r(2)>0.9967) with a lower limit of quantification (1.0ng/mL). The extraction recovery was in the range of 79.4-84.2% for tivantinib and 80.3% for carbamazepine (internal standard, IS). The intra- and inter-day precision was below 8.9% and accuracy was from -7.2% to 9.5%. No notable matrix effect and astaticism was observed for tivantinib. The method has been successfully applied to a pharmacokinetic study of tivantinib in rats for the first time, which provides the basis for the further development and application of tivantinib. PMID:27179187

  11. mMass as a Software Tool for the Annotation of Cyclic Peptide Tandem Mass Spectra

    PubMed Central

    Niedermeyer, Timo H. J.; Strohalm, Martin

    2012-01-01

    Natural or synthetic cyclic peptides often possess pronounced bioactivity. Their mass spectrometric characterization is difficult due to the predominant occurrence of non-proteinogenic monomers and the complex fragmentation patterns observed. Even though several software tools for cyclic peptide tandem mass spectra annotation have been published, these tools are still unable to annotate a majority of the signals observed in experimentally obtained mass spectra. They are thus not suitable for extensive mass spectrometric characterization of these compounds. This lack of advanced and user-friendly software tools has motivated us to extend the fragmentation module of a freely available open-source software, mMass (http://www.mmass.org), to allow for cyclic peptide tandem mass spectra annotation and interpretation. The resulting software has been tested on several cyanobacterial and other naturally occurring peptides. It has been found to be superior to other currently available tools concerning both usability and annotation extensiveness. Thus it is highly useful for accelerating the structure confirmation and elucidation of cyclic as well as linear peptides and depsipeptides. PMID:23028676

  12. Characterization of linear and branched polyacrylates by tandem mass spectrometry.

    PubMed

    Chaicharoen, Kittisak; Polce, Michael J; Singh, Anirudha; Pugh, Coleen; Wesdemiotis, Chrys

    2008-10-01

    The unimolecular degradation of alkali-metal cationized polyacrylates with the repeat unit CH(2)CH(COOR) and a variety of ester pendants has been examined by tandem mass spectrometry. The fragmentation patterns resulting from collisionally activated dissociation depend sensitively on the size of the ester alkyl substituent (R). With small alkyl groups, as in poly(methyl acrylate), lithiated or sodiated oligomers (M) decompose via free-radical chemistry, initiated by random homolytic C-C bond cleavages along the polymer chain. The radical ions formed this way dissociate further by backbiting rearrangements and beta scissions to yield a distribution of terminal fragments with one of the original end groups and internal fragments with 2-3 repeat units. If the ester alkyl group bears three or more carbon atoms, cleavages within the ester moieties become the predominant decomposition channel. This distinct reactivity is observed if R = t-butyl, n-butyl, or the mesogenic group (CH(2))(11)-O-C(6)H(4)-C(6)H(4)-CN. The [M+alkali metal](+) ions of the latter polyacrylates dissociate largely by charge-remote 1,5-H rearrangements that convert COOR to COOH groups by expulsion of 1-alkenes. The acid groups may displace an alcohol unit from a neighboring ester pendant to form a cyclic anhydride, unless hindered by steric effects. Using atom transfer radical polymerization, hyperbranched polyacrylates were prepared carrying ester groups both within and between the branches. Unique alkenes and alcohols are cleaved from ester groups at the branching points, enabling determination of the branching architecture. PMID:18373231

  13. Accurate mass determination of short-lived isotopes by a tandem Penning-trap mass spectrometer

    SciTech Connect

    Stolzenberg, H.; Becker, S.; Bollen, G.; Kern, F.; Kluge, H.; Otto, T.; Savard, G.; Schweikhard, L. ); Audi, G. ); Moore, R.B. ); The ISOLDE Collaboration

    1990-12-17

    A mass spectrometer consisting of two Penning traps has been set up for short-lived isotopes at the on-line mass separator ISOLDE at CERN. The ion beam is collected and cooled in the first trap. After delivery to the second trap, high-accuracy direct mass measurements are made by determining the cyclotron frequency of the stored ions. Measurements have been performed for {sup 118}Cs--{sup 137}Cs. A resolving power of over 10{sup 6} and an accuracy of 1.4{times}10{sup {minus}7} have been achieved, corresponding to about 20 keV.

  14. 10 K Ring Electrode Trap—Tandem Mass Spectrometer for Infrared Spectroscopy of Mass Selected Ions

    NASA Astrophysics Data System (ADS)

    Goebbert, Daniel J.; Meijer, Gerard; Asmis, Knut R.

    2009-03-01

    A novel instrumental setup for measuring infrared photodissociation spectra of buffer gas cooled, mass-selected ions is described and tested. It combines a cryogenically cooled, linear radio frequency ion trap with a tandem mass spectrometer, optimally coupling continuous ion sources to pulsed laser experiments. The use of six independently adjustable DC potentials superimposed over the trapping radio frequency field provides control over the ion distribution within, as well as the kinetic energy distribution of the ions extracted from the ion trap. The scheme allows focusing the ions in space and time, such that they can be optimally irradiated by a pulsed, widely tunable infrared photodissociation laser. Ion intensities are monitored with a time-of-flight mass spectrometer mounted orthogonally to the ion trap axis.

  15. High-accuracy mass spectrometry for fundamental studies.

    PubMed

    Kluge, H-Jürgen

    2010-01-01

    Mass spectrometry for fundamental studies in metrology and atomic, nuclear and particle physics requires extreme sensitivity and efficiency as well as ultimate resolving power and accuracy. An overview will be given on the global status of high-accuracy mass spectrometry for fundamental physics and metrology. Three quite different examples of modern mass spectrometric experiments in physics are presented: (i) the retardation spectrometer KATRIN at the Forschungszentrum Karlsruhe, employing electrostatic filtering in combination with magnetic-adiabatic collimation-the biggest mass spectrometer for determining the smallest mass, i.e. the mass of the electron anti-neutrino, (ii) the Experimental Cooler-Storage Ring at GSI-a mass spectrometer of medium size, relative to other accelerators, for determining medium-heavy masses and (iii) the Penning trap facility, SHIPTRAP, at GSI-the smallest mass spectrometer for determining the heaviest masses, those of super-heavy elements. Finally, a short view into the future will address the GSI project HITRAP at GSI for fundamental studies with highly-charged ions. PMID:20530821

  16. Determination of perchlorate in infant formula by isotope dilution ion chromatography/tandem mass spectrometry

    PubMed Central

    Wang, Z.; Lau, B.P.-Y.; Tague, B.; Sparling, M.; Forsyth, D.

    2011-01-01

    A sensitive and selective isotope dilution ion chromatography/tandem mass spectrometry (ID IC-MS/MS) method was developed and validated for the determination of perchlorate in infant formula. The perchlorate was extracted from infant formula by using 20 ml of methanol and 5 ml of 1% acetic acid. All samples were spiked with 18O4 isotope-labelled perchlorate internal standard prior to extraction. After purification on a graphitised carbon solid-phase extraction column, the extracts were injected into an ion chromatography system equipped with an Ionpac AS20 column for separation of perchlorate from other anions. The presence of perchlorate in samples was quantified by isotope dilution mass spectrometry. Analysis of both perchlorate and its isotope-labelled internal standard was carried out on a Waters Quattro Ultima triple quadrupole mass spectrometer operating in a multiple reaction monitoring (MRM) negative ionisation mode. The method was validated for linearity and range, accuracy, precision, sensitivity, and matrix effects. The limit of quantification (LOQ) was 0.4 μg 1−1 for liquid infant formula and 0.95 μg kg−1 for powdered infant formula. The recovery ranged from 94% to 110% with an average of 98%. This method was used to analyse 39 infant formula, and perchlorate concentrations ranging from

  17. Improved Sequence Tag Generation Method for Peptide Identification in Tandem Mass Spectrometry

    PubMed Central

    Cao, Xia; Nesvizhskii, Alexey I.

    2013-01-01

    The sequence tag-based peptide identification methods are a promising alternative to the traditional database search approach. However, a more comprehensive analysis, optimization, and comparison with established methods are necessary before these methods can gain widespread use in the proteomics community. Using the InsPecT open source code base (Tanner et al., Anal Chem. 2005, 77:4626–39), we present an improved sequence tag generation method that directly incorporates multi-charged fragment ion peaks present in many tandem mass spectra of higher charge states. We also investigate the performance of sequence tagging under different settings using control datasets generated on five different types of mass spectrometers, as well as using a complex phosphopeptide-enriched sample. We also demonstrate that additional modeling of InsPecT search scores using a semi-parametric approach incorporating the accuracy of the precursor ion mass measurement provides additional improvement in the ability to discriminate between correct and incorrect peptide identifications. The overall superior performance of the sequence tag-based peptide identification method is demonstrated by comparison with a commonly used SEQUEST/PeptideProphet approach. PMID:18785767

  18. Confirmation and quantification of clenbuterol in horse urine using liquid chromatography tandem mass spectrometry triple quadrupole.

    PubMed

    Bishop, Jennifer; Heffron, Brendan; Taddei, Lisa; Benoit, Marc; Hurt, Laura; Costello, Sara; Gross, Melissa; Negrusz, Adam

    2015-03-01

    Clenbuterol (CLE) is used in horses as a bronchodilator and for its anabolic steroid-like effects. CLE is a Class 3 drug according to current Association of Racing Commissioners International (ARCI) Uniform Classification Guidelines. The Racing Medication and Testing Consortium recommended a urine CLE threshold of 140 pg/mL after careful scientific review of the results of studies describing the disposition of CLE in the horse and this threshold was adopted by the ARCI. Enzyme-linked immunosorbent assay was previously used to screen samples for CLE in Illinois, but could not detect such low concentrations in urine. Thus, a liquid-liquid extraction of CLE from urine followed by quantification by liquid chromatography-tandem mass spectrometry was developed and validated. Method validation included testing stability, ion suppression and enhancement, precision, accuracy and uncertainty. Intra-, interday and total precision and accuracy were calculated for each control and found to be within the ±15% acceptance range. The Guide to the Expression of Uncertainty in Measurement approach was used to calculate uncertainty, which was 11% at the 95% confidence level. In the past 5 years, only 15 samples were reported as positive for CLE in Illinois. This new method was used in a pilot program to screen and confirm samples received from thoroughbred and harness horses. PMID:25505053

  19. Targeted Tandem Mass Spectrometry for High-Throughput Comparative Proteomics Employing NanoLC-FTICR MS with External Ion Dissociation

    SciTech Connect

    Kang, Hyuk; Pasa-Tolic, Liljiana; Smith, Richard D.

    2007-05-03

    ABSTRACT-Targeted tandem mass spectrometry (MS/MS) is an attractive proteomic approach that allows selective identification of peptides exhibiting abundance differences between culture conditions and/or diseased states. Herein, we report on a targeted LC-MS/MS capability realized with a 7 Tesla Fourier transform ion cyclotron resonance (FTICR) mass spectrometer equipped with a quadrupole interface that provides data-dependent ion selection, accumulation, and dissociation externally to the ICR trap. Identification of a subset of differentially abundant proteins from Shewanella oneidensis grown under suboxic vs. aerobic conditions demonstrates the feasibility of such approach. High mass resolution offered by FTICR and effective on-the-fly elution time correction facilitated accurate selection of targets, while high mass measurement accuracy MS/MS data resulted in unambiguous peptide identifications.

  20. Determination of dapoxetine in rat plasma by ultra-performance liquid chromatography-tandem mass spectrometry.

    PubMed

    Kim, Tae Kon; Kim, In Sook; Hong, Seok Hyun; Choi, Yun Kyoung; Kim, Hohyun; Yoo, Hye Hyun

    2013-05-01

    In this study, we describe and validate a rapid and sensitive method for quantitation of dapoxetine in rat plasma by using ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry (UPLC-ESI/MS/MS). Plasma samples were prepared by protein precipitation with acetonitrile, and sildenafil was used as an internal standard (IS). The mobile phase consisted of 0.5% formic acid/acetonitrile (60:40, v/v); a C18 reversed-phase column (2.0 × 50 mm, 1.7 μm) was used for chromatographic separation. Multiple reaction monitoring (MRM) was used in the positive ion mode for mass spectrometric detection. The calibration curve for dapoxetine was linear (r(2)=0.999) in the concentration range of 1-500 ng/mL. The intra- and inter-day precision was between 3.8% and 8.3%, and the intra- and inter-day accuracy was between 101.1% and 109.0%. Dapoxetine was found to be stable in various conditions with the recoveries>87.0% (RSD <7.2%). The method was found to be specific, precise, and accurate, and no matrix effect was observed. Our results suggest that this method can be successfully applied in pharmacokinetic studies of dapoxetine in rat plasma. PMID:23542722

  1. Dynamic Bayesian Network for Accurate Detection of Peptides from Tandem Mass Spectra.

    PubMed

    Halloran, John T; Bilmes, Jeff A; Noble, William S

    2016-08-01

    A central problem in mass spectrometry analysis involves identifying, for each observed tandem mass spectrum, the corresponding generating peptide. We present a dynamic Bayesian network (DBN) toolkit that addresses this problem by using a machine learning approach. At the heart of this toolkit is a DBN for Rapid Identification (DRIP), which can be trained from collections of high-confidence peptide-spectrum matches (PSMs). DRIP's score function considers fragment ion matches using Gaussians rather than fixed fragment-ion tolerances and also finds the optimal alignment between the theoretical and observed spectrum by considering all possible alignments, up to a threshold that is controlled using a beam-pruning algorithm. This function not only yields state-of-the art database search accuracy but also can be used to generate features that significantly boost the performance of the Percolator postprocessor. The DRIP software is built upon a general purpose DBN toolkit (GMTK), thereby allowing a wide variety of options for user-specific inference tasks as well as facilitating easy modifications to the DRIP model in future work. DRIP is implemented in Python and C++ and is available under Apache license at http://melodi-lab.github.io/dripToolkit . PMID:27397138

  2. Determination of phenylephrine in human plasma using ultra-performance liquid chromatography-tandem mass spectrometry.

    PubMed

    Feng, Sheng; Zhao, Qian; Jiang, Ji; Hu, Pei

    2013-02-01

    This paper described a sensitive and rapid method based on ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) for the determination of phenylephrine in human plasma. Plasma samples were pre-purified by solid-phase extraction (SPE). The chromatographic separation was achieved with BEH HILIC column using a mixture of 10mM pH 3.5 ammonium formate and acetonitrile (10:90, v/v) under isocratic conditions at a flow rate of 0.4 mL/min. The mass spectrometry was carried out using positive electrospray ionization (ESI) and data acquisition was carried out in the multiple reaction monitoring (MRM) mode. The method was fully validated over the concentration range of 10.0-5000 pg/mL. The lower limit of quantification (LLOQ) was 10.0 pg/mL. Inter- and intra-batch precision was less than 15% and the accuracy was within 85-115%. Extraction recovery was 78.5%. Selectivity, matrix effects and stability were also validated. The method was applied to the pharmacokinetic study of phenylephrine hydrochloride in Chinese subjects. PMID:23314401

  3. Determination of faropenem in human plasma and urine by liquid chromatography-tandem mass spectrometry.

    PubMed

    Gao, Shouhong; Chen, Wansheng; Tao, Xia; Miao, Haijun; Yang, Shaolin; Wu, Rong

    2008-01-01

    A simple, rapid and sensitive liquid chromatography/electrospray tandem mass spectrometry (LC-MS/MS) quantitative detection method, using cefalexin as internal standard, was developed for the analysis of faropenem in human plasma and urine. After precipitation of the plasma proteins with acetonitrile, the analytes were separated on a C18 reversed-phase column with 0.1% formic acid-methanol (45:55, v/v) and detected by electrospray ionization mass spectrometry in positive multiple reaction monitoring mode. Calibration curves with good linearities (r=0.9991 for plasma sample and r=0.9993 for urine sample) were obtained in the range 5-4000 ng/mL for faropenem. The limit of detection was 5 ng/mL. Recoveries were around 90% for the extraction from human plasma, and good precision and accuracy were achieved. This method is feasible for the evaluation of pharmacokinetic profiles of faropenem in humans, and to our knowledge, it is the first time the pharmacokinetic of faropenem has been elucidated in vivo using LC-MS/MS. PMID:17604362

  4. Quantitative determination of ondansetron in human plasma by enantioselective liquid chromatography-tandem mass spectrometry.

    PubMed

    Liu, Ke; Dai, Xiaojian; Zhong, Dafang; Chen, Xiaoyan

    2008-03-15

    A sensitive and enantioselective method was developed and validated for the determination of ondansetron enantiomers in human plasma using enantioselective liquid chromatography-tandem mass spectrometry. The enantiomers of ondansetron were extracted from plasma using ethyl acetate under alkaline conditions. HPLC separation was performed on an ovomucoid column using an isocratic mobile phase of methanol-5 mM ammonium acetate-acetic acid (20:80:0.02, v/v/v) at a flow rate of 0.40 mL/min. Acquisition of mass spectrometric data was performed in multiple reaction monitoring mode, using the transitions of m/z 294-->170 for ondansetron enantiomers, and m/z 285-->124 for tropisetron (internal standard). The method was linear in the concentration range of 0.10-40 ng/mL for each enantiomer using 200 microL of plasma. The lower limit of quantification (LLOQ) for each enantiomer was 0.10 ng/mL. The intra- and inter-assay precision was 3.7-11.6% and 5.6-12.3% for R-(-)-ondansetron and S-(+)-ondansetron, respectively. The accuracy was 100.4-107.1% for R-(-)-ondansetron and 103.3-104.9% for S-(+)-ondansetron. No chiral inversion was observed during the plasma storage, preparation and analysis. The method was successfully applied to characterize the pharmacokinetic profiles of ondansetron enantiomers in healthy volunteers after an intravenous infusion of 8 mg racemic ondansetron. PMID:18299256

  5. Quantitative analysis of phenibut in rat brain tissue extracts by liquid chromatography-tandem mass spectrometry.

    PubMed

    Grinberga, Solveiga; Zvejniece, Liga; Liepinsh, Edgars; Dambrova, Maija; Pugovics, Osvalds

    2008-12-01

    Phenibut (3-phenyl-4-aminobutyric acid) is a gamma-aminobutyric acid mimetic drug, which is used clinically as a mood elevator and tranquilizer. In the present work, a rapid, selective and sensitive liquid chromatography-tandem mass spectrometry method for quantification of phenibut in biological matrices has been developed. The method is based on protein precipitation with acidic acetonitrile followed by isocratic chromatographic separation using acetonitrile-formic acid (0.1% in water; 8:92, v/v) mobile phase on a reversed-phase column. Detection of the analyte was performed by electrospray ionization mass spectrometry in multiple reaction monitoring mode with the precursor-to-product ion transition m/z 180.3 --> m/z 117.2. The calibration curve was linear over the concentration range 50-2000 ng/mL. The lower limit of quantification for phenibut in rat brain extracts was 50 ng/mL. Acceptable precision and accuracy were obtained over the whole concentration range. The validated method was successfully applied in a pharmacological study to analyze phenibut concentration in rat brain tissue extract samples. PMID:19034959

  6. Determination of lincomycin and tylosin residues in honey by liquid chromatography/tandem mass spectrometry.

    PubMed

    Thompson, Thomas S; Noot, Donald K; Calvert, Jane; Pernal, Stephen F

    2005-01-01

    A simple and rapid analytical method was developed for the determination of lincomycin and tylosin residues in honey as part of field studies examining the efficacy and target animal safety of these antibiotics to control American foulbrood disease in honey bees. Residues of the antibiotics were determined using liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS). Honey samples were diluted and injected directly into the LC/MS/MS system without additional cleanup by solid-phase extraction or liquid-liquid partitioning. A six-port valve system was utilized to selectively route eluant from the LC column into the mass spectrometer only during a relatively short portion of the chromatographic run corresponding to the elution of the analytes of interest. Minimal contamination of the MS source chamber was observed despite the analysis of large numbers of samples. Using internal standard quantitation, excellent accuracy and precision were obtained with no apparent matrix-to-matrix variation. Based on the analysis of fortified replicates, the mean percent deviation from the theoretical concentration and the percent relative standard deviation were both less than 10% for tylosin over an analytical range of 10-1000 microg/kg. Slightly higher mean percent deviations and relative standard deviations were observed for the analysis of lincomycin in fortified replicate samples. The method detection limits were determined to be 5 and 2 microg/kg for lincomycin and tylosin, respectively. PMID:15645470

  7. Increased throughput of proteomics analysis by multiplexing high-resolution tandem mass spectra.

    PubMed

    Ledvina, A R; Savitski, M M; Zubarev, A R; Good, D M; Coon, J J; Zubarev, R A

    2011-10-15

    High-resolution and high-accuracy Fourier transform mass spectrometry (FTMS) is becoming increasingly attractive due to its specificity. However, the speed of tandem FTMS analysis severely limits the competitive advantage of this approach relative to faster low-resolution quadrupole ion trap MS/MS instruments. Here we demonstrate an entirely FTMS-based analysis method with a 2.5-3.0-fold greater throughput than a conventional FT MS/MS approach. The method consists of accumulating together the MS/MS fragments ions from multiple precursors, with subsequent high-resolution analysis of the mixture. Following acquisition, the multiplexed spectrum is deconvoluted into individual MS/MS spectra which are then combined into a single concatenated file and submitted for peptide identification to a search engine. The method is tested both in silico using a database of MS/MS spectra as well as in situ using a modified LTQ Orbitrap mass spectrometer. The performance of the method in the experiment was consistent with theoretical expectations. PMID:21913643

  8. ANALYSIS OF POLYCYCLIC AROMATIC HYDROCARBONS BY ION TRAP TANDEM MASS SPECTROMETRY

    EPA Science Inventory

    An ion-trap mass spectrometer with a wave board and tandem mass spectrometry software was used to analyze gas chromatographically separated polycyclic aromatic hydrocarbons (PAHs) by using collision-induced dissociation (CID). The nonresonant (multiple collision) mode was used to...

  9. Ion-retarding lens improves the abundance sensitivity of tandem mass spectrometers

    NASA Technical Reports Server (NTRS)

    Kaiser, K. A.; Stevens, C. M.

    1969-01-01

    Ion-retarding lens which increases the abundance sensitivity of tandem magnetic-analyzer mass spectrometers measures isotopes of low abundance in mass positions adjacent to isotopes of high abundance. The lens increases the abundance sensitivity for isotopes lying farther from high abundance isotopes than the energy cutoff of the lens.

  10. The Effects of Mass Accuracy on the Validation of MS/MS Data

    PubMed Central

    Orlando, R.; Lim, J.M.; Zohrabyan, G.; Atwood, J.; Weatherly, D.B.; Nuccio, A.

    2010-01-01

    RP-9 Objective: Analyze how precursor and fragment mass tolerance affect the number of true positives and false positives. Introduction: Mass spectrometry coupled to database searching is a powerful and popular protein identification tool. A typical shotgun proteomics experiment begins with degrading intact proteins into peptides. The peptide mixture then undergoes LC-MS/MS analysis, and the resulting experimental spectra are compared to theoretical spectra derived from protein, cDNA, or EST databases. Successful database searching is dependent on database size, post-translational modifications, and precursor and fragment ion m/z tolerance. Method: A standard protein set was made containing 62 verified T. cruzi recombinant proteins spiked into an E. coli lysate. This mixture was digested then analyzed by LC-MS/MS using an LTQ-Orbitrap. Resulting spectra were searched against forward, reverse, and concatenated databases using Sequest, Mascot, and X!Tandem. Peptide probabilities were calculated using ProteinProphet, and peptide false discovery rates (FDR's) were calculated by using ProteoIQ. It is necessary to use a standardized protein mixture to determine the number of true positives (T. cruzi proteins) and false positives (random proteins) found as a function of m/z search tolerance. Preliminary Results: At a 95% probability, more true positives are discovered as ion precursor mass accuracy is increased; however, more false positives are also discovered and at a higher rate. For example, as mass accuracy is increased from +/−1000ppm to +/−20ppm, the number of spectra corresponding to true positives increases by 50% while the number for false positives increases by 380%. Using a 5% FDR filter with the same mass accuracy change yields a 37% increase in true positive matches, while leaving the number of false positives unchanged. Conclusions: FDR filtering can result in more successful data validation than probability filtering when performing high resolution

  11. High-speed tandem mass spectrometric in situ imaging by nanospray desorption electrospray ionization mass spectrometry.

    PubMed

    Lanekoff, Ingela; Burnum-Johnson, Kristin; Thomas, Mathew; Short, Joshua; Carson, James P; Cha, Jeeyeon; Dey, Sudhansu K; Yang, Pengxiang; Prieto Conaway, Maria C; Laskin, Julia

    2013-10-15

    Nanospray desorption electrospray ionization (nano-DESI) combined with tandem mass spectrometry (MS/MS), high-resolution mass analysis of the fragment ions (m/Δm = 17 500 at m/z 200), and rapid spectral acquisition enabled simultaneous imaging and identification of a large number of metabolites and lipids from 92 selected m/z windows (±1 Da) with a spatial resolution of better than 150 μm. Mouse uterine sections of implantation sites on day 6 of pregnancy were analyzed in the ambient environment without any sample pretreatment. MS/MS imaging was performed by scanning the sample under the nano-DESI probe at 10 μm/s, while higher-energy collision-induced dissociation (HCD) spectra were acquired for a targeted inclusion list of 92 m/z values at a rate of ∼6.3 spectra/s. Molecular ions and their corresponding fragments, separated by high-resolution mass analysis, were assigned on the basis of accurate mass measurement. Using this approach, we were able to identify and image both abundant and low-abundance isobaric and isomeric species within each m/z window. MS/MS analysis enabled efficient separation and identification of isomeric and isobaric phospholipids that are difficult to separate in full-scan mode. Furthermore, we identified several metabolites associated with early pregnancy and obtained the first 2D images of these molecules. PMID:24040919

  12. High-Speed Tandem Mass Spectrometric in Situ Imaging by Nanospray Desorption Electrospray Ionization Mass Spectrometry

    SciTech Connect

    Lanekoff, Ingela T.; Burnum-Johnson, Kristin E.; Thomas, Mathew; Short, Joshua TL; Carson, James P.; Cha, Jeeyeon; Dey, Sudhansu K.; Yang, Pengxiang; Prieto Conaway, Maria C.; Laskin, Julia

    2013-10-15

    Nanospray desorption electrospray ionization (nano-DESI) combined with tandem mass spectrometry (MS/MS), high-resolution mass analysis (m/m=17,500 at m/z 200), and rapid spectral acquisition enabled simultaneous imaging and identification of more than 300 molecules from 92 selected m/z windows (± 1 Da) with a spatial resolution of better than 150 um. Uterine sections of implantation sites on day 6 of pregnancy were analyzed in the ambient environment without any sample pre-treatment. MS/MS imaging was performed by scanning the sample under the nano-DESI probe at 10 um/s while acquiring higher-energy collision-induced dissociation (HCD) spectra for a targeted inclusion list of 92 m/z values at a rate of ~6.3 spectra/s. Molecular ions and their corresponding fragments, separated using high-resolution mass analysis, were assigned based on accurate mass measurement. Using this approach, we were able to identify and image both abundant and low-abundance isobaric species within each m/z window. MS/MS analysis enabled efficient separation and identification of isobaric sodium and potassium adducts of phospholipids. Furthermore, we identified several metabolites associated with early pregnancy and obtained the first 2D images of these molecules.

  13. Quantitative determination of perfluorooctanoic acid in serum and plasma by liquid chromatography tandem mass spectrometry.

    PubMed

    Flaherty, John M; Connolly, Paul D; Decker, Emily R; Kennedy, S Mark; Ellefson, Mark E; Reagen, William K; Szostek, Bogdan

    2005-05-25

    A selective and sensitive method for analysis of perfluorooctanoic acid (PFOA) in human serum and plasma, utilizing liquid chromatography tandem mass spectrometry (LC-MS/MS), has been developed and thoroughly validated to satisfy strict FDA guidelines for bioanalytical methods. A simple, automated sample preparation procedure, involving extraction of the target analyte with acetonitrile on protein precipitation media in a 96-well plate format was developed, allowing efficient handling of large numbers of samples. The proposed method uses the calibration standards prepared in a surrogate matrix (rabbit serum or plasma) and (13)C-labeled PFOA as the internal standard to account for matrix effects, instrument drift, and extraction efficiency. Human serum and plasma could not be used for matrix matching of calibration standards as endogenous levels of PFOA observed in the control human serum and plasma significantly exceeded the targeted lower limit of quantitation (LLOQ) of the method. Precision and accuracy of the method were demonstrated by analysis of rabbit serum and plasma control samples fortified at 0.5, 5, and 40 ng/mL PFOA and human serum and plasma fortified at 1.0, 5.0, 40 ng/mL PFOA. The LLOQ of 0.5 ng/mL PFOA was experimentally demonstrated for rabbit and human serum and plasma. Within-day precision and accuracy, short-term stability, freeze-thaw stability, equivalence of response between PFOA and APFO (the ammonium salt of PFOA), and dilution of concentrated samples were also investigated. The results of the validation experiments comply with the precision and accuracy limits defined by the FDA guidance document: "Guidance for Industry, Bioanalytical Method Validation", May 2001. PMID:15833298

  14. Comparison of High Resolution and Tandem Mass Spectrometry for the Analysis of Nerve Agent Metabolites in Urine

    PubMed Central

    Hamelin, Elizabeth I.; Bragg, William; Shaner, Rebecca L.; Swaim, Leigh L.; Johnson, Rudolph C.

    2015-01-01

    Rationale Although use is prohibited, concerns remain for human exposure to nerve agents during decommissioning, research, and warfare. High-resolution mass spectrometry (HRMS) was compared to tandem mass spectrometry (MS/MS) analysis for the quantitation of five urinary metabolites specific to VX, Russian VX, soman, sarin and cyclosarin nerve agents. The HRMS method was further evaluated for qualitative screening of metabolites not included in the test panel. Methods Nerve agent metabolites were extracted from urine using solid phase extraction, separated using hydrophilic interaction chromatography and analyzed using both tandem and high resolution mass spectrometry. MS/MS results were obtained using selected reaction monitoring with unit resolution; HRMS results were obtained using a mass extraction window of 10 ppm at a mass resolution of 50,000. The benchtop Orbitrap HRMS instrument was operated in full scan mode, to measure the presence of unexpected agents. Results The assessment of two quality control samples demonstrated high accuracy (99.5-104%) and high precision (2-9%) for both HRMS and MS/MS. Sensitivity, as described by the limit of detection, was overlapping for both detectors (0.2-0.7 ng/mL). Additionally, the HRMS method positively confirmed the presence of a nerve agent metabolite, not included in the test panel, using the accurate mass and relative retention time. Conclusions The precision, accuracy, and sensitivity were comparable between the current MS/MS method and this newly developed HRMS analysis for five nerve agent metabolites. HRMS showed additional capabilities beyond the current method by confirming the presence of a metabolite not included in the test panel. PMID:23821563

  15. Benzodiazepines and metabolites from biological fluids by liquid chromatography electrospray tandem mass spectrometry.

    PubMed

    Morris-Kukoski, Cynthia L; Schaff, Jason E; Reda, Louis J

    2012-01-01

    Solid-phase extraction and liquid chromatography-tandem mass spectrometry are invaluable techniques for the determination of benzodiazepines and metabolites in biological matrices. The reason for using tandem mass spectrometry is to increase limits of detection without the need for chemical derivatization. Here we describe a technique for the detection of 26 benzodiazepines and metabolites at a detection limit of approximately 1-2 ng/mL in blood and 1-5 ng/mL in urine when screened using a data-dependent scan method. PMID:22767106

  16. High explosives vapor detection by atmospheric sampling glow discharge ionization/tandem mass spectrometry

    SciTech Connect

    McLuckey, S.A.; Goeringer, D.E.; Asano, K.G.

    1996-02-01

    The combination of atmospheric sampling glow discharge ionization with tandem mass spectrometry for the detection of traces of high explosives is described. Particular emphasis is placed on use of the quadrupole ion trap as the type of tandem mass spectrometer. Atmospheric sampling glow discharge provides a simple, rugged, and efficient means for anion formation while the quadrupole ion trap provides for efficient tandem mass spectrometry. Mass selective ion accumulation and non-specific ion activation methods can be used to overcome deleterious effects arising from ion/ion interactions. Such interactions constitute the major potential technical barrier to the use of the ion trap for real-time monitoring of targeted compounds in uncontrolled and highly variable matrices. Tailored waveforms can be used to effect both mass selective ion accumulation and ion activation. Concatenated tailored waveforms allow for both functions in a single experiment thereby providing the capability for monitoring several targeted species simultaneously. The combination of atmospheric sampling glow discharge ionization with a state-of-the-art analytical quadrupole ion trap is a highly sensitive and specific detector for traces of high explosives. The combination is also small and inexpensive relative to virtually any other form of tandem mass spectrometry. The science and technology underlying the glow discharge/ion trap combination is sufficiently mature to form the basis for an engineering effort to make the detector portable. 85 refs.

  17. Application of matrix calculation 1: Design and adjustment of a tandem mass spectrometer for Collision-Activated Dissociation (CAD)

    NASA Astrophysics Data System (ADS)

    1982-02-01

    A matrix representation of the ion optics of the analyzing stage has been used in a computer model of a tandem mass spectrometer with simultaneous detection for CAD. The matrix algorithm of this model is discussed here as an elegant way of describing the ion optics in a first-order approximation. The accuracy of the calculations is illustrated by comparing calculated and measured adjustments of the instrument under normal experiment conditions. The ion-optical possibilities with respect to transmission, mass resolution influence of several ion optical parameters on the shape and position of the mass focal plane is discussed. The experimental values of mass range, mass resolution and ion transmission agree very well with the calculations. Moreover, the computer model appears to be a useful tool for giving clear insight into the operation of the rather complex ion optics of the instrument. The calculations have been further developed towards higher accuracy, making possible automatic focusing of the mass focal plane onto the detector.

  18. Charge Detection Mass Spectrometry with Almost Perfect Charge Accuracy.

    PubMed

    Keifer, David Z; Shinholt, Deven L; Jarrold, Martin F

    2015-10-20

    Charge detection mass spectrometry (CDMS) is a single-particle technique where the masses of individual ions are determined from simultaneous measurement of each ion's mass-to-charge ratio (m/z) and charge. CDMS has many desirable features: it has no upper mass limit, no mass discrimination, and it can analyze complex mixtures. However, the charge is measured directly, and the poor accuracy of the charge measurement has severely limited the mass resolution achievable with CDMS. Since the charge is quantized, it needs to be measured with sufficient accuracy to assign each ion to its correct charge state. This goal has now been largely achieved. By reducing the pressure to extend the trapping time and by implementing a novel analysis method that improves the signal-to-noise ratio and compensates for imperfections in the charge measurement, the uncertainty has been reduced to less than 0.20 e rmsd (root-mean-square deviation). With this unprecedented precision peaks due to different charge states are resolved in the charge spectrum. Further improvement can be achieved by quantizing the charge (rounding the measured charge to the nearest integer) and culling ions with measured charges midway between the integral values. After ions with charges more than one standard deviation from the mean are culled, the fraction of ions assigned to the wrong charge state is estimated to be 6.4 × 10(-5) (i.e., less than 1 in 15 000). Since almost all remaining ions are assigned to their correct charge state, the uncertainty in the mass is now almost entirely limited by the uncertainty in the m/z measurement. PMID:26418830

  19. QUANTIFICATION OF CERAMIDE SPECIES IN BIOLOGICAL SAMPLES BY LIQUID CHROMATOGRAPHY-ELECTROSPRAY TANDEM MASS SPECTROMETRY

    PubMed Central

    Kasumov, Takhar; Huang, Hazel; Chung, Yoon-Mi; Zhang, Renliang; McCullough, Arthur J.; Kirwan, John P.

    2010-01-01

    We present an optimized and validated liquid chromatography-electrospray ionization tandem mass spectrometric (LC-ESI-MS/MS) method for the simultaneous measurement of concentrations of different ceramide species in biological samples. The method of analysis of tissue samples is based on Bligh and Dyer extraction, reverse-phase HPLC separation and multiple reaction monitoring of ceramides. Preparation of plasma samples also requires isolation of sphingolipids by silica gel column chromatography prior to LC-ESI-MS/MS analysis. The limits of detection and quantification are in a range of 5–50 pg/ml for distinct ceramides. The method was reliable for inter-assay and intra-assay precision, accuracy and linearity. Recovery of ceramide subspecies from human plasma, rat liver and muscle tissue were 78–91%, 70–99%, and 71–95%, respectively. The separation and quantification of several endogenous long-chain and very-long-chain ceramides using two non-physiological odd chain ceramide (C17 and C25) internal standards was achieved within a single 21 min chromatographic run. The technique was applied to quantify distinct ceramide species in different rat tissues (muscle, liver, and heart) and in human plasma. Using this analytical technique we demonstrated that a clinical exercise training intervention reduces the levels of ceramides in plasma of obese adults. This technique could be extended for quantification of other ceramides and sphyngolipids with no significant modification. PMID:20178771

  20. Faster and more accurate graphical model identification of tandem mass spectra using trellises

    PubMed Central

    Wang, Shengjie; Halloran, John T.; Bilmes, Jeff A.; Noble, William S.

    2016-01-01

    Tandem mass spectrometry (MS/MS) is the dominant high throughput technology for identifying and quantifying proteins in complex biological samples. Analysis of the tens of thousands of fragmentation spectra produced by an MS/MS experiment begins by assigning to each observed spectrum the peptide that is hypothesized to be responsible for generating the spectrum. This assignment is typically done by searching each spectrum against a database of peptides. To our knowledge, all existing MS/MS search engines compute scores individually between a given observed spectrum and each possible candidate peptide from the database. In this work, we use a trellis, a data structure capable of jointly representing a large set of candidate peptides, to avoid redundantly recomputing common sub-computations among different candidates. We show how trellises may be used to significantly speed up existing scoring algorithms, and we theoretically quantify the expected speedup afforded by trellises. Furthermore, we demonstrate that compact trellis representations of whole sets of peptides enables efficient discriminative learning of a dynamic Bayesian network for spectrum identification, leading to greatly improved spectrum identification accuracy. Contact: bilmes@uw.edu or william-noble@uw.edu Supplementary information: Supplementary data are available at Bioinformatics online. PMID:27307634

  1. Quantitative determination of methylnaltrexone in human serum using liquid chromatography-tandem mass spectrometry.

    PubMed

    Oswald, Stefan; Schumacher, Gitta; Siegmund, Werner

    2011-12-15

    Methylnaltrexone (MNTX) is a novel peripherally acting μ-opioid antagonist that prevents peripheral side effects of opioid drugs such as constipation without affecting the analgesia. We developed a selective and sensitive assay to measure MTNX concentrations in human serum. The drug was measured after protein precipitation with perchloric acid using naltrexone as internal standard and liquid chromatography-tandem mass spectrometry (LC-MS/MS) for detection. The chromatography was performed isocratically on a RP18 column using 25 mM ammonium acetate buffer (pH 4)/acetonitrile (90%/10%; flow rate 200 μl/min) as mobile phase. The MS/MS analysis was performed in positive ionization mode monitoring the m/z transitions 356.4/284.2 for MNTX and 342.4/324.2 for naltrexone. The method was validated according to selectivity, linearity, accuracy, precision, recovery, matrix effects and stability. The validation range for MNTX in serum was 0.5-250 ng/ml. The developed LC-MS/MS was shown to be valid and successfully applied to measure serum-concentration-time curves of MNTX in a pilot study in healthy volunteers. PMID:21880450

  2. Differential Proteomic Analysis of Human Saliva using Tandem Mass Tags Quantification for Gastric Cancer Detection

    PubMed Central

    Xiao, Hua; Zhang, Yan; Kim, Yong; Kim, Sung; Kim, Jae Joon; Kim, Kyoung Mee; Yoshizawa, Janice; Fan, Liu-Yin; Cao, Cheng-Xi; Wong, David T. W.

    2016-01-01

    Novel biomarkers and non-invasive diagnostic methods are urgently needed for the screening of gastric cancer to reduce its high mortality. We employed quantitative proteomics approach to develop discriminatory biomarker signatures from human saliva for the detection of gastric cancer. Salivary proteins were analyzed and compared between gastric cancer patients and matched control subjects by using tandem mass tags (TMT) technology. More than 500 proteins were identified with quantification, and 48 of them showed significant difference expression (p < 0.05) between normal controls and gastric cancer patients, including 7 up-regulated proteins and 41 down-regulated proteins. Five proteins were selected for initial verification by ELISA and three were successfully verified, namely cystatin B (CSTB), triosephosphate isomerase (TPI1), and deleted in malignant brain tumors 1 protein (DMBT1). All three proteins could differentiate gastric cancer patients from normal control subjects, dramatically (p < 0.05). The combination of these three biomarkers could reach 85% sensitivity and 80% specificity for the detection of gastric cancer with accuracy of 0.93. This study provides the proof of concept of salivary biomarkers for the non-invasive detection of gastric cancer. It is highly encouraging to turn these biomarkers into an applicable clinical test after large scale validation. PMID:26911362

  3. Determination of betamethasone in human plasma by liquid chromatography with tandem mass.

    PubMed

    Qu, Ting-Ting; Zhang, Rui; Wang, Ben-Jie; Liu, Xiao-Yan; Yuan, Gui-Yan; Guo, Rui-Chen

    2008-04-01

    A sensitive and selective liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed and validated for the determination of betamethasone in human plasma. The analyte was isocratically eluted on a Venusil XBP C8 column (200 mm x 3.9 mm ID, 5 microm) with methanol-water mol x L(-1) ammonium formate) (80:20) at a flow rate of 0.4 mL x min(-1), and detected (containing 5 mmol x L(-1) ammonium formate) (80:20) at a flow rate of 0.4 mL x min(-1), and detected with a triple quad LC-MS/MS using ESI with positive ionization. Ions monitored in the multiple reaction monitoring (MRM) mode were m/z 393.3-->355.2 for betamethasone and m/z 361.3-->343.2 for prednisolone (IS). Betamethasone was extracted from 0.5 mL human plasma with ethyl acetate. The average recovery is 88.24% and the low limit of quantitation (LLOQ) was 0.5 ng x mL(-1). The 3-day validation study demonstrated excellent precision and accuracy across the calibration range of 0.5-80.0 ng x mL(-1). The method was successfully applied to the pharmacokinetic study of compound betamethason injection in healthy Chinese volunteers. PMID:18664204

  4. Differential Proteomic Analysis of Human Saliva using Tandem Mass Tags Quantification for Gastric Cancer Detection.

    PubMed

    Xiao, Hua; Zhang, Yan; Kim, Yong; Kim, Sung; Kim, Jae Joon; Kim, Kyoung Mee; Yoshizawa, Janice; Fan, Liu-Yin; Cao, Cheng-Xi; Wong, David T W

    2016-01-01

    Novel biomarkers and non-invasive diagnostic methods are urgently needed for the screening of gastric cancer to reduce its high mortality. We employed quantitative proteomics approach to develop discriminatory biomarker signatures from human saliva for the detection of gastric cancer. Salivary proteins were analyzed and compared between gastric cancer patients and matched control subjects by using tandem mass tags (TMT) technology. More than 500 proteins were identified with quantification, and 48 of them showed significant difference expression (p < 0.05) between normal controls and gastric cancer patients, including 7 up-regulated proteins and 41 down-regulated proteins. Five proteins were selected for initial verification by ELISA and three were successfully verified, namely cystatin B (CSTB), triosephosphate isomerase (TPI1), and deleted in malignant brain tumors 1 protein (DMBT1). All three proteins could differentiate gastric cancer patients from normal control subjects, dramatically (p < 0.05). The combination of these three biomarkers could reach 85% sensitivity and 80% specificity for the detection of gastric cancer with accuracy of 0.93. This study provides the proof of concept of salivary biomarkers for the non-invasive detection of gastric cancer. It is highly encouraging to turn these biomarkers into an applicable clinical test after large scale validation. PMID:26911362

  5. Analysis of acrylamide in coffee and cocoa by isotope dilution liquid chromatography-tandem mass spectrometry.

    PubMed

    Aguas, Patricia C; Fitzhenry, Matthew J; Giannikopoulos, Georgina; Varelis, Peter

    2006-08-01

    An accurate and precise method for the quantification of acrylamide using stable isotope dilution liquid chromatography-tandem mass spectrometry was developed and used to measure acrylamide in coffee and cocoa samples. The sample preparation involved extraction of the analyte and its internal standard, 13C3-acrylamide, into water and subsequent defatting of the aqueous extract with dichloromethane. An aliquot of the resulting aqueous extract was then azeotropically dried under reduced pressure and subsequently purified using an aminopropyl-bonded silica cartridge. The purified extracts were then chromatographed on a 5-microm 2.1 x 150 mm Hypercarb column, the effluent of which was monitored for the analyte and its internal standard using positive-ion APCI-selected reaction monitoring. The intra-laboratory reproducibility of the method, expressed as a relative coefficient of variation (%, n=5), was determined at four levels of concentration (12.3, 42.3, 139.3 and 464.8 microg kg(-1)) and was found to vary between 0.6-2.5%. The accuracy of the method was assessed using a reference sample of coffee. The average result obtained using our method differed from the assigned value of the reference material by less than 1%. An analysis of a cocoa sample revealed that the method is capable of precisely estimating acrylamide in challenging matrices down to a level of at least 12.3 microg kg(-1). PMID:16819634

  6. Determination of 3-mercaptopyruvate in rabbit plasma by high performance liquid chromatography tandem mass spectrometry.

    PubMed

    Stutelberg, Michael W; Vinnakota, Chakravarthy V; Mitchell, Brendan L; Monteil, Alexandre R; Patterson, Steven E; Logue, Brian A

    2014-02-15

    Accidental or intentional cyanide poisoning is a serious health risk. The current suite of FDA approved antidotes, including hydroxocobalamin, sodium nitrite, and sodium thiosulfate is effective, but each antidote has specific major limitations, such as large effective dosage or delayed onset of action. Therefore, next generation cyanide antidotes are being investigated to mitigate these limitations. One such antidote, 3-mercaptopyruvate (3-MP), detoxifies cyanide by acting as a sulfur donor to convert cyanide into thiocyanate, a relatively nontoxic cyanide metabolite. An analytical method capable of detecting 3-MP in biological fluids is essential for the development of 3-MP as a potential antidote. Therefore, a high performance liquid chromatography tandem mass spectrometry (HPLC-MS-MS) method was established to analyze 3-MP from rabbit plasma. Sample preparation consisted of spiking the plasma with an internal standard ((13)C3-3-MP), precipitation of plasma proteins, and reaction with monobromobimane to inhibit the characteristic dimerization of 3-MP. The method produced a limit of detection of 0.1μM, a linear dynamic range of 0.5-100μM, along with excellent linearity (R(2)≥0.999), accuracy (±9% of the nominal concentration) and precision (<7% relative standard deviation). The optimized HPLC-MS-MS method was capable of detecting 3-MP in rabbits that were administered sulfanegen, a prodrug of 3-MP, following cyanide exposure. Considering the excellent performance of this method, it will be utilized for further investigations of this promising cyanide antidote. PMID:24480329

  7. Analysis of nerve agent metabolites from nail clippings by liquid chromatography tandem mass spectrometry.

    PubMed

    Appel, Amanda S; Logue, Brian A

    2016-09-15

    While several methods for the bioanalysis of nerve agents or their metabolites have been developed for the verification of nerve agent exposure, these methods are generally limited in the amount of time after an exposure that markers of exposure can be detected (due to rapid metabolism from biological matrices). In this study, a method for the analysis of nerve agent hydrolysis products from nail clippings was developed to allow evaluation of nails as a long-term repository of these markers. Pinacolyl methylphosphonic acid (PMPA) and isopropyl methylphosphonic acid (IMPA) were extracted from nail samples with N,N-dimethylformamide and subsequently analyzed by liquid chromatography-tandem mass spectrometry. Limits of detection for PMPA and IMPA were 0.3μg/kg and 7.5μg/kg and linear ranges were 0.75-300μg/kg and 30-1500μg/kg, respectively. Precision was within 10% and 8% for PMPA and IMPA, respectively, and accuracy was 100±12% for both analytes. The approach presented here is complementary to current methods for nerve agent exposure verification, and should allow for long-term determination of nerve agent poisoning. PMID:27474780

  8. Ethyl glucuronide determination in meconium and hair by hydrophilic interaction liquid chromatography-tandem mass spectrometry.

    PubMed

    Tarcomnicu, Isabela; van Nuijs, Alexander L N; Aerts, Katrien; De Doncker, Mireille; Covaci, Adrian; Neels, Hugo

    2010-03-20

    Ethyl glucuronide (EtG) detection in non-conventional matrices, such as hair and meconium, can provide useful information on alcohol abuse over a long time frame, for example during pregnancy or after a withdrawal treatment. This study reports on the development, validation and application of a new hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS) method for the analysis of EtG in meconium and hair. For each matrix, the sample preparation and the chromatographic separation were thoroughly optimised. Additionally, experiments with reversed-phase liquid chromatography were also performed in the development stages. Analyses were carried out using a Phenomenex Luna HILIC column (150 mm x 3 mm, 5 microm) and a mobile phase composed by ammonium acetate 2mM and acetonitrile, in gradient. Different SPE cartridges (Oasis MAX, Oasis WAX, aminopropyl silica) and solvents were tested in order to obtain the highest recoveries and cleanest extracts. Optimal results were obtained for meconium with aminopropyl cartridges, while for hair an incubation of 16 h with 2 mL of water and acetonitrile (50/50, v/v) provided good results. The analytical method was validated for both matrices (meconium and hair) by assessing linearity, precision, accuracy, recovery and limit of quantification. The calibration curve concentrations ranged from 50 to 1200 pg/mg for meconium and from 20 to 1000 pg/mg for hair. Real meconium and hair samples were analyzed and results were consistent with literature. PMID:20061101

  9. A rapid quantitative method of carisoprodol and meprobamate by liquid chromatography-tandem mass spectrometry.

    PubMed

    Essler, Shannon; Bruns, Kerry; Frontz, Michael; McCutcheon, J Rod

    2012-11-01

    The identification and quantitation of carisoprodol (Soma) and its chief metabolite meprobamate, which is also a clinically prescribed drug, remains a challenge for forensic toxicology laboratories. Carisoprodol and meprobamate are notable for their widespread use as muscle relaxants and their frequent identification in the blood of impaired drivers. Routine screening is possible in both an acidic/neutral pH screen and a traditional basic screen. An improvement in directed testing quantitations was desirable over the current options of an underivatized acidic/neutral extraction or a basic screen, neither of which used ideal internal standards. A new method was developed that utilized a simple protein precipitation, deuterated internal standards and a short 2-min isocratic liquid chromatography separation, followed by multiple reaction monitoring with tandem mass spectrometry. The linear quantitative range for carisoprodol was determined to be 1-35mg/L and for meprobamate was 0.5-50mg/L. The method was validated for specificity and selectivity, matrix effects, and accuracy and precision. PMID:23040985

  10. Determination of trinexapac in wheat by liquid chromatography-electrospray ionization tandem mass spectrometry.

    PubMed

    Hiemstra, Maurice; de Kok, André

    2003-09-24

    A quantitative and confirmatory method for the analysis of trinexapac (free acid metabolite of trinexapac-ethyl) in wheat is described. Residues were extracted from wheat with acetonitrile in aqueous phosphate buffer (pH 7) overnight. The extract was directly injected into the HPLC system. Chromatographic separation was achieved on an octadecylsilica column, and detection was performed by negative ion electrospray ionization tandem mass spectrometry. The precursor ion of trinexapac [M - H](-) at m/z 223 was subjected to collisional fragmentation with argon to yield two intense diagnostic product ions at m/z 135 and 179, respectively. Accuracy and specificity for routine analysis of trinexapac were demonstrated. The validated concentration range was 10-200 microg/kg based on a 0.10 g/mL wheat sample extract. Recoveries were within the range of 71-94%, with associated relative standard deviations better than 10%. The limit of detection for trinexapac in wheat was estimated at 5 microg/kg. The method has been applied to a survey of 100 samples of wheat. In 46% of the samples analyzed, a quantifiable amount of trinexapac was detected, ranging from 10 to 110 microg/kg. It has been demonstrated that analyses of trinexapac accurately reflect the total amount of residues of the plant growth regulator, trinexapac-ethyl, in the wheat samples following field application. No residues of the parent compound, trinexapac-ethyl, in wheat were detected. PMID:13129284

  11. Pharmacokinetic study of dendrobine in rat plasma by ultra-performance liquid chromatography tandem mass spectrometry.

    PubMed

    Wang, Shuanghu; Wu, Haiya; Geng, Peiwu; Lin, Yingying; Liu, Zezheng; Zhang, Lijing; Ma, Jianshe; Zhou, Yunfang; Wang, Xianqin; Wen, Congcong

    2016-07-01

    Dendrobine, considered as the major active alkaloid compound, has been used for the quality control and discrimination of Dendrobium which is documented in the Chinese Pharmacopoeia. In this work, a sensitive and simple ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method for determination of dendrobine in rat plasma is developed. After addition of caulophyline as an internal standard (IS), protein precipitation by acetonitrile-methanol (9:1, v/v) was used to prepare samples. Chromatographic separation was achieved on a UPLC BEH C18 (2.1 ×100 mm, 1.7 µm) column with acetonitrile and 0.1% formic acid as the mobile phase with gradient elution. An electrospray ionization source was applied and operated in positive ion mode; multiple reaction monitoring mode was used for quantification using target fragment ions m/z 264.2 → 70.0 for dendrobine and m/z 205.1 → 58.0 for IS. Calibration plots were linear throughout the range 2-1000 ng/mL for dendrobine in rat plasma. The RSDs of intra-day and inter-day precision were both <13%. The accuracy of the method was between 95.4 and 103.9%. The method was successfully applied to pharmacokinetic study of dendrobine after intravenous administration. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26525040

  12. Determination of Heterocyclic Amines and Acrylamide in Agricultural Products with Liquid Chromatography-Tandem Mass Spectrometry

    PubMed Central

    Lee, Kyung-Jun; Lee, Gae-Ho; Kim, HaeSol; Oh, Min-Seok; Chu, Seok; Hwang, In Ju; Lee, Jee-yeon; Choi, Ari; Kim, Cho-il

    2015-01-01

    Heterocyclic amines (HCAs) and acrylamide are unintended hazardous substances generated by heating or processing of foods and are known as carcinogenic and mutagenic agents by the animal experiments. A simple method was established for a rapid and accurate determination of 12 types of HCAs (IQ, MeIQ, Glu-P-1, Glu-P-2, MeIQx, Trp-P-1, Trp-P-2, PhIP, AαC, MeAαC, Harman and Norharman) and acrylamide in three food matrices (non-fat liquid, non-fat solid and fat solid) by isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS). In every sample, a mixture of internal standards including IQ-d3, MeIQx-d3, PhIP-d3, Trp-P-2-13C2-15N and MeAαC-d3 was spiked for quantification of HCAs and 13C3-acrylamide was also spiked for the analysis of acrylamide. HCAs and acrylamide in sample were extracted with acetonitrile and water, respectively, and then two solid-phase extraction cartridges, ChemElut: HLB for HCAs and Accucat: HLB for acrylamide, were used for efficiently removing interferences such as pigment, lipid, polar, nonpolar and ionic compounds. Established method was validated in terms of recovery, accuracy, precision, limit of detection, limit of quantitation, and linearity. This method showed good precision (RSD < 20%), accuracy (71.8~119.1%) and recovery (66.0~118.9%). The detection limits were < 3.1 ng/g for all analytes. The correlation coefficients for all the HCAs and acrylamide were > 0.995, showing excellent linearity. These methods for the detection of HCAs and acrylamide by LC-MS/MS were applied to real samples and were successfully used for quantitative monitoring in the total diet study and this can be applied to risk assessment in various food matrices. PMID:26483884

  13. Simultaneous determination of 3-mercaptopyruvate and cobinamide in plasma by liquid chromatography-tandem mass spectrometry.

    PubMed

    Stutelberg, Michael W; Dzisam, Joseph K; Monteil, Alexandre R; Petrikovics, Ilona; Boss, Gerry R; Patterson, Steven E; Rockwood, Gary A; Logue, Brian A

    2016-01-01

    The current suite of Food and Drug Administration (FDA) approved antidotes (i.e., sodium nitrite, sodium thiosulfate, and hydroxocobalamin) are effective for treating cyanide poisoning, but individually, each antidote has major limitations (e.g., large effective dosage or delayed onset of action). To mitigate these limitations, next-generation cyanide antidotes are being investigated, including 3-mercaptopyruvate (3-MP) and cobinamide (Cbi). Analytical methods capable of detecting these therapeutics individually and simultaneously (for combination therapy) are essential for the development of 3-MP and Cbi as potential cyanide antidotes. Therefore, a liquid chromatography-tandem mass-spectrometry method for the simultaneous analysis of 3-MP and Cbi was developed. Sample preparation of 3-MP consisted of spiking plasma with an internal standard ((13)C3-3-MP), precipitation of plasma proteins, and derivatizing 3-MP with monobromobimane to produce 3-mercaptopyruvate-bimane. Preparation of Cbi involved denaturing plasma proteins with simultaneous addition of excess cyanide to convert each Cbi species to dicyanocobinamide (Cbi(CN)2). The limits of detection for 3-MP and Cbi were 0.5μM and 0.2μM, respectively. The linear ranges were 2-500μM for 3-MP and 0.5-50μM for Cbi. The accuracy and precision for 3-MP were 100±9% and <8.3% relative standard deviation (RSD), respectively. For Cbi(CN)2, the accuracy was 100±13% and the precision was <9.5% RSD. The method presented here was used to determine 3-MP and Cbi from treated animals and may ultimately facilitate FDA approval of these antidotes for treatment of cyanide poisoning. PMID:26655110

  14. Analysis of small carbohydrates in several bioactive botanicals by gas chromatography with mass spectrometry and liquid chromatography with tandem mass spectrometry.

    PubMed

    Moldoveanu, Serban; Scott, Wayne; Zhu, Jeff

    2015-11-01

    Bioactive botanicals contain natural compounds with specific biological activity, such as antibacterial, antioxidant, immune stimulating, and taste improving. A full characterization of the chemical composition of these botanicals is frequently necessary. A study of small carbohydrates from the plant materials of 18 bioactive botanicals is further described. The study presents the identification of the carbohydrate using a gas chromatographic-mass spectrometric analysis that allows detection of molecules as large as maltotetraose, after changing them into trimethylsilyl derivatives. A number of carbohydrates in the plant (fructose, glucose, mannose, sucrose, maltose, xylose, sorbitol, and myo-, chiro-, and scyllo-inositols) were quantitated using a novel liquid chromatography with tandem mass spectrometric technique. Both techniques involved new method developments. The gas chromatography with mass spectrometric analysis involved derivatization and separation on a Rxi(®)-5Sil MS column with H2 as a carrier gas. The liquid chromatographic separation was obtained using a hydrophilic interaction type column, YMC-PAC Polyamine II. The tandem mass spectrometer used an electrospray ionization source in multiple reaction monitoring positive ion mode with the detection of the adducts of the carbohydrates with Cs(+) ions. The validated quantitative procedure showed excellent precision and accuracy allowing the analysis in a wide range of concentrations of the analytes. PMID:26315495

  15. Determination of irinotecan and SN38 in human plasma by TurboFlow™ liquid chromatography-tandem mass spectrometry.

    PubMed

    Herviou, P; Richard, D; Roche, L; Pinguet, J; Libert, F; Eschalier, A; Durando, X; Authier, N

    2016-01-25

    Irinotecan is a cytotoxic agent used in the treatment of metastatic colorectal cancer. Irinotecan is a prodrug when is converted in vivo to an active metabolite SN38, which has potent pharmacological activity. SN38 is then inactivated and excreted as SN38-glucuronide. High-performance liquid chromatography-mass spectrometry is a widely used bioanalysis technique that can be coupled to the turbulent-flow extraction line to shorten preparation time. A technique was developed to quantify irinotecan and its metabolite by liquid chromatography-tandem mass spectrometry coupled with a turbulent-flow online extraction method. Assays were performed on 100 μL of plasma after protein precipitation. The supernatant is injected directly into the extraction column, transferred to the chromatographic column, and analyzed by tandem mass spectrometry. Linearity, reproducibility and repeatability of the method were validated on a concentration range of 25-2500 ng/mL for irinotecan and 5-500 ng/mL for SN38. For the low limit of quantification of irinotecan and SN38, precision is 6.31% and 8.73%, and accuracy is 84.0% and 91.8%, respectively. The SN38-glucuronide determination protocol included a hydrolyzation step. This method was successfully used to quantify irinotecan, SN38 and SN38-G in human plasma in a clinical trial. PMID:26580826

  16. Silver Coating for High-Mass-Accuracy Imaging Mass Spectrometry of Fingerprints on Nanostructured Silicon.

    PubMed

    Guinan, Taryn M; Gustafsson, Ove J R; McPhee, Gordon; Kobus, Hilton; Voelcker, Nicolas H

    2015-11-17

    Nanostructure imaging mass spectrometry (NIMS) using porous silicon (pSi) is a key technique for molecular imaging of exogenous and endogenous low molecular weight compounds from fingerprints. However, high-mass-accuracy NIMS can be difficult to achieve as time-of-flight (ToF) mass analyzers, which dominate the field, cannot sufficiently compensate for shifts in measured m/z values. Here, we show internal recalibration using a thin layer of silver (Ag) sputter-coated onto functionalized pSi substrates. NIMS peaks for several previously reported fingerprint components were selected and mass accuracy was compared to theoretical values. Mass accuracy was improved by more than an order of magnitude in several cases. This straightforward method should form part of the standard guidelines for NIMS studies for spatial characterization of small molecules. PMID:26460234

  17. Combined Dynamic Arrays for Storing and Searching Semi-Ordered Tandem Mass Spectrometry Data

    Technology Transfer Automated Retrieval System (TEKTRAN)

    When performing bioinformatics analysis on tandem mass spectrometry data, there is a computational need to efficiently store and sort these semi-ordered data sets. To solve this problem, a new data structure based on dynamic arrays was designed and implemented in an algorithm that parses semi-order...

  18. Multiresidue analysis of pesticides in straw roughage by liquid chromatography - tandem mass spectrometry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A multiresidue analytical method using a modification of the “quick, easy, cheap, effective, rugged, and safe” (QuEChERS) sample preparation approach combined with liquid chromatography–tandem mass spectrometry (LC-MS/MS) analysis was established and validated for the rapid determination of 69 pesti...

  19. Making the Case for Objective Performance Metrics in Newborn Screening by Tandem Mass Spectrometry

    ERIC Educational Resources Information Center

    Rinaldo, Piero; Zafari, Saba; Tortorelli, Silvia; Matern, Dietrich

    2006-01-01

    The expansion of newborn screening programs to include multiplex testing by tandem mass spectrometry requires understanding and close monitoring of performance metrics. This is not done consistently because of lack of defined targets, and interlaboratory comparison is almost nonexistent. Between July 2004 and April 2006 (N = 176,185 cases), the…

  20. MEASUREMENT OF OXIDATIVE STRESS PARAMETERS USING LIQUID CHROMATOGRAPHY - TANDEM MASS SPECTROSCOPY (LC-MS/MS)

    EPA Science Inventory

    What is the study?
    An invited review article. Measurement of oxidative stress parameters using liquid chromatography-tandem mass spectroscopy (LC-MS/MS)
    Why was it done?
    Although oxidative stress is frequently cited as a cause of various adverse biological eff...

  1. [Determination of aflatoxins in cereals and oils by liquid chromatography-triple quadrupole tandem mass spectrometry].

    PubMed

    Wang, Xiupin; Li, Peiwu; Yang, Yang; Zhang, Wen; Zhang, Qi; Fan, Sufang; Yu, Li; Wang, Lin; Chen, Xiaomei; Li, Ying; Jiang, Jun

    2011-06-01

    The high performance liquid chromatography (HPLC)-triple quadrupole tandem mass spectrometry was applied for the determination of the aflatoxins: B1 (AFB1), B2 (AFB2), G1 (AFG1) and G2 (AFG2), in cereals and oils. The samples were first extracted by ultrasonic method. The optimized conditions of ultrasonic extraction were as follows: temperature of 50 degrees C, extraction time of 3 min, methanol-water (containing 40 g/L NaCl) (80: 20, v/v) solution as the medium and a ratio of sample to solvent of 1 : 3 (g: mL). The extracts were then purified using an immunoaffinity column. The separation was performed on a C18 column with mobile phases of 10 mmol/L ammonium acetate and methanol in gradient elution. The sensitive detection of the four AFT compounds by electrospray ionization mass spectrometry (ESI-MS) was carried out in selected reaction monitoring (SRM) mode with aflatoxin M1 (AFM1) as the internal standard. Under the optimized conditions, the limits of detection of AFB1, AFB2, AFG1 and AFG2 were 0.002, 0.004, 0.004 and 0.012 microg/kg, respectively. The recoveries of aflatoxins in different spiked cereals and oils were in the range from 87% to 111%. The intra-day and inter-day precisions were not more than 6.7% and 5.6%, respectively. In comparison with the external standard method, this method can effectively inhibit the matrix effects, and greatly improve the accuracy. PMID:22032163

  2. Determination of Bedaquiline in Human Serum Using Liquid Chromatography-Tandem Mass Spectrometry

    PubMed Central

    Bolhuis, Mathieu; van Hateren, Kai; Sturkenboom, Marieke; Akkerman, Onno; de Lange, Wiel; Greijdanus, Ben; van der Werf, Tjip; Touw, Daan

    2015-01-01

    Bedaquiline, a diarylquinoline for the treatment of multidrug-resistant tuberculosis (TB), relies on exposure-dependent killing. As data on drug exposure in specific populations are scarce, pharmacokinetic studies may be of interest. No simple and robust validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been reported to date. Therefore, a new method using a quadrupole mass spectrometer was developed for analysis of bedaquiline and N-monodesmethyl bedaquiline (M2) in human serum, using deuterated bedaquiline as the internal standard. The calibration curve was linear over a range of 0.05 (lower limit of quantification [LLOQ]) to 6.00 mg/liter for both bedaquiline and M2, with correlation coefficient values of 0.997 and 0.999, respectively. The calculated accuracy ranged from 1.9% to 13.6% for bedaquiline and 2.9% to 8.5% for M2. Within-run precision ranged from 3.0% to 7.2% for bedaquiline and 3.1% to 5.2% for M2, and between-run precision ranged from 0.0% to 4.3% for bedaquiline and 0.0% to 4.6% for M2. Evaluation of serum concentrations in a patient receiving bedaquiline showed high levels at the end of treatment, reflecting accumulation of the drug. More observational pharmacokinetic data are needed to relate altered drug concentrations to clinical outcome or adverse drug effects. A simple LC-MS/MS method to quantify bedaquiline and M2 levels in human serum using a deuterated internal standard has been validated. This method can be used in clinical studies and daily practice. PMID:26149993

  3. Determination of bedaquiline in human serum using liquid chromatography-tandem mass spectrometry.

    PubMed

    Alffenaar, Jan-Willem C; Bolhuis, Mathieu; van Hateren, Kai; Sturkenboom, Marieke; Akkerman, Onno; de Lange, Wiel; Greijdanus, Ben; van der Werf, Tjip; Touw, Daan

    2015-09-01

    Bedaquiline, a diarylquinoline for the treatment of multidrug-resistant tuberculosis (TB), relies on exposure-dependent killing. As data on drug exposure in specific populations are scarce, pharmacokinetic studies may be of interest. No simple and robust validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been reported to date. Therefore, a new method using a quadrupole mass spectrometer was developed for analysis of bedaquiline and N-monodesmethyl bedaquiline (M2) in human serum, using deuterated bedaquiline as the internal standard. The calibration curve was linear over a range of 0.05 (lower limit of quantification [LLOQ]) to 6.00 mg/liter for both bedaquiline and M2, with correlation coefficient values of 0.997 and 0.999, respectively. The calculated accuracy ranged from 1.9% to 13.6% for bedaquiline and 2.9% to 8.5% for M2. Within-run precision ranged from 3.0% to 7.2% for bedaquiline and 3.1% to 5.2% for M2, and between-run precision ranged from 0.0% to 4.3% for bedaquiline and 0.0% to 4.6% for M2. Evaluation of serum concentrations in a patient receiving bedaquiline showed high levels at the end of treatment, reflecting accumulation of the drug. More observational pharmacokinetic data are needed to relate altered drug concentrations to clinical outcome or adverse drug effects. A simple LC-MS/MS method to quantify bedaquiline and M2 levels in human serum using a deuterated internal standard has been validated. This method can be used in clinical studies and daily practice. PMID:26149993

  4. Determination of zolpidem in human plasma by liquid chromatography-tandem mass spectrometry for clinical application.

    PubMed

    Byeon, Ji-Yeong; Lee, Hye-In; Lee, Yun-Jeong; Lee, Jung-Eun; Kim, Se-Hyung; Kim, Young-Hoon; Na, Han-Sung; Jang, Choon-Gon; Lee, Seok-Yong

    2015-04-01

    Zolpidem (ZPD) is widely described for the short-term treatment of insomnia. We have developed and validated a simple and rapid liquid chromatography analytical method using tandem mass spectrometry (LC-MS/MS) for the quantification of ZPD in human plasma. Using dibucaine as an internal standard (IS), the analyte was extracted with methyl t-butyl ether (MTBE). Chromatographic separation of ZPD was performed on a reversed-phase Luna C18 column (50 mm × 2.0 mm i.d., 5 μm particles) with a mobile phase of 10mM ammonium formate buffer (pH 3.0)-methanol (15:85, v/v) at a flow rate of 250 μm/min. The total run-time was 2.5 min and the retention times of ZPD and IS were 0.66 and 0.74 min, respectively. The mass-to-charge transition monitored for quantification of ZPD and IS was 308.2→235.2 and 344.0→271.0, respectively. The lower limit of quantification (LLOQ) using 100 μL of human plasma was 0.05 ng/mL and the calibration curves were linear over a range of 0.05-200 ng/mL (r(2)>0.9964). The mean accuracy and precision for intra- and inter-run validation of ZPD were within acceptable limits. In the present LC-MS/MS method, we showed improved sensitivity for quantification of the ZPD in human plasma using lower volume of plasma compared with previously described analytical methods for ZPD. This validated method was successfully applied to a pharmacokinetic study in humans. PMID:25728370

  5. Greazy: Open-Source Software for Automated Phospholipid Tandem Mass Spectrometry Identification.

    PubMed

    Kochen, Michael A; Chambers, Matthew C; Holman, Jay D; Nesvizhskii, Alexey I; Weintraub, Susan T; Belisle, John T; Islam, M Nurul; Griss, Johannes; Tabb, David L

    2016-06-01

    Lipid identification from data produced with high-throughput technologies is essential to the elucidation of the roles played by lipids in cellular function and disease. Software tools for identifying lipids from tandem mass (MS/MS) spectra have been developed, but they are often costly or lack the sophistication of their proteomics counterparts. We have developed Greazy, an open source tool for the automated identification of phospholipids from MS/MS spectra, that utilizes methods similar to those developed for proteomics. From user-supplied parameters, Greazy builds a phospholipid search space and associated theoretical MS/MS spectra. Experimental spectra are scored against search space lipids with similar precursor masses using a peak score based on the hypergeometric distribution and an intensity score utilizing the percentage of total ion intensity residing in matching peaks. The LipidLama component filters the results via mixture modeling and density estimation. We assess Greazy's performance against the NIST 2014 metabolomics library, observing high accuracy in a search of multiple lipid classes. We compare Greazy/LipidLama against the commercial lipid identification software LipidSearch and show that the two platforms differ considerably in the sets of identified spectra while showing good agreement on those spectra identified by both. Lastly, we demonstrate the utility of Greazy/LipidLama with different instruments. We searched data from replicates of alveolar type 2 epithelial cells obtained with an Orbitrap and from human serum replicates generated on a quadrupole-time-of-flight (Q-TOF). These findings substantiate the application of proteomics derived methods to the identification of lipids. The software is available from the ProteoWizard repository: http://tiny.cc/bumbershoot-vc12-bin64 . PMID:27186799

  6. Atmospheric sampling glow discharge ionizataion and triple quadrupole tandem mass spectrometry for explosives vapor detection

    SciTech Connect

    McLuckey, S.A.; Goeringer, D.E.; Asano, K.G.; Hart, K.J.; Glish, G.L.; Grant, B.C.; Chambers, D.M.

    1993-08-01

    The detection and identification of trace vapors of hidden high explosives is an excellent example of a targeted analysis problem. It is desirable to push to ever lower levels the quantity or concentration of explosives material that provides an analytical signal, while at the same time discriminating against all other uninteresting material. The detection system must therefore combine high sensitivity with high specificity. This report describes the philosophy behind the use of atmospheric sampling glow discharge ionization, which is a sensitive, rugged, and convenient means for forming anions from explosives molecules, with tandem mass spectrometry, which provides unparalleled specificity in the identification of explosives-related ions. Forms of tandem mass spectrometry are compared and contrasted to provide a summary of the characteristics to be expected from an explosives detector employing mass spectrometry/mass spectrometry. The instrument developed for the FAA, an atmospheric sampling glow discharge/triple quadrupole mass spectrometer, is described in detail with particular emphasis on the ion source/spectrometer interface and on the capabilities of the spectrometer. Performance characteristics of the system are also described as they pertain to explosives of interest including a description of an automated procedure for the detection and identification of specific explosives. A comparison of various tandem mass spectrometers mated with atmospheric sampling glow discharge is then described and preliminary studies with a vapor preconcentration system provided by the FAA will be described.

  7. Chemical modification of deoxyribonucleic acids: Quantitation of 3-methylthymidine and O4-methylthymidine by tandem mass spectrometry

    NASA Astrophysics Data System (ADS)

    Wood, Joe M.; Hoke, Steven H., II; Graham Cooks, R.; Chae, Whi-Gun; Chang, Ching-Jer

    1991-12-01

    Quantitation of 3-methylthymidine and O4-methylthymidine generated in the reaction of calf thymus DNA with methyl methanesulfonate (MeMS) and 1-methyl-1nitrosourea (MeNU) by mass spectrometry is reported. Quantitative precision of 7% or better is achieved on samples of 10-12 -10-13 mole in the HPLC and a final stage of separation before quantification by tandem mass spectrometry using desorption chemical ionization. Synthetic CD3-labeled nucleosides were used as internal standards for mass spectral quantification. A unique mass spectrometric scanning procedure, which allowed simultaneous MS--MS product ion analysis of both the analyte and the internal standard, was utilized to enchance precision and accuracy in these low level determinations. MeNU (a potent carcinogen) resulted in 18&%; 3-methylation and 0.17% O4-methylation of deoxythymidine whereas MeMS (a weak carcinogen) produced only 6.8% 3-methylation and 0.005% of deoxythymidine. These results demonstrate that the sensitivity and accuracy of this method should be adequate for the detection and quantification of methyl-nucleosides at the sub-picomole level at which mutation is induced in cell cultures.

  8. High Energy Collisions on Tandem Time-of-Flight Mass Spectrometers

    NASA Astrophysics Data System (ADS)

    Cotter, Robert J.

    2013-05-01

    Long before the introduction of matrix-assisted laser desorption/ionization (MALDI), electrospray ionization (ESI), Orbitraps, and any of the other tools that are now used ubiquitously for proteomics and metabolomics, the highest performance mass spectrometers were sector instruments, providing high resolution mass measurements by combining an electrostatic energy analyzer (E) with a high field magnet (B). In its heyday, the four sector mass spectrometer (or EBEB) was the crown jewel, providing the highest performance tandem mass spectrometry using single, high energy collisions to induce fragmentation. During a time in which quadrupole and tandem triple quadrupole instruments were also enjoying increased usage and popularity, there were, nonetheless, some clear advantages for sectors over their low collision energy counterparts. Time-of-flight (TOF) mass spectrometers are high voltage, high vacuum instruments that have much in common with sectors and have inspired the development of tandem instruments exploiting single high energy collisions. In this retrospective, we recount our own journey to produce high performance TOFs and tandem TOFs, describing the basic theory, problems, and the advantages for such instruments. An experiment testing impulse collision theory (ICT) underscores the similarities with sector mass spectrometers where this concept was first developed. Applications provide examples of more extensive fragmentation, side chain cleavages, and charge-remote fragmentation, also characteristic of high energy sector mass spectrometers. Moreover, the so-called curved-field reflectron has enabled the design of instruments that are simpler, collect and focus all of the ions, and may provide the future technology for the clinic, for tissue imaging, and the characterization of microorganisms.

  9. Simultaneous analysis of ten phytohormones in Sargassum horneri by high-performance liquid chromatography with electrospray ionization tandem mass spectrometry.

    PubMed

    Li, Yan; Zhou, Chengxu; Yan, Xiaojun; Zhang, Jinrong; Xu, Jilin

    2016-05-01

    Phytohormones have attracted wide attention due to their important biological functions. However, their detection is still a challenge because of their complex composition, low abundance and diverse sources. In this study, a novel method of high-performance liquid chromatography with electrospray ionization tandem mass spectrometry was developed and validated for the simultaneous determination of ten phytohormones including indole-3-acetic acid, isopentenyladenine, isopentenyl adenosine, trans-zeatin riboside, zeatin, strigolactones, abscisic acid, salicylic acid, gibberellin A3, and jasmonic acid in Sargassum horneri (S. horneri). The phytohormones were extracted from freeze-dried S. horneri with methanol/water/methanoic acid (15:4:1, v/v/v) analyzed on a Hypersil Gold C18 column and detected by electrospray ionization tandem triple quadrupole mass spectrometry in the multiple reaction monitoring mode. The experimental conditions for the extraction and analysis of phytohormones were optimized and validated in terms of reproducibility, linearity, sensitivity, recovery, accuracy, and stability. Distributions of the phytohormones in the stems, blades, and gas bladder of the S. horneri in drift, fixed, and semi-fixed growing states were investigated for the first time. The observed contents of the phytohormones in S. horneri range from not detected to 5066.67 ng/g (fresh weight). Most phytohormones are distributed mainly in the stems of S. horneri in drift and semi-fixed states. PMID:26990813

  10. Simultaneous quantification of trantinterol and its metabolites in human urine by ultra performance liquid chromatography-tandem mass spectrometry.

    PubMed

    Qin, Feng; Wang, Lijuan; Li, Kunjie; Xiong, Zhili; Li, Famei

    2015-08-01

    A rapid, selective and sensitive ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed to simultaneously determine trantinterol and its major metabolites in human urine. Waters Oasis HLB C18 solid phase extraction cartridges were used in the urine sample preparation. The separation was carried out on an ACQUITY UPLC™ BEH C18 column with methanol-0.2% formic acid (30:70, v/v) as the mobile phase at a flow rate of 0.25mL/min. The detection was performed on a triple quadrupole tandem mass spectrometer by multiple reaction monitoring (MRM) mode via electrospray ionization (ESI) source. The linear calibration curves for trantinterol, arylhydroxylamine trantinterol (N-OH-trantinterol), the tert-butyl hydroxylated trantinterol (tert-OH-trantinterol) and the 1-carbonyl trantinterol (trantinterol-COOH) were obtained in the concentration range of 0.414-207, 0.578-385, 0.168-84.0, and 0.954-477ng/mL, respectively. The linear correlation coefficients were greater than 0.990. The intra and inter-day precision (relative standard deviation, RSD) values were less than 12% and the accuracy (relative error, RE) was 6.7-11%. The method herein described was superior to previous methods in sample throughput and sensitivity and successfully applied to the human excretion study. PMID:26093121

  11. Determination of rizatriptan in human plasma by liquid chromatographic-eletrospray tandem mass spectrometry: application to a pharmacokinetic study.

    PubMed

    Guo, Ji-fen; Zhang, Ai-jun; Zhao, Ling; Sun, Xiao-hong; Zhao, Yi-min; Gao, Hong-zhi; Liu, Ze-yuan; Qiao, Shan-yi

    2006-01-01

    A sensitive liquid chromatographic-tandem mass spectrometry(LC-MS/MS) method was developed for the determination of rizatriptan in human plasma. The analytes were extracted from plasma samples by liquid-liquid extraction, separated on a Zorbax XDB C8 column (150 x 4.6 mm i.d.) and detected by tandem mass spectrometry with an electrospray ionization interface. Zomitriptan was used as the internal standard. The method had a lower limit of quantitation of 50 pg/mL for rizatriptan, which showed more sensitivity and speed of analysis compared with reported methods. The within- and between-day precision was measured to be below 11.71% and accuracy between -5.87 and 0.86% for all quality control samples. This quantitation method was successfully applied to the evaluation of the pharmacokinetic profiles of rizatriptan after single oral administration of 5, 10 and 15 mg rizatriptan tablets to 10 healthy volunteers (five males and five females). PMID:15954161

  12. Sensitive liquid chromatography-tandem mass spectrometry method for the simultaneous determination of paracetamol and guaifenesin in human plasma.

    PubMed

    Chen, Xiaoyan; Huang, Jia; Kong, Zhang; Zhong, Dafang

    2005-03-25

    A rapid and sensitive method for the simultaneous determination of paracetamol and guaifenesin in human plasma was developed and validated, using high-performance liquid chromatographic separation with tandem mass spectrometric detection. After extracted from plasma samples by diethyl ether-dichloromethane (3:2, v/v), the analytes and internal standard osalmide were chromatographed on a C18 column. Detection was performed on a triple quadrupole tandem mass spectrometer by selected reaction monitoring (SRM) mode via atmospheric pressure chemical ionization (APCI). The method was linear in the concentration range of 0.05-20.0 microg/ml for paracetamol and 5.0-2000.0 ng/ml for guaifenesin. The intra- and inter-day precision was within 14% for both paracetamol and guaifenesin. The assay accuracy was within +/-2.4% for the analytes. This is the first assay method described for the simultaneous determination of paracetamol and guaifenesin in plasma using one chromatographic run. The method was successfully employed in a pharmacokinetic study after an oral administration of a multicomponent formulation, containing 650 mg paracetamol, 200 mg guaifenesin, 60 mg pseudoephedrine and 20 mg dextrorphan. PMID:15686994

  13. Determination of nalmefene by high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry.

    PubMed

    Fang, Wenfang B; Andrenyak, David M; Moody, David E; Nuwayser, Elie S

    2005-04-01

    Nalmefene is an opioid antagonist used in the treatment of alcoholism and opioid overdose. A highly sensitive method was developed to measure nalmefene in human and rabbit plasma and rabbit serum. Nalbuphine was used as internal standard. Liquid-liquid extraction was applied using n-butyl chloride/acetonitrile (4:1). High-performance liquid chromatography interfaced by electrospray ionization to a tandem mass spectrometer was used for quantitation. Primary validation experiments were conducted using human plasma then it was cross-validated in rabbit plasma and rabbit serum. Specificity (peak-area ratio of blank plasma or serum to its internal standard as percent of peak-area ratio of blank plasma or serum fortified with 0.1 ng/mL nalmefene to its internal standard) ranged from 2.09 to 5.29 with a mean of 3.21% for human plasma and from 4.08 to 6.63 with a mean of 5.55% for rabbit plasma and from 2.47 to 6.17 with a mean of 3.62% for rabbit serum. The mean recovery for nalmefene was 80% in human plasma. The calibration range was from 0.1 to 100 ng/mL. Intrarun accuracy of the lower limit of quantitation (0.1 ng/mL) in all matrices was within 18.0% of target with intrarun precision within 13.6%. At 0.3, 35, and 75 ng/mL, the intrarun accuracy in all matrices was within 11.9% of target with intrarun precision within 6.6%. The inter-run accuracy in human plasma was within 8.0% of target with inter-run precision within 6.6%. Nalmefene was stable in human and rabbit plasma and rabbit serum for up to 24 h at room temperature and in human plasma after three freeze-thaw cycles. Following intravenous injection of 5 mg/kg nalmefene to rabbits, the mean area under curve for 0 to 24 h was 1116 (ng)(mL)(-1)(h), and the mean plasma clearance was 67.9 (mL)(min)(-1)(kg)(-1). PMID:15842759

  14. Quantitation of protein post-translational modifications using isobaric tandem mass tags.

    PubMed

    Liang, Hui-Chung; Lahert, Emma; Pike, Ian; Ward, Malcolm

    2015-01-01

    Post-translational modifications (PTMs) of proteins are known to modulate many cellular processes and their qualitative and quantitative evaluation is fundamental for understanding the mechanisms of biological events. Over the past decade, improvements in sample preparation techniques and enrichment strategies, the development of quantitative labeling strategies, the launch of a new generation of mass spectrometers and the creation of bioinformatics tools for the interrogation of ever larger datasets has established MS-based quantitative proteomics as a powerful workflow for global proteomics, PTM analysis and the elucidation of key biological mechanisms. With the advantage of their multiplexing capacity and the flexibility of an ever-growing family of different peptide-reactive groups, isobaric tandem mass tags facilitate quantitative proteomics and PTM experiments and enable higher sample throughput. In this review, we focus on the technical concept and utility of the isobaric tandem mass tag labeling approach to PTM analysis, including phosphorylation, glycosylation and S-nitrosylation. PMID:25697195

  15. Tandem Affinity Purification Combined with Mass Spectrometry to Identify Components of Protein Complexes

    PubMed Central

    Kaiser, Peter; Meierhofer, David; Wang, Xiaorong; Huang, Lan

    2011-01-01

    Most biological processes are governed by multiprotein complexes rather than individual proteins. Identification of protein complexes therefore is becoming increasingly important to gain a molecular understanding of cells and organisms. Mass spectrometry–based proteomics combined with affinity-tag-based protein purification is one of the most effective strategies to isolate and identify protein complexes. The development of tandem-affinity purification approaches has revolutionized proteomics experiments. These two-step affinity purification strategies allow rapid, effective purification of protein complexes and, at the same time, minimize background. Identification of even very low-abundant protein complexes with modern sensitive mass spectrometers has become routine. Here, we describe two general strategies for tandem-affinity purification followed by mass spectrometric identification of protein complexes. PMID:18370112

  16. Linkage Position and Residue Identification of Disaccharides by Tandem Mass Spectrometry and Linear Discriminant Analysis

    SciTech Connect

    Hui Zhang; Steve M. Brokman; Ning Fang; Nicola L. Pohl; Edward S. Yeung

    2008-03-20

    The discrimination of isomeric disaccharides with different linkage types and different monosaccharide residues--glucose (Glc), galactose (Gal), and mannose (Man) at the non-reducing end - was investigated with tandem mass spectrometry (MS/MS) and linear discriminant analysis (LDA). Conventional matrix-assisted laser desorption/ionization (MALDI)-MS has strong interference peaks from matrix ions in the low mass region (<500 Da). This greatly limits the application of MALDI-MS for the analysis of small molecules such as saccharides. We solved this problem by using LDI with acidic fullerene matrix, which gives a very clean background in the low-mass region. Disaccharides with different linkage types give different tandem mass spectral profiles from various cross-ring fragmentation pathways. Disaccharides with the same linkage type but with three different kinds of monosaccharide residues bear the same fragmentation profiles. However, the relative ratios of the fragment ion intensities were found to be distinctly different among the three disaccharide isomers. By employing statistical tools such as LDA to classify the tandem mass spectra, disaccharide isomers with either different linkages or different monosaccharide residues were successfully classified.

  17. Linkage Position and Residue Identification of Disaccharides by Tandem mass Spectrometry and linear Discriminant Analysis

    SciTech Connect

    Hui Zhang; Steve M. Brokman; Ning Fang; Nicola L. Pohl; Edward S. Yeung

    2008-03-20

    The discrimination of isomeric disaccharides with different linkage types and different monosaccharide residues--glucose (Glc), galactose (Gal), and mannose (Man) at the non-reducing end--was investigated with tandem mass spectrometry (MS/MS) and linear discriminant analysis (LDA). Conventional matrix-assisted laser desorption/ionization (MALDI)-MS has strong interference peaks from matrix ions in the low mass region (<500 Da). This greatly limits the application of MALDI-MS for the analysis of small molecules such as saccharides. We solved this problem by using LDI with acidic fullerene matrix, which gives a very clean background in the low-mass region. Disaccharides with different linkage types give different tandem mass spectral profiles from various cross-ring fragmentation pathways. Disaccharides with the same linkage type but with three different kinds of monosaccharide residues bear the same fragmentation profiles. However, the relative ratios of the fragment ion intensities were found to be distinctly different among the three disaccharide isomers. By employing statistical tools such as LDA to classify the tandem mass spectra, disaccharide isomers with either different linkages or different monosaccharide residues were successfully classified.

  18. Determination of five macrolide antibiotic residues in raw milk using liquid chromatography-electrospray ionization tandem mass spectrometry.

    PubMed

    Wang, Jian; Leung, Daniel; Lenz, Steven P

    2006-04-19

    A confirmatory method using liquid chromatography-electrospray ionization tandem mass spectrometry for determination of five macrolide antibiotics including spiramycin, tilmicosin, oleandomycin, erythromycin, and tylosin in raw milk is presented. Macrolides were extracted from raw milk by acetonitrile, and sample extracts were further cleaned up using solid-phase extraction cartridges. Data acquisition was achieved using multiple reaction monitoring, that is, two transitions, to provide a high degree of sensitivity and specificity. Matrix-matched standard calibration curves with the use of roxithromycin as an internal standard were utilized to achieve the best accuracy of the method. Both a conventional validation procedure and a designed experiment were applied to study the accuracy and precision of the method. The measurement uncertainty arising from accuracy and precision was estimated. The method accuracy, expressed as a percentage of overall recovery, was approximately 100%, and its intermediate precision was <10%. LC-ESI/MS/MS method detection limits (S/N > or = 3:1) of five macrolides were <0.3 microg/kg. PMID:16608203

  19. Quantification and pharmacokinetics of crizotinib in rats by liquid chromatography-tandem mass spectrometry.

    PubMed

    Qiu, Feng; Gu, Yanan; Wang, Tingting; Gao, Yingying; Li, Xiao; Gao, Xiangyu; Cheng, Shan

    2016-06-01

    Crizotinib is a small molecule inhibitor of anaplastic lymphoma kinase (ALK) and can be used to treat ALK-positive nonsmall-cell lung cancer. A rapid and simple high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the quantification of crizotinib in rat plasma using a chemical synthetic compound buspirone as the internal standard (IS). The plasma samples were pretreated by a simple protein precipitation with methanol-acetonitrile (1:1, v/v). Chromatographic separation was successfully achieved on an Agilent Zorbax XDB C18 column (2.1 × 50 mm, 3.5 µm). The gradient elution system was composed of 0.1% formic acid aqueous solution and 0.1% formic acid in methanol solution. The flow rate was set at 0.50 mL/min. The multiple reaction monitoring was based on the transitions of m/z = 450.3 → 177.1 for crizotinib and 386.2 → 122.2 for buspirone (IS). The assay was successfully validated to demonstrate the selectivity, matrix effect, linearity, lower limit of quantification, accuracy, precision, recovery and stability according to the international guidelines. The lower limit of quantification was 1.00 ng/mL in 50 μL of rat plasma. This LC-MS/MS assay was successfully applied to the quantification and pharmacokinetic study of crizotinib in rats after intravenous and oral administration of crizotinib. The oral absolute bioavailability of crizotinib in rats was 68.6 ± 9.63%. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26467669

  20. Simultaneous quantification of multiple urinary naphthalene metabolites by liquid chromatography tandem mass spectrometry.

    PubMed

    Ayala, Daniel C; Morin, Dexter; Buckpitt, Alan R

    2015-01-01

    Naphthalene is an environmental toxicant to which humans are exposed. Naphthalene causes dose-dependent cytotoxicity to murine airway epithelial cells but a link between exposure and human pulmonary disease has not been established. Naphthalene toxicity in rodents depends on P450 metabolism. Subsequent biotransformation results in urinary elimination of several conjugated metabolites. Glucuronide and sulfate conjugates of naphthols have been used as markers of naphthalene exposure but, as the current studies demonstrate, these assays provide a limited view of the range of metabolites generated from the parent hydrocarbon. Here, we present a liquid chromatography tandem mass spectrometry method for measurement of the glucuronide and sulfate conjugates of 1-naphthol as well as the mercapturic acids and N-acetyl glutathione conjugates from naphthalene epoxide. Standard curves were linear over 2 log orders. On column detection limits varied from 0.91 to 3.4 ng; limits of quantitation from 1.8 to 6.4 ng. The accuracy of measurement of spiked urine standards was -13.1 to + 5.2% of target and intra-day and inter-day variability averaged 7.2 (± 4.5) and 6.8 (± 5.0) %, respectively. Application of the method to urine collected from mice exposed to naphthalene at 15 ppm (4 hrs) showed that glutathione-derived metabolites accounted for 60-70% of the total measured metabolites and sulfate and glucuronide conjugates were eliminated in equal amounts. The method is robust and directly measures several major naphthalene metabolites including those derived from glutathione conjugation of naphthalene epoxide. The assays do not require enzymatic deconjugation, extraction or derivatization thus simplifying sample work up. PMID:25853821

  1. Quantitative determination of sarsasapogenin in rat plasma using liquid chromatography-tandem mass spectrometry.

    PubMed

    Yang, Bo; Liu, Zhirui; Hu, Jing; Lai, Xiaodan; Xia, Peiyuan

    2016-06-01

    Sarsasapogenin, a natural compound from Chinese medical herb Anemarrhena asphodeloides Bge., has recently received a great deal of attention due to its various bioactivities. In this study, an easy and applicable liquid chromatography tandem mass spectrometry method for the quantification of sarsasapogenin in rat plasma was developed. Sample preparation was accomplished through a simple one-step protein precipitation procedure with methanol. Negative electrospray ionization was performed using multiple reactions monitoring (MRM) mode with transitions of m/z 417.4/273.2 for sarsasapogenin, and 415.2/271.4 for diosgenin (internal standard). The calibration curve was linear over the range of 0.5-500ng/mL (r=0.9994), with a lower limit of quantification at 0.5ng/mL. The RSD of intra- and inter-day precision was below 6.41%, and accuracy ranged from 87.60% to 99.20%. The RSD of matrix effect and recovery yield was within ±15% of nominal concentrations and sarsasapogenin was stable during stability tests. This validated method had been successfully applied to the preclinical pharmacokinetic studies of sarsasapogenin in rats. The half-life (t1/2) was (15.1±2.3), (16.1±3.0) and (15.4±3.9) h after single intragastric administration of 25, 50 and 100mg/kg sarsasapogenin, respectively. And it was found that, the area under the plasma concentration versus time curve (AUC0-72h) and the maximum plasma concentration (Cmax) were linearly related to dose. PMID:27107248

  2. Determination of triapine, a ribonucleotide reductase inhibitor, in human plasma by liquid chromatography tandem mass spectrometry.

    PubMed

    Feng, Ye; Kunos, Charles A; Xu, Yan

    2015-09-01

    Triapine is an inhibitor of ribonucleotide reductase (RNR). Studies have shown that triapine significantly decreases the activity of RNR and enhanced the radiation-mediated cytotoxicity in cervical and colon cancer. In this work, we have developed and validated a selective and sensitive LC-MS/MS method for the determination of triapine in human plasma. In this method, 2-[(3-fluoro-2-pyridinyl)methylene] hydrazinecarbothioamide (NSC 266749) was used as the internal standard (IS); plasma samples were prepared by deproteinization with acetonitrile; tripaine and the IS were separated on a Waters Xbridge Shield RP18 column (3.5 µm; 2.1 × 50 mm) using a mobile phase containing 25.0% methanol and 75.0% ammonium bicarbonate buffer (10.0 mM, pH 8.50; v/v); column eluate was monitored by positive turbo-ionspray tandem mass spectrometry; and quantitation of triapine was carried out in multiple-reaction-monitoring mode. The method developed had a linear calibration range of 0.250-50.0 ng/mL with correlation coefficient of 0.999 for triapine in human plasma. The IS-normalized recovery and the IS-normalized matrix factor of triapine were 101-104% and 0.89-1.05, respectively. The accuracy expressed as percentage error and precision expressed as coefficient of variation were ≤±6 and ≤8%, respectively. The validated LC-MS/MS method was applied to the measurement of triapine in patient samples from a phase I clinical trial. PMID:25677991

  3. Identification and Quantification of Dimethylamylamine in Geranium by Liquid Chromatography Tandem Mass Spectrometry

    PubMed Central

    Li, J.S.; Chen, M.; Li, Z.C.

    2012-01-01

    A sensitive and reliable method of liquid chromatography–electrospray ionization/tandem mass spectrometry (LC-ESI/MS/ MS) was developed and validated for determining 1,3-dimethylamylamine (1,3-DMAA) and 1,4-dimethylamylamine (1,4-DMAA) in geranium plants (Pelargonium graveolens). The sample was extracted with 0.5 M HCl and purified by liquid-liquid partition with hexane. The parameters for reverse-phase (C18) LC and positive ESI/MS/MS were optimized. The matrix effect, specificity, linearity, precision, accuracy and reproducibility of the method were determined and evaluated. The method was linear over a range of 0.10–10.00 ng/mL examined, with R2 of 0.99 for both 1,3-DMAA and 1,4-DMAA. The recoveries from spiked concentrations between 5.00–40.00 ng/g were 85.1%–104.9% for 1,3-DMAA, with relative standard deviation (RSD) of 2.9%–11.0%, and 82.9%–101.8% for 1,4-DMAA, with RSD of 3.2%–11.7%. The instrument detection limit was 1–2 pg for both DMAAs. The quantification limit was estimated to be 1–2 ng/g for the plant sample. This method was successfully applied to the quantitative determination of 1,3- and 1,4-DMAA in both geranium plant and geranium oil. PMID:22915838

  4. Determination of 3-mercaptopyruvate in rabbit plasma by high performance liquid chromatography tandem mass spectrometry

    PubMed Central

    Stutelberg, Michael W.; Vinnakota, Chakravarthy V.; Mitchell, Brendan L.; Monteil, Alexandre R.; Patterson, Steven E.; Logue, Brian A.

    2014-01-01

    Accidental or intentional cyanide poisoning is a serious health risk. The current suite of FDA approved antidotes, including hydroxocobalamin, sodium nitrite, and sodium thiosulfate is effective, but each antidote has specific major limitations, such as large effective dosage or delayed onset of action. Therefore, next generation cyanide antidotes are being investigated to mitigate these limitations. One such antidote, 3-mercaptopyruvate (3-MP), detoxifies cyanide by acting as a sulfur donor to convert cyanide into thiocyanate, a relatively nontoxic cyanide metabolite. An analytical method capable of detecting 3-MP in biological fluids is essential for the development of 3-MP as a potential antidote. Therefore, a high performance liquid chromatography tandem mass spectrometry (HPLC-MS-MS) method was established to analyze 3-MP from rabbit plasma. Sample preparation consisted of spiking the plasma with an internal standard (13C3-3-MP), precipitation of plasma proteins, and reaction with monobromobimane to inhibit the characteristic dimerization of 3-MP. The method produced a limit of detection of 0.1 µM, a linear dynamic range of 0.5–100 µM, along with excellent linearity (R2 ≥ 0.999), accuracy (±9% of the nominal concentration) and precision (<7% relative standard deviation). The optimized HPLC-MS-MS method was capable of detecting 3-MP in rabbits that were administered sulfanegen, a prodrug of 3-MP, following cyanide exposure. Considering the excellent performance of this method, it will be utilized for further investigations of this promising cyanide antidote. PMID:24480329

  5. Simultaneous Quantification of Multiple Urinary Naphthalene Metabolites by Liquid Chromatography Tandem Mass Spectrometry

    PubMed Central

    Ayala, Daniel C.; Morin, Dexter; Buckpitt, Alan R.

    2015-01-01

    Naphthalene is an environmental toxicant to which humans are exposed. Naphthalene causes dose-dependent cytotoxicity to murine airway epithelial cells but a link between exposure and human pulmonary disease has not been established. Naphthalene toxicity in rodents depends on P450 metabolism. Subsequent biotransformation results in urinary elimination of several conjugated metabolites. Glucuronide and sulfate conjugates of naphthols have been used as markers of naphthalene exposure but, as the current studies demonstrate, these assays provide a limited view of the range of metabolites generated from the parent hydrocarbon. Here, we present a liquid chromatography tandem mass spectrometry method for measurement of the glucuronide and sulfate conjugates of 1-naphthol as well as the mercapturic acids and N-acetyl glutathione conjugates from naphthalene epoxide. Standard curves were linear over 2 log orders. On column detection limits varied from 0.91 to 3.4 ng; limits of quantitation from 1.8 to 6.4 ng. The accuracy of measurement of spiked urine standards was -13.1 to + 5.2% of target and intra-day and inter-day variability averaged 7.2 (± 4.5) and 6.8 (± 5.0) %, respectively. Application of the method to urine collected from mice exposed to naphthalene at 15 ppm (4 hrs) showed that glutathione-derived metabolites accounted for 60-70% of the total measured metabolites and sulfate and glucuronide conjugates were eliminated in equal amounts. The method is robust and directly measures several major naphthalene metabolites including those derived from glutathione conjugation of naphthalene epoxide. The assays do not require enzymatic deconjugation, extraction or derivatization thus simplifying sample work up. PMID:25853821

  6. Quantitative analysis of glycerol levels in human urine by liquid chromatography-tandem mass spectrometry.

    PubMed

    Dong, Ying; Ma, Yanhua; Yan, Kuan; Shen, Li; Wang, Xiaobing; Xu, Youxuan; He, Genye; Wu, Yun; Lu, Jianghai; Yang, Zhiyong; Feng, Feifei

    2014-04-15

    Glycerol has the latent capacity to act as a plasma volume expander and disguise blood doping practices. Therefore, it has been prohibited in sports as a masking agent by the World Anti-Doping Agency (WADA) since January 2010 and a urinary threshold (1mg/mL) was recommended recently [1]. The purpose of this study was to establish and validate a novel quantitative method for the determination of urinary glycerol concentrations using a liquid chromatography-tandem mass spectrometry approach. This simple yet highly specific method made use of the derivatization of glycerol by benzoyl chloride in aqueous solution at 40°C followed by analysis via LC-ESI-MS/MS without sample pre-concentration or cleanup. The assay was linear over the concentration range of 1.0-1000μg/mL for glycerol in human urine. The lower limit of detection (LLOD) and lower limit of quantitation (LLOQ) were 0.3μg/mL and 1.0μg/mL, respectively. The intra- and inter-day precision of the method at three concentration levels (3, 500 and 900μg/mL) was less than 12.2%. The method also afforded satisfactory results in terms of accuracy, derivatization yield, extraction recovery, matrix effect and specificity. The method has been successfully applied to the detection of glycerol in "Quality Assurance Program" samples provided by the World Association of Anti-Doping Scientists (WAADS) and routine doping-control samples in our laboratory. PMID:24657408

  7. Reliable and sensitive determination of dutasteride in human plasma by liquid chromatography-tandem mass spectrometry.

    PubMed

    Contractor, Pritesh; Kurani, Hemal; Guttikar, Swati; Shrivastav, Pranav S

    2013-09-01

    An accurate and precise method was developed and validated using LC-MS/MS to quantify dutasteride in human plasma. The analyte and dutasteride-13C6 as internal standard (IS) were extracted from 300 μL plasma volume using methyl tert-butyl ether-n-hexane (80:20, v/v). Chromatographic analysis was performed on a Gemini C18 (150 × 4.6 mm, 5 µm) column using acetonitrile-5 mm ammonium formate, pH adjusted to 4.0 with formic acid (85:15, v/v) as the mobile phase. Tandem mass spectrometry in positive ionization mode was used to quantify dutasteride by multiple reaction monitoring. The entire data processing was done using Watson LIMS(TM) software, which provided excellent data integrity and high throughput with improved operational efficiency. The calibration curve was linear in the range of 0.1-25 ng/mL, with intra-and inter-batch values for accuracy and precision (coefficient of variation) ranging from 95.8 to 104.0 and from 0.7 to 5.3%, respectively. The mean overall recovery across quality controls was ≥95% for the analyte and IS, while the interference of matrix expressed as IS-normalized matrix factors ranged from 1.01 to 1.02. The method was successfully applied to support a bioequivalence study of 0.5 mg dutasteride capsules in 24 healthy subjects. Assay reproducibility was demonstrated by reanalysis of 103 incurred samples. PMID:23636821

  8. Analysis of drugs of abuse in wastewater by hydrophilic interaction liquid chromatography-tandem mass spectrometry.

    PubMed

    van Nuijs, Alexander L N; Tarcomnicu, Isabela; Bervoets, Lieven; Blust, Ronny; Jorens, Philippe G; Neels, Hugo; Covaci, Adrian

    2009-10-01

    The simultaneous analysis of nine drugs of abuse (DOAs) and their metabolites (amphetamine, methamphetamine, methylenedioxymethamphetamine, methadone, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine, cocaine, benzoylecgonine, ecgonine methyl ester and 6-monoacetylmorphine) in wastewater based on hydrophilic interaction liquid chromatography (HILIC) coupled to tandem mass spectrometry (MS/MS) was optimised and validated. For each analyte, the deuterated analogue was used for quantification. The separation by HILIC showed good performance for all compounds, especially for the hydrophilic compounds, which elute early (amphetamine-like stimulants) or show no retention (ecgonine methyl ester) in reversed-phase liquid chromatography. Sample preparation based on solid-phase extraction was optimised by comparing Oasis HLB and Oasis MCX sorbents for various parameters such as sample pH, amount of sorbent bed and washing solvent. The method was validated for each compound by assessing the following parameters (following International Conference on Harmonisation guidelines): specificity, limit of quantification (LOQ), linearity, accuracy, precision, recovery and matrix effects. LOQs were 2 ng/L for 6-monoacetylmorphine, ecgonine methyl ester and amphetamine and 1 ng/L for the rest of the compounds, corresponding with the lowest point in the calibration curve. Except for 6-monoacetylmorphine, all compounds were detected from 1 to 819 ng/L in influent wastewater samples (n = 12) collected from 11 different wastewater treatment plants across Belgium. The presence of ecgonine methyl ester in wastewater could be demonstrated for the first time. In the future, the new HILIC-MS/MS method will be applied to assess the use of DOAs in Belgium using the "sewage epidemiology" approach. PMID:19685341

  9. Determination of macrocyclic lactone drug residues in animal muscle by liquid chromatography/tandem mass spectrometry.

    PubMed

    He, Limin; Zhao, Donghao; Su, Yijuan; Liu, Yahong; Nie, Jianrong; Lian, Jin

    2009-01-01

    A robust, credible, and practical multiresidue method based on liquid chromatography/tandem/mass spectrometry (LC/MS/MS) was developed for the simultaneous determination of 9 macrocyclic lactone drugs (abamectin B1a, doramectin, erythromycin, ivermectin B1a, josamycin, kitasamycin, roxithromycin, tilmicosin, and tylosin A) in bovine, porcine, chicken, and sheep muscles. The drugs were extracted with acetonitrile, and the extracts were defatted with n-hexane and further cleaned up on a C18 solid-phase extraction cartridge. LC/MS/MS data acquisition was achieved by using the multiple-reaction monitoring (MRM) mode, i.e., 2 transitions, to provide a high degree of sensitivity and repeatability. Matrix-matched standard calibration curves were used to achieve the best accuracy of the method by compensating for the matrix effect. The calibration graphs were linear (r > 0.998) from 10 to 1000 ng/mL for erythromycin, josamycin, kitasamycin, roxithromycin, tilmicosin, and tylosin, and from 5 to 250 ng/mL for abamectin, doramectin, and ivermectin. The average recoveries of the 9 drugs were between 64.5 and 105%, calculated by using matrix-matched calibration, with relative standard deviation values ranging from 1.6 to 14%. The limits of detection were 0.1 microg/kg for erythromycin, josamycin, roxithromycin, and tylosin; 0.2 microg/kg for tilmicosin and kitasamycin; and 0.5 microg/kg for abamectin, doramectin, and ivermectin. For confirmation, the MRM ratios for the 9 drug residues in the samples and the solvent were evaluated and found to be within the ratio criteria set by the guidelines of the European Union. PMID:19382593

  10. Quality control for building libraries from electrospray ionization tandem mass spectra.

    PubMed

    Yang, Xiaoyu; Neta, Pedatsur; Stein, Stephen E

    2014-07-01

    Electrospray ionization (ESI) tandem mass spectrometry coupled with liquid chromatography is a routine technique for identifying and quantifying compounds in complex mixtures. The identification step can be aided by matching acquired tandem mass spectra (MS(2)) against reference library spectra as is routine for electron ionization (EI) spectra from gas chromatography/mass spectrometry (GC/MS). However, unlike the latter spectra, ESI MS(2) spectra are likely to originate from various precursor ions for a given target molecule and may be acquired at varying energies and resolutions and have characteristic noise signatures, requiring processing methods very different from EI to obtain complete and high quality reference spectra for individual analytes. This paper presents procedures developed for creating a tandem mass spectral library that addresses these factors. Library building begins by acquiring MS(2) spectra for all major MS(1) peaks in an infusion run, followed by assigning MS(2) spectra to clusters and creating a consensus spectrum for each. Intensity-based constraints for cluster membership were developed, as well as peak testing to recognize and eliminate suspect peaks and reduce noise. Consensus spectra were then examined by a human evaluator using a number of criteria, including a fraction of annotated peaks and consistency of spectra for a given ion at different energies. These methods have been developed and used to build a library from >9000 compounds, yielding 230,000 spectra. PMID:24896981

  11. Electrospray tandem mass spectrometric analysis of a dimeric conjugate, salvialeriafone and related compounds

    PubMed Central

    2012-01-01

    Background Electrospray tandem mass spectrometry approach is widely used for the rapid characterization of natural products. This paper describes the gas-phased ESI-MS/MS fragmentation of abietane-type diterpenoids and their novel dimeric conjugate, salvialeriafone (1) using both positive and negative ion electrospray ionization quadropole time-of-flight mass spectrometry (ESI-QqTOF-MS/MS) hybrid instrument. Diterpenoids are widely distributed throughout the plant kingdom and posses interesting biological activities. Results ESI-QqTOF-MS (positive ion mode) of diterpenoids 1–6 under collision-induced dissociation tandem mass spectrometric analysis (CID-MS/MS) showed the characteristic losses of water, carbonmonoxide and propene molecules, while analysis in negative ion mode showed the characteristic losses of water, carbon monoxide, methane molecules and methyl radical. Results demonstrated the differences in the product ions and base peaks due to the differences in the skeleton. A novel dimeric conjugate, salvialeriafone (1) showed characteristic fragmentation pattern and was found to be more prone to form radical ions, as compared to monomeric diterpenoids. The fragmentation pathways of characteristic fragments were proposed with the aid of HRESIMS. Conclusions Extensive tandem mass spectrometric studies of salvialeriafone (1) and related diterpenoids 2–6 were conducted and their characteristic fragments were identified. The knowledge of the fragmentation pattern of these diterpenoids will be useful for the characterization of new dimers of this class of compounds. PMID:23079186

  12. Spectral probabilities of top-down tandem mass spectra

    SciTech Connect

    Liu, Xiaowen; Segar, Matthew W.; Li, Shuai Cheng; Kim, Sangtae

    2014-01-24

    In mass spectrometry (MS)-based proteomics, accurate estimation of statistical signicance of peptide and protein identications is desired for determining whether they are actually correct. Probabilistic models, such as the generating function method, have been successfully applied to compute statistical signicance of peptide-spectrum matches (PSMs) in bottom-up MS, but it is limited to PSMs of short peptides without post-translational modications (PTMs). Recently, top-down MS has be- come available in many laboratories, which often identies intact proteins with PTMs. In this paper, we propose an extended generating function (EGF) method for accurately computing statistical signicance of protein- spectrum matches (PrSMs) with PTMs.

  13. High performance liquid chromatography: Tandem mass spectrometric determination of cisplatin levels in different visceral pleura layers of rats

    PubMed Central

    XIA, HUI; ZHANG, WEN; LI, YINGJIE; YU, CHANGHAI

    2015-01-01

    The aim of the present study was to investigate the concentration of cisplatin in different layers of the visceral pleura in rats, following drug administration. In this study, a sensitive and specific liquid chromatography method coupled with electrospray ionization-tandem mass spectrometry was established to investigate the disposition of cisplatin in different layers of the visceral pleura in rats. Methodological data, including specificity, linearity, accuracy, recovery, precision and lower limits of quantification, confirmed that this novel method may be used to efficiently quantify the cisplatin concentrations in visceral pleura of rats following administration of the drug. Furthermore, the results demonstrated that the desired drug concentration was not achieved in the outer or inner elastic layers of the visceral pleura following injection with cisplatin through various administration methods. PMID:26137076

  14. Quantitative determination of uridine in rabbit plasma and urine by liquid chromatography coupled to a tandem mass spectrometry.

    PubMed

    Kang, Wonku

    2012-04-01

    Recently a pyrimidine nucleoside, uridine, has been show to have a protective effect on cultured human corneal epithelial cells, and on dry eye animal model and patients. In this study, we introduce a sensitive liquid chromatography/tandem mass spectrometry method for the determination of uridine in rabbit plasma and urine. After protein precipitation with methanol including methaqualone (internal standard), the analyte was chromatographed on a reversed-phase column with a mobile phase of 0.1% formic acid aqueous solution and methanol (1:4, v/v). The accuracy and precision of the assay were in accordance with Food and Drug Administration regulations for the validation of bioanalytical methods. This method was used to measure the concentrations of uridine in plasma and urine after a single oral administration of 450 mg/kg uridine in rabbits. PMID:22392515

  15. Data supporting the rat brain sample preparation and validation assays for simultaneous determination of 8 neurotransmitters and their metabolites using liquid chromatography-tandem mass spectrometry.

    PubMed

    Wojnicz, Aneta; Ortiz, José Avendaño; Casas, Ana I; Freitas, Andiara E; López, Manuela G; Ruiz-Nuño, Ana

    2016-06-01

    The data presented in this article supports the rat brain sample preparation procedure previous to its injection into the liquid chromatography-tandem mass spectrometry (LC-MS/MS) system to monitor levels of adrenaline, noradrenaline, glutamic acid, γ-aminobutyric acid, dopamine, 5-hydroxytryptamine, 5-hydroxyindole acetic acid, and 3-methoxy-4-hydroxyphenylglycol. In addition, we describe the method validation assays (such as calibration curve, lower limit of quantification, precision and accuracy intra- and inter-day, selectivity, extraction recovery and matrix effect, stability, and carry-over effect) according to the United States Food and Drug Administration and European Medicine Agency to measure in one step different neurotransmitters and their metabolites. The data supplied in this article is related to the research study entitled: "Simultaneous determination of 8 neurotransmitters and their metabolite levels in rat brain using liquid chromatography in tandem with mass spectrometry: application to the murine Nrf2 model of depression" (Wojnicz et al. 2016) [1]. PMID:27054183

  16. Parallel Reaction Monitoring: A Targeted Experiment Performed Using High Resolution and High Mass Accuracy Mass Spectrometry

    PubMed Central

    Rauniyar, Navin

    2015-01-01

    The parallel reaction monitoring (PRM) assay has emerged as an alternative method of targeted quantification. The PRM assay is performed in a high resolution and high mass accuracy mode on a mass spectrometer. This review presents the features that make PRM a highly specific and selective method for targeted quantification using quadrupole-Orbitrap hybrid instruments. In addition, this review discusses the label-based and label-free methods of quantification that can be performed with the targeted approach. PMID:26633379

  17. Determination of suvorexant in human plasma using 96-well liquid-liquid extraction and HPLC with tandem mass spectrometric detection.

    PubMed

    Breidinger, S A; Simpson, R C; Mangin, E; Woolf, E J

    2015-10-01

    A method, using liquid chromatography with tandem mass spectrometric detection (LC-MS/MS), was developed for the determination of suvorexant (MK-4305, Belsomra(®)), a selective dual orexin receptor antagonist for the treatment insomnia, in human plasma over the concentration range of 1-1000ng/mL. Stable isotope labeled (13)C(2)H3-suvorexant was used as an internal standard. The sample preparation procedure utilized liquid-liquid extraction, in the 96-well format, of a 100μL plasma sample with methyl t-butyl ether. The compounds were chromatographed under isocratic conditions on a Waters dC18 (50×2.1mm, 3μm) column with a mobile phase consisting of 30/70 (v/v %) 10mM ammonium formate, pH3/acetonitrile at a flow rate of 0.3mL/min. Multiple reaction monitoring of the precursor-to-product ion pairs for suvorexant (m/z 451→186) and (13)C(2)H3-suvorexant (m/z 455→190) on an Applied Biosystems API 4000 tandem mass spectrometer was used for quantitation. Intraday assay precision, assessed in six different lots of control plasma, was within 10% CV at all concentrations, while assay accuracy ranged from 95.6 to 105.0% of nominal. Quality control (QC) samples in plasma were stored at -20°C. Initial within day analysis of QCs after one freeze-thaw cycle showed accuracy within 9.5% of nominal with precision (CV) of 6.7% or less. The plasma QC samples were demonstrated to be stable for up to 25 months at -20°C. The method described has been used to support clinical studies during Phase I through III of clinical development. PMID:26343269

  18. Ion mobility tandem mass spectrometry enhances performance of bottom-up proteomics.

    PubMed

    Helm, Dominic; Vissers, Johannes P C; Hughes, Christopher J; Hahne, Hannes; Ruprecht, Benjamin; Pachl, Fiona; Grzyb, Arkadiusz; Richardson, Keith; Wildgoose, Jason; Maier, Stefan K; Marx, Harald; Wilhelm, Mathias; Becher, Isabelle; Lemeer, Simone; Bantscheff, Marcus; Langridge, James I; Kuster, Bernhard

    2014-12-01

    One of the limiting factors in determining the sensitivity of tandem mass spectrometry using hybrid quadrupole orthogonal acceleration time-of-flight instruments is the duty cycle of the orthogonal ion injection system. As a consequence, only a fraction of the generated fragment ion beam is collected by the time-of-flight analyzer. Here we describe a method utilizing postfragmentation ion mobility spectrometry of peptide fragment ions in conjunction with mobility time synchronized orthogonal ion injection leading to a substantially improved duty cycle and a concomitant improvement in sensitivity of up to 10-fold for bottom-up proteomic experiments. This enabled the identification of 7500 human proteins within 1 day and 8600 phosphorylation sites within 5 h of LC-MS/MS time. The method also proved powerful for multiplexed quantification experiments using tandem mass tags exemplified by the chemoproteomic interaction analysis of histone deacetylases with Trichostatin A. PMID:25106551

  19. Ion Mobility Tandem Mass Spectrometry Enhances Performance of Bottom-up Proteomics

    PubMed Central

    Helm, Dominic; Vissers, Johannes P. C.; Hughes, Christopher J.; Hahne, Hannes; Ruprecht, Benjamin; Pachl, Fiona; Grzyb, Arkadiusz; Richardson, Keith; Wildgoose, Jason; Maier, Stefan K.; Marx, Harald; Wilhelm, Mathias; Becher, Isabelle; Lemeer, Simone; Bantscheff, Marcus; Langridge, James I.; Kuster, Bernhard

    2014-01-01

    One of the limiting factors in determining the sensitivity of tandem mass spectrometry using hybrid quadrupole orthogonal acceleration time-of-flight instruments is the duty cycle of the orthogonal ion injection system. As a consequence, only a fraction of the generated fragment ion beam is collected by the time-of-flight analyzer. Here we describe a method utilizing postfragmentation ion mobility spectrometry of peptide fragment ions in conjunction with mobility time synchronized orthogonal ion injection leading to a substantially improved duty cycle and a concomitant improvement in sensitivity of up to 10-fold for bottom-up proteomic experiments. This enabled the identification of 7500 human proteins within 1 day and 8600 phosphorylation sites within 5 h of LC-MS/MS time. The method also proved powerful for multiplexed quantification experiments using tandem mass tags exemplified by the chemoproteomic interaction analysis of histone deacetylases with Trichostatin A. PMID:25106551

  20. A review of statistical methods for protein identification using tandem mass spectrometry

    PubMed Central

    Serang, Oliver; Noble, William

    2012-01-01

    Tandem mass spectrometry has emerged as a powerful tool for the characterization of complex protein samples, an increasingly important problem in biology. The effort to efficiently and accurately perform inference on data from tandem mass spectrometry experiments has resulted in several statistical methods. We use a common framework to describe the predominant methods and discuss them in detail. These methods are classified using the following categories: set cover methods, iterative methods, and Bayesian methods. For each method, we analyze and evaluate the outcome and methodology of published comparisons to other methods; we use this comparison to comment on the qualities and weaknesses, as well as the overall utility, of all methods. We discuss the similarities between these methods and suggest directions for the field that would help unify these similar assumptions in a more rigorous manner and help enable efficient and reliable protein inference. PMID:22833779

  1. A review of clinical diagnostic applications of liquid chromatography-tandem mass spectrometry.

    PubMed

    Shushan, Bori

    2010-01-01

    Liquid chromatography coupled with tandem mass spectrometry (LC/MS/MS) technology is emerging as a complementary method to traditional methodology used for clinical applications. Enhanced specificity and high-throughput capabilities are providing significant benefits to clinical diagnostic laboratories conducting routine analyses. This technology is expected to expand rapidly as scientists focus on more complicated challenges that can be solved efficiently by adding LC/MS/MS to their arsenal of techniques. PMID:20949635

  2. Application of dispersive liquid-liquid microextraction for the determination of phosphatidylethanol in blood by liquid chromatography tandem mass spectrometry.

    PubMed

    Cabarcos, Pamela; Ángel Cocho, José; Moreda, Antonio; Míguez, Martha; Jesús Tabernero, María; Fernández, Purificación; María Bermejo, Ana

    2013-07-15

    Phosphatidylethanol (PEth) is a phospholipid which requires for its metabolic formation the presence of relatively high ethanol levels. PEth is thus a promising marker to quentify ethanol abuse. Dispersive liquid-liquid microextraction has become a popular technique because it is fast, inexpensive, easy to operate and consumes low volume of organic solvent. In this method, the appropriate mixture of extraction solvent (230 μL dichloromethane) and disperser solvent (630 μL acetone) are injected into the sample by syringe, rapidly. The liquid chromatography method using a reversed phase-C8 column and a negative ion mode electrospray ionization tandem mass spectrometry detection instrument was developed for the determination of small amounts of PEth that might be present in blood samples, using phosphatidylbutanol (PBut) as an internal standard. The sensitivity of detection obtained with tandem MS was better than that of previous methods. Good linearity was obtained for a range of LOQ-10 μg/mL for PEth, whereas all of the deviations in precision and accuracy were less than 15% except for the LLOQ, where it should not exceed 20%. A set of 50 blood samples were analyzed by such method and whole blood concentrations of PEth 16:0/18:1 ranged from LLOQ to 1.71 μg/mL. PMID:23622544

  3. Generalized method for probability-based peptide and protein identification from tandem mass spectrometry data and sequence database searching.

    PubMed

    Ramos-Fernández, Antonio; Paradela, Alberto; Navajas, Rosana; Albar, Juan Pablo

    2008-09-01

    Tandem mass spectrometry-based proteomics is currently in great demand of computational methods that facilitate the elimination of likely false positives in peptide and protein identification. In the last few years, a number of new peptide identification programs have been described, but scores or other significance measures reported by these programs cannot always be directly translated into an easy to interpret error rate measurement such as the false discovery rate. In this work we used generalized lambda distributions to model frequency distributions of database search scores computed by MASCOT, X!TANDEM with k-score plug-in, OMSSA, and InsPecT. From these distributions, we could successfully estimate p values and false discovery rates with high accuracy. From the set of peptide assignments reported by any of these engines, we also defined a generic protein scoring scheme that enabled accurate estimation of protein-level p values by simulation of random score distributions that was also found to yield good estimates of protein-level false discovery rate. The performance of these methods was evaluated by searching four freely available data sets ranging from 40,000 to 285,000 MS/MS spectra. PMID:18515861

  4. Fast multi-blind modification search through tandem mass spectrometry.

    PubMed

    Na, Seungjin; Bandeira, Nuno; Paek, Eunok

    2012-04-01

    With great biological interest in post-translational modifications (PTMs), various approaches have been introduced to identify PTMs using MS/MS. Recent developments for PTM identification have focused on an unrestrictive approach that searches MS/MS spectra for all known and possibly even unknown types of PTMs at once. However, the resulting expanded search space requires much longer search time and also increases the number of false positives (incorrect identifications) and false negatives (missed true identifications), thus creating a bottleneck in high throughput analysis. Here we introduce MODa, a novel "multi-blind" spectral alignment algorithm that allows for fast unrestrictive PTM searches with no limitation on the number of modifications per peptide while featuring over an order of magnitude speedup in relation to existing approaches. We demonstrate the sensitivity of MODa on human shotgun proteomics data where it reveals multiple mutations, a wide range of modifications (including glycosylation), and evidence for several putative novel modifications. Based on the reported findings, we argue that the efficiency and sensitivity of MODa make it the first unrestrictive search tool with the potential to fully replace conventional restrictive identification of proteomics mass spectrometry data. PMID:22186716

  5. LESSONS IN DE NOVO PEPTIDE SEQUENCING BY TANDEM MASS SPECTROMETRY

    PubMed Central

    Medzihradszky, Katalin F.; Chalkley, Robert J.

    2015-01-01

    Mass spectrometry has become the method of choice for the qualitative and quantitative characterization of protein mixtures isolated from all kinds of living organisms. The raw data in these studies are MS/MS spectra, usually of peptides produced by proteolytic digestion of a protein. These spectra are “translated” into peptide sequences, normally with the help of various search engines. Data acquisition and interpretation have both been automated, and most researchers look only at the summary of the identifications without ever viewing the underlying raw data used for assignments. Automated analysis of data is essential due to the volume produced. However, being familiar with the finer intricacies of peptide fragmentation processes, and experiencing the difficulties of manual data interpretation allow a researcher to be able to more critically evaluate key results, particularly because there are many known rules of peptide fragmentation that are not incorporated into search engine scoring. Since the most commonly used MS/MS activation method is collision-induced dissociation (CID), in this article we present a brief review of the history of peptide CID analysis. Next, we provide a detailed tutorial on how to determine peptide sequences from CID data. Although the focus of the tutorial is de novo sequencing, the lessons learned and resources supplied are useful for data interpretation in general. PMID:25667941

  6. Collision-induced dissociation pathways of anabolic steroids by electrospray ionization tandem mass spectrometry.

    PubMed

    Guan, Fuyu; Soma, Lawrence R; Luo, Yi; Uboh, Cornelius E; Peterman, Scott

    2006-04-01

    Anabolic steroids are structurally similar compounds, and their product-ion spectra obtained by tandem mass spectrometry under electrospray ionization conditions are quite difficult to interpret because of poly-ring structures and lack of a charge-retaining center in their chemical structures. In the present study, the fragmentation of nine anabolic steroids of interest to the racing industry was investigated by using triple quadrupole mass spectrometer, Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer, and a linear ion trap instrument. With the aid of an expert system software (Mass Frontier version 3.0), accurate mass measurements, and multiple stage tandem mass spectrometric (MS(n)) experiments, fragmentation pathways were elucidated for boldenone, methandrostenolone, tetrahydrogestrinone (THG), trenbolone, normethandrolone and mibolerone. Small differences in the chemical structures of the steroids, such as an additional double-bond or a methyl group, result in significantly different fragmentation pathways. The fragmentation pathways proposed in this paper allow interpretation of major product ions of other anabolic steroids reported by other researchers in a recent publication. The proposed fragmentation pathways are helpful for characterization of new steroids. The approach used in this study for elucidation of the fragmentation pathways is helpful in interpretation of complicated product-ion spectra of other compounds, drugs and their metabolites. PMID:16488153

  7. Simultaneous determination of cocaine and opiates in dried blood spots by electrospray ionization tandem mass spectrometry.

    PubMed

    Antelo-Domínguez, Ángel; Cocho, José Ángel; Tabernero, María Jesús; Bermejo, Ana María; Bermejo-Barrera, Pilar; Moreda-Piñeiro, Antonio

    2013-12-15

    A sample pre-treatment method based on blood spot collection filter cards was optimized as a means of using small volume samples for the screening and confirmation of cocaine and opiates abuse. Dried blood spots (DBSs) were prepared by dispersing 20 µL of whole blood specimens previously mixed with the internal standards (deuterated analogs of each target), and subjecting the whole DBS to extraction with 5 mL of methanol under orbital-horizontal shaking (180 rpm) for 10 min. Determinations were based on direct electrospray ionization tandem mass spectrometry (ESI-MS/MS) by injecting the re-dissolved methanol extract with the delivery solution (acetonitrile-water-formic acid, 80:19.875:0.125) at a flow rate of 60 µL min(-1), and using multiple reaction monitoring (MRM) mode with the m/z (precursor ion)→m/z (product ion) transitions for acquisition. Matrix effect has been found to be statistically significant (Multiple Range Test) when assessing cocaine, BZE, codeine and morphine, and the use of the standard addition method (dispersion of whole blood previously mixed with standards onto the filter papers) was needed for accurate determinations. The developed DBS-ESI-MS/MS procedure offered good intra-day and inter-day precisions (lower than 10% and 12%, respectively), as well as good intra-day and inter-day accuracies (inter-day absolute recoveries, expressed as the mean analytical recovery over three target concentration levels, of 103%, 100%, 101%, 98% and 100% for cocaine, BZE, codeine, morphine and 6-MAM, respectively). The high sensitivity inherent to MS/MS determinations combined with the minimal dilution of sample allowed low limits of quantification for all targets, and the developed method results therefore adequate for cocaine and opiates screening and confirmation purposes. The procedure was finally applied to DBSs prepared from whole blood from polydrug abusers, and results were compared with those obtained after a conventional sample pretreatment

  8. Sensitive liquid chromatography/tandem mass spectrometry method for the simultaneous determination of nine local anesthetic drugs.

    PubMed

    Tonooka, Keiko; Naruki, Nobuhiko; Honma, Kou; Agei, Kohei; Okutsu, Mayumi; Hosono, Tetsuji; Kunisue, Yoko; Terada, Masaru; Tomobe, Koji; Shinozuka, Tatsuo

    2016-08-01

    A high-performance liquid chromatography-tandem mass spectrometry (LC/MS/MS) with electrospray ionization (ESI) procedure for the simultaneous determination of nine local anesthetic drugs (procaine, mepivacaine, lidocaine, ropivacaine, oxybuprocaine, tetracaine, bupivacaine, T-caine and dibucaine) in human serum is described. The chromatographic separation was performed on a Mightysil-RP-18 GP II column (2.0mm×150mm, particle size 5μm). The mobile phase consisted of 10mM acetic ammonium buffer (pH 5.4) and acetonitrile and was delivered at a flow rate of 0.20mL/min. The triple quadrupole mass spectrometer was operated in positive ion mode, and multiple reaction monitoring was used for drug quantification. Solid-phase extraction of the nine local anesthetic drugs added to the human serum was performed with an Oasis(®) HLB extraction cartridges column. The method was linear for the investigated drugs over the concentration range of 10-100ng/mL. The recoveries of these drugs were in the range of 81.4-144%. The standard deviation (SD) values for all analytes were <0.10 for both intraday and interday accuracy and precision. The selectivity, accuracy and precision of this method are satisfactory for clinical and forensic applications. The sensitive and selective method offers the opportunity for the simultaneous screening and quantification, for clinical and forensic purposes, of almost all local anesthetics available in Japan. PMID:26986505

  9. Determination of amlodipine in human plasma using automated online solid-phase extraction HPLC-tandem mass spectrometry: application to a bioequivalence study of Chinese volunteers.

    PubMed

    Shentu, Jianzhong; Fu, Lizhi; Zhou, Huili; Hu, Xing Jiang; Liu, Jian; Chen, Junchun; Wu, Guolan

    2012-11-01

    An automated method (XLC-MS/MS) that uses online solid-phase extraction coupled with HPLC-tandem mass spectrometry was reported here for the first time to quantify amlodipine in human plasma. Automated pre-purification of plasma was performed using 10 mm × 2 mm HySphere C8 EC-SE online solid-phase extraction cartridges. After being eluted from the cartridge, the analyte and the internal standard were separated by HPLC and detected by tandem mass spectrometry. Mass spectrometric detection was achieved in the multiple reaction monitoring mode using a quadrupole tandem mass spectrometer in the positive electrospray ionization mode. The XLC-MS/MS method was validated and yielded excellent specificity. The calibration curve ranged from 0.10 to 10.22 ng/mL, and both the intra- and inter-day precision and accuracy values were within 8%. This method proved to be less laborious and was faster per analysis (high-throughput) than offline sample preparation methods. This method has been successfully applied in clinical pharmacokinetic and bioequivalence analyses. PMID:22770846

  10. Assigning in vivo carbamylation and acetylation in human lens proteins using tandem mass spectrometry and database searching

    NASA Astrophysics Data System (ADS)

    Park, Zee-Yong; Sadygov, Rovshan; Clark, Judy M.; Clark, John I.; Yates, John R., III

    2007-01-01

    In this paper, we show that ion trap mass spectrometers can differentiate acetylation and carbamylation modifications based on database search results for a lens protein sample. These types of modifications are difficult to distinguish on ion trap instruments because of their lower resolution and mass accuracy. The results were corroborated by using accurate mass information derived from MALDI TOF MS analysis of eluted peptides from a duplicate capillary RPLC separation. Tandem mass spectra of lysine carbamylated peptides were further verified by manual assignments of fragment ions and by the presence of characteristic fragment ions of carbamylated peptides. It was also observed that carbamylated peptides show a strong neutral loss of the carbamyl group in collision induced dissociation (CID), a feature that can be prognostic for carbamylation. In a lens tissue sample of a 67-year-old patient, 12 in vivo carbamylation sites were detected on 7 different lens proteins and 4 lysine acetylation sites were detected on 3 different lens proteins. Among the 12 in vivo carbamylation sites, 9 are novel in vivo carbamylation modification sites. Notably, in vivo carbamylation of [gamma]S crystallin, [beta]A4 crystallin, [beta]B1 crystallin, and [beta]B2 crystallin observed in this study have never been reported before.

  11. High-accuracy mass measurements of neutron-rich Kr isotopes

    SciTech Connect

    Delahaye, P.; Kellerbauer, A.; Audi, G.; Lunney, D.; Blaum, K.; George, S.; Carrel, F.; Herfurth, F.; Yazidjian, C.; Herlert, A.; Schweikhard, L.; Kluge, H.-J.

    2006-09-15

    The atomic masses of the neutron-rich krypton isotopes {sup 84,86-95}Kr have been determined with the tandem Penning trap mass spectrometer ISOLTRAP with uncertainties ranging from 20 to 220 ppb. The masses of the short-lived isotopes {sup 94}Kr and {sup 95}Kr were measured for the first time. The masses of the radioactive nuclides {sup 89}Kr and {sup 91}Kr disagree by 4 and 6 standard deviations, respectively, from the present Atomic-Mass Evaluation database. The resulting modification of the mass surface with respect to the two-neutron separation energies as well as implications for mass models and stellar nucleosynthesis are discussed.

  12. Electrospray Ionization Tandem Mass Spectrometry (ESI-MS/MS)-Based Shotgun Lipidomics

    SciTech Connect

    Mezengie, Giorgis I.

    2011-01-11

    In the past decade, many new strategies for mass spectrometry (MS)-based analyses of lipids have been developed. Lipidomics is one of the most promising research fields to emerge as a result of these advances in MS. Currently, mass spectrometric analysis of lipids involves two complementary approaches: direct infusion (shotgun lipidomics) and liquid chromatography coupled to MS. In this chapter, I will demonstrate the approach of shotgun lipidomics using electrospray ionization tandem MS for the analysis of lipid molecular species directly from crude biological extracts of tissue or fluids.

  13. Determination of capsaicin, dihydrocapsaicin, and nonivamide in self-defense weapons by liquid chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry.

    PubMed

    Reilly, C A; Crouc, D J; Yost, G S; Fatah, A A

    2001-04-01

    Sensitive and selective liquid chromatography-mass spectrometry (LC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS-MS) methods for the analysis of capsaicin, dihydrocapsaicin, and nonivamide in pepper spray products have been developed. Chromatographic separation of the capsaicinoid analogues was achieved using a reversed-phase HPLC column and a stepwise gradient of methanol and distilled water containing 0.1% (v/v) formic acid. Identification and quantification of the capsaicinoids was achieved by electrospray ionization single-stage mass spectrometry monitoring the protonated molecules of the internal standard (m/z 280), capsaicin (m/z 306), dihydrocapsaicin (m/z 308), and nonivamide (m/z 294) or by tandem mass spectrometry monitoring the appropriate precursor-to-product-ion transitions. The plot of concentration versus peak area ratio was linear over the range of 10-750 ng/ml using LC-MS and 10-500 ng/ml using LC-MS-MS. However, to accurately quantify the capsaicinoids in the pepper spray products calibration curves between 10 and 1000 ng were constructed and fit using a weighted quadratic equation. Using the quadratic curve, the accuracy of the assay ranged from 91 to 102% for all analytes. The intra-assay precision (RSD) for capsaicin was 2% at 25 ng/ml, 10% at 500 ng/ml, and 3% at 800 ng/ml. The inter-assay precision (RSD) for capsaicin was 6% at 25 ng/ml, 6% at 500 ng/ml, and 9% at 800 ng/ml. Similar values for inter- and intra-assay precision were experimentally obtained for both dihydrocapsaicin and nonivamide. The analysis of selected pepper spray products demonstrated that the capsaicinoid concentration in the products ranged from 0.7 to 40.5 microg/microl. PMID:11330795

  14. Quantitative Caffeine Analysis Using a Surface Sampling Probe Electrospray Ionization Tandem Mass Spectrometry System

    SciTech Connect

    Ford, Michael J; Deibel, Michael A.; Tomkins, Bruce A; Van Berkel, Gary J

    2005-01-01

    Quantitative determination of caffeine on reversed-phase C8 thin-layer chromatography plates using a surface sampling electrospray ionization system with tandem mass spectrometry detection is reported. The thin-layer chromatography/electrospray tandem mass spectrometry method employed a deuterium-labeled caffeine internal standard and selected reaction monitoring detection. Up to nine parallel caffeine bands on a single plate were sampled in a single surface scanning experiment requiring 35 min at a surface scan rate of 44 {mu}m/s. A reversed-phase HPLC/UV caffeine assay was developed in parallel to assess the mass spectrometry method performance. Limits of detection for the HPLC/UV and thin-layer chromatography/electrospray tandem mass spectrometry methods determined from the calibration curve statistics were 0.20 ng injected (0.50 {mu}L) and 1.0 ng spotted on the plate, respectively. Spike recoveries with standards and real samples ranged between 97 and 106% for both methods. The caffeine content of three diet soft drinks (Diet Coke, Diet Cherry Coke, Diet Pepsi) and three diet sport drinks (Diet Turbo Tea, Speed Stack Grape, Speed Stack Fruit Punch) was measured. The HPLC/UV and mass spectrometry determinations were in general agreement, and these values were consistent with the quoted values for two of the three diet colas. In the case of Diet Cherry Coke and the diet sports drinks, the determined caffeine amounts using both methods were consistently higher (by 8% or more) than the literature values.

  15. Simultaneous determination of phenolic compounds in Equisetum palustre L. by ultra high performance liquid chromatography with tandem mass spectrometry combined with matrix solid-phase dispersion extraction.

    PubMed

    Wei, Zuofu; Pan, Youzhi; Li, Lu; Huang, Yuyang; Qi, Xiaolin; Luo, Meng; Zu, Yuangang; Fu, Yujie

    2014-11-01

    A method based on matrix solid-phase dispersion extraction followed by ultra high performance liquid chromatography with tandem mass spectrometry is presented for the extraction and determination of phenolic compounds in Equisetum palustre. This method combines the high efficiency of matrix solid-phase dispersion extraction and the rapidity, sensitivity, and accuracy of ultra high performance liquid chromatography with tandem mass spectrometry. The influential parameters of the matrix solid-phase dispersion extraction were investigated and optimized. The optimized conditions were as follows: silica gel was selected as dispersing sorbent, the ratio of silica gel to sample was selected to be 2:1 (400/200 mg), and 8 mL of 80% methanol was used as elution solvent. Furthermore, a fast and sensitive ultra high performance liquid chromatography with tandem mass spectrometry method was developed for the determination of nine phenolic compounds in E. palustre. This method was carried out within <6 min, and exhibited satisfactory linearity, precision, and recovery. Compared with ultrasound-assisted extraction, the proposed matrix solid-phase dispersion procedure possessed higher extraction efficiency, and was more convenient and time saving with reduced requirements on sample and solvent amounts. All these results suggest that the developed method represents an excellent alternative for the extraction and determination of active components in plant matrices. PMID:25132205

  16. Determination of rutin in rat plasma by ultra performance liquid chromatography tandem mass spectrometry and application to pharmacokinetic study.

    PubMed

    Chen, Mengchun; Zhang, Xiaoqian; Wang, Hao; Lin, Baoli; Wang, Shuanghu; Hu, Guoxin

    2015-04-01

    A sensitive and rapid ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS-MS) method for the determination of rutin in rat plasma was developed and validated. After addition of tolbutamide as internal standard (IS), protein precipitation by acetonitrile was used as sample preparation. The chromatographic separation was performed on an Acquity UPLC BEH C18 column (2.1 × 50 mm, 1.7 μm particle size), using acetonitrile-0.1% formic acid as the mobile phase with gradient elution, delivered at a flow-rate of 0.4 mL/min. Mass spectrometric analysis was performed using a XEVO TQD mass spectrometer coupled with an electro-spray ionization (ESI) source in the positive ion mode. The MRM transitions of m/z 610.91→302.98 and m/z 271.2→155.1 were used to quantify for rutin and tolbutamide, respectively. This assay method has been fully validated in terms of specificity, linearity, recovery and matrix effect, accuracy, precision and stability. Calibration curves were linear in the concentration ranges of 25-2000 ng/mL for rutin. Only 3 min was needed for an analytical run. This developed method was successfully used for determination of rutin in rat plasma for pharmacokinetic study. PMID:25030991

  17. Simultaneous determination of levophencynonate and its metabolite demethyl levophencynonate in human plasma by liquid chromatography tandem mass spectrometry.

    PubMed

    Li, Bo; Qi, Wenyuan; Shi, Aixin; Hu, Xin; Cheng, Gang

    2016-08-01

    A sensitive and convenient high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) method was developed to determine levophencynonate and demethyl levophencynonate levels in human plasma simultaneously. Chromatographic separation was achieved on a SHIMADZU Shim-Pack XR C8 column and mass spectrometric analysis was performed by an API5000 mass spectrometer coupled with an electro-spray ionization (ESI) source in the positive ion mode. The MRM transitions of m/z 358.4→156.4 and 344.5→144.2 were used to quantify levophencynonate and demethyl levophencynonate, respectively. This analytical method was fully validated with specificity, linearity, lower limit of quantitation (LLOQ), accuracy, precision, stability, matrix effect and recovery. The linearity of this method were developed to be within the concentration ranges of 10-4000pg/mL for levophencynonate and 25-8000pg/mL for demethyl levophencynonate in human plasma. This method was used in a clinical study which was administrated with single oral dose for Chinese healthy subjects to investigate the pharmacokinetics of levophencynonate and demethyl levophencynonate. PMID:27304783

  18. Rapid chiral separation of racemic cetirizine in human plasma using subcritical fluid chromatography-tandem mass spectrometry.

    PubMed

    Eom, Han Young; Kang, Myunghee; Kang, Seung Woo; Kim, Unyong; Suh, Joon Hyuk; Kim, Junghyun; Cho, Hyun-Deok; Jung, Yura; Yang, Dong-Hyug; Han, Sang Beom

    2016-01-01

    A method for fast chiral separation of cetirizine and quantitation of levocetirizine in human plasma using subcritical fluid chromatography with tandem mass spectrometry was developed and validated. The chromatographic separation was performed using a Chiralpak IE column (2.1 mm×150 mm, 5 μm) with an isocratic elution of CO2/organic modifier (55/45, v/v) at a flow rate of 0.85 mL/min. The organic modifier was composed of water/methanol (5/95, v/v). The makeup flow was optimized at water/methanol (10/90, v/v) and 0.2 mL/min. The most influential parameters on the separation of cetirizine affecting resolution, retention time and sensitivity were selected by fractional factorial design. The 3 selected factors were optimized by response surface methodology. Tandem mass spectrometry was used at electrospray ionization, positive ion mode, and multiple-reaction monitoring mode. Isotope-labeled cetirizine-d4 was used as the internal standard. The sample preparation of human plasma was conducted by solid phase extraction of hydrophilic-lipophilic balance (HLB) type. The developed method was validated for selectivity, linearity, precision, accuracy, recovery, limit of quantitation (LOQ), and limit of detection (LOD). The real human plasma samples were analyzed and the pharmacokinetic results were compared with results of previous research. The developed method was found to be reliable based on the similarity between the results of the current and previous methods. The chiral separation for cetirizine and economic feasibility were compared with those of previous studies using normal phase-HPLC or reversed phase-HPLC. The established analytical method could be successfully applied to pharmacokinetic study with reduction in the analysis time and costs. PMID:26440285

  19. [Rapid analysis of 28 primary aromatic amines in aqueous food simulants by high performance liquid chromatography-tandem mass spectrometry].

    PubMed

    Xiao, Xiaofeng; Wang, Jianling; Yang, Juanjuan; Liu, Tingfei; Chen, Tong; He, Jun; Deng, Hongyi; Gao, Qiyan

    2013-01-01

    A novel method for rapid analysis of the migration amounts of 28 primary aromatic amines (PAAs) in aqueous food simulants (10% ethanol, 30 g/L acetic acid and 20% ethanol aqueous solution) was developed using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). After the migration test, the soaking solution was cooled down from 100 degrees C, vortexed, filtered through a hydrophilic polytetrafluoroethylene filter with a disposable syringe, and then the filtrate was analyzed by HPLC-MS/MS. A Zorbax SB-Phenyl column (250 mm x 4.6 mm, 5 microm) was selected for chromatography. The mobile phase consisted of water and 0.1% formic acid-25% acetonitrile-methanol solution with gradient elution. The 28 PAAs in aqueous food simulants were detected by tandem mass spectrometer operated in positive electrospray ionization (ESI+) and multiple reaction monitoring (MRM) mode. The limits of quantification for the 28 PAAs were between 0.002 microg/L and 10 microg/L. The linearity of the method was good with correlation coefficients (r2) greater than 0.995 over the concentration range from 5 microg/L or 10 microg/L to 100 microg/L. The average recoveries of the 28 PAAs were between 76.6% and 114% with the relative standard deviations between 1.53% and 8.97% at the levels of 10, 20, and 40 microg/L. The method shows rapid pretreatment, the lower limits of quantification, good recoveries and accuracies, and meets the requirement of European Union (EU) No 10/2011 regulation for the specific migration of PAAs. The method has been applied to analyze the 28 PAAs in different aqueous food simulants from the migration test of 30 batches of food contact material samples exported to EU. PMID:23667988

  20. Simultaneous quantification of atenolol and chlorthalidone in human plasma by ultra-performance liquid chromatography-tandem mass spectrometry.

    PubMed

    Shah, Jaivik V; Patel, Daxesh P; Shah, Priyanka A; Sanyal, Mallika; Shrivastav, Pranav S

    2016-02-01

    A simple, sensitive and reproducible ultra-performance liquid chromatography-tandem mass spectrometry method has been developed for the simultaneous determination of atenolol, a β-adrenergic receptor-blocker and chlorthalidone, a monosulfonamyl diuretic in human plasma, using atenolol-d7 and chlorthalidone-d4 as the internal standards (ISs). Following solid-phase extraction on Phenomenex Strata-X cartridges using 100 μL human plasma sample, the analytes and ISs were separated on an Acquity UPLC BEH C18 (50 mm × 2.1 mm, 1.7 µm) column using a mobile phase consisting of 0.1% formic acid-acetonitrile (25:75, v/v). A tandem mass spectrometer equipped with electrospray ionization was used as a detector in the positive ionization mode for both analytes. The linear concentration range was established as 0.50-500 ng/mL for atenolol and 0.25-150 ng/mL for chlorthalidone. Extraction recoveries were within 95-103% and ion suppression/enhancement, expressed as IS-normalized matrix factors, ranged from 0.95 to 1.06 for both the analytes. Intra-batch and inter-batch precision (CV) and accuracy values were 2.37-5.91 and 96.1-103.2%, respectively. Stability of analytes in plasma was evaluated under different conditions, such as bench-top, freeze-thaw, dry and wet extract and long-term. The developed method was superior to the existing methods for the simultaneous determination of atenolol and chlorthalidone in human plasma with respect to the sensitivity, chromatographic analysis time and plasma volume for processing. Further, it was successfully applied to support a bioequivalence study of 50 mg atenolol + 12.5 mg chlorthalidone in 28 healthy Indian subjects. PMID:26096961

  1. Identification of GABAC Receptor Protein Homeostasis Network Components from Three Tandem Mass Spectrometry Proteomics Approaches

    PubMed Central

    Wang, Ya-Juan; Han, Dong-Yun; Tabib, Tracy; Yates, John R.; Mu, Ting-Wei

    2013-01-01

    Gamma-amino butyric acid type C (GABAC) receptors inhibit neuronal firing primarily in retina. Maintenance of GABAC receptor protein homeostasis in cells is essential for its function. However, a systematic study of GABAC receptor protein homeostasis (proteostasis) network components is absent. Here, co-immunoprecipitation of human GABAC-ρ1 receptor complexes was performed in HEK293 cells overexpressing ρ1 receptors. To enhance the coverage and reliability of identified proteins, immunoisolated ρ1 receptor complexes were subjected to three tandem mass spectrometry (MS)-based proteomic analyses: namely, gel-based tandem MS (GeLC-MS/MS), solution-based tandem MS (SoLC-MS/MS), and multidimensional protein identification technology (MudPIT). From the 107 identified proteins, we assembled GABAC-ρ1 receptor proteostasis network components, including proteins with protein folding, degradation, and trafficking functions. We studied representative individual ρ1 receptor interacting proteins, including calnexin, a lectin chaperone that facilitates glycoprotein folding, and LMAN1, a glycoprotein trafficking receptor, and global effectors that regulate protein folding in cells based on bioinformatics analysis, including HSF1, a master regulator of the heat shock response, and XBP1, a key transcription factor of the unfolded protein response. Manipulating selected GABAC receptor proteostasis network components is a promising strategy to regulate GABAC receptor folding, trafficking, degradation and thus function to ameliorate related retinal diseases. PMID:24079818

  2. Simultaneous determination of buprenorphine, norbuprenorphine and naloxone in human plasma by liquid chromatography/tandem mass spectrometry.

    PubMed

    Liu, Yongzhen; Li, Xiaohua; Xu, Allan; Nasser, Azmi F; Heidbreder, Christian

    2016-02-20

    A simple, sensitive and rapid liquid chromatography/electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) method was developed and validated for simultaneous quantification of naloxone, buprenorphine and its metabolite norbuprenorphine in human plasma. Human plasma samples were extracted using a single step liquid-liquid extraction, and then separated on an Imtakt Unison UK-C18 column (2.1×50mm, 3μm) using alkaline mobile phases with gradient elution. All of the analytes were detected in positive ion mode using multiple reaction monitoring (MRM). The method was validated and the specificity, linearity, lower limit of quantitation, precision, accuracy, recoveries and stability were determined. The linear range was 20-10000pg/mL for buprenorphine and norbuprenorphine; and 1-500pg/mL for naloxone. The correlation coefficient (R(2)) values for all three analytes were ≥0.995. The precision and accuracy for intra-day and inter-day were <11.0%. The recoveries were >63% and matrix effects were tracked by the deuterated internal standards (IS) with the IS-normalized matrix factor ranging from 0.96 to 1.33 for all three analytes. The validated method was successfully applied in a clinical pharmacokinetic study with low dose administration of sublingual buprenorphine and naloxone. PMID:26730511

  3. Evaluation of laser diode thermal desorption-tandem mass spectrometry (LDTD-MS-MS) in forensic toxicology.

    PubMed

    Bynum, Nichole D; Moore, Katherine N; Grabenauer, Megan

    2014-10-01

    Many forensic laboratories experience backlogs due to increased drug-related cases. Laser diode thermal desorption (LDTD) has demonstrated its applicability in other scientific areas by providing data comparable with instrumentation, such as liquid chromatography-tandem mass spectrometry, in less time. LDTD-MS-MS was used to validate 48 compounds in drug-free human urine and blood for screening or quantitative analysis. Carryover, interference, limit of detection, limit of quantitation, matrix effect, linearity, precision and accuracy and stability were evaluated. Quantitative analysis indicated that LDTD-MS-MS produced precise and accurate results with the average overall within-run precision in urine and blood represented by a %CV <14.0 and <7.0, respectively. The accuracy for all drugs in urine ranged from 88.9 to 104.5% and 91.9 to 107.1% in blood. Overall, LDTD has the potential for use in forensic toxicology but before it can be successfully implemented that there are some challenges that must be addressed. Although the advantages of the LDTD system include minimal maintenance and rapid analysis (∼10 s per sample) which makes it ideal for high-throughput forensic laboratories, a major disadvantage is its inability or difficulty analyzing isomers and isobars due to the lack of chromatography without the use of high-resolution MS; therefore, it would be best implemented as a screening technique. PMID:25217542

  4. High-throughput multiclass method for antibiotic residue analysis by liquid chromatography-tandem mass spectrometry.

    PubMed

    Chico, J; Rúbies, A; Centrich, F; Companyó, R; Prat, M D; Granados, M

    2008-12-12

    A simple and rapid method has been developed for the residue analysis of 39 antibiotics (tetracyclines, quinolones, penicillins, sulfonamides and macrolides) in foodstuffs of animal origin. The method combines an effective extraction technique, which uses water-methanol as extracting solvent, with ultra-high-pressure liquid chromatography-tandem mass spectrometry, allowing both confirmation and quantification in a single chromatographic run. The multiresidue method has been validated in chicken muscle matrix according to European Union Decision 2002/657/EC. It has been implemented as a routine method in a Public Health Laboratory, instead of the five plates test and LC methods previously used. PMID:18992888

  5. Tandem mass spectrometric fragmentation patterns of known and new steviol glycosides with structure proposals.

    PubMed

    Zimmermann, Benno F

    2011-06-15

    Stevia rebaudiana contains several steviol glycosides that have a sweet flavor. They are up to 450 times sweeter than sucrose, but some have an undesirable aftertaste. Up to 2010, ten different steviol glycosides have been described from the leaves or purified extracts of S. rebaudiana. In this paper, the tandem mass spectrometric fragmentation patterns of these ten compounds are compiled, along with a scheme for structural elucidation. This scheme is then applied to 12 steviol glycosides that have not yet been described. The proposed structures of five steviol glycosides have been confirmed by other authors. PMID:21594932

  6. Automated Lipid A Structure Assignment from Hierarchical Tandem Mass Spectrometry Data

    NASA Astrophysics Data System (ADS)

    Ting, Ying S.; Shaffer, Scott A.; Jones, Jace W.; Ng, Wailap V.; Ernst, Robert K.; Goodlett, David R.

    2011-05-01

    Infusion-based electrospray ionization (ESI) coupled to multiple-stage tandem mass spectrometry (MS n ) is a standard methodology for investigating lipid A structural diversity (Shaffer et al. J. Am. Soc. Mass. Spectrom. 18(6), 1080-1092, 2007). Annotation of these MS n spectra, however, has remained a manual, expert-driven process. In order to keep up with the data acquisition rates of modern instruments, we devised a computational method to annotate lipid A MS n spectra rapidly and automatically, which we refer to as hierarchical tandem mass spectrometry (HiTMS) algorithm. As a first-pass tool, HiTMS aids expert interpretation of lipid A MS n data by providing the analyst with a set of candidate structures that may then be confirmed or rejected. HiTMS deciphers the signature ions (e.g., A-, Y-, and Z-type ions) and neutral losses of MS n spectra using a species-specific library based on general prior structural knowledge of the given lipid A species under investigation. Candidates are selected by calculating the correlation between theoretical and acquired MS n spectra. At a false discovery rate of less than 0.01, HiTMS correctly assigned 85% of the structures in a library of 133 manually annotated Francisella tularensis subspecies novicida lipid A structures. Additionally, HiTMS correctly assigned 85% of the structures in a smaller library of lipid A species from Yersinia pestis demonstrating that it may be used across species.

  7. Improving quantitative precision and throughput by reducing calibrator use in liquid chromatography-tandem mass spectrometry.

    PubMed

    Rule, Geoffrey S; Rockwood, Alan L

    2016-05-01

    To improve efficiency in our mass spectrometry laboratories we have made efforts to reduce the number of calibration standards utilized for quantitation over time. We often analyze three or more batches of 96 samples per day, on a single instrument, for a number of assays. With a conventional calibration scheme at six concentration levels this amounts to more than 5000 calibration points per year. Modern LC-tandem mass spectrometric instrumentation is extremely rugged however, and isotopically labelled internal standards are widely available. This made us consider whether alternative calibration strategies could be utilized to reduce the number of calibration standards analyzed while still retaining high precision and accurate quantitation. Here we demonstrate how, by utilizing a single calibration point in each sample batch, and using the resulting response factor (RF) to update an existing, historical response factor (HRF), we are able to obtain improved precision over a conventional multipoint calibration approach, as judged by quality control samples. The laboratory component of this study was conducted with an existing LC tandem mass spectrometric method for three androgen analytes in our production laboratory. Using examples from both simulated and laboratory data we illustrate several aspects of our single point alternative calibration strategy and compare it with a conventional, multipoint calibration approach. We conclude that both the cost and burden of preparing multiple calibration standards with every batch of samples can be reduced while at the same time maintaining, or even improving, analytical quality. PMID:27086099

  8. Gas Chromatography/Atmospheric Pressure Chemical Ionization Tandem Mass Spectrometry for Fingerprinting the Macondo Oil Spill.

    PubMed

    Lobodin, Vladislav V; Maksimova, Ekaterina V; Rodgers, Ryan P

    2016-07-01

    We report the first application of a new mass spectrometry technique (gas chromatography combined to atmospheric pressure chemical ionization tandem mass spectrometry, GC/APCI-MS/MS) for fingerprinting a crude oil and environmental samples from the largest accidental marine oil spill in history (the Macondo oil spill, the Gulf of Mexico, 2010). The fingerprinting of the oil spill is based on a trace analysis of petroleum biomarkers (steranes, diasteranes, and pentacyclic triterpanes) naturally occurring in crude oil. GC/APCI enables soft ionization of petroleum compounds that form abundant molecular ions without (or little) fragmentation. The ability to operate the instrument simultaneously in several tandem mass spectrometry (MS/MS) modes (e.g., full scan, product ion scan, reaction monitoring) significantly improves structural information content and sensitivity of analysis. For fingerprinting the oil spill, we constructed diagrams and conducted correlation studies that measure the similarity between environmental samples and enable us to differentiate the Macondo oil spill from other sources. PMID:27281271

  9. [Microchip-based reversed-phase liquid chromatography-tandem mass spectrometry platform for protein analysis].

    PubMed

    Liang, Yu; Wu, Ci; Dai, Zhongpeng; Liang, Zuocheng; Liang, Zhen; Zhang, Lihua; Zhang, Yukui

    2011-06-01

    Due to the high throughput and high sensitivity, the hyphenation of microchip-based high performance liquid chromatography with tandem mass spectrometry has been paid much attention. In our recent work, with poly (lauryl methacrylate-co-trimethylolpropane trimethacrylate) monolithic materials prepared in microchannels as trap and separation columns, conventional micro-liquid chromatography pumps and valves for fluidic control, and a small-bore open-tube capillary attached to the outlet channel as chip-mass spectrometer (MS) interface, the microchip-based reversed-phase liquid chromatography-tandem mass spectrometry (RPLC-MS/MS) platform was established, and applied for the identification of proteins. By such platform, 100 ng digest of bovine serum albumin (BSA) was successfully analyzed with the sequence coverages as 39.37%, 37.89% and 34.10% (with the relative standard deviation (RSD) of 7.3%) in three runs, separately. To evaluate the chip-to-chip reproducibility, BSA was identified by such platform with the microchips from different batches containing trap column, separation column and chip-MS interface. The obtained sequence coverage and the number of peptides identified were comparable. All these results showed high sensitivity and good reproducibility of such platform, demonstrating the great potential for rapid protein analysis. PMID:22032155

  10. Fast quantitative detection of cocaine in beverages using nanoextractive electrospray ionization tandem mass spectrometry.

    PubMed

    Hu, Bin; Peng, Xuejiao; Yang, Shuiping; Gu, Haiwei; Chen, Huanwen; Huan, Yanfu; Zhang, Tingting; Qiao, Xiaolin

    2010-02-01

    Without any sample pretreatment, effervescent beverage fluids were manually sprayed into the primary ion plume created by using a nanoelectrospray ionization source for direct ionization, and the analyte ions of interest were guided into an ion trap mass spectrometer for tandem mass analysis. Functional ingredients (e.g., vitamins, taurine, and caffeine, etc.) and spiked impurity (e.g., cocaine) in various beverages, such as Red Bull energy drink, Coco-cola, and Pepsi samples were rapidly identified within 1.5 s. The limit of detection was found to be 7-15 fg (S/N = 3) for cocaine in different samples using the characteristic fragment (m/z 150) observed in the MS(3) experiments. Typical relative standard deviation and recovery of this method were 6.9%-8.6% and 104%-108% for direct analysis of three actual samples, showing that nanoextractive electrospray ionization tandem mass spectrometry is a useful technique for fast screening cocaine presence in beverages. PMID:19939702

  11. De Novo Correction of Mass Measurement Error in Low Resolution Tandem MS Spectra for Shotgun Proteomics

    NASA Astrophysics Data System (ADS)

    Egertson, Jarrett D.; Eng, Jimmy K.; Bereman, Michael S.; Hsieh, Edward J.; Merrihew, Gennifer E.; MacCoss, Michael J.

    2012-12-01

    We report an algorithm designed for the calibration of low resolution peptide mass spectra. Our algorithm is implemented in a program called FineTune, which corrects systematic mass measurement error in 1 min, with no input required besides the mass spectra themselves. The mass measurement accuracy for a set of spectra collected on an LTQ-Velos improved 20-fold from -0.1776 ± 0.0010 m/z to 0.0078 ± 0.0006 m/z after calibration (avg ± 95 % confidence interval). The precision in mass measurement was improved due to the correction of non-linear variation in mass measurement accuracy across the m/z range.

  12. In Silico Identification Software (ISIS): A Machine Learning Approach to Tandem Mass Spectral Identification of Lipids

    SciTech Connect

    Kangas, Lars J.; Metz, Thomas O.; Isaac, Georgis; Schrom, Brian T.; Ginovska-Pangovska, Bojana; Wang, Luning; Tan, Li; Lewis, Robert R.; Miller, John H.

    2012-05-15

    Liquid chromatography-mass spectrometry-based metabolomics has gained importance in the life sciences, yet it is not supported by software tools for high throughput identification of metabolites based on their fragmentation spectra. An algorithm (ISIS: in silico identification software) and its implementation are presented and show great promise in generating in silico spectra of lipids for the purpose of structural identification. Instead of using chemical reaction rate equations or rules-based fragmentation libraries, the algorithm uses machine learning to find accurate bond cleavage rates in a mass spectrometer employing collision-induced dissocia-tion tandem mass spectrometry. A preliminary test of the algorithm with 45 lipids from a subset of lipid classes shows both high sensitivity and specificity.

  13. Application of dual tree complex wavelet transform in tandem mass spectrometry.

    PubMed

    Murugesan, Selvaraaju; Tay, David B H; Cooke, Ira; Faou, Pierre

    2015-08-01

    Mass Spectrometry (MS) is a widely used technique in molecular biology for high throughput identification and sequencing of peptides (and proteins). Tandem mass spectrometry (MS/MS) is a specialised mass spectrometry technique whereby the sequence of peptides can be determined. Preprocessing of the MS/MS data is indispensable before performing any statistical analysis on the data. In this work, preprocessing of MS/MS data is proposed based on the Dual Tree Complex Wavelet Transform (DTCWT) using almost symmetric Hilbert pair of wavelets. After the preprocessing step, the identification of peptides is done using the database search approach. The performance of the proposed preprocessing technique is evaluated by comparing its performance against Discrete Wavelet Transform (DWT) and Stationary Wavelet Transform (SWT). The preprocessing performed using DTCWT identified more peptides compared to DWT and SWT. PMID:26004826

  14. Analysis of acetamiprid in vegetables using gas chromatography-tandem mass spectrometry.

    PubMed

    Mateu-Sánchez, Manuel; Moreno, Mercedes; Arrebola, F Javier; Martínez Vidal, José Luis

    2003-05-01

    A new analytical method has been validated for determining the insecticide acetamiprid in vegetables using gas chromatography (OC) and different mass spectrometric detection techniques, such as full-scan mass spectrometry (MS), and tandem mass spectrometry (MS/MS). For this purpose, a previous extraction of the vegetable sample was carried out with ethyl acetate. In GC-MS/MS, the lowest detectable concentration was 0.001 mg kg(-1), the average recovery rates at various fortification levels (0.015 and 0.030 mg kg(-1)) ranged between 82.4 and 85.7% and the relative standard deviations were lower than 12.2% in all cases. PMID:12769368

  15. Suitability of tandem-in-time mass spectrometry for polybrominated diphenylether measurement in fish and shellfish samples: comparison with high resolution mass spectrometry.

    PubMed

    Pirard, Catherine; De Pauw, Edwin; Focant, Jean-François

    2006-05-19

    The first part of the present study focused on the development of an alternative automated sample preparation method for the measurement of selected polybrominated diphenyl ethers (PBDEs) in fish and shellfish. A previously developed automated method has been further optimized and simplified to decrease blank levels and cost. Sorbent and solvent quantities have been significantly reduced without altering extract quality. The second part of the study consisted of comparing tandem-in-time quadrupole ion storage mass spectrometry (QISTMS/MS) to high resolution mass spectrometry (HRMS) for the isotope dilution (ID) measurement step after gas chromatography (GC) separation. Both mass spectrometric methods performed similarly in terms of accuracy but better precision was observed for HRMS. Although better sensitivity can be attained with the high resolution sector instrument, method limits of quantification (mLOQs) were very similar for both approaches as they were dependent on the procedural blanks levels. The mLOQ values ranged between 0.04 and 3.56 ng/g fat, depending on the congener. They allowed the unambiguous identification and quantification of all target analytes, except for BDE-183, in most considered fish extracts. An analytical procedure based on rapid automated sample preparation and QISTMS/MS appeared to be suitable for the measurement of PBDEs in fish and shellfish speciment under quality assurance/quality control (QA/QC) criteria. PMID:16564052

  16. Design and performance of an instrument for electron impact tandem mass spectrometry and action spectroscopy of mass/charge selected macromolecular ions stored in RF ion trap*

    NASA Astrophysics Data System (ADS)

    Ranković, Milos Lj.; Giuliani, Alexandre; Milosavljević, Aleksandar R.

    2016-06-01

    A new apparatus was designed, coupling an electron gun with a linear quadrupole ion trap mass spectrometer, to perform m/ z (mass over charge) selected ion activation by electron impact for tandem mass spectrometry and action spectroscopy. We present in detail electron tracing simulations of a 300 eV electron beam inside the ion trap, design of the mechanical parts, electron optics and electronic circuits used in the experiment. We also report examples of electron impact activation tandem mass spectra for Ubiquitin protein, Substance P and Melittin peptides, at incident electron energies in the range from 280 eV to 300 eV.

  17. Liquid chromatography-tandem mass spectrometry to determine the stability of collagen pentapeptide (KTTKS) in rat skin.

    PubMed

    Park, Eun Ji; Kim, Myung Sun; Choi, Yun Lim; Shin, Young-Hee; Lee, Hye Suk; Na, Dong Hee

    2012-09-15

    The objective of this study was to develop a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to determine the stability of collagen pentapeptide (KTTKS), which is a subfragment of collagen and has been proved to promote the extracellular release of collagen in skin fibroblast, in rat skin. The chromatographic condition was optimized on an Acclaim C-18 column (2.1 mm × 150 mm, 3 μm) under isocratic elution using a mobile phase consisting of deionized water and acetonitrile (87:13, v/v) mixture containing 5mM pentafluoropropionic acid as an ion-pairing reagent. The quantitation of KTTKS was performed on a triple quadrupole mass spectrometer in multiple reaction monitoring mode. The calibration curve showed good linearity in the concentration range of 0.05-10.0 μg/mL (r(2)>0.999). The intra- and inter-day precisions were 0.8-6.5% and 2.4-5.8%, respectively, and the intra- and inter-day accuracies were 96.3-102.7% and 92.8-98.5%, respectively. The developed LC-MS/MS method was successfully applied to investigate the degradation rate and sites of KTTKS in rat skin homogenate. KTTKS was found to be very susceptible to the peptide bond cleavage by aminopeptidases present in the skin. PMID:22921149

  18. Stable isotope labeling tandem mass spectrometry (SILT): integration with peptide identification and extension to data-dependent scans.

    PubMed

    Elbert, Donald L; Mawuenyega, Kwasi G; Scott, Evan A; Wildsmith, Kristin R; Bateman, Randall J

    2008-10-01

    Quantitation of relative or absolute amounts of proteins by mass spectrometry can be prone to large errors. The use of MS/MS ion intensities and stable isotope labeling, which we term stable isotope labeling tandem mass spectrometry (SILT), decreases the effects of contamination from unrelated compounds. We present a software package (SILTmass) that automates protein identification and quantification by the SILT method. SILTmass has the ability to analyze the kinetics of protein turnover, in addition to relative and absolute protein quantitation. Instead of extracting chromatograms to find elution peaks, SILTmass uses only scans in which a peptide is identified and that meet an ion intensity threshold. Using only scans with identified peptides, the accuracy and precision of SILT is shown to be superior to precursor ion intensities, particularly at high or low dilutions of the isotope labeled compounds or with low amounts of protein. Using example scans, we demonstrate likely reasons for the improvements in quantitation by SILT. The appropriate use of variable modifications in peptide identification is described for measurement of protein turnover kinetics. The combination of identification with SILT facilitates quantitation without peak detection and helps to ensure the appropriate use of variable modifications for kinetics experiments. PMID:18774841

  19. Liquid chromatography-tandem mass spectrometric assay for the light sensitive survivin suppressant sepantronium bromide (YM155) in mouse plasma.

    PubMed

    Dolman, M Emmy M; den Hartog, Ilona J M; Molenaar, Jan J; Schellens, Jan H M; Beijnen, Jos H; Sparidans, Rolf W

    2014-04-01

    A quantitative bioanalytical liquid chromatography-tandem mass spectrometric (LC-MS/MS) assay for sepantronium bromide (YM155), an inhibitor of survivin, was developed and validated. Under reduced light exposure, plasma samples were pre-treated using protein precipitation with acetonitrile containing AT7519 as internal standard. After dilution with water, the extract was directly injected into the reversed-phase liquid chromatographic system. The eluate was transferred into the electrospray interface with positive ionization and compounds detected in the selected reaction monitoring mode of a triple quadrupole mass spectrometer. The assay was validated in a 0.5-100ng/ml calibration range with r(2)=0.9981±0.0007 using double logarithmic calibration (n=5). Within day precisions (n=6) were 3.6-8.8% and between day (3 days; n=18) precisions 6.5-11.1%. Accuracies were between 92 and 111% for the whole calibration range. The light sensitive drug sepantronium was sufficiently stable under all relevant analytical conditions. Finally, the assay was successfully used to determine plasma drug levels in mice after administration of sepantronium bromide by continuous infusion from subcutaneously implanted osmotic pumps. PMID:24518133

  20. Simultaneous determination of six phenolic constituents of danshen in human serum using liquid chromatography/tandem mass spectrometry.

    PubMed

    Li, Xiaochuan; Yu, Chen; Cai, Yongbao; Liu, Gangyi; Jia, Jingying; Wang, Yiping

    2005-06-01

    The six phenolic constituents are water-soluble components extracted from the Chinese medical herb danshen, the dried roots of Salvia miltiorrhiza Bunge (Labiatae). An liquid chromatography/tandem mass spectrometry (LC/MS/MS)-based method has been developed for the simultaneous quantification of six phenolic constituents of danshen (magnesium lithospermate B (MLB), rosmarinic acid (RA) and lithospermic acid (LA), caffeic acid (CAA), protocatechuic aldehyde (3,4-dihydroxybenzaldehyde, Pal), 3,4-dihydroxyphenyllactic acid (danshensu)) in human serum with chloramphenicol as internal standard. The serum samples were treated by special liquid-liquid extraction, and the analytes were determined using electrospray negative ionization mass spectrometry in the multiple reaction monitoring (MRM) mode, with sufficient sensitivity to allow analysis of human serum samples generated following administration of a clinically relevant dose. Good linearity over the range 8-2048 ng/mL for six phenolic constituents was observed. The intra- and inter-day precisions (CV) of analysis were <13%, and the accuracy ranged from 88 to 116%. This quantitation method was successfully applied to a pharmacokinetic study of i.v. drip infusion of Danshen injection fluid in human. PMID:15866491

  1. Optimized ultra performance liquid chromatography tandem high resolution mass spectrometry method for the quantification of paraquat in plasma and urine.

    PubMed

    Lu, Haihua; Yu, Jing; Wu, Linlin; Xing, Jingjing; Wang, Jun; Huang, Peipei; Zhang, Jinsong; Xiao, Hang; Gao, Rong

    2016-08-01

    A simple, sensitive and specific ultra performance liquid chromatography coupled to electrospray tandem high resolution mass spectrometry (UPLC-ESI-HRMS/MS) method has been developed and validated for quantification of paraquat in plasma and urine. The sample preparation was carried out by one-step protein precipitation with acetonitrile. The paraquat was separated with a HILIC column in 10min. Detection was performed using Q Exactive Orbitrap mass spectrometer by Targeted-MS/MS scan mode. Methodological parameters, such as ammonium formate concentration, formic acid concentration, spray voltage, capillary temperature, heater temperature and normalized collision energy were optimized to achieve the highest sensitivity. The calibration curve was linear over the concentration range of LOQ-1000ng/mL. LOD was 0.1 and 0.3ng/mL, LOQ was 0.3 and 0.8ng/mL for urine and plasma, respectively. The intra- and inter-day precisions were <7.97% and 4.78% for plasma and urine. The accuracies were within the range 93.51-100.90%. The plasma and urine matrices had negligible relative matrix effect in this study. This method was successfully applied to determine paraquat concentration in plasma samples with hemoperfusion from 5 suspected paraquat poisoning patients. PMID:27270261

  2. Liquid Chromatography with Tandem Mass Spectrometry: A Sensitive Method for the Determination of Dehydrodiisoeugenol in Rat Cerebral Nuclei.

    PubMed

    Zhang, You-Bo; Yang, Xin-Bao; Yang, Xiu-Wei; Xu, Wei; Li, Fei; Gonzezal, Frank J

    2016-01-01

    A new liquid chromatography-tandem mass spectrometry (LC-MS/MS) method is developed for the quantification of dehydrodiisoeugenol (DDIE) in rat cerebral nuclei after single intravenous administration. DDIE and daidzein (internal standard) were separated on a Diamonsil™ ODS C18 column with methanol-water containing 0.1% formic acid (81:19, v/v) as a mobile phase. Detection of DDIE was performed on a positive electrospray ionization source using a triple quadrupole mass spectrometer. DDIE and daidzein were monitored at m/z 327.2→188.0 and m/z 255.0→199.2, respectively, in multiple reaction monitoring mode. This method enabled quantification of DDIE in various brain areas, including, cortex, hippocampus, striatum, hypothalamus, cerebellum and brainstem, with high specificity, precision, accuracy, and recovery. The data herein demonstrate that our new LC-MS/MS method is highly sensitive and suitable for monitoring cerebral nuclei distribution of DDIE. PMID:27005607

  3. High performance liquid chromatography-tandem mass spectrometric determination of rupatadine in human plasma and its pharmacokinetics.

    PubMed

    Tian, Yuan; Zhang, Jingjing; Lin, Hui; Liang, Jiabi; Zhang, Zunjian; Chen, Yun

    2008-08-01

    A simple, rapid, sensitive and selective liquid chromatographic-tandem mass spectrometric (LC-MS/MS) method was developed and validated for the quantification of rupatadine in human plasma using estazolam as internal standard (IS). Following liquid-liquid extraction, the analytes were separated using a mobile phase of methanol-ammonium acetate (pH 2.2; 5mM) (50:50, v/v) on a reverse phase C18 column and analyzed by a triple-quadrupole mass spectrometer in the positive ion and multiple reaction monitoring (MRM) mode, m/z 416-->309 for rupatadine and m/z 295-->267 for the IS. The assay exhibited a linear dynamic range of 0.1-100 ng/ml for rupatadine in human plasma. The lower limit of quantification (LLOQ) was 0.1 ng/ml with a relative standard deviation of less than 20%. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. The validated LC-MS/MS method has been successfully applied to study the pharmacokinetics of rupatadine in healthy volunteers. PMID:18472381

  4. Analysis of Androgenic Steroids in Environmental Waters by Large-volume Injection Liquid Chromatography Tandem Mass Spectrometry

    PubMed Central

    Backe, Will J.; Ort, Christoph; Brewer, Alex J.; Field, Jennifer A.

    2014-01-01

    A new method was developed for the analysis of natural and synthetic androgenic steroids and their selected metabolites in aquatic environmental matrices using direct large-volume injection (LVI) high performance liquid chromatography (HPLC) tandem mass spectrometry (MS/MS). Method accuracy ranged from 88 to 108% for analytes with well-matched internal standards. Precision, quantified by relative standard deviation (RSD), was less than 12%. Detection limits for the method ranged from 1.2 to 360 ng/L. The method was demonstrated on a series of 1-hr composite wastewater influent samples collected over a day with the purpose of assessing temporal profiles of androgen loads in wastewater. Testosterone, androstenedione, boldenone, and nandrolone were detected in the sample series at concentrations up to 290 ng/L and loads up to 535 mg. Boldenone, a synthetic androgen, had a temporal profile that was strongly correlated to testosterone, a natural human androgen, suggesting its source may be endogenous. An analysis of the sample particulate fraction revealed detectable amounts of sorbed testosterone and androstenedione. Androstenedione sorbed to the particulate fraction accounted for an estimated five to seven percent of the total androstenedione mass. PMID:21391574

  5. Determination of antimigraine compounds rizatriptan, zolmitriptan, naratriptan and sumatriptan in human serum by liquid chromatography/electrospray tandem mass spectrometry.

    PubMed

    Vishwanathan, K; Bartlett, M G; Stewart, J T

    2000-01-01

    Development of a rapid, sensitive and selective method for the determination of antimigraine drugs from human serum is essential for understanding the pharmacokinetics of these drugs when administered concurrently. Solid phase extraction (SPE) using Oasis HLB was used to extract the drugs (sumatriptan, naratriptan, zolmitriptan and rizatriptan) and the internal standard bufotenine from serum. A method based on liquid chromatography/tandem mass spectrometry (LC/MS/MS) was developed and validated to simultaneously quantitate these antimigraine drugs from human serum. The precursor and major product ions of the analytes were monitored on a triple quadrupole mass spectrometer with positive ion electrospray ionization (ESI) in the multiple reaction monitoring (MRM) mode. The base peak in all the analytes is formed by alpha cleavage associated with protonation of the secondary amine. Mechanisms for the formation of the collision-induced dissociation products of these antimigraine compounds are proposed. Linear calibration curves were generated from 1-100 ng/mL with all coefficients of determination greater than 0.99. The inter- and intraday precision (%RSD) were less than 9.3% and accuracy (%error) was less than 9.8% for all components. The limits of detection (LOD) for the method were 250 pg/mL for sumatriptan and 100 pg/mL for the remaining analytes based on a signal-to-noise ratio of 3. PMID:10637423

  6. Direct determination of glyphosate, glufosinate, and AMPA in soybean and corn by liquid chromatography/tandem mass spectrometry.

    PubMed

    Chamkasem, Narong; Harmon, Tiffany

    2016-07-01

    Glyphosate, glufosinate, and aminomethylphosphonic acid (AMPA) are amphoteric, low mass, high water soluble, and do not have chromophore. They are very difficult to be retained on a reversed phase HPLC and detected by UV or fluorescence detectors. A liquid chromatography/tandem mass spectrometry (LC-MS/MS) method was developed to determine these analytes in soybean and corn using a reversed phase with weak anion-exchange and cation-exchange mixed-mode Acclaim™ Trinity™ Q1 column. The sample was shaken with water containing ethylenediaminetetraacetic acid disodium salt (Na2EDTA) and acetic acid for 10 min to precipitate protein and extract the analytes into the solution. The supernatant was passed thru an Oasis HLB SPE to retain suspended particulates and non-polar interferences. The sample was directly injected and analyzed in 6 min by LC-MS/MS with no sample concentration or derivatization steps. Three isotopically labeled internal standards corresponding to each analyte were used to counter matrix suppression effect. Linearity of the detector response with a minimum coefficient of determination (R (2)) of more than 0.995 was demonstrated in the range of 10 to 1000 ng/mL for each analyte. Accuracy (recovery %) and precision (relative standard deviation or RSD %) were evaluated at the fortification levels of 0.1, 0.5, and 2 μg/g in seven replicates in both soybean and corn samples. PMID:27150204

  7. Context-Sensitive Markov Models for Peptide Scoring and Identification from Tandem Mass Spectrometry

    PubMed Central

    Grover, Himanshu; Wallstrom, Garrick; Wu, Christine C.

    2013-01-01

    Abstract Peptide and protein identification via tandem mass spectrometry (MS/MS) lies at the heart of proteomic characterization of biological samples. Several algorithms are able to search, score, and assign peptides to large MS/MS datasets. Most popular methods, however, underutilize the intensity information available in the tandem mass spectrum due to the complex nature of the peptide fragmentation process, thus contributing to loss of potential identifications. We present a novel probabilistic scoring algorithm called Context-Sensitive Peptide Identification (CSPI) based on highly flexible Input-Output Hidden Markov Models (IO-HMM) that capture the influence of peptide physicochemical properties on their observed MS/MS spectra. We use several local and global properties of peptides and their fragment ions from literature. Comparison with two popular algorithms, Crux (re-implementation of SEQUEST) and X!Tandem, on multiple datasets of varying complexity, shows that peptide identification scores from our models are able to achieve greater discrimination between true and false peptides, identifying up to ∼25% more peptides at a False Discovery Rate (FDR) of 1%. We evaluated two alternative normalization schemes for fragment ion-intensities, a global rank-based and a local window-based. Our results indicate the importance of appropriate normalization methods for learning superior models. Further, combining our scores with Crux using a state-of-the-art procedure, Percolator, we demonstrate the utility of using scoring features from intensity-based models, identifying ∼4-8 % additional identifications over Percolator at 1% FDR. IO-HMMs offer a scalable and flexible framework with several modeling choices to learn complex patterns embedded in MS/MS data. PMID:23289783

  8. Positive and negative tandem mass spectrometric fingerprints of lipids from the halophilic Archaea Haloarcula marismortuis⃞

    PubMed Central

    de Souza, Lauro M.; Müller-Santos, Marcelo; Iacomini, Marcello; Gorin, Philip A. J.; Sassaki, Guilherme L.

    2009-01-01

    Lipids from the extremely halophilic Archaea, Haloarcula marismortui, contain abundant phytanyl diether phospholipids, namely archaetidic acid (AA), archaetidylglycerol (AG), archaetidylglycerosulfate (AGS), with mainly archaetidylglycerophosphate methyl ester (AGP-Me). These were accompanied by a triglycosyl archaeol (TGA), lacking characteristic sulfate groups. Tandem-mass spectrometry was employed to provide fingerprints for identifying these known lipids, as well as small amounts of unsaturated phospholipids. These contained 3 and 6 double bonds in their archaeol moiety, suggested by negative tandem-MS of intact phospholipids, as indicated by differences between their pseudo-molecular ion and specific fragment ions designated as π2. The core ether lipids were confirmed by electrospray ionization mass spectrometry (ESI-MS) as 2,3-di-O-phytanyl-sn-glycerol (C20, C20), which gave rise to a precursor-ion at m/z 660 [M+Li]+, and its fragment ion at m/z 379 [M+Li]+, consistent with mono-O-phytanyl-glycerol. Furthermore, lithiated ions at m/z 654 (MS1), 379 (MS2) and m/z 648 (MS1), 373 (MS2), combined with 1H/13C NMR chemical shifts at δ 5.31-121.6 (C2/2′-H2/2′), 5.08-124.9 (C6/6′-H6/6′) and 5.10-126.0 (10/10′-H10/10′) confirmed the presence of unsaturated homologs of archaeol. We carried out a comprehensive study on the lipids present in cells of H. marismortui. We used positive and negative ESI-MS with tandem-MS, which served as a fingerprint analysis for identifying the majority of component lipids. PMID:19258281

  9. Screening of newborn infants for cholestatic hepatobiliary disease with tandem mass spectrometry

    PubMed Central

    Mushtaq, Imran; Logan, Stuart; Morris, Michael; Johnson, Andrew W; Wade, Angie M; Kelly, Deirdre; Clayton, Peter T

    1999-01-01

    Objective To assess the feasibility of screening for cholestatic hepatobiliary disease and extrahepatic biliary atresia by using tandem mass spectrometry to measure conjugated bile acids in dried blood spots obtained from newborn infants at 7-10 days of age for the Guthrie test. Setting Three tertiary referral clinics and regional neonatal screening laboratories. Design Unused blood spots from the Guthrie test were retrieved for infants presenting with cholestatic hepatobiliary disease and from the two cards stored on either side of each card from an index child. Concentrations of conjugated bile acids measured by tandem mass spectrometry in the two groups were compared. Main outcome measures Concentrations of glycodihydroxycholanoates, glycotrihydroxycholanoates, taurodihydroxycholanoates, and taurotrihydroxycholanoates. Receiver operator curves were plotted to determine which parameter (or combination of parameters) would best predict the cases of cholestatic hepatobiliary disease and extrahepatic biliary atresia. The sensitivity and specificity at a selection of cut off values for each bile acid species and for total bile acid concentrations for the detection of the two conditions were calculated. Results 218 children with cholestatic hepatobiliary disease were eligible for inclusion in the study. Two children without a final diagnosis and five who presented at <14 days of age were excluded. Usable blood spots were obtained from 177 index children and 708 comparison children. Mean concentrations of all four bile acid species were significantly raised in children with cholestatic hepatobiliary disease and extrahepatic biliary atresia compared with the unaffected children (P<0.0001). Of 177 children with cholestatic hepatobiliary disease, 104 (59%) had a total bile acid concentration >33 μmol/l (97.5th centile value for comparison group). Of the 61 with extrahepatic biliary atresia, 47 (77%) had total bile acid concentrations >33

  10. On-line monitoring of bioreactions of Bacillus polymyxa and Klebsiella oxytoca by membrane introduction tandem mass spectrometry with flow injection analysis sampling

    SciTech Connect

    Hayward, M.J.; Kotiaho, Tapio; Lister, A.K.; Cooks, R.G.; Austin, G.D.; Narayan, Ramani; Tsao, G.T. )

    1990-09-01

    Membrane introduction mass spectrometry with flow injection analysis sampling has been utilized for on-line monitoring of the major products and the volatile metabolites of fermentation of the Bacillus polymyxa and Klebsiella oxytoca organisms. A flow injection sampling system was used to rapidly deliver fermentation broth or an external standard to the mass spectrometer. Analyte introduction occurred via a direct insertion membrane probe in which the aqueous solutions flowed past a membrane located within the ion source of the mass spectrometer. For both organisms, concentrations of the liquid-phase products acetic acid, acetoin, 2,3-butanediol, and ethanol, were monitored as a function of time after permeation through the membrane and ionization by chemical ionization. Tandem mass spectrometry confirmed that these measurements were made without interference. Off-line gas chromatography was utilized to test the accuracy of these measurements, and excellent agreement was found. The use of tandem mass spectrometry has allowed the detection of additional compounds that were previously not known to be present in measurable amounts.

  11. Accurate and Efficient Resolution of Overlapping Isotopic Envelopes in Protein Tandem Mass Spectra

    PubMed Central

    Xiao, Kaijie; Yu, Fan; Fang, Houqin; Xue, Bingbing; Liu, Yan; Tian, Zhixin

    2015-01-01

    It has long been an analytical challenge to accurately and efficiently resolve extremely dense overlapping isotopic envelopes (OIEs) in protein tandem mass spectra to confidently identify proteins. Here, we report a computationally efficient method, called OIE_CARE, to resolve OIEs by calculating the relative deviation between the ideal and observed experimental abundance. In the OIE_CARE method, the ideal experimental abundance of a particular overlapping isotopic peak (OIP) is first calculated for all the OIEs sharing this OIP. The relative deviation (RD) of the overall observed experimental abundance of this OIP relative to the summed ideal value is then calculated. The final individual abundance of the OIP for each OIE is the individual ideal experimental abundance multiplied by 1 + RD. Initial studies were performed using higher-energy collisional dissociation tandem mass spectra on myoglobin (with direct infusion) and the intact E. coli proteome (with liquid chromatographic separation). Comprehensive data at the protein and proteome levels, high confidence and good reproducibility were achieved. The resolving method reported here can, in principle, be extended to resolve any envelope-type overlapping data for which the corresponding theoretical reference values are available. PMID:26439836

  12. Screening newborns for metabolic disorders based on targeted metabolomics using tandem mass spectrometry.

    PubMed

    Yoon, Hye-Ran

    2015-09-01

    The main purpose of newborn screening is to diagnose genetic, metabolic, and other inherited disorders, at their earliest to start treatment before the clinical manifestations become evident. Understanding and tracing the biochemical data obtained from tandem mass spectrometry is vital for early diagnosis of metabolic diseases associated with such disorders. Accordingly, it is important to focus on the entire diagnostic process, including differential and confirmatory diagnostic options, and the major factors that influence the results of biochemical analysis. Compared to regular biochemical testing, this is a complex process carried out by a medical physician specialist. It is comprised of an integrated program requiring multidisciplinary approach such as, pediatric specialist, expert scientist, clinical laboratory technician, and nutritionist. Tandem mass spectrometry is a powerful tool to improve screening of newborns for diverse metabolic diseases. It is likely to be used to analyze other treatable disorders or significantly improve existing newborn tests to allow broad scale and precise testing. This new era of various screening programs, new treatments, and the availability of detection technology will prove to be beneficial for the future generations. PMID:26512346

  13. Determination of bromate in drinking water by ultraperformance liquid chromatography-tandem mass spectrometry.

    PubMed

    Alsohaimi, Ibrahim Hotan; Alothman, Zeid Abdullah; Khan, Mohammad Rizwan; Abdalla, Mohammad Abulhassan; Busquets, Rosa; Alomary, Ahmad Khodran

    2012-10-01

    Bromate is a byproduct formed as a result of disinfection of bromide-containing source water with ozone or hypochlorite. The International Agency for Research on Cancer has recognized bromate as a possible human carcinogen, thus it is essential to determine in drinking water. Present work highlights a development of sensitive and fast analytical method for bromate determination in drinking water by using ultraperformance liquid chromatography-tandem mass spectrometry. The quality parameters of the developed method were established, obtaining very low limit of detection (0.01 ng/mL), repeatability and reproducibility have been found to be less than 3% in terms of relative standard deviation when analyzing a bromate standard at 0.05 μg/mL with 0.4 min analysis time. Developed method was applied for the analysis of metropolitan and bottled water from Saudi Arabia; 22 samples have been analyzed. Bromate was detected in the metropolitan water samples (from desalinization source) at concentrations ranging between 3.43 and 75.04 ng/mL and in the bottled water samples at concentrations ranging between 2.07 and 21.90 ng/mL. Moreover, in comparison to established analytical methods such as liquid chromatography-tandem mass spectrometry, the proposed method was found to be very sensitive, selective and rapid for the routine analysis of bromate at low level in drinking water. PMID:22815069

  14. Analysis of alcohols, as dimethylglycine esters, by electrospray ionization tandem mass spectrometry.

    PubMed

    Johnson, D W

    2001-03-01

    Dimethylglycine (DMG) esters are new derivatives for the rapid, sensitive and selective analysis of primary and secondary alcohols, in complex mixtures, by electrospray ionization tandem mass spectrometry (ESI-MS/MS). Their development was inspired by the use of the complementary dimethylaminoethyl esters for the trace, rapid analysis of fatty acids. DMG esters are simply prepared by heating a dichloromethane solution of the imidazolide of dimethylglycine, containing triethylamine, and an alcohol. DMG esters of long-chain fatty alcohols, isoprenoidal alcohols and hydroxy-acids are analysed by electrospray ionization tandem mass spectrometry with a precursor ion of m/z 104 scan. Diols, glyceryl esters, glyceryl ethers and some sterols are analysed by a neutral loss of 103 Da scan. Trimethylglycine (TMG) ester iodides, prepared by alkylation of DMG esters with methyl iodide, are more sensitive derivatives for molecules containing secondary alcohol groups, such as cholesterol and gibberellic acid. They are analysed by a precursor ion of m/z 118 scan. DMG or TMG derivatives were shown to be at least comparable and sometimes an order of magnitude more sensitive than N-methylpyridyl ether derivatives for ESI-MS/MS analysis of the different classes of alcohols. Applications of these derivatives for the diagnosis of inherited disorders and the analysis of natural products are presented. PMID:11312519

  15. Ultra performance liquid chromatography tandem mass spectrometry performance evaluation for analysis of antibiotics in natural waters.

    PubMed

    Tamtam, Fatima; Mercier, Fabien; Eurin, Joëlle; Chevreuil, Marc; Le Bot, Barbara

    2009-03-01

    An ultra performance liquid chromatography electrospray tandem mass spectrometry (UPLC/MS/MS) method was developed and validated for the determination of 17 antibiotics in natural waters in one single extraction and chromatographic procedure. Gradient separation conditions were optimised for 17 compounds belonging to five different antibiotic groups: quinolones (oxolinic acid, nalidixic acid, pipemidic acid, flumequine), fluoroquinolones (enoxacin, ciprofloxacin, norfloxacin, ofloxacin, enrofloxacin, sarafloxacin, danofloxacin, difloxacin, lomefloxacin), sulphonamides (sulphamethoxazole, sulphamethazine), nitro-imidazole (ornidazole) and diaminopyrimidine (trimethoprim). The separation of all compounds, obtained using a 1.7 microm particle size column (100 mm x 2.1 mm), was achieved within 10 min time. Water samples were adjusted to pH 7 and extracted using Oasis hydrophilic-lipophilic balance (HLB) solid phase extraction cartridges. After elution with methanol and concentration, extracts were injected in a C18 column (Acquity UPLC BEH C18) and detected by tandem mass spectrometry. Average recovery from 100 ng L(-1) fortified samples was higher than 70% for most of the compounds, with relative standard deviations below 20%. Performances of the method (recoveries, detection limit, quantification limit and relative standard deviation) and matrix effects were studied, and results obtained showed that method was suitable for routine analysis of antibiotics in surface water. Samples analysis from Seine River (France) confirmed the interest of antibiotic contamination evaluation in that area. PMID:19148627

  16. Screening newborns for metabolic disorders based on targeted metabolomics using tandem mass spectrometry

    PubMed Central

    2015-01-01

    The main purpose of newborn screening is to diagnose genetic, metabolic, and other inherited disorders, at their earliest to start treatment before the clinical manifestations become evident. Understanding and tracing the biochemical data obtained from tandem mass spectrometry is vital for early diagnosis of metabolic diseases associated with such disorders. Accordingly, it is important to focus on the entire diagnostic process, including differential and confirmatory diagnostic options, and the major factors that influence the results of biochemical analysis. Compared to regular biochemical testing, this is a complex process carried out by a medical physician specialist. It is comprised of an integrated program requiring multidisciplinary approach such as, pediatric specialist, expert scientist, clinical laboratory technician, and nutritionist. Tandem mass spectrometry is a powerful tool to improve screening of newborns for diverse metabolic diseases. It is likely to be used to analyze other treatable disorders or significantly improve existing newborn tests to allow broad scale and precise testing. This new era of various screening programs, new treatments, and the availability of detection technology will prove to be beneficial for the future generations. PMID:26512346

  17. Determination of ecliptasaponin A in rat plasma and tissues by liquid chromatography-tandem mass spectrometry.

    PubMed

    Zhao, Jing; Liu, Erwei; Han, Lifeng; Wang, Linlin; Zhang, Yi; Wang, Tao; Fang, Shiming; Gao, Xiumei

    2016-06-01

    A sensitive, rapid and specific high-performance liquid chromatography tandem mass spectrometry method (HPLC-MS/MS) was developed to determine ecliptasaponin A in rat plasma and tissues after oral administration. Ginsenoside Rg1 was used as the internal standard (IS). The plasma and tissues samples were prepared by liquid-liquid extraction with ethyl acetate and separated on an Eclipse Plus C18 column (2.1 mm × 150 mm, 5 µm) at a flow rate of 0.4 mL/min using acetonitrile and water (containing 0.05% acetic acid) as the mobile phase. The tandem mass detection was carried out with eletrospray ionization in negative mode. Quantification was performed by using multiple reaction monitoring (MRM), which monitored the fragmentation of m/z 633.4→587.2 for ecliptasaponin A and m/z 859.4→637.4 for the IS. The calibration curves obtained were linear in different matrices, and the lower limit of quantification (LLOQ) achieved was 0.5 ng/mL both for rat plasma and tissues. The intra- and inter-day precisions were below 15%. This method was successfully applied to pharmacokinetic study of ecliptasaponin A in rat plasma and tissues after oral administration. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26378987

  18. Triacylglycerol profile in cocoa liquors using MALDI-TOF and LC-ESI tandem mass spectrometry.

    PubMed

    Bono, Luca; Seraglia, Roberta; Roverso, Marco; Di Carro, Marina; Magi, Emanuele

    2014-09-01

    Triacylglycerols are responsible for chocolate's peculiar melting behavior: the type and position of fatty acids on the glycerol molecule strongly affect the melting range of cocoa butter. For this reason, the characterization of triglyceride composition in cocoa products is particularly important. In this work, triacylglycerols extracted from cocoa liquor samples were analyzed by matrix-assisted laser desorption/ionization time-of-flight (TOF) and electrospray ionization tandem mass spectrometry (MS/MS) coupled to liquid chromatography. Extracted samples were initially analyzed by direct injection in MS to obtain information on triglyceride molecular weights; relevant MS parameters were optimized, and the possible formation of the adducts [M + Na](+) and [M + NH(4)](+) was studied. Tandem mass experiments (both with triple quadrupole and TOF/TOF) were performed to study the fragmentation pathways (in particular, the loss of palmitic, stearic and oleic acid) and identify the triacylglycerols in cocoa liquors. Some signals of the spectra obtained with both MS techniques could indicate the presence of diacylglycerols in the cocoa extract, but different experimental evidences demonstrated that they were generated by the in-source fragmentation of triglycerides. A nonaqueous reversed-phase chromatographic separation was also developed and used to support the identification of the analytes; nine triacylglycerols were recognized in the cocoa liquor extracts. The three different batches of Ecuador cocoa liquor did not show significant differences in the triacylglycerol profile. PMID:25230186

  19. [Determination of azaspiracid-1 in shellfishes by liquid chromatography with tandem mass spectrometry].

    PubMed

    Yao, Jianhua; Tan, Zhijun; Zhou, Deqing; Guo, Mengmeng; Xing, Lihong; Yang, Shouguo

    2010-04-01

    A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the determination of azaspiracid-1 (AZA1) in shellfishes was described. After being extracted using methanol and water (80:20, v/v), the extract was cleaned-up by solid phase extraction (SPE) of MAX column, then determined by using a reversed-phase high performance liquid chromatography (HPLC) isocratic program coupled with tandem mass spectrometry in selected reaction monitoring mode (SRM). And the extract was eluted with acetonitrile-water (80:20, v/v) on an Atlantis dC18 column (150 mm x 4.6 mm, 5.0 microm) with mobile phase containing 50 mmol/L formic acid and 2 mmol/L ammonium formate. The detection limit was 11.00 pg/g. The calibration curve was linear (R2 = 0.998 1) in the range of 48.85-2 442 ng/L. The average recoveries of the shellfish tissue extract at three spiked levels (36.64, 73.27, 146.54 pg/g) were from 75.8% to 82.5% (n = 6). The relative standard derivations (RSDs) were less than 10%. The 112 shellfish samples from the local markets of Dalian, Qingdao, Guangzhou were detected by the method, and AZA1 was detected in some samples from Dalian and Guangzhou. The results showed that the method is simple, rapid, sensitive and suitable for the detection of AZA1 in shellfishes. PMID:20712117

  20. Improved Reagents for Newborn Screening of Mucopolysaccharidosis Types I, II, and VI by Tandem Mass Spectrometry

    PubMed Central

    2015-01-01

    Tandem mass spectrometry for the multiplex and quantitative analysis of enzyme activities in dried blood spots on newborn screening cards has emerged as a powerful technique for early assessment of lysosomal storage diseases. Here we report the design and process-scale synthesis of substrates for the enzymes α-l-iduronidase, iduronate-2-sulfatase, and N-acetylgalactosamine-4-sulfatase that are used for newborn screening of mucopolysaccharidosis types I, II, and VI. The products contain a bisamide unit that is hypothesized to readily protonate in the gas phase, which improves detection sensitivity by tandem mass spectrometry. The products contain a benzoyl group, which provides a useful site for inexpensive deuteration, thus facilitating the preparation of internal standards for the accurate quantification of enzymatic products. Finally, the reagents are designed with ease of synthesis in mind, thus permitting scale-up preparation to support worldwide newborn screening of lysosomal storage diseases. The new reagents provide the most sensitive assay for the three lysosomal enzymes reported to date as shown by their performance in reactions using dried blood spots as the enzyme source. Also, the ratio of assay signal to that measured in the absence of blood (background) is superior to all previously reported mucopolysaccharidosis types I, II, and VI assays. PMID:24694010

  1. Determination of biogenic amines in beer and wine by capillary electrophoresis-tandem mass spectrometry.

    PubMed

    Daniel, Daniela; Dos Santos, Vagner Bezerra; Vidal, Denis Tadeu Rajh; do Lago, Claudimir Lucio

    2015-10-16

    A capillary electrophoresis-tandem mass spectrometry (CE-MS/MS) method for the simultaneous assessment of nine biogenic amines (spermine, spermidine, putrescine, cadaverine, histamine, phenylethylamine, tryptamine, tyramine, and urocanic acid) in commercial samples of beer and wine is introduced. The samples were submitted to a simple clean-up step with poly(vinylpolypyrrolidone) followed by filtration. Electrophoretic separation in a polyvinyl alcohol (PVA)-coated capillary using 0.5 mol L(-1) acetic acid (pH 2.5) as background electrolyte and detection by electrospray-tandem mass spectrometry was employed. The range of the correlation coefficients of the calibration curves of the analyzed compounds was 0.996-0.999, and the limits of detection and limits of quantification were in the range of 1-2 μg L(-1) and 3-8 μg L(-1), respectively. The recovery values for samples spiked at three concentration levels (0.2, 0.5, and 1.0 mg L(-1)) ranged from 87 to 113% with standard deviation not greater than 5.8%. The use of a PVA-coated silica capillary allows suppressing the electroosmotic flow and, consequently, increasing of the separation efficiency. The method was successfully used to determine biogenic amines in commercial samples of beer and wine. PMID:26362807

  2. Liquid chromatographic tandem mass spectrometric determination of five coccidiostats in poultry eggs and feed.

    PubMed

    Mortier, Leen; Daeseleire, Els; Van Peteghem, Carlos

    2005-06-25

    A method is described which permits the quantitative detection of the chemical coccidiostats halofuginone, robenidine, diclazuril, nicarbazin and dimetridazole and its main metabolite 2-hydroxydimetridazole in poultry eggs and feed. Sample preparations were kept very simple and are based upon extraction with an organic solvent. Sample extracts were injected into the liquid chromatography tandem mass spectrometry (LC-MS/MS) system on a C18 column and a gradient elution was performed. Dimetridazole-D3 and diclazuril-bis, a structural analogue of diclazuril, were used as internal standards. Detection was performed on a triple quadrupole mass spectrometer in the selected reaction monitoring mode after ionisation in the positive or negative electrospray ionisation mode. Argon was applied as collision gas for collision induced dissociation. Validation of the methods was performed based on Commission Decision 2002/657/EC [Official Journal of the European Communities L221 (2002) 8]. PMID:15893963

  3. Quantification of galactosylsphingosine in the twitcher mouse using electrospray ionization-tandem mass spectrometry.

    PubMed

    Whitfield, P D; Sharp, P C; Taylor, R; Meikle, P

    2001-12-01

    Globoid cell leukodystrophy (Krabbe disease) is an autosomal recessive inherited neurodegenerative disorder caused by the deficiency of the lysosomal enzyme beta-galactosylceramidase. The pathogenesis of the disorder has been proposed to arise from the accumulation of the cytotoxic metabolite galactosylsphingosine (psychosine). The twitcher mouse is a naturally occurring murine model of globoid cell leukodystrophy. We have developed a rapid, sensitive, and specific mass spectrometric method for determining the galactosylsphingosine concentration in the tissues of twitcher mice. Galactosylsphingosine is extracted from the tissues in methanol, isolated using strong cation-exchange and C18 solid-phase extraction chromatography, and then directly analyzed using electrospray ionization-tandem mass spectrometry. A lactosylsphingosine internal standard has been employed for quantification. The assay demonstrated significant accumulation of galactosylsphingosine in the brain, spinal cord, and kidney of twitcher mice. It is anticipated that this method may be of use in the monitoring of experimental therapies for globoid cell leukodystrophy. PMID:11734583

  4. Recent advances of liquid chromatography-(tandem) mass spectrometry in clinical and forensic toxicology - An update.

    PubMed

    Remane, Daniela; Wissenbach, Dirk K; Peters, Frank T

    2016-09-01

    Liquid chromatography (LC) coupled to mass spectrometry (MS) or tandem mass spectrometry (MS/MS) is a well-established and widely used technique in clinical and forensic toxicology as well as doping control especially for quantitative analysis. In recent years, many applications for so-called multi-target screening and/or quantification of drugs, poisons, and or their metabolites in biological matrices have been developed. Such methods have proven particularly useful for analysis of so-called new psychoactive substances that have appeared on recreational drug markets throughout the world. Moreover, the evolvement of high resolution MS techniques and the development of data-independent detection modes have opened new possibilities for applications of LC-(MS/MS) in systematic toxicological screening analysis in the so called general unknown setting. The present paper will provide an overview and discuss these recent developments focusing on the literature published after 2010. PMID:27452180

  5. Determination of albendazole sulfoxide in human plasma by using liquid chromatography-tandem mass spectrometry.

    PubMed

    Saraner, Nihal; Özkan, Güler Yağmur; Güney, Berrak; Alkan, Erkin; Burul-Bozkurt, Nihan; Sağlam, Onursal; Fikirdeşici, Ezgi; Yıldırım, Mevlüt

    2016-06-01

    A rapid, simple and sensitive method was developed and validated using liquid chromatography-tandem mass spectrometry (LC-MS/MS) for determination of albendazole sulfoxide (ABZOX) in human plasma. The plasma samples were extracted by protein precipitation using albendazole sulfoxide-d3 as internal standard (IS). The chromatographic separation was performed on Waters Xbridge C18Column (100×4.6mm, 3.5μm) with a mobile phase consisting of ammonia solution, water and methanol at a flow rate of 0.70mL/min. ABZOX was detected and identified by mass spectrometry with electrospray ionization (ESI) in positive ion and multiple-reaction monitoring (MRM) mode. The method was linear in the range of 3-1500ng/mL for ABZOX. This method was successfully applied to the bioequivalence study in human plasma samples. PMID:27060508

  6. Tandem mass spectrometric analysis of glyphosate, glufosinate, aminomethylphosphonic acid and methylphosphinicopropionic acid.

    PubMed

    Goodwin, Lee; Startin, James R; Goodall, David M; Keely, Brendan J

    2003-01-01

    A detailed MS(n) study of glyphosate, glufosinate and their main metabolites, aminomethylphosphonic acid and methylphosphinicopropionic acid, using an ion trap mass spectrometer, was performed. The analytes show good response in negative ion electrospray mass spectrometry (ES-MS) as [M-H](-) ions. Tandem-MS spectra reveal a wealth of structurally specific ions, allowing characterisation of the fragmentation pathways of the four analytes in their native form for the first time. The ions formed at each stage of fragmentation reveal ions common to each analyte, such as phosphinate, as well as analyte specific transitions. Simplex optimisation allows optimum trapping and fragmentation parameters to be determined leading to improved response for particular transitions and transition sequences, and revealing previously unseen ions. PMID:12717770

  7. Functional group composition of ambient and source organic aerosols determined by tandem mass spectrometry

    NASA Astrophysics Data System (ADS)

    Dron, J.; El Haddad, I.; Temime-Roussel, B.; Jaffrezo, J.-L.; Wortham, H.; Marchand, N.

    2010-04-01

    The functional group composition of various organic aerosols (OA) is being investigated using a recently developed analytical approach based on atmospheric pressure chemical ionisation-tandem mass spectrometry (APCI-MS/MS). The determinations of the three functional groups' contents are performed quantitatively by neutral loss (carboxylic and carbonyl groups) and precursor ion (nitro groups) scanning modes of a tandem mass spectrometer. Major organic aerosol sources are studied: vehicular emission and wood combustion for primary aerosol sources; and a secondary organic aerosol (SOA) produced through photo-oxidation of o-xylene. The results reveal significant differences in the functional group contents of these source aerosols. The laboratory generated SOA is dominated by carbonyls while carboxylics are preponderate in the wood combustion particles. On the other hand, vehicular emissions are characterised by a strong nitro content. The total amount of the three functional groups accounted for 1.7% (vehicular) to 13.5% (o-xylene photo-oxidation) of the organic carbon. The diagnostic functional group ratios are then used to tentatively differentiate sources of particles collected in an urban background environment located in an Alpine valley (Chamonix, France) during a strong winter pollution event. The three functional groups under study account for a total functionalisation rate of 2.2 to 3.8% of the organic carbon in this ambient aerosol, which is also dominated by carboxylic moieties. In this particular case study of a deep alpine valley during winter, we show that the nitro- and carbonyl-to-carboxylic diagnostic ratios can be a useful tool to distinguish the sources. In these conditions, the total OA concentrations are highly dominated by wood combustion OA. This result is confirmed by an organic markers source apportionment approach which assesses a wood burning organic carbon contribution of about 60%. Finally, examples of functional group mass spectra of all

  8. Automated Glycan Sequencing from Tandem Mass Spectra of N-Linked Glycopeptides.

    PubMed

    Yu, Chuan-Yih; Mayampurath, Anoop; Zhu, Rui; Zacharias, Lauren; Song, Ehwang; Wang, Lei; Mechref, Yehia; Tang, Haixu

    2016-06-01

    Mass spectrometry has become a routine experimental tool for proteomic biomarker analysis of human blood samples, partly due to the large availability of informatics tools. As one of the most common protein post-translational modifications (PTMs) in mammals, protein glycosylation has been observed to alter in multiple human diseases and thus may potentially be candidate markers of disease progression. While mass spectrometry instrumentation has seen advancements in capabilities, discovering glycosylation-related markers using existing software is currently not straightforward. Complete characterization of protein glycosylation requires the identification of intact glycopeptides in samples, including identification of the modification site as well as the structure of the attached glycans. In this paper, we present GlycoSeq, an open-source software tool that implements a heuristic iterated glycan sequencing algorithm coupled with prior knowledge for automated elucidation of the glycan structure within a glycopeptide from its collision-induced dissociation tandem mass spectrum. GlycoSeq employs rules of glycosidic linkage as defined by glycan synthetic pathways to eliminate improbable glycan structures and build reasonable glycan trees. We tested the tool on two sets of tandem mass spectra of N-linked glycopeptides cell lines acquired from breast cancer patients. After employing enzymatic specificity within the N-linked glycan synthetic pathway, the sequencing results of GlycoSeq were highly consistent with the manually curated glycan structures. Hence, GlycoSeq is ready to be used for the characterization of glycan structures in glycopeptides from MS/MS analysis. GlycoSeq is released as open source software at https://github.com/chpaul/GlycoSeq/ . PMID:27111718

  9. High accuracy fuel flowmeter. Phase 2C and 3: The mass flowrate calibration of high accuracy fuel flowmeters

    NASA Technical Reports Server (NTRS)

    Craft, D. William

    1992-01-01

    A facility for the precise calibration of mass fuel flowmeters and turbine flowmeters located at AMETEK Aerospace Products Inc., Wilmington, Massachusetts is described. This facility is referred to as the Test and Calibration System (TACS). It is believed to be the most accurate test facility available for the calibration of jet engine fuel density measurement. The product of the volumetric flow rate measurement and the density measurement, results in a true mass flow rate determination. A dual-turbine flowmeter was designed during this program. The dual-turbine flowmeter was calibrated on the TACS to show the characteristics of this type of flowmeter. An angular momentum flowmeter was also calibrated on the TACS to demonstrate the accuracy of a true mass flowmeter having a 'state-of-the-art' design accuracy.

  10. High accuracy fuel flowmeter. Phase 2C and 3: The mass flowrate calibration of high accuracy fuel flowmeters

    NASA Astrophysics Data System (ADS)

    Craft, D. William

    1992-02-01

    A facility for the precise calibration of mass fuel flowmeters and turbine flowmeters located at AMETEK Aerospace Products Inc., Wilmington, Massachusetts is described. This facility is referred to as the Test and Calibration System (TACS). It is believed to be the most accurate test facility available for the calibration of jet engine fuel density measurement. The product of the volumetric flow rate measurement and the density measurement, results in a true mass flow rate determination. A dual-turbine flowmeter was designed during this program. The dual-turbine flowmeter was calibrated on the TACS to show the characteristics of this type of flowmeter. An angular momentum flowmeter was also calibrated on the TACS to demonstrate the accuracy of a true mass flowmeter having a 'state-of-the-art' design accuracy.

  11. Systematic Characterization of High Mass Accuracy Influence on False Discovery and Probability Scoring in Peptide Mass Fingerprinting

    PubMed Central

    Dodds, Eric D.; Clowers, Brian H.; Hagerman, Paul J.; Lebrilla, Carlito B.

    2009-01-01

    While the bearing of mass measurement error upon protein identification is sometimes underestimated, uncertainty in observed peptide masses unavoidably translates to ambiguity in subsequent protein identifications. While ongoing instrumental advances continue to make high accuracy mass spectrometry (MS) increasingly accessible, many proteomics experiments are still conducted with rather large mass error tolerances. Additionally, the ranking schemes of most protein identification algorithms do not include a meaningful incorporation of mass measurement error. This report provides a critical evaluation of mass error tolerance as it pertains to false positive peptide and protein associations resulting from peptide mass fingerprint (PMF) database searching. High accuracy, high resolution PMFs of several model proteins were obtained using matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry (MALDI-FTICR-MS). Varying levels of mass accuracy were simulated by systematically modulating the mass error tolerance of the PMF query and monitoring the effect on figures of merit indicating the PMF quality. Importantly, the benefits of decreased mass error tolerance are not manifest in Mowse scores when operating at tolerances in the low parts per million range, but become apparent with the consideration of additional metrics that are often overlooked. Furthermore, the outcomes of these experiments support the concept that false discovery is closely tied to mass measurement error in PMF analysis. Clear establishment of this relation demonstrates the need for mass error aware protein identification routines and argues for a more prominent contribution of high accuracy mass measurement to proteomic science. PMID:17980142

  12. Low-mass ions produced from peptides by high-energy collision-induced dissociation in tandem mass spectrometry.

    PubMed

    Falick, A M; Hines, W M; Medzihradszky, K F; Baldwin, M A; Gibson, B W

    1993-11-01

    High-energy collision-induced dissociation (CID) mass spectrometry provides a rapid and sensitive means for determining the primary sequence of peptides. The low-mass region (below mass 300) of a large number of tandem CID spectra of peptides has been analyzed. This mass region contains several types of informative fragment ions, including dipeptide ions, immonium ions, and other related ions. Useful low-mass ions are also present in negative-ion CID spectra. Immonium ions (general structure [H2N=CH-R](+), where R is the amino acid side chain) and related ions characteristic of specific amino acid residues give information as to the presence or absence of these residues in the peptide being analyzed. Tables of observed immonium and reiated ions for the 20 standard amino acids and for a number of modified amino acids are presented. A database consisting of 228 high-energy CID spectra of peptides has been established, and the frequency of occurrence of various ions indicative of specific ammo acid residues has been determined. Two model computer-aided schemes for analysis of the ammo-acid content of unknown peptides have been developed and tested against the database. PMID:24227532

  13. Simultaneous quantification of olanzapine and its metabolite N-desmethylolanzapine in human plasma by liquid chromatography tandem mass spectrometry for therapeutic drug monitoring.

    PubMed

    Lou, Hong-gang; Ruan, Zou-rong; Jiang, Bo; Chen, Jin-liang

    2015-05-01

    A simple, sensitive, and selective liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed and validated for the simultaneous quantification of olanzapine (OLZ) and its metabolite N-desmethylolanzapine (DMO) in human plasma for therapeutic drug monitoring. Sample preparation was performed by one-step protein precipitation with methanol. The analytes were chromatographed on a reversed-phase YMC-ODS-AQ C18 Column (2.0 × 100 mm,3 µm) by a gradient program at a flow rate of 0.30 mL/min. Quantification was performed on a triple quadrupole tandem mass spectrometer via electrospray ionization in positive ion mode. The method was validated for selectivity, linearity, accuracy, precision, matrix effect, recovery and stability. The calibration curve was linear over the concentration range 0.2-120 ng/mL for OLZ and 0.5-50 ng/mL for DMO. Intra- and interday precisions for OLZ and DMO were <11.29%, and the accuracy ranged from 95.23 to 113.16%. The developed method was subsequently applied to therapeutic drug monitoring for psychiatric patients receiving therapy of OLZ tablets. The method seems to be suitable for therapeutic drug monitoring of patients undergoing therapy with OLZ and might contribute to prediction of the risk of adverse reactions. PMID:25297964

  14. Single-step multiresidue determination of ten multiclass veterinary drugs in pork, milk, and eggs using liquid chromatography with tandem mass spectrometry.

    PubMed

    Park, Jin-A; Zhang, Dan; Kim, Dong-Soon; Kim, Seong-Kwan; Cho, Kyeong-Su; Jeong, Dana; Shim, Jae-Han; Kim, Jin-Suk; Abd El-Aty, A M; Shin, Ho-Chul

    2015-08-01

    A multiclass, multiresidue determination method is reported for the detection of ten veterinary drugs, including scopolamine, metoclopramide, acriflavine, berberine, tripelennamine, diphenhydramine, acrinol, triamcinolone, loperamide, and roxithromycin in pork, milk, and eggs. The method involves a simple extraction using 0.1% formic acid in acetonitrile, followed by defatting with n-hexane, centrifugation, and filtration prior to liquid chromatography with tandem mass spectrometric analysis. As ion suppression and enhancement effects are reported, matrix-matched calibrations are used for quantification, with determination coefficients ≥0.9765. For the majority of the tested analytes, the intra- and interday accuracy (expressed as recovery %) range from 70.6 to 94.6% and from 70.1 to 93.3%, respectively, and the precision (expressed as relative standard deviation) ranges from 0.5 to 19.8% and from 2.8 to 18.4% in all matrices. The limits of quantification range between 0.5 and 10 ng/g. The validated tandem mass spectrometry method is successfully applied to market samples; the target analytes are not detected in any of the tested samples. In terms of accuracy, no extract cleanup is deemed necessary. The developed method is feasible for the simultaneous detection of the tested analytes in pork, milk, and eggs. PMID:26033853

  15. The analysis of diagnostic markers of genetic disorders in human blood and urine using tandem mass spectrometry with liquid secondary ion mass spectrometry

    NASA Astrophysics Data System (ADS)

    Millington, David S.; Kodo, Naoki; Terada, Naoto; Roe, Diane; Chace, Donald H.

    1991-12-01

    A method has been developed for the rapid diagnosis of metabolic diseases based on the analysis of characteristic metabolites in body fluids by fast atom bombardment or liquid secondary ion tandem mass spectrometry (FAB-MS--MS or LSIMS--MS). Acylcarnitine profiles were obtained from 100 [mu]l urine. 200 [mu]l plasma or 25 [mu]l whole blood spotted onto filter paper by simple solvent extraction, esterification and analysis using a precursor ion scan function on a triple quadrupole mass spectrometer. Specificity and sensitivity were improved by adding a small percentage of sodium octyl sulfate to the liquid matrix, which forms ion pairs with acylcarnitine esters. Acylglycines in urine were specifically detected as a group using a different precursor ion scan function. By forming methyl esters, metabolic profiles of both acylcarnitines and acylglycines were achieved in the same sample loading by application of alternating scan functions. Quantitative analysis of selected metabolites was achieved by use of stable isotope-labeled internal standards. Amino acid profiles were obtained from 100 [mu]l plasma and 25 [mu]l whole blood spots using butyl esters and a neutral loss scan function. The quantitative analysis of phenylalanine and tyrosine was achieved in these samples using stable isotope dilution. This capability will facilitate the diagnosis of phenylketonuria and other amino acidemias. These new methods have the requirements of speed, accuracy and capability for automation necessary for large-scale neonatal screening of inborn errors of matabolism.

  16. Clustering and Filtering Tandem Mass Spectra Acquired in Data-Independent Mode

    NASA Astrophysics Data System (ADS)

    Pak, Huisong; Nikitin, Frederic; Gluck, Florent; Lisacek, Frederique; Scherl, Alexander; Muller, Markus

    2013-12-01

    Data-independent mass spectrometry activates all ion species isolated within a given mass-to-charge window ( m/z) regardless of their abundance. This acquisition strategy overcomes the traditional data-dependent ion selection boosting data reproducibility and sensitivity. However, several tandem mass (MS/MS) spectra of the same precursor ion are acquired during chromatographic elution resulting in large data redundancy. Also, the significant number of chimeric spectra and the absence of accurate precursor ion masses hamper peptide identification. Here, we describe an algorithm to preprocess data-independent MS/MS spectra by filtering out noise peaks and clustering the spectra according to both the chromatographic elution profiles and the spectral similarity. In addition, we developed an approach to estimate the m/z value of precursor ions from clustered MS/MS spectra in order to improve database search performance. Data acquired using a small 3 m/z units precursor mass window and multiple injections to cover a m/z range of 400-1400 was processed with our algorithm. It showed an improvement in the number of both peptide and protein identifications by 8 % while reducing the number of submitted spectra by 18 % and the number of peaks by 55 %. We conclude that our clustering method is a valid approach for data analysis of these data-independent fragmentation spectra. The software including the source code is available for the scientific community.

  17. Molecular resolution and fragmentation of fulvic acid by electrospray ionization/multistage tandem mass spectrometry

    USGS Publications Warehouse

    Leenheer, J.A.; Rostad, C.E.; Gates, Paul M.; Furlong, E.T.; Ferrer, I.

    2001-01-01

    Molecular weight distributions of fulvic acid from the Suwannee River, Georgia, were investigated by electrospray ionization/quadrupole mass spectrometry (ESI/QMS), and fragmentation pathways of specific fulvic acid masses were investigated by electrospray ionization/ion trap multistage tandem mass spectrometry (ESI/MST/MS). ESI/QMS studies of the free acid form of low molecular weight poly(carboxylic acid) standards in 75% methanol/25% water mobile phase found that negative ion detection gave the optimum generation of parent ions that can be used for molecular weight determinations. However, experiments with poly(acrylic acid) mixtures and specific high molecular weight standards found multiply charged negative ions that gave a low bias to molecular mass distributions. The number of negative charges on a molecule is dependent on the distance between charges. ESI/MST/MS of model compounds found characteristic water loss from alcohol dehydration and anhydride formation, as well as CO2 loss from decarboxylation, and CO loss from ester structures. Application of these fragmentation pathways to specific masses of fulvic acid isolated and fragmented by ESI/MST/MS is indicative of specific structures that can serve as a basis for future structural confirmation after these hypothesized structures are synthesized.

  18. Advanced Laser Architecture for Two-Step Laser Tandem Mass Spectrometer

    NASA Technical Reports Server (NTRS)

    Fahey, Molly E.; Li, Steven X.; Yu, Anthony W.; Getty, Stephanie A.

    2016-01-01

    Future astrobiology missions will focus on planets with significant astrochemical or potential astrobiological features, such as small, primitive bodies and the icy moons of the outer planets that may host diverse organic compounds. These missions require advanced instrument techniques to fully and unambiguously characterize the composition of surface and dust materials. Laser desorptionionization mass spectrometry (LDMS) is an emerging instrument technology for in situ mass analysis of non-volatile sample composition. A recent Goddard LDMS advancement is the two-step laser tandem mass spectrometer (L2MS) instrument to address the need for future flight instrumentation to deconvolve complex organic signatures. The L2MS prototype uses a resonance enhanced multi-photon laser ionization mechanism to selectively detect aromatic species from a more complex sample. By neglecting the aliphatic and inorganic mineral signatures in the two-step mass spectrum, the L2MS approach can provide both mass assignments and clues to structural information for an in situ investigation of non-volatile sample composition. In this paper we will describe our development effort on a new laser architecture that is based on the previously flown Lunar Orbiter Laser Altimeter (LOLA) laser transmitter for the L2MS instrument. The laser provides two discrete midinfrared wavelengths (2.8 m and 3.4 m) using monolithic optical parametric oscillators and ultraviolet (UV) wavelength (266 nm) on a single laser bench with a straightforward development path toward flight readiness.

  19. Determination of abacavir, tenofovir, darunavir, and raltegravir in human plasma and saliva using liquid chromatography coupled with tandem mass spectrometry.

    PubMed

    Yamada, Eiko; Takagi, Ritsuo; Sudo, Koji; Kato, Shingo

    2015-10-10

    A liquid chromatography-tandem mass spectrometry assay for the determination of abacavir (ABC), tenofovir (TFV), darunavir (DRV), and raltegravir (RAL) in human plasma and saliva was developed and validated to investigate the applicability of saliva as an appropriate specimen for therapeutic drug monitoring. As internal standards, TFV was chosen for ABC, ABC was chosen for TFV, RAL for DRV, and DRV for RAL. Sample preparation involved protein precipitation with acetonitrile, evaporation of solvent using a centrifugal evaporator, and reconstitution by dissolving the residue in mobile phase. Liquid chromatography was performed on a C18 reverse phase column (1.5 × 50 mm, 5 μm) isocratically at a flow rate of 0.2 mL/min using 5mM formic acid-3% (v/v) acetonitrile as the mobile phase for ABC and TFV and 5mM formic acid-35% (v/v) acetonitrile as the mobile phase for DRV and RAL. The run time was 6 min, and the retention time was approximately 2.0 min for TFV, 2.5 min for RAL, and 4-4.5 min for ABC and DRV. Analytes were detected using tandem mass spectrometry in positive electrospray ionization mode. The precursor/product ion transitions (m/z) were 287.3/191.2 for ABC, 288.5/176.2 for TFV, 548.3/392.3 for DRV, and 445.3/109.5 for RAL, and were monitored on a triple-quadrupole mass spectrometer operated in the multiple reaction monitoring mode. The linearity of the assay was assessed in the range 1-10,000 ng/mL for all four drugs. Within-run and between-run mean accuracy, precision, and the extraction recovery for all drugs were -14.5-18.1%, 1.2-13.1%, and 86.0-111.1%, respectively. The proposed assay is sufficiently sensitive and accurate to quantify these drugs in plasma and saliva, and is suitable for investigating the relationship between drug concentrations in plasma and saliva. PMID:26112927

  20. Determining elemental composition of phytochemicals in camelina seed meal by high mass accuracy and spectral accuracy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An optimized single run evaluation that would accurately determine the elemental composition of as many compounds present in an extract would greatly aid in the evaluation of plant tissues. For phytochemicals, we have used accurate mass analysis to quickly characterize the potential chemical formula...

  1. Mining Large Scale Tandem Mass Spectrometry Data for Protein Modifications Using Spectral Libraries.

    PubMed

    Horlacher, Oliver; Lisacek, Frederique; Müller, Markus

    2016-03-01

    Experimental improvements in post-translational modification (PTM) detection by tandem mass spectrometry (MS/MS) has allowed the identification of vast numbers of PTMs. Open modification searches (OMSs) of MS/MS data, which do not require prior knowledge of the modifications present in the sample, further increased the diversity of detected PTMs. Despite much effort, there is still a lack of functional annotation of PTMs. One possibility to narrow the annotation gap is to mine MS/MS data deposited in public repositories and to correlate the PTM presence with biological meta-information attached to the data. Since the data volume can be quite substantial and contain tens of millions of MS/MS spectra, the data mining tools must be able to cope with big data. Here, we present two tools, Liberator and MzMod, which are built using the MzJava class library and the Apache Spark large scale computing framework. Liberator builds large MS/MS spectrum libraries, and MzMod searches them in an OMS mode. We applied these tools to a recently published set of 25 million spectra from 30 human tissues and present tissue specific PTMs. We also compared the results to the ones obtained with the OMS tool MODa and the search engine X!Tandem. PMID:26653734

  2. ON THE ACCURACY OF WEAK-LENSING CLUSTER MASS RECONSTRUCTIONS

    SciTech Connect

    Becker, Matthew R.; Kravtsov, Andrey V.

    2011-10-10

    We study the bias and scatter in mass measurements of galaxy clusters resulting from fitting a spherically symmetric Navarro, Frenk, and White model to the reduced tangential shear profile measured in weak-lensing (WL) observations. The reduced shear profiles are generated for {approx}10{sup 4} cluster-sized halos formed in a {Lambda}CDM cosmological N-body simulation of a 1 h{sup -1} Gpc box. In agreement with previous studies, we find that the scatter in the WL masses derived using this fitting method has irreducible contributions from the triaxial shapes of cluster-sized halos and uncorrelated large-scale matter projections along the line of sight. Additionally, we find that correlated large-scale structure within several virial radii of clusters contributes a smaller, but nevertheless significant, amount to the scatter. The intrinsic scatter due to these physical sources is {approx}20% for massive clusters and can be as high as {approx}30% for group-sized systems. For current, ground-based observations, however, the total scatter should be dominated by shape noise from the background galaxies used to measure the shear. Importantly, we find that WL mass measurements can have a small, {approx}5%-10%, but non-negligible amount of bias. Given that WL measurements of cluster masses are a powerful way to calibrate cluster mass-observable relations for precision cosmological constraints, we strongly emphasize that a robust calibration of the bias requires detailed simulations that include more observational effects than we consider here. Such a calibration exercise needs to be carried out for each specific WL mass estimation method, as the details of the method determine in part the expected scatter and bias. We present an iterative method for estimating mass M{sub 500c} that can eliminate the bias for analyses of ground-based data.

  3. Liquid chromatography-tandem mass spectrometric assay for eltrombopag in 50μL of human plasma: a pharmacokinetic study.

    PubMed

    Maddela, Rambabu; Gajula, Ramakrishna; Pilli, Nageswara Rao; Siddiraju, Sridhar; Maddela, Srinubabu; Makula, Ajitha

    2014-09-01

    Eltrombopag is a thrombopoietin receptor agonist, used in the treatment of thrombocytopenia. This paper describes a liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay method for the determination of eltrombopag in human plasma samples using eltrombopag 13C4 as internal standard (IS). Analyte and the IS were extracted from 50μL of human plasma using protein precipitation technique with no drying, evaporation and reconstitution steps. The chromatographic separation was achieved on a C18 column by using a mixture of 10mM ammonium formate (pH3) and acetonitrile (10:90, v/v) as the mobile phase at a flow rate of 1.0mL/min. The linearity of the method was established in the concentration range 50.0-10007ng/mL with r(2)≥0.99. The intra-day and inter-day precision and accuracy results in four validation batches across five concentration levels were well within the acceptance limits. The proposed method was found to be applicable to pharmacokinetic studies. PMID:24887483

  4. Rapid test by liquid chromatography/tandem mass spectrometry to evaluate equine urine reactivity towards 17beta-OH steroids.

    PubMed

    Fidani, Marco; Casagni, Eleonora; Montana, Marco; Pasello, Emanuela; Pecoraro, Chiara; Gambaro, Veniero

    2006-01-01

    Bacteria frequently found in equine urine samples may cause degradation of 17beta-OH steroids. A simple liquid chromatography/tandem mass spectrometry (LC/MS/MS) method has been developed to evaluate the microbiological contamination of equine urine as a marker of poor storage conditions. Norethandrolone was used as the internal standard, and the linearity, sensitivity, precision and accuracy of the method were evaluated. 17beta-OH oxidation was demonstrated for testosterone, nandrolone, trenbolone and boldenone, but did not occur in alpha-epimers such as alpha-boldenone and epitestosterone, demonstrating the stereoselectivity of the reaction. A rapid test was performed by spiking one of the four 17beta-OH steroids in samples of diluted equine urine. The steroids were transformed into their respective ketones in the presence of bacterial activity. The test allows direct injection of diluted samples into the LC/MS system, without the need for prior extraction. Results show that the best method of storage is freezing at -18 degrees C. Urine specimens should be analyzed as soon as possible after thawing. This allows bacterial degradation of equine urine to be arrested temporarily, so that the urine can be used for qualitative or quantitative analysis of 17beta-OH steroids. PMID:16862626

  5. [Determination of 39 polychlorinated biphenyls in indoor dust using ultrasonic extraction and gas chromatography-tandem mass spectrometry].

    PubMed

    Wang, Bingling; Zhang, Xiaoling; Zhang, Qi; Lu, Xiaomei; Cui, Yuan; Zhang, Zhengdong

    2014-01-01

    A method for the determination of 39 polychlorinated biphenyls (PCBs) in indoor dust was developed. A vacuum cleaner was used for gathering the house dust. N-Hexane-dichloromethane (1: 1, v/v) was added and the extraction was performed in an ultrasonic bath. The supernatant was concentrated and then 0.1 mL n-hexane-dichloromethane (1: 1, v/v) was added. Gas chromatography-tandem mass spectrometry (GC-MS/MS) in selected-reaction monitoring (SRM) mode has been investigated for the determination of the 39 PCBs congeners in indoor dust. The 39 PCBs had highly efficient separation within 30 min and showed good linearity in the range of 0.1 - 100 microg/L with the correlation coefficients of 0.991 0 - 0.999 9. The spiked recoveries were 57.2% - 120.3%. The intra-day relative standard deviations (RSDs) were between 0.3% and 24.7%, while the inter-day RSDs were between 0.6% and 29.9%. This method has good linearity, high sensitivity, high accuracy and precision. Also, it is simple, rapid and low solvent consumption. The low chemical background interference allowed it to be used in more complex matrices. PMID:24783872

  6. Determination of eleven coccidiostats in animal feed by liquid chromatography-tandem mass spectrometry at cross contamination levels.

    PubMed

    Cronly, Mark; Behan, P; Foley, B; Malone, E; Shearan, P; Regan, L

    2011-08-26

    A confirmatory multi-residue method has been developed to allow for the detection, confirmation and quantification of eleven coccidiostats in animal feed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The method can be used to determine halofuginone, robenidine, nicarbazin, diclazuril, decoquinate, semduramicin, lasalocid, monensin, salinomycin, narasin, maduramicin at levels relating to unavoidable carry over as stated in Regulation 2009/8/EC. Feed samples are extracted with water and acetonitrile with the addition of anhydrous magnesium sulphate and sodium chloride. The extract then undergoes a freezing out step before being diluted and injected onto the LC-MS/MS system. The LC-MS/MS system is run in MRM mode with both positive and negative electrospray ionisation and can confirm all eleven analytes in a run time of 19 min. The sensitivity of the method allows quantification and confirmation for all coccidiostats at a 0.5% carry over level. The method was validated over three days in accordance with of European legislation; Commission Decision 2002/657/EC. Validation criteria of accuracy, precision, decision limit (CCα), and detection capability (CCβ) along with measurement uncertainty are calculated for all analytes. The method was then successfully used to analyse a number of feed samples that contained various coccidiostat substances. PMID:21742113

  7. [Simultaneous determination of six components in hair dyes by ultra performance liquid chromatography-tandem mass spectrometry].

    PubMed

    You, Feiming

    2015-01-01

    A sensitive method was developed for the simultaneous determination of six components which included 4, 4'-diaminodiphenylamine sulfate hydrate and 2,4-diaminophenol sulfate, etc. in hair dyes by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). After extracted by water through ultrasonic extraction, the samples were analyzed by UPLC-MS/MS. The separation was performed on a Waters BEH-C18 column (100 mmx 2.1 mm, 1.7 microm) with gradient elution of 10 mmol/L ammonium acetate and acetonitrile. The electrospray ionization (ESI) source in positive ion mode was used for the analysis of the six components in the multiple reaction monitoring (MRM) mode. The results showed good linear relationships with all the correlation coefficients (R2) more than 0.99. The limits of detection (LODs, S/N=3) for the six components were in the range of 0.26-4.6 mg/kg. The average recoveries of the six components in the spiked samples were in the range of 83.0%-92.2% with the relative standard deviations (RSDs, n=6) of 5.4%-11.2%. The precision, accuracy, mean recoveries and the matrix effects satisfied the requirements of cosmetic sample measurement. The proposed method has been applied to the determination of six dyes in actual samples. This method is simple, accurate and effective for the simultaneous determination of the six components in hair dyes. PMID:25958662

  8. Strategies in protein sequencing and characterization: multi-enzyme digestion coupled with alternate CID/ETD tandem mass spectrometry.

    PubMed

    Nardiello, Donatella; Palermo, Carmen; Natale, Anna; Quinto, Maurizio; Centonze, Diego

    2015-01-01

    A strategy based on a simultaneous multi-enzyme digestion coupled with electron transfer dissociation (ETD) and collision-induced dissociation (CID) was developed for protein sequencing and characterization, as a valid alternative platform in ion-trap based proteomics. The effect of different proteolytic procedures using chymotrypsin, trypsin, a combination of both, and Lys-C, was carefully evaluated in terms of number of identified peptides, protein coverage, and score distribution. A systematic comparison between CID and ETD is shown for the analysis of peptides originating from the in-solution digestion of standard caseins. The best results were achieved with a trypsin/chymotrypsin mix combined with CID and ETD operating in alternating mode. A post-database search validation of MS/MS dataset was performed, then, the matched peptides were cross checked by the evaluation of ion scores, rank, number of experimental product ions, and their relative abundances in the MS/MS spectrum. By integrated CID/ETD experiments, high quality-spectra have been obtained, thus allowing a confirmation of spectral information and an increase of accuracy in peptide sequence assignments. Overlapping peptides, produced throughout the proteins, reduce the ambiguity in mapping modifications between natural variants and animal species, and allow the characterization of post translational modifications. The advantages of using the enzymatic mix trypsin/chymotrypsin were confirmed by the nanoLC and CID/ETD tandem mass spectrometry of goat milk proteins, previously separated by two-dimensional gel electrophoresis. PMID:25479873

  9. Analysis of thyreostatic drugs in thyroid samples by liquid chromatography tandem mass spectrometry: comparison of two sample treatment strategies.

    PubMed

    Abuín, S; Companyó, R; Centrich, F; Rúbies, A; Prat, M D

    2008-10-17

    A method based on ultra-performance liquid chromatography-electrospray ionisation-tandem mass spectrometry (UPLC-MS/MS) for the determination of six thyreostatic drugs in thyroid tissue has been optimised and validated in accordance with Decision 2002/657/EC. Sample extraction was evaluated in methanol and in ethyl acetate, the latter which gave better results. Two clean-up strategies were compared: one based on silica cartridges (SPE), and the other, on gel permeation chromatography (GPC). Recoveries ranged from 40% to 79% for the SPE approach and from 80% to 109% for GPC. Quantification was performed with blank tissue samples spiked with the analytes in the range 50-500microgkg(-1). 5,6-Dimethyl-2-thiouracil and 2-mercaptobenzimidazole-d(4) were used as internal standards. Decision limit (CCalpha) and detection capability (CCbeta) ranged from 1 to 15microgkg(-1) and from 6 to 25microgkg(-1), respectively. The accuracy of the method was calculated as percent error, which was less than 10%. The relative standard deviation in reproducibility conditions ranged between 2% and 14%. PMID:18768184

  10. Analysis of thyreostatic drugs in thyroid samples by ultra-performance liquid chromatography tandem mass spectrometry detection.

    PubMed

    Abuín, S; Centrich, F; Rúbies, A; Companyó, R; Prat, M D

    2008-06-01

    A method based on ultra-performance liquid chromatography-electrospray ionisation-tandem mass spectrometry for the determination of six thyreostatic drugs in thyroid tissue has been optimised and validated in accordance with the Decision 2002/657/EC. Samples are extracted with methanol and the extracts cleaned-up on silica cartridges. The recoveries range from 40% for 6-phenyl-2-thiouracil to 79% for 2-thiouracil. Quantification is carried out with blank tissue samples spiked with the analytes in the range 25-500 microg kg(-1). 5,6-Dimethyl-2-thiouracil is used as internal standard. CCalpha and CCbeta are in the ranges 4.3-16.1 microg kg(-1) and 8.7-20.7 microg kg(-1), respectively. Accuracy, expressed as percentage of error, is lower than 6% and relative standard deviation in reproducibility conditions falls between 5.6 and 10.3%. Nowadays, the proposed method is routinely implemented in the laboratory of the Agència de Salut Pública de Barcelona and allows processing of up to 20 samples per day. PMID:18486656

  11. High-throughput analysis of 19 endogenous androgenic steroids by ultra-performance convergence chromatography tandem mass spectrometry.

    PubMed

    Quanson, Jonathan L; Stander, Marietjie A; Pretorius, Elzette; Jenkinson, Carl; Taylor, Angela E; Storbeck, Karl-Heinz

    2016-09-15

    11-Oxygenated steroids such as 11-ketotestosterone and 11-ketodihydrotestosterone have recently been shown to play a putative role in the development and progression of castration resistant prostate cancer. In this study we report on the development of a high throughput ultra-performance convergence chromatography tandem mass spectrometry (UPC(2)-MS/MS) method for the analysis of thirteen 11-oxygenated and six canonical C19 steroids isolated from a cell culture matrix. Using an Acquity UPC(2) BEH 2-EP column we found that UPC(2) resulted in superior selectivity, increased chromatographic efficiency and a scattered elution order when compared to conventional reverse phase ultra-performance liquid chromatography (UPLC). Furthermore, there was a significant improvement in sensitivity (5-50 times). The lower limits of quantification ranged between 0.01-10ngmL(-1), while the upper limit of quantification was 100ngmL(-1) for all steroids. Accuracy, precision, intra-day variation, recovery, matrix effects and process efficiency were all evaluated and found to be within acceptable limits. Taken together we show that the increased power of UPC(2)-MS/MS allows the analyst to complete in vitro assays at biologically relevant concentrations for the first time and in so doing determine the routes of steroid metabolism which is vital for studies of androgen responsive cancers, such as prostate cancer, and could highlight new mechanisms of disease progression and new targets for cancer therapy. PMID:27479683

  12. Application of a sensitive liquid chromatographic/tandem mass spectrometric method to pharmacokinetic study of nalmefene in humans.

    PubMed

    Li, Ping; Chen, Xiaoyan; Dai, Xiaojian; Wen, Aidong; Zhang, Yifan; Zhong, Dafang

    2007-06-01

    A sensitive, specific and rapid liquid chromatographic/tandem mass spectrometric (LC/MS/MS) method was developed and validated for quantification of nalmefene in human plasma. An aliquot of 200 microL plasma sample was simply precipitated by 400 microL methanol. Separation of nalmefene and the internal standard hydromorphone from the interferences was achieved on a C(18) column followed by MS/MS detection. The analytes were monitored in the positive ionization mode with a TurboIonspray source. The method had a total chromatographic run time of 4.5 min and linear calibration curves over the concentration range of 10-5000 pg/mL. The lower limit of quantification (LLOQ) was 10 pg/mL. The intra- and inter-day precision was less than 10.1% determined from QC samples at concentrations of 30, 300 and 4500 pg/mL, and the accuracy was within +/-3.4%. As the method was more sensitive (10 times higher) than those reported previously, we investigated the pharmacokinetics of nalmefene in healthy volunteers after a single intravenous injection of low dose (30 microg) of nalmefene hydrochloride for the first time. PMID:17329173

  13. Quantitation of five organophosphorus nerve agent metabolites in serum using hydrophilic interaction liquid chromatography and tandem mass spectrometry

    PubMed Central

    Hamelin, Elizabeth I.; Schulze, Nicholas D.; Shaner, Rebecca L.; Coleman, Rebecca M.; Lawrence, Richard J.; Crow, Brian S.; Jakubowski, E. M.; Johnson, Rudolph C.

    2015-01-01

    Although nerve agent use is prohibited, concerns remain for human exposure to nerve agents during decommissioning, research, and warfare. Exposure can be detected through the analysis of the hydrolysis products in urine as well as blood. An analytical method to detect exposure to five nerve agents, including VX, VR (Russian VX), GB (sarin), GD (soman) and GF (cyclosarin), through the analysis of the hydrolysis products, which are the primary metabolites, in serum has been developed and characterized. This method uses solid phase extraction coupled with high performance liquid chromatography for separation and isotopic dilution tandem mass spectrometry for detection. An uncommon buffer of ammonium fluoride was used to enhance ionization and improve sensitivity when coupled with hydrophilic interaction liquid chromatography resulting in detection limits from 0.3–0.5 ng/mL. The assessment of two quality control samples demonstrated high accuracy (101–105%) and high precision (5–8%) for the detection of these five nerve agent hydrolysis products in serum. PMID:24633507

  14. Simultaneous Determination of Fucoxanthin and Its Deacetylated Metabolite Fucoxanthinol in Rat Plasma by Liquid Chromatography-Tandem Mass Spectrometry.

    PubMed

    Zhang, Yiping; Wu, Hao; Wen, Hongmei; Fang, Hua; Hong, Zhuan; Yi, Ruizao; Liu, Rui

    2015-10-01

    Fucoxanthin and its deacetylated metabolite fucoxanthinol are two major carotenoids that have been confirmed to possess various pharmacological properties. In the present study, fucoxanthinol was identified as the deacetylated metabolite of fucoxanthin, after intravenous (i.v.) and intragastric gavage (i.g.) administration to rats at doses of 2 and 65 mg/kg, respectively, by liquid chromatography-tandem mass spectrometric (LC-MS/MS) analysis. Next, an accurate and precise LC-MS/MS method was developed to quantitatively determine fucoxanthin and fucoxanthinol in rat plasma. Plasma samples were resolved by LC-MS/MS on a reverse-phase SB-C18 column that was equilibrated and eluted with acetonitrile (A)/aqueous 0.1% formic acid (B; 92/8, v/v) at a flow rate of 0.5 mL/min. Analytes were monitored by multiple-reaction monitoring (MRM) under positive electrospray ionization mode. The precursor/product transitions (m/z) were 659.3→109.0 for fucoxanthin, 617.2→109.0 for fucoxanthinol, and 429.4→313.2 for the internal standard (IS). Calibration curves for fucoxanthin and fucoxanthinol were linear over concentrations ranging from 1.53 to 720 and 1.17 to 600 ng/mL, respectively. The inter- and intraday accuracy and precision were within ±15%. The method was applied successfully in a pharmacokinetic study and the resulting oral fucoxanthin bioavailability calculated. PMID:26512677

  15. Simultaneous Determination of Fucoxanthin and Its Deacetylated Metabolite Fucoxanthinol in Rat Plasma by Liquid Chromatography-Tandem Mass Spectrometry

    PubMed Central

    Zhang, Yiping; Wu, Hao; Wen, Hongmei; Fang, Hua; Hong, Zhuan; Yi, Ruizao; Liu, Rui

    2015-01-01

    Fucoxanthin and its deacetylated metabolite fucoxanthinol are two major carotenoids that have been confirmed to possess various pharmacological properties. In the present study, fucoxanthinol was identified as the deacetylated metabolite of fucoxanthin, after intravenous (i.v.) and intragastric gavage (i.g.) administration to rats at doses of 2 and 65 mg/kg, respectively, by liquid chromatography-tandem mass spectrometric (LC-MS/MS) analysis. Next, an accurate and precise LC-MS/MS method was developed to quantitatively determine fucoxanthin and fucoxanthinol in rat plasma. Plasma samples were resolved by LC-MS/MS on a reverse-phase SB-C18 column that was equilibrated and eluted with acetonitrile (A)/aqueous 0.1% formic acid (B; 92/8, v/v) at a flow rate of 0.5 mL/min. Analytes were monitored by multiple-reaction monitoring (MRM) under positive electrospray ionization mode. The precursor/product transitions (m/z) were 659.3→109.0 for fucoxanthin, 617.2→109.0 for fucoxanthinol, and 429.4→313.2 for the internal standard (IS). Calibration curves for fucoxanthin and fucoxanthinol were linear over concentrations ranging from 1.53 to 720 and 1.17 to 600 ng/mL, respectively. The inter- and intraday accuracy and precision were within ±15%. The method was applied successfully in a pharmacokinetic study and the resulting oral fucoxanthin bioavailability calculated. PMID:26512677

  16. Quantitation of five organophosphorus nerve agent metabolites in serum using hydrophilic interaction liquid chromatography and tandem mass spectrometry.

    PubMed

    Hamelin, Elizabeth I; Schulze, Nicholas D; Shaner, Rebecca L; Coleman, Rebecca M; Lawrence, Richard J; Crow, Brian S; Jakubowski, E M; Johnson, Rudolph C

    2014-08-01

    Although nerve agent use is prohibited, concerns remain for human exposure to nerve agents during decommissioning, research, and warfare. Exposure can be detected through the analysis of hydrolysis products in urine as well as blood. An analytical method to detect exposure to five nerve agents, including VX, VR (Russian VX), GB (sarin), GD (soman), and GF (cyclosarin), through the analysis of the hydrolysis products, which are the primary metabolites, in serum has been developed and characterized. This method uses solid-phase extraction coupled with high-performance liquid chromatography for separation and isotopic dilution tandem mass spectrometry for detection. An uncommon buffer of ammonium fluoride was used to enhance ionization and improve sensitivity when coupled with hydrophilic interaction liquid chromatography resulting in detection limits from 0.3 to 0.5 ng/mL. The assessment of two quality control samples demonstrated high accuracy (101-105%) and high precision (5-8%) for the detection of these five nerve agent hydrolysis products in serum. PMID:24633507

  17. Quantification of nardosinone in rat plasma using liquid chromatography-tandem mass spectrometry and its pharmacokinetics application.

    PubMed

    Lu, Zhihe; Zhou, Peng; Zhan, Yuzhu; Su, Jingrong; Yi, Deliang

    2015-01-01

    A rapid, sensitive and high-throughput liquid chromatography-tandem mass spectrometry (LC-MS-MS) method was established and validated to assay the concentration of nardosinone, a main active compound isolated from Nardostachys chinensis, in rat plasma. Plasma samples were processed by protein precipitation with acetonitrile and separated on a Venusil MP-C18 column (50 × 2.1 mm, 5 µm) at an isocratic flow rate of 0.6 mL/min using methanol-0.1% formic acid in water (55 : 45, v/v) as mobile phase, and total run time was 2.5 min. MS-MS detection was accomplished in selected reaction monitoring mode with positive electrospray ionization. The calibration curve was linear over the concentration range of 9.60-320 ng/mL with lower limit of quantification of 9.60 ng/mL. The intra- and inter-day precisions were below 12.3% in terms of relative standard deviation, and the accuracy was within ±9.0% in terms of relative error. Extraction recovery, matrix effect and stability were also satisfactory in rat plasma. The developed method was successfully applied to a pharmacokinetic study of nardosinone following an intravenous injection at a dose of 1.04 mg/kg to Sprague-Dawley rats. PMID:26116832

  18. Folate Profiling in Potato (Solanum tuberosum) Tubers by Ultrahigh-Performance Liquid Chromatography-Tandem Mass Spectrometry.

    PubMed

    Van Daele, Jeroen; Blancquaert, Dieter; Kiekens, Filip; Van Der Straeten, Dominique; Lambert, Willy E; Stove, Christophe P

    2014-03-31

    An ultrahigh-performance liquid chromatography-tandem mass spectrometry method was developed and validated for the profiling of six folate species in potatoes. The calibration curves cover a wide, linear range (the lower and upper limits of quantitation range between 0.22-0.24 and 216.07-242.28 μg/100 g of fresh weight), allowing sensitive determination in small amounts of potato flesh. With a single exception, the acceptance criteria for intra- and interday precision and accuracy were met: for all quality controls, the percent relative standard deviation and the percent bias were lower than 15% (or 20% at the lower limit of quantitation). Application of the method on tubers at different stages of maturation demonstrated the large variability within a single variety: the folate content and polyglutamylation rate varied between 10.35 and 24.01 μg/100 g of fresh weight and between 4.96% and 60.49%, respectively. Additionally, the two-dimensional folate profiling of mature tubers demonstrated an increase in folate from center to peel, combined with a stable species distribution and polyglutamylation rate. PMID:24655154

  19. High Throughput Liquid Chromatography-Tandem Mass Spectrometry Assay for Mercapturic Acids of Acrolein and Crotonaldehyde in Cigarette Smokers’ Urine

    PubMed Central

    Carmella, Steven G.; Chen, Menglan; Zarth, Adam; Hecht, Stephen S.

    2014-01-01

    3-Hydroxypropylmercapturic acid (3-HPMA) and 3-hydroxy-1-methylpropylmercapturic acid (HMPMA) are urinary metabolites of the toxicants acrolein and crotonaldehyde, respectively. Virtually all human urine samples contain these metabolites, resulting from the action of glutathione-S-transferases on acrolein and crotonaldehyde, which are lipid peroxidation products, environmental and dietary contaminants, and constituents of cigarette smoke. We have developed a high throughput liquid chromatography-tandem mass spectrometry method for quantitative analysis of 3-HPMA and HMPMA in large numbers of small urine samples, as would be required in molecular epidemiology and clinical studies relating levels of these metabolites to cancer risk. Solid-phase extraction on mixed mode reverse phase-anion exchange 96-well plates provided sufficient purification for LC-MS/MS analysis, which was performed by auto-injection using a 96-well format, and resulted in clean, readily interpretable chromatograms, with detection limits of 4.5 pmol/mL urine for 3-HPMA and 3.5 pmol/mL urine for HMPMA. Accuracy was 92% for 3-HPMA and 97% for HMPMA while inter-day precision was 9.1% (coefficient of variation) for 3-HPMA and 11.0% for HMPMA. The method was applied to more than 2600 urine samples from smokers; mean levels of 3-HPMA and HMPMA were 4800 ± 5358 (S.D.) pmol/ml and 3302 ± 3341 pmol/ml, respectively. PMID:23934173

  20. Determination of acrylamide in coffee and chocolate by pressurised fluid extraction and liquid chromatography-tandem mass spectrometry.

    PubMed

    Pardo, O; Yusà, V; Coscollà, C; León, N; Pastor, A

    2007-07-01

    A selective and sensitive procedure has been developed and validated for the determination of acrylamide in difficult matrices, such as coffee and chocolate. The proposed method includes pressurised fluid extraction (PFE) with acetonitrile, florisil clean-up purification inside the PFE extraction cell and detection by liquid chromatography (LC) coupled to atmospheric pressure ionisation in positive mode tandem mass spectrometry (APCI-MS-MS). Comparison of ionisation sources (atmospheric pressure chemical ionisation (APCI), atmospheric pressure photoionization (APPI) and the combined APCI/APPI) and clean-up procedures were carried out to improve the analytical signal. The main parameters affecting the performance of the different ionisation sources were previously optimised using statistical design of experiments (DOE). PFE parameters were also optimised by DOE. For quantitation, an isotope dilution approach was used. The limit of quantification (LOQ) of the method was 1 microg kg(-1) for coffee and 0.6 microg kg(-1) for chocolate. Recoveries ranged between 81-105% in coffee and 87-102% in chocolate. The accuracy was evaluated using a coffee reference test material FAPAS T3008. Using the optimised method, 20 coffee and 15 chocolate samples collected from Valencian (Spain) supermarkets, were investigated for acrylamide, yielding median levels of 146 microg kg(-1) in coffee and 102 microg kg(-1) in chocolate. PMID:17613050

  1. Determining mycotoxins in baby foods and animal feeds using stable isotope dilution and liquid chromatography tandem mass spectrometry.

    PubMed

    Zhang, Kai; Wong, Jon W; Krynitsky, Alexander J; Trucksess, Mary W

    2014-09-10

    We developed a stable isotope dilution assay with liquid chromatography tandem mass spectrometry (LC-MS/MS) to determine multiple mycotoxins in baby foods and animal feeds. Samples were fortified with [(13)C]-uniformly labeled mycotoxins as internal standards ([(13)C]-IS) and prepared by solvent extraction (50% acetonitrile in water) and filtration, followed by LC-MS/MS analysis. Mycotoxins in each sample were quantitated with the corresponding [(13)C]-IS. In general, recoveries of aflatoxins (2-100 ng/g), deoxynivalenol, fumonisins (50-2000 ng/g), ochratoxin A (20-1000 ng/kg), T-2 toxin, and zearalenone (40-2000 ng/g) in tested matrices (grain/rice/oatmeal-based formula, animal feed, dry cat/dog food) ranged from 70 to 120% with relative standard deviations (RSDs) <20%. The method provides sufficient selectivity, sensitivity, accuracy, and reproducibility to screen for aflatoxins at ng/g concentrations and deoxynivalenol and fumonisins at low μg/g concentrations in baby foods and animal feeds, without using conventional standard addition or matrix-matched calibration standards to correct for matrix effects. PMID:25153173

  2. Determination of five macrolide antibiotic residues in eggs using liquid chromatography/electrospray ionization tandem mass spectrometry.

    PubMed

    Wang, Jian; Leung, Daniel; Butterworth, Fred

    2005-03-23

    A method using liquid chromatography electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) for the determination of trace levels of five macrolide antibiotics (spiramycin, tilmicosin, oleandomycin, erythromycin, and tylosin) in eggs is presented. Data acquisition under MS/MS was achieved by applying multiple reaction monitoring (MRM) of two or three fragment ion transitions to provide a high degree of sensitivity and specificity for both quantification and confirmation. Matrix-matched standard calibration curves were used to achieve the best accuracy of the method. A fully nested experimental design was used to study the measurement uncertainty arising from intermediate precision and trueness or proportional bias. The overall recoveries, that is, those determined by the nested experiments, of spiramycin, tilmicosin, oleandomycin, erythromycin, and tylosin at fortified levels of 60, 100, 200, and 300 microg/kg were 96.8, 98.2, 98.3, 98.8, and 95.4%, respectively. The LC/ESI-MS/MS method detection limits (S/N > or = 3:1) of five macrolides were <1.0 microg/kg. PMID:15769104

  3. Quantification of roxatidine in human plasma by liquid chromatography electrospray ionization tandem mass spectrometry: application to a bioequivalence study.

    PubMed

    Ryu, Ju-Hee; Choi, Sang-Jun; Lee, Heon-Woo; Choi, Seung-Ki; Lee, Kyung-Tae

    2008-12-01

    A sensitive and specific method using a one-step liquid-liquid extraction (LLE) with ethyl acetate followed by high-performance liquid chromatography (HPLC) coupled with positive ion electrospray ionization tandem mass spectrometry (ESI-MS/MS) detection was developed and validated for the determination of roxatidine in human plasma using famotidine as an internal standard (IS). Data acquisition was carried out in multiple reaction monitoring (MRM) mode, by monitoring the transitions m/z 307.3-->107.1 for roxatidine and m/z 338.4-->189.1 for famotidine. Chromatographic separation was performed on a reverse phase Hydrosphere C(18) column at 0.2 mL min(-1) using a mixture of methanol-ammonium formate buffer as mobile phase (20:80, v/v; adjusted to pH 3.9 with formic acid). The achieved lower limit of quantification (LLOQ) was 1.0 ng mL(-1) and the standard calibration curve for roxatidine was linear (r(2)=0.998) over the studied range (1-1000 ng mL(-1)) with acceptable accuracy and precision. Roxatidine was found to be stable in human plasma samples under short-, long-term storage and processing conditions. The developed method was validated and successfully applied to the bioequivalence study of roxatidine administrated as a single oral dose (75 mg as roxatidine acetate hydrochloride) to healthy female Korean volunteers. PMID:18977187

  4. Evaluation of low-pressure gas chromatography-tandem mass spectrometry method for the analysis of >140 pesticides in fish.

    PubMed

    Sapozhnikova, Yelena

    2014-04-30

    A multiresidue method for the analysis of 143 pesticide residues in fish was developed and evaluated using fast, low-pressure gas chromatography/triple-quadrupole tandem mass spectrometry (LP-GC/MS-MS). The method was based on a QuEChERS (quick, easy, cheap, effective, rugged, safe) extraction with acetonitrile and dispersive solid-phase extraction (d-SPE) cleanup with zirconium-based sorbent. The developed method was evaluated at four spiking levels (1, 5, 50, and 100 ng/g) and further validated by analysis of NIST Standard Reference Materials (SRMs) 1974b and 1947 for selected pesticides with certified concentrations. Acceptable recoveries (70-120%) and standard deviations below 20% were achieved for the majority of pesticides from fortified samples. The measured values for both SRMs agreed with certified values (71-115% accuracy, 4-14% relative standard deviations) for all pesticides, except for p,p-DDD + o,p-DDT (45%) and heptachlor (133%) in SRM 1974b and except for mirex (58%) and trans-chlordane (136%) in SRM 1947. The developed method is fast, simple, and inexpensive with detection limits of 0.5-5 ng/g. Residues of dimethoate, hexachlorobenzene, BHC, lindane, nonachlor, chlorpyrifos, trifluralin, p,p-DDE, p,p-DDD, o,p-DDD, o,p-DDT, p,p-DDD, and chlordane were measured in catfish samples from the market. PMID:24387765

  5. Characterization of an Ion Mobility-Multiplexed Collision Induced Dissociation-Tandem Time-of-Flight Mass Spectrometry Approach

    PubMed Central

    Ibrahim, Yehia M.; Prior, David C.; Baker, Erin S.; Smith, Richard D.; Belov, Mikhail E.

    2010-01-01

    The confidence in peptide (and protein) identifications with ion mobility spectrometry time-of-flight mass spectrometry (IMS-TOFMS) is expected to drastically improve with the addition of information from an efficient ion dissociation step prior to MS detection. High throughput IMS-TOFMS analysis imposes a strong need for multiplexed ion dissociation approaches where multiple precursor ions yield complex sets of fragment ions that are often intermingled with each other in both the drift time and m/z domains. We have developed and evaluated an approach for collision-induced dissociation (CID) using IMS-TOFMS instrument. It has been shown that precursor ions activated inside an rf-device with an axial dc-electric field produce abundant fragment ions which are radially confined with the rf-field and collisionally cooled at an elevated pressure, resulting in high CID efficiencies comparable or higher than those measured in triple-quadrupole instruments. We have also developed an algorithm for deconvoluting these complex multiplexed tandem MS spectra by clustering both the precursor and fragment ions into matching drift time profiles and by utilizing the high mass measurement accuracy achievable with TOFMS. In a single IMS separation from direct infusion of tryptic digest of bovine serum albumin (BSA), we have reliably identified 20 unique peptides using a multiplexed CID approach downstream of the IMS separation. Peptides were identified based upon the correlation between the precursor and fragment drift time profiles and by matching the profile representative masses to those of in silico BSA tryptic peptides and their fragments. The false discovery rate (FDR) of peptide identifications from multiplexed MS/MS spectra was less than 1%. PMID:20596241

  6. Quantification of L-ergothioneine in human plasma and erythrocytes by liquid chromatography-tandem mass spectrometry.

    PubMed

    Wang, Ling-Zhi; Thuya, Win-Lwin; Toh, Dorothy Su-Lin; Lie, Michael George-Limenta; Lau, Jie-Ying Amelia; Kong, Li-Ren; Wan, Seow-Ching; Chua, Kian-Ngiap; Lee, Edmund Jon-Deoon; Goh, Boon-Cher

    2013-03-01

    A sensitive analytical method has been developed and validated for the quantification of L-ergothioneine in human plasma and erythrocytes by liquid chromatography-tandem mass spectrometry. A commercially available isotope-labeled L-ergothioneine-d9 is used as the internal standard. A simple protein precipitation with acetonitrile is utilized for bio-sample preparation prior to analysis. Chromatographic separation of L-ergothioneine is conducted using gradient elution on Alltime C18 (150 mm × 2.1 mm, 5 µ). The run time is 6 min at a constant flow rate of 0.45 ml/min. The mass spectrometer is operated under a positive electrospray ionization condition with multiple reaction monitoring mode. The mass transitions of L-ergothioneine and L-ergothioneine-d9 are m/z 230 > 127 and m/z 239 > 127, respectively. Excellent linearity [coefficient of determination (r(2)) ≥ 0.9998] can be achieved for L-ergothioneine quantification at the ranges of 10 to 10,000 ng/ml, with the intra-day and inter-day precisions at 0.9-3.9% and 1.3-5.7%, respectively, and the accuracies for all quality control samples between 94.5 and 101.0%. This validated analytical method is suitable for pharmacokinetic monitoring of L-ergothioneine in human and erythrocytes. Based on the determination of bio-samples from five healthy subjects, the mean concentrations of L-ergothioneine in plasma and erythrocytes are 107.4 ± 20.5 ng/ml and 1285.0 ± 1363.0 ng/ml, respectively. PMID:23494799

  7. Molecular Isotopic Distribution Analysis (MIDAs) with adjustable mass accuracy.

    PubMed

    Alves, Gelio; Ogurtsov, Aleksey Y; Yu, Yi-Kuo

    2014-01-01

    In this paper, we present Molecular Isotopic Distribution Analysis (MIDAs), a new software tool designed to compute molecular isotopic distributions with adjustable accuracies. MIDAs offers two algorithms, one polynomial-based and one Fourier-transform-based, both of which compute molecular isotopic distributions accurately and efficiently. The polynomial-based algorithm contains few novel aspects, whereas the Fourier-transform-based algorithm consists mainly of improvements to other existing Fourier-transform-based algorithms. We have benchmarked the performance of the two algorithms implemented in MIDAs with that of eight software packages (BRAIN, Emass, Mercury, Mercury5, NeutronCluster, Qmass, JFC, IC) using a consensus set of benchmark molecules. Under the proposed evaluation criteria, MIDAs's algorithms, JFC, and Emass compute with comparable accuracy the coarse-grained (low-resolution) isotopic distributions and are more accurate than the other software packages. For fine-grained isotopic distributions, we compared IC, MIDAs's polynomial algorithm, and MIDAs's Fourier transform algorithm. Among the three, IC and MIDAs's polynomial algorithm compute isotopic distributions that better resemble their corresponding exact fine-grained (high-resolution) isotopic distributions. MIDAs can be accessed freely through a user-friendly web-interface at http://www.ncbi.nlm.nih.gov/CBBresearch/Yu/midas/index.html. PMID:24254576

  8. Molecular Isotopic Distribution Analysis (MIDAs) with Adjustable Mass Accuracy

    NASA Astrophysics Data System (ADS)

    Alves, Gelio; Ogurtsov, Aleksey Y.; Yu, Yi-Kuo

    2014-01-01

    In this paper, we present Molecular Isotopic Distribution Analysis (MIDAs), a new software tool designed to compute molecular isotopic distributions with adjustable accuracies. MIDAs offers two algorithms, one polynomial-based and one Fourier-transform-based, both of which compute molecular isotopic distributions accurately and efficiently. The polynomial-based algorithm contains few novel aspects, whereas the Fourier-transform-based algorithm consists mainly of improvements to other existing Fourier-transform-based algorithms. We have benchmarked the performance of the two algorithms implemented in MIDAs with that of eight software packages (BRAIN, Emass, Mercury, Mercury5, NeutronCluster, Qmass, JFC, IC) using a consensus set of benchmark molecules. Under the proposed evaluation criteria, MIDAs's algorithms, JFC, and Emass compute with comparable accuracy the coarse-grained (low-resolution) isotopic distributions and are more accurate than the other software packages. For fine-grained isotopic distributions, we compared IC, MIDAs's polynomial algorithm, and MIDAs's Fourier transform algorithm. Among the three, IC and MIDAs's polynomial algorithm compute isotopic distributions that better resemble their corresponding exact fine-grained (high-resolution) isotopic distributions. MIDAs can be accessed freely through a user-friendly web-interface at http://www.ncbi.nlm.nih.gov/CBBresearch/Yu/midas/index.html.

  9. Fast-atom bombardment and tandem mass spectrometry of macrolide antibiotics.

    PubMed

    Cerny, R L; Macmillan, D K; Gross, M L; Mallams, A K; Pramanik, B N

    1994-03-01

    Molecular weights of macrolide antibiotics can be determined from either (M + H)(+) or (M + Met)(+), the latter desorbed from alkali metal salt-saturated matrices. The ion chemistry of macrolides, as determined by tandem mass spectrometry (MS/MS), is different for ions produced as metallated than those formed as (M + H)(+) species. An explanation for these differences is the location of the charge. For protonated species, the charge is most likely situated on a functional group with high proton affinity, such as the dimethylamino group of the ammo sugar. The alkali metal ion, however, is bonded to the highly oxygenated aglycone. As a result, the collision-activated dissociation spectra of protonated macrolides are simple with readily identifiable fragment ions in both the high and low mass regions but no fragments in the middle mass range. In contrast, the cationized species give complex spectra with many abundant ions, most of which are located in the high mass range. The complementary nature of the fragmentation of these two species recommends the study of both by MS/MS when determining the structure or confirming the identity of these biomaterials. PMID:24222544

  10. Differentiation of Linear and Cyclic Polymer Architectures by MALDI Tandem Mass Spectrometry (MALDI-MS2)

    NASA Astrophysics Data System (ADS)

    Yol, Aleer M.; Dabney, David E.; Wang, Shih-Fan; Laurent, Boyd A.; Foster, Mark D.; Quirk, Roderic P.; Grayson, Scott M.; Wesdemiotis, Chrys

    2013-01-01

    [M + Ag]+ ions from cyclic and linear polystyrenes and polybutadienes, formed by matrix-assisted laser desorption ionization (MALDI), give rise to significantly different fragmentation patterns in tandem mass spectrometry (MS2) experiments. In both cases, fragmentation starts with homolytic cleavage at the weakest bond, usually a C-C bond, to generate two radicals. From linear structures, the separated radicals depolymerize extensively by monomer losses and backbiting rearrangements, leading to low-mass radical ions and much less abundant medium- and high-mass closed-shell fragments that contain one of the original end groups, along with internal fragments. With cyclic structures, depolymerization is less efficient, as it can readily be terminated by intramolecular H-atom transfer between the still interconnected radical sites (disproportionation). These differences in fragmentation reactivity result in substantially different fragment ion distributions in the MS2 spectra. Simple inspection of the relative intensities of low- versus high-mass fragments permits conclusive determination of the macromolecular architecture, while full spectral interpretation reveals the individual end groups of linear polymers or the identity of the linker used to form the cyclic polymer.

  11. Tandem Mass Spectrometry for Structural Identification of Sesquiterpene Alkaloids from the Stems of Dendrobium nobile Using LC-QToF.

    PubMed

    Wang, Yan-Hong; Avula, Bharathi; Abe, Naohito; Wei, Feng; Wang, Mei; Ma, Shuang-Cheng; Ali, Zulfiqar; Elsohly, Mahmoud A; Khan, Ikhlas A

    2016-05-01

    Dendrobium nobile is one of the fundamental herbs in traditional Chinese medicine. Sesquiterpene alkaloids are the main active components in this plant. Due to weak ultraviolet absorption and low content in D. nobile, these sesquiterpene alkaloids have not been extensively studied using chromatographic methods. Herein, tandem mass spectrometry combined with liquid chromatography separation provides a tool for the identification and characterization of the alkaloids from D. nobile. A total of nine sesquiterpene alkaloids were characterized by ultrahigh-performance liquid chromatography tandem mass spectrometry. These alkaloids can be classified into two subgroups that are represented by dendrobine and nobilonine. Tandem mass spectrometric studies revealed the fragmentation pathways of these two subgroup alkaloids that were used for the identification and characterization of other alkaloids in D. nobile. Characterization of these alkaloids using accurate mass and diagnostic fragments provided a reliable methodology for the analysis of D. nobile by ultrahigh-performance liquid chromatography tandem mass spectrometry. The limit of detection was defined as the signal-to-noise ratio equal to 3 : 1. Limits of detection of dendrobine and nobilonine were less than 30 ng/mL. The developed method was applied for the analysis of various Dendrobium species and related dietary supplements. Alkaloids were identified from D. nobile, but not detected from commercial samples including 13 other Dendrobium species and the 7 dietary supplements. PMID:27054915

  12. ACCURACY OF REMOTELY SENSED SO2 MASS EMISSION RATES

    EPA Science Inventory

    Remote sensing data of single-stack power plant emissions and local wind speed have been analyzed to determined SO2 mass flux for comparison with EPA referenced methods. Four days of SO2 data were gathered from a moving platform by three upward-viewing remote sensors -- two ultra...

  13. Determination of amphetamine and methamphetamine in umbilical cord using liquid chromatography-tandem mass spectrometry

    PubMed Central

    Jones, Joseph; Rios, Rosemarie; Jones, Mary; Lewis, Douglas; Plate, Charles

    2009-01-01

    The use of meconium as a drug-screening matrix for newborns has been the gold standard of care for the past two decades. A recent study using matched pairs of meconium and umbilical cord demonstrated a high degree of agreement. The use of liquid chromatography-tandem mass spectrometry as a means to confirm amphetamines presumptive positive umbilical cord specimens for amphetamine and methamphetamine is described here for the first time. The limit of detection for both compounds was 0.2 ng/g. The limit of quantitation for both compounds was 0.6 ng/g. The assay was linear for both compounds up to 100 ng/g. PMID:19783234

  14. A comparison of salivary testosterone measurement using immunoassays and tandem mass spectrometry.

    PubMed

    Welker, Keith M; Lassetter, Bethany; Brandes, Cassandra M; Prasad, Smrithi; Koop, Dennis R; Mehta, Pranjal H

    2016-09-01

    Enzyme immunoassays (EIAs) are widely used to measure salivary testosterone. However, little is known about how accurately different EIAs assess testosterone, partially because estimates across various EIAs differ considerably. We compared testosterone concentrations across EIAs of three commonly used manufacturers (DRG International, Salimetrics, and IBL International) to liquid chromatography tandem mass spectrometry (LC-MS/MS). Relative to EIAs from Salimetrics and IBL International, EIAs supplied by DRG International provided the closest approximation to LC-MS/MS testosterone concentrations, followed closely by EIAs from Salimetrics, and then IBL. Additionally, EIAs tended to inflate estimates of lower testosterone concentrations in women. Examining our results and comparing them to existing data revealed that testosterone EIAs had decreased linear correspondence with LC-MS/MS in comparison to cortisol EIAs. Overall, this paper provides researchers with information to better measure testosterone in their research and more accurately compare testosterone measurements across different methods. PMID:27295182

  15. Characterization of protein N-glycosylation by tandem mass spectrometry using complementary fragmentation techniques

    DOE PAGESBeta

    Ford, Kristina L.; Zeng, Wei; Heazlewood, Joshua L.; Bacic, Antony

    2015-08-28

    The analysis of post-translational modifications (PTMs) by proteomics is regarded as a technically challenging undertaking. While in recent years approaches to examine and quantify protein phosphorylation have greatly improved, the analysis of many protein modifications, such as glycosylation, are still regarded as problematic. Limitations in the standard proteomics workflow, such as use of suboptimal peptide fragmentation methods, can significantly prevent the identification of glycopeptides. The current generation of tandem mass spectrometers has made available a variety of fragmentation options, many of which are becoming standard features on these instruments. Lastly, we have used three common fragmentation techniques, namely CID, HCD,more » and ETD, to analyze a glycopeptide and highlight how an integrated fragmentation approach can be used to identify the modified residue and characterize the N-glycan on a peptide.« less

  16. Characterization of protein N-glycosylation by tandem mass spectrometry using complementary fragmentation techniques

    SciTech Connect

    Ford, Kristina L.; Zeng, Wei; Heazlewood, Joshua L.; Bacic, Antony

    2015-08-28

    The analysis of post-translational modifications (PTMs) by proteomics is regarded as a technically challenging undertaking. While in recent years approaches to examine and quantify protein phosphorylation have greatly improved, the analysis of many protein modifications, such as glycosylation, are still regarded as problematic. Limitations in the standard proteomics workflow, such as use of suboptimal peptide fragmentation methods, can significantly prevent the identification of glycopeptides. The current generation of tandem mass spectrometers has made available a variety of fragmentation options, many of which are becoming standard features on these instruments. Lastly, we have used three common fragmentation techniques, namely CID, HCD, and ETD, to analyze a glycopeptide and highlight how an integrated fragmentation approach can be used to identify the modified residue and characterize the N-glycan on a peptide.

  17. Protonation Sites, Tandem Mass Spectrometry and Computational Calculations of o-Carbonyl Carbazolequinone Derivatives

    PubMed Central

    Martínez-Cifuentes, Maximiliano; Clavijo-Allancan, Graciela; Zuñiga-Hormazabal, Pamela; Aranda, Braulio; Barriga, Andrés; Weiss-López, Boris; Araya-Maturana, Ramiro

    2016-01-01

    A series of a new type of tetracyclic carbazolequinones incorporating a carbonyl group at the ortho position relative to the quinone moiety was synthesized and analyzed by tandem electrospray ionization mass spectrometry (ESI/MS-MS), using Collision-Induced Dissociation (CID) to dissociate the protonated species. Theoretical parameters such as molecular electrostatic potential (MEP), local Fukui functions and local Parr function for electrophilic attack as well as proton affinity (PA) and gas phase basicity (GB), were used to explain the preferred protonation sites. Transition states of some main fragmentation routes were obtained and the energies calculated at density functional theory (DFT) B3LYP level were compared with the obtained by ab initio quadratic configuration interaction with single and double excitation (QCISD). The results are in accordance with the observed distribution of ions. The nature of the substituents in the aromatic ring has a notable impact on the fragmentation routes of the molecules. PMID:27399676

  18. Determination of amphetamine and methamphetamine in umbilical cord using liquid chromatography-tandem mass spectrometry.

    PubMed

    Jones, Joseph; Rios, Rosemarie; Jones, Mary; Lewis, Douglas; Plate, Charles

    2009-11-01

    The use of meconium as a drug-screening matrix for newborns has been the gold standard of care for the past two decades. A recent study using matched pairs of meconium and umbilical cord demonstrated a high degree of agreement. The use of liquid chromatography-tandem mass spectrometry as a means to confirm amphetamines presumptive positive umbilical cord specimens for amphetamine and methamphetamine is described here for the first time. The limit of detection for both compounds was 0.2 ng/g. The limit of quantitation for both compounds was 0.6 ng/g. The assay was linear for both compounds up to 100 ng/g. PMID:19783234

  19. Protonation Sites, Tandem Mass Spectrometry and Computational Calculations of o-Carbonyl Carbazolequinone Derivatives.

    PubMed

    Martínez-Cifuentes, Maximiliano; Clavijo-Allancan, Graciela; Zuñiga-Hormazabal, Pamela; Aranda, Braulio; Barriga, Andrés; Weiss-López, Boris; Araya-Maturana, Ramiro

    2016-01-01

    A series of a new type of tetracyclic carbazolequinones incorporating a carbonyl group at the ortho position relative to the quinone moiety was synthesized and analyzed by tandem electrospray ionization mass spectrometry (ESI/MS-MS), using Collision-Induced Dissociation (CID) to dissociate the protonated species. Theoretical parameters such as molecular electrostatic potential (MEP), local Fukui functions and local Parr function for electrophilic attack as well as proton affinity (PA) and gas phase basicity (GB), were used to explain the preferred protonation sites. Transition states of some main fragmentation routes were obtained and the energies calculated at density functional theory (DFT) B3LYP level were compared with the obtained by ab initio quadratic configuration interaction with single and double excitation (QCISD). The results are in accordance with the observed distribution of ions. The nature of the substituents in the aromatic ring has a notable impact on the fragmentation routes of the molecules. PMID:27399676

  20. Rapid and multi-level characterization of trastuzumab using sheathless capillary electrophoresis-tandem mass spectrometry

    PubMed Central

    Gahoual, Rabah; Burr, Alicia; Busnel, Jean-Marc; Kuhn, Lauriane; Hammann, Phillipe; Beck, Alain; François, Yannis-Nicolas; Leize-Wagner, Emmanuelle

    2013-01-01

    Monoclonal antibodies (mAbs) are highly complex proteins that display a wide range of microheterogeneity that requires multiple analytical methods for full structure assessment and quality control. As a consequence, the characterization of mAbs on different levels is particularly product - and time - consuming. This work presents the characterization of trastuzumab sequence using sheathless capillary electrophoresis (referred as CESI) – tandem mass spectrometry (CESI-MS/MS). Using this bottom-up proteomic-like approach, CESI-MS/MS provided 100% sequence coverage for both heavy and light chain via peptide fragment fingerprinting (PFF) identification. The result was accomplished in a single shot, corresponding to the analysis of 100 fmoles of digest. The same analysis also enabled precise characterization of the post-translational hot spots of trastuzumab, used as a representative widely marketed therapeutic mAb, including the structural confirmation of the five major N-glycoforms. PMID:23563524

  1. Determination of ethylglucuronide in oral fluid by ultra-performance liquid chromatography- tandem mass spectrometry.

    PubMed

    Hegstad, S; Johnsen, L; Mørland, J; Christophersen, A S

    2009-05-01

    An ultra-performance liquid chromatography-tandem mass spectrometry method has been developed and validated for the determination of ethylglucuronide (EtG) in oral fluid. Sample clean-up was achieved by solid-phase extraction with a Hyper-SEP SAX column. Negative ionization was performed in the multiple reaction monitoring mode. Two transitions were monitored for the analyte and one for the internal standard EtG-d(5). The calibration range was 4.4-222 ng/mL. The recovery of the analyte ranged from 86 to 99%, and the between-assay precisions ranged from 5 to 9% RSD. The limit of quantification was found to be 4.4 ng/mL. The concentration of EtG in oral fluid collected 2-14 h after a moderate alcohol intake varied from 13.3 to 57.7 ng/mL. PMID:19470222

  2. Characterization of protein N-glycosylation by tandem mass spectrometry using complementary fragmentation techniques

    PubMed Central

    Ford, Kristina L.; Zeng, Wei; Heazlewood, Joshua L.; Bacic, Antony

    2015-01-01

    The analysis of post-translational modifications (PTMs) by proteomics is regarded as a technically challenging undertaking. While in recent years approaches to examine and quantify protein phosphorylation have greatly improved, the analysis of many protein modifications, such as glycosylation, are still regarded as problematic. Limitations in the standard proteomics workflow, such as use of suboptimal peptide fragmentation methods, can significantly prevent the identification of glycopeptides. The current generation of tandem mass spectrometers has made available a variety of fragmentation options, many of which are becoming standard features on these instruments. We have used three common fragmentation techniques, namely CID, HCD, and ETD, to analyze a glycopeptide and highlight how an integrated fragmentation approach can be used to identify the modified residue and characterize the N-glycan on a peptide. PMID:26379696

  3. Gapped Spectral Dictionaries and Their Applications for Database Searches of Tandem Mass Spectra

    NASA Astrophysics Data System (ADS)

    Jeong, Kyowon; Kim, Sangtae; Bandeira, Nuno; Pevzner, Pavel A.

    Generating all plausible de novo interpretations of a peptide tandem mass (MS/MS) spectrum (Spectral Dictionary) and quickly matching them against the database represent a recently emerged alternative approach to peptide identification. However, the sizes of the Spectral Dictionaries quickly grow with the peptide length making their generation impractical for long peptides. We introduce Gapped Spectral Dictionaries (all plausible de novo interpretations with gaps) that can be easily generated for any peptide length thus addressing the shortcoming of the Spectral Dictionary approach. We show that Gapped Spectral Dictionaries are small thus opening a possibility of using them to speed-up MS/MS database searches. Our MS-GappedDictionary algorithm (based on Gapped Spectral Dictionaries) enables proteogenomics applications that are prohibitively time consuming with existing approaches. We further introduce gapped tags that have advantages over the conventional peptide sequence tags in filtration-based MS/MS database searches.

  4. Tandem mass spectrometry of herbicide residues in lipid-rich tissue.

    PubMed

    Headley, J V; Peru, K M; Arts, M T

    1995-12-01

    A tandem mass spectrometry procedure, originally developed for bacterial biofilms was adapted for the identification of herbicide residues in lipid-rich tissue of amphipods collected from microcosms in a prairie wetland. For this application, the amounts of tissue employed (less than 1 mg wet weight), and detection of target analytes at picogram levels, were similar to the values reported for bacterial biofilms. Described is an application of the technique for the identification of residues of the herbicide S-2,3,3-trichloroallyl diisopropyl thiocarbamate (triallate; trade name Avadex-BW). For amphipods collected from microcosms exposed to the herbicide 2-[4-(2,4-dichlorophenoxy)phenoxy]propionic acid methyl ester (diclofop-methyl, trade name Hoe Grass), there were detectable levels of only the hydrolysis product, diclofop acid, in the lipid-rich tissue. Other transformation products reported for bacterial biofilms were not observed in the amphipods. PMID:8633778

  5. Determination of prostaglandin analogs in cosmetic products by high performance liquid chromatography with tandem mass spectrometry.

    PubMed

    Wittenberg, James B; Zhou, Wanlong; Wang, Perry G; Krynitsky, Alexander J

    2014-09-12

    A method was developed and validated for the determination of 16 prostaglandin analogs in cosmetic products. The QuEChERS (Quick, Easy, Cheap, Efficient, Rugged, Safe) liquid-liquid extraction method, typically used for pesticide residue analysis, was utilized as the sample preparation technique. The prostaglandin analogs were chromatographically separated and quantified using high performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS). Thirty-one cosmetic products were surveyed, and 13 products were determined to contain a prostaglandin analog with amounts ranging from 27.4 to 297μg/g. The calculated concentrations for the cosmetic products were in a similar range when compared to the concentrations of three different prostaglandin analog-containing prescription products. PMID:25085824

  6. Determination of 23 phthalic acid esters in food by liquid chromatography tandem mass spectrometry.

    PubMed

    Xu, Dunming; Deng, Xiaojun; Fang, Enhua; Zheng, Xianghua; Zhou, Yu; Lin, Liyi; Chen, Luping; Wu, Ming; Huang, Zhiqiang

    2014-01-10

    A rapid and sensitive method was developed for the determination of 23 phthalates in food samples including milk-based products, distilled liquor, wine, beverage, grain, meat, oil, biscuit (cookie), and canned food by liquid chromatography tandem mass spectrometry (LC-MS/MS). Liquid samples were exacted by acetonitrile, while solid samples were prepared by QuEChERS or glass-based SPE methods. The 23 phthalates were separated on Poroshell 120 EC-C18 column and followed by positive electrospray ionization as well as multi-reaction monitoring provided by a triple-quadrupole tandem mass spectrometer. To reduce contamination, the plastic materials were avoided in sample handling and preparation . The LODs were between 0.8 and 15 μg kg(-1) and LOQs were between 10 and 100 μg kg(-1). By using different concentrations: 100, 500, and 1000 μg kg(-1)) for DINP and DIDP; 50, 100, and 1000 μg kg(-1) for other 21 phthalate compounds, the spiked recoveries were within 75.5-115.2% and the relative standard deviations (RSDs) were in the range of 3.2-18.9%. The proposed protocol was then applied to the analysis of 623 real samples collected from the two sides of the Taiwan Straits, and the DEHP was found in almost all samples tested in this study, with levels ranging from 0.02 to 2685 mg kg(-1). The present study demonstrated a rapid, sensitive, and accurate method for determining 23 phthalates in foodstuffs. PMID:24326131

  7. Multiresidue analysis of pesticides with hydrolyzable functionality in cooked vegetables by liquid chromatography tandem mass spectrometry.

    PubMed

    Lee, Sung Joong; Park, Semin; Choi, Jin Young; Shim, Jae-Han; Shin, Eun-Ho; Choi, Jeong-Heui; Kim, Soo Taek; Abd El-Aty, A M; Jin, Jong Sung; Bae, Dong Won; Shin, Sung Chul

    2009-07-01

    It would be preferable for pesticide residues substituted by hydrolyzable functionality to be analyzed after cooking because their structures are apt to degrade during boiling and/or heating. A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the quantitative determination of 44 pesticide residues with hydrolyzable functional group in five typical vegetable widely consumed in Republic of Korea is described. The sample clean-up was carried out according to the method of Food Code No. 83 established by the Korea Food and Drug Administration (KFDA). Zorbox XDB-C(18) column was selected for the analysis because of the best peak separation. The LC mobile phase consisted of water and 5 mm methanolic ammonium formate, which resulted in a peak shape with good symmetry at each run. Tandem mass spectroscopic (MS/MS) experiments were performed in ESI positive mode and the multiple reaction monitoring modes. A conventional matrix effect was modified to more comprehensive form 100gamma(ij) (%). A high matrix effect (<-30%) was detected for the seven polar pesticides, namely thiamethoxam, clothianidin, acetamiprid, aldicarb, thiacloprid, pirimicarb and methabenzthiazuron. The limits of detection were in the range of 0.1-8.1 microg/kg, indicating a good sensitivity. Most of the recoveries ranged from 70 to 131% with RSDs

  8. Acute neurotoxicity associated with recreational use of methylmethaqualone confirmed by liquid chromatography tandem mass spectrometry.

    PubMed

    Ceschi, A; Giardelli, G; Müller, D M; Elavumkudy, S; Manini, A F; Rauber-Lüthy, C; Hofer, K E

    2013-01-01

    Methylmethaqualone is a sedative designer drug created by adding a methyl group to the 3-phenyl ring of methaqualone, and is at present not subject to restrictive regulation in many countries. To our knowledge, no case of methylmethaqualone abuse has been published to date in the scientific literature, and the only sources of information are users' reports on Web discussion forums and data from preclinical animal studies. We report a case of oral methylmethaqualone abuse confirmed by liquid chromatography tandem mass spectrometry in a 24-year-old previously healthy Caucasian male. Observed symptoms and signs such as central nervous system depression alternating with excitation, psychomotor agitation, muscle hyperactivity, and tachycardia were compatible with methaqualone-induced adverse effects. Except for the mild tachycardia (115 beats/min), other vital signs were normal: blood pressure 134/89 mmHg, body temperature 36.2°C (97.16°F), and peripheral oxygen saturation 99% while breathing room air. The ECG showed no prolongation of the QT interval and the QRS duration was normal. Laboratory analysis revealed a slight increase in creatine kinase (368 U/L) and alanine aminotransferase (90 U/L) serum concentrations. Blood alcohol concentration was 0.32 g/L. Methylmethaqualone was identified in a serum sample collected on admission which was analyzed by a liquid chromatography tandem mass spectrometry toxicological screening method using turbulent flow online extraction. After a few days the patient ingested the same amount of substance with identical symptoms. Based on the chemical structure and animal data, and according to this case report and users' Web reports, methylmethaqualone appears to have a similar acute toxicity profile to methaqualone, with marked psychomotor stimulation. Symptoms of acute toxicity can be expected to resolve with supportive care. PMID:23298217

  9. Development and validation of a liquid chromatography-tandem mass spectrometric assay for quantitative analyses of triptans in hair.

    PubMed

    Vandelli, Daniele; Palazzoli, Federica; Verri, Patrizia; Rustichelli, Cecilia; Marchesi, Filippo; Ferrari, Anna; Baraldi, Carlo; Giuliani, Enrico; Licata, Manuela; Silingardi, Enrico

    2016-04-01

    Triptans are specific drugs widely used for acute treatment of migraine, being selective 5HT1B/1D receptor agonists. A proper assumption of triptans is very important for an effective treatment; nevertheless patients often underuse, misuse, overuse or use triptans inconsistently, i.e., not following the prescribed therapy. Drug analysis in hair can represent a powerful tool for monitoring the compliance of the patient to the therapy, since it can greatly increase the time-window of detection compared to analyses in biological fluids, such as plasma or urine. In the present study, a liquid chromatography-tandem mass spectrometric (LC-MS/MS) method has been developed and validated for the quantitative analysis in human hair of five triptans commonly prescribed in Italy: almotriptan (AL), eletriptan (EP), rizatriptan (RIZ), sumatriptan (SUM) and zolmitriptan (ZP). Hair samples were decontaminated and incubated overnight in diluted hydrochloric acid; the extracts were purified by mixed-mode SPE cartridges and analyzed by LC-MS/MS under gradient elution in positive multiple reaction monitoring (MRM) mode. The procedure was fully validated in terms of selectivity, linearity, limit of detection (LOD) and lower limit of quantitation (LLOQ), accuracy, precision, carry-over, recovery, matrix effect and dilution integrity. The method was linear in the range 10-1000pg/mg hair, with R(2) values of at least 0.990; the validated LLOQ values were in the range 5-7pg/mg hair. The method offered satisfactory precision (RSD <10%), accuracy (90-110%) and recovery (>85%) values. The validated procedure was applied on 147 authentic hair samples from subjects being treated in the Headache Centre of Modena University Hospital in order to verify the possibility of monitoring the corresponding hair levels for the taken triptans. PMID:26970848

  10. Liquid chromatography tandem mass spectrometry method for characterization of monoaromatic nitro-compounds in atmospheric particulate matter.

    PubMed

    Kitanovski, Zoran; Grgić, Irena; Vermeylen, Reinhilde; Claeys, Magda; Maenhaut, Willy

    2012-12-14

    Nitrogen-containing organic compounds in the atmosphere have drawn attention owing to their impact on aerosol chemistry and physics and their potential adverse effects on the biosphere. Among them, nitrocatechols and their homologs have recently been associated with biomass burning. In the present study, nitrocatechols, nitrophenols, nitroguaiacols and nitrosalicylic acids (NSAs) were simultaneously quantified for the first time by using a new analytical method based on liquid chromatography/tandem mass spectrometry, which was systematically optimized and validated. Several analyte specific issues regarding the sample preparation and chromatographic analysis were addressed in order to ensure method sensitivity, precision, and accuracy. Sample matrix effects were thoroughly investigated in order to ensure method specificity. The method was found to be sensitive with limits of detection ranging from 0.1 to 1.0 μg L(-1), and with accuracy generally between 90 and 104%. The relative standard deviations for repeatability and intermediate precision were better than 4% and 9%, respectively. The method was applied to the analysis of winter and summer PM(10) samples from the city of Ljubljana, Slovenia. Aerosol concentrations as high as 152 and 134 ng m(-3) were obtained for the major aerosol nitro-aromatics: 4-nitrocatechol (4NC) and methyl-nitrocatechols (MNCs), respectively. Up to 500-times higher concentrations of 4NC and MNCs were found in winter compared to summer aerosols. The correlation analysis for winter samples showed that 4NC, MNCs, and NSAs are strongly inter-correlated (R(2)=0.84-0.96). Significant correlations between these analytes and anhydrosugars support their proposed origin from biomass burning. The studied nitro-aromatics were found to constitute a non-negligible fraction (around 1%) of the organic carbon. PMID:23122275

  11. Ultra-performance liquid chromatography tandem mass spectrometry for the rapid simultaneous analysis of nine organophosphate esters in milk powder.

    PubMed

    Guo, Xindong; Mu, Tongna; Xian, Yanping; Luo, Donghui; Wang, Chao

    2016-04-01

    Organophosphate esters (OPEs) are common flame retardants that are used in a wide variety of products. These compounds might migrate into and pollute food products. An analytical method involving an improved approach called the "quick, easy, cheap, effective, rugged, and safe" (QuEChERS) method and ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) was developed to simultaneously measure trace levels of nine OPEs in milk powder. Separation of the nine OPEs was optimized on a reversed-phase column within 7 min. The stable isotope tri-n-butyl phosphate-d27 (TBP-d27) was used as an internal standard. This method was validated in terms of its linearity, sensitivity, precision, accuracy and matrix effects. Matrix-matched calibration curves were constructed with 1/x(2) as the weighting factor for all of the target compounds resulting in coefficients of regression lines between 0.9938 and 0.9999. The average accuracy was between 73.5% and 110.2%. Intra- and inter-assay precisions for six replicates ranged from 3.9% to 8.9% or below 11%, respectively. The limits of detection (LODs) were in the range of 0.1-0.25 μg/kg, and the limits of quantification (LOQs) were below 1.5 μg/kg. Significant matrix effects have been observed, but suppression or enhancement of the signal was compensated for by the use of an isotopically labeled internal standard. This validated method was successfully applied to determine the concentrations of the OPEs in milk powder. PMID:26593541

  12. Quantification of Polybrominated and Polychlorinated Biphenyls in Human Matrices by Isotope-Dilution Gas Chromatography-Tandem Mass Spectrometry.

    PubMed

    Marder, M Elizabeth; Panuwet, Parinya; Hunter, Ronald E; Ryan, P Barry; Marcus, Michele; Barr, Dana Boyd

    2016-09-01

    We have developed a highly sensitive and selective analytical method capable of quantifying a total of 15 polybrominated and polychlorinated biphenyls (11 PBBs and 4 PCBs) in human serum. Samples were subjected to liquid-liquid extraction followed by solid-phase extraction prior to measurement using gas chromatography-tandem mass spectrometry in multiple reaction monitoring mode. Quantification was performed using isotope-dilution calibration covering a concentration range of 0.005-12.5 ng/mL. Limits of detection for all target compounds were in the low range (0.7-6.5 pg/mL). The method was validated using in-house pooled human serum fortified at two concentrations (0.5 ng/mL and 1.0 ng/mL), whole semen fortified at one concentration (0.25 ng/mL), and NIST Standard Reference Material (SRM) 1958, which includes five of the target compounds. Method accuracies for all target compounds ranged from 84 to 119% with relative standard deviations (RSDs) of <19%. The measured values for the five target compounds present in the SRM agreed with the certified reference values (89-119% accuracy with RSDs <9%). As this method was developed to support ongoing epidemiologic investigations, we evaluated its suitability by analyzing subsets of serum and whole semen samples from the Michigan PBB Registry cohort. PBB-153, PCB-118, PCB-138, PCB-153 and PCB-180 were detected in all serum samples analyzed, with PBB-77 and PBB-101 detected less frequently in serum. PBB-153, PCB-118, PCB-138, PCB-153 and PCB-180 were detected in at least one whole semen sample. PMID:27445313

  13. Determination of propofol glucuronide from hair sample by using mixed mode anion exchange cartridge and liquid chromatography tandem mass spectrometry.

    PubMed

    Kwak, Jae-Hwan; Kim, Hye Kyung; Choe, Sanggil; In, Sangwhan; Pyo, Jae Sung

    2016-03-15

    The main objective of this study was to develop and validate a simpler and less time consuming analytical method for determination of propofol glucuronide from hair sample, by using mixed mode anion exchange cartridge and liquid chromatography-tandem mass spectrometry (LC-MS/MS). The study uses propofol glucuronide, a major metabolite of propofol, as a marker for propofol abuse. The hair sample was digested in sodium hydroxide solution and loaded in mixed-mode anion cartridge for solid phase extraction. Water and ethyl acetate were used as washing solvents to remove interfering substances from the hair sample. Consequently, 2% formic acid in ethyl acetate was employed to elute propofol glucuronide from the sorbent of mixed-mode anion cartridge, and analyzed by LC-MS/MS. The method validation parameters such as selectivity, specificity, LOD, LLOQ, accuracy, precision, recovery, and matrix effect were also tested. The linearity of calibration curves showed good correlation, with correlation coefficient 0.998. The LOD and LLOQ of the propofol glucuronide were 0.2 pg/mg and 0.5 pg/mg, respectively. The intra and inter-day precision and accuracy were acceptable within 15%. The mean values of recovery and matrix effect were in the range of 91.7-98.7% and 87.5-90.3%, respectively, signifying that the sample preparation, washing and extraction procedure were efficient, and there was low significant hair matrix effect for the extraction of propofol glucuronide from hair sample on the mixed mode anion cartridge. To evaluate the suitability of method, the hair of propofol administered rat was successfully analyzed with this method. PMID:26946424

  14. Liquid chromatography with tandem mass spectrometry quantification of urinary proanthocyanin A2 dimer and its potential use as a biomarker of cranberry intake.

    PubMed

    Walsh, Jason M; Ren, Xiaobai; Zampariello, Carly; Polasky, Daniel A; McKay, Diane L; Blumberg, Jeffrey B; Chen, C-Y Oliver

    2016-01-01

    The lack of a biomarker for the consumption of cranberries has confounded the interpretation of several studies investigating the effect of cranberry products, especially juices, on health outcomes. The objectives of this pilot study were to develop a liquid chromatography tandem mass spectrometric method for the quantification of the proanthocyanin dimer A-2 in human urine and validate urinary proanthocyanin dimer A-2 as a biomarker of cranberry intake. Five healthy, nonsmoking, premenopausal women (20-30 years of age, body mass index: 18.5-25 kg/m(2) ) were assigned to consume a cranberry beverage containing 140 mg proanthocyanin and 35 kilocalories at 237 mL/day, according to a weekly dosing schedule for 7 weeks. Eleven 24 h and morning spot urine samples each were collected from each subject. A reliable, sensitive method for the detection of proanthocyanin dimer A-2 in urine using liquid chromatography with tandem mass spectrometry was developed with a limit of quantitation of 0.25 ng/mL and a relative standard deviation of 7.26%, precision of 5.7%, and accuracy of 91.7%. While proanthocyanin dimer A-2 was quantifiable in urine, it did not appear to be excreted in a concentration that corresponded to the dosing schedule and intake of cranberry juice. PMID:26573891

  15. Analysis of organophosphate flame retardant diester metabolites in human urine by liquid chromatography electrospray ionisation tandem mass spectrometry.

    PubMed

    Van den Eede, Nele; Neels, Hugo; Jorens, Philippe G; Covaci, Adrian

    2013-08-16

    A new analytical method was developed for the determination of dialkyl and diaryl phosphates (DAPs), which are metabolites of organophosphate triesters (PFRs), in human urine. Target DAPs included dibutyl phosphate (DBP), diphenyl phosphate (DPHP), bis(2-butoxyethyl) phosphate (BBOEP), bis(2-chloroethyl) phosphate (BCEP), bis(1-chloro-2-propyl) phosphate (BCPP), and bis(1,3-dichloro-2-propyl) phosphate (BDCIPP). Sample preparation was based on solid phase extraction using a weak anion exchange sorbent (Oasis WAX). Although several instrumental techniques have been tested, best results were obtained with reversed phase liquid chromatography-negative electrospray ionisation tandem mass spectrometry (LC-ESI-MS/MS) taking the total analysis time into account. Method accuracy at 3ng/mL in pooled urine ranged between 69 and 119% (recovery), while inter-day imprecision (as relative standard deviation) was <31%. The performance of the LC-MS/MS method was compared to a method based on gas chromatography-electron impact tandem mass spectrometry (GC-MS/MS) and a good correlation (Pearson r=0.82, p<0.01) between the results of these two methods was obtained for DPHP. LC-MS/MS analysis was more suitable for DPHP and BBOEP with respective method limits of quantification (mLOQ) of 0.3 and 0.15ng/mL. In contrast, GC-MS/MS had a better sensitivity for BCEP, BCIPP, and BDCIPP, their respective mLOQs being 0.1, 0.06, 0.02ng/mL, compared to 1.2, 3.7, and 0.5ng/mL by LC-MS/MS. A set of urine samples from volunteers was analysed, in which DPHP was the major DAP metabolite. A significant increase of DPHP levels was observed in the group of smokers (geometric mean of 1.55ng/mL) compared to the non-smokers (geometric mean of 0.88ng/mL). Metabolic transformation of triphenyl phosphate to DPHP by metabolic enzymes induced in smokers could be an explanation for this observation. PMID:23849782

  16. Improved mass resolution and mass accuracy in TOF-SIMS spectra and images using argon gas cluster ion beams.

    PubMed

    Shon, Hyun Kyong; Yoon, Sohee; Moon, Jeong Hee; Lee, Tae Geol

    2016-06-01

    The popularity of argon gas cluster ion beams (Ar-GCIB) as primary ion beams in time-of-flight secondary ion mass spectrometry (TOF-SIMS) has increased because the molecular ions of large organic- and biomolecules can be detected with less damage to the sample surfaces. However, Ar-GCIB is limited by poor mass resolution as well as poor mass accuracy. The inferior quality of the mass resolution in a TOF-SIMS spectrum obtained by using Ar-GCIB compared to the one obtained by a bismuth liquid metal cluster ion beam and others makes it difficult to identify unknown peaks because of the mass interference from the neighboring peaks. However, in this study, the authors demonstrate improved mass resolution in TOF-SIMS using Ar-GCIB through the delayed extraction of secondary ions, a method typically used in TOF mass spectrometry to increase mass resolution. As for poor mass accuracy, although mass calibration using internal peaks with low mass such as hydrogen and carbon is a common approach in TOF-SIMS, it is unsuited to the present study because of the disappearance of the low-mass peaks in the delayed extraction mode. To resolve this issue, external mass calibration, another regularly used method in TOF-MS, was adapted to enhance mass accuracy in the spectrum and image generated by TOF-SIMS using Ar-GCIB in the delayed extraction mode. By producing spectra analyses of a peptide mixture and bovine serum albumin protein digested with trypsin, along with image analyses of rat brain samples, the authors demonstrate for the first time the enhancement of mass resolution and mass accuracy for the purpose of analyzing large biomolecules in TOF-SIMS using Ar-GCIB through the use of delayed extraction and external mass calibration. PMID:26861497

  17. Accuracy of radionuclide imaging in distinguishing renal masses from normal variants

    SciTech Connect

    Older, R.A.; Korobkin, M.; Workman, J.; Cleeve, D.M.; Cleeve, L.K.; Sullivan, D.; Webster, G.D.

    1980-08-01

    To determine the accuracy of scintigraphy in distinguishing true renal masses from normal variants, 40 patients with excretory urographic findings indicating a possible, but not definite, mass lesion were studied. Scintigraphy correctly identified 17 true masses and 17 normal variants. Four false positive and two false negative results were obtained.

  18. Probability-Based Pattern Recognition and Statistical Framework for Randomization: Modeling Tandem Mass Spectrum/Peptide Sequence False Match Frequencies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Estimating and controlling the frequency of false matches between a peptide tandem mass spectrum and candidate peptide sequences is an issue pervading proteomics research. To solve this problem, we designed an unsupervised pattern recognition algorithm for detecting patterns with various lengths fr...

  19. An Undergraduate Experiment for the Measurement of Perfluorinated Surfactants in Fish Liver by Liquid Chromatography-Tandem Mass Spectrometry

    ERIC Educational Resources Information Center

    Stock, Naomi L.; Martin, Jonathan W.; Ye, Yun; Mabury, Scott A.

    2007-01-01

    A laboratory experiment that provides students a hands-on introduction to the specific techniques of liquid chromatography-tandem mass spectrometry (LC-MS/MS) and electrospray ionization is presented. The students can thus practice the analytical principles of sample extraction, detection, quantification, and quality control using a fresh fish…

  20. ESTIMATION OF MUTAGENIC/CARCINOGENIC POTENTIAL OF ENVIRONMENTAL CONTAMINANTS BY ION-MOLECULE REACTIONS AND TANDEM MASS SPECTROMETRY

    EPA Science Inventory

    The ability to produce and detect products of model DNA/carcinogen ion-molecule reactions is demonstrated in the ion source and the collision cell of a triple quadrupole tandem mass spectrometer. eaction between adenine and benzoyl chloride in the ion source is shown to produce t...

  1. Simplified analysis of glyphosate and aminomethylphosphonic acid in water, vegetation, and soil by liquid chromatography-tandem mass spectrometry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A simple, fast, efficient, and sensitive method was developed for analysis of glyphosate and its degradate, aminomethylphosphonic acid (AMPA), in water, vegetation, and soil. Aqueous extracts were passed through reverse phase and cation exchange columns and directly injected into a tandem mass spect...

  2. Optimized liquid chromatography tandem mass spectrometry approach for the determination of diquat and paraquat herbicides.

    PubMed

    Hao, Chunyan; Zhao, Xiaoming; Morse, David; Yang, Paul; Taguchi, Vince; Morra, Franca

    2013-08-23

    Liquid chromatography tandem mass spectrometry (LC-MS/MS) determination of quaternary ammonium herbicides diquat (DQ) and paraquat (PQ) can be very challenging due to their complicated chromatographic and mass spectrometric behaviors. Various multiple reaction monitoring (MRM) transitions from radical cations M(+) and singly charged cations [M-H](+), have been reported for LC-MS/MS quantitation under different chromatographic and mass spectrometric conditions. However, interference peaks were observed for certain previously reported MRM transitions in our study. Using a Dionex Acclaim(®) reversed-phase and HILIC mixed-mode LC column, we evaluated the most sensitive MRM transitions from three types of quasi-molecular ions of DQ and PQ, elucidated the cross-interference phenomena, and demonstrated that the rarely mentioned MRM transitions from dications M(2+) offered the best selectivity for LC-MS/MS analysis. Experimental parameters, such as IonSpray (IS) voltage, source temperature, declustering potential (DP), column oven temperature, collision energy (CE), acid and salt concentrations in the mobile phases were also optimized and an uncommon electrospray ionization (ESI) capillary voltage of 1000V achieved the highest sensitivity. Employing the proposed dication transitions 92/84.5 for DQ and 93/171 for PQ, the direct aqueous injection LC-MS/MS method developed was able to provide a method detection limit (MDL) of 0.1μg/L for the determination of these two herbicides in drinking water. PMID:23871562

  3. Dissociation reactions of protonated anthracycline antibiotics following electrospray ionization-tandem mass spectrometry

    NASA Astrophysics Data System (ADS)

    Sleno, Lekha; Campagna-Slater, Valerie; Volmer, Dietrich A.

    2006-09-01

    Fragmentation pathways of doxorubicin, a common cancer therapy agent, and three closely related analogs (epirubicin, daunorubicin, idarubicin) were compared using electrospray ionization with tandem mass spectrometry. This class of antibiotics with anti-tumour activity has important structural features, with a tetracyclic aromatic, polyketide portion, which is glycosylated with an amino sugar in order to exhibit its biological activity. Collision-induced dissociation spectra revealed very similar product ions for each analog, however, important differences were seen in the relative abundances and the ease at which certain fragments were formed. Fragment ions observed included those from cleavage of the glycosidic bond, loss of the side chain from the aglycone moiety, water losses and loss of a methyl radical. Following cleavage of the glycosidic bond, the charge can either reside on the aglycone portion or the sugar moiety, and each of these primary fragments undergoes several secondary dissociation pathways, depending on the collision energy. By ramping the collision voltage, we were able to correlate the changes in fragmentation behavior with small alterations in the structure of the precursor ion. The detailed study of the fragmentation behavior of doxorubicin was supported by accurate mass measurements, using an electrospray-time of flight instrument, as well as MS3 data from a quadrupole-linear ion trap mass spectrometer. Computational studies were also performed to help explain the role of certain functional groups in the fragmentation reactions.

  4. Identification of forced degradation products of tamsulosin using liquid chromatography/electrospray ionization tandem mass spectrometry.

    PubMed

    Namdev, Deepak; Borkar, Roshan M; Raju, B; Kalariya, Pradipbhai D; Rahangdale, Vinodkumar T; Gananadhamu, S; Srinivas, R

    2014-01-01

    A rapid and gradient high-performance liquid chromatography combined with quadrupole time-of-flight electrospray ionization tandem mass spectrometry (LC/Q-TOF-ESI-MS/MS) method has been developed for the identification and structural characterization of stressed degradation products of tamsulosin. Tamsulosin, a selective α1-adrenoceptor antagonist, was subjected to forced degradation studies under hydrolytic (acid, base and neutral), oxidative, photolytic and thermal stress conditions as per ICH guidelines Q1A (R2). The drug degraded significantly under hydrolytic (base and neutral), thermal, oxidative and photolytic conditions, while it was stable to acid hydrolytic stress conditions. A total of twelve degradation products were formed and the chromatographic separation of the drug and its degradation products were achieved on a GRACE C-18 column (250mm×4.6mm, 5μm). All the degradants have been identified and characterized by LC/ESI-MS/MS and accurate mass measurements. To elucidate the structures of degradation products, fragmentation of the [M+H](+) ions of tamsulosin and its degradation products was studied by using LC-MS/MS experiments combined with accurate mass measurements. The product ions of all the protonated degradation products were compared with the product ions of protonated tamsulosin to assign most probable structures for the observed degradation products. PMID:24083958

  5. Analyzing Protease Specificity and Detecting in Vivo Proteolytic Events Using Tandem Mass Spectrometry

    SciTech Connect

    Gupta, Nitin; Hixson, Kim K.; Culley, David E.; Smith, Richard D.; Pevzner, Pavel A.

    2010-07-01

    While trypsin remains the most commonly used protease in mass spectrometry, other proteases may be employed for increasing peptide-coverage or generating overlapping peptides. Knowledge of the accurate specifcity rules of these proteases is helpful for database search tools to detect peptides, and becomes crucial when mass spectrometry is used to discover in vivo proteolytic cleavages. In this study, we use tandem mass spectrometry to analyze the specifcity rules of selected proteases and describe MS- Proteolysis, a software tool for identifying putative sites of in vivo proteolytic cleavage. Our analysis suggests that the specifcity rules for some commonly used proteases can be improved, e.g., we find that V8 protease cuts not only after Asp and Glu, as currently expected, but also shows a smaller propensity to cleave after Gly for the conditions tested in this study. Finally, we show that comparative analysis of multiple proteases can be used to detect putative in vivo proteolytic sites on a proteome-wide scale.

  6. Peptides derivatized with bicyclic quaternary ammonium ionization tags. Sequencing via tandem mass spectrometry.

    PubMed

    Setner, Bartosz; Rudowska, Magdalena; Klem, Ewelina; Cebrat, Marek; Szewczuk, Zbigniew

    2014-10-01

    Improving the sensitivity of detection and fragmentation of peptides to provide reliable sequencing of peptides is an important goal of mass spectrometric analysis. Peptides derivatized by bicyclic quaternary ammonium ionization tags: 1-azabicyclo[2.2.2]octane (ABCO) or 1,4-diazabicyclo[2.2.2]octane (DABCO), are characterized by an increased detection sensitivity in electrospray ionization mass spectrometry (ESI-MS) and longer retention times on the reverse-phase (RP) chromatography columns. The improvement of the detection limit was observed even for peptides dissolved in 10 mM NaCl. Collision-induced dissociation tandem mass spectrometry of quaternary ammonium salts derivatives of peptides showed dominant a- and b-type ions, allowing facile sequencing of peptides. The bicyclic ionization tags are stable in collision-induced dissociation experiments, and the resulted fragmentation pattern is not significantly influenced by either acidic or basic amino acid residues in the peptide sequence. Obtained results indicate the general usefulness of the bicyclic quaternary ammonium ionization tags for ESI-MS/MS sequencing of peptides. PMID:25303389

  7. CREATININE DETERMINATION IN URINE BY LIQUID CHROMATOGRAPHY-ELECTROSPRAY IONIZATION-TANDEM MASS SPECTROMETRY METHOD.

    PubMed

    Dereziński, Paweł; Klupczyńska, Agnieszka; Sawicki, Wojciech; Kokot, Zenon J

    2016-01-01

    Creatinine determination in urine is used to estimate the completeness of the 24-h urine collection, compensation for variable diuresis and as a preliminary step in protein profiling in urine. Despite the fact that a wide range of methods of measuring creatinine level in biofluids has been developed, many of them are adversely affected by interfering substances. A new liquid chromatography-tandem mass spectrometry method for creatinine determination in urine has been developed. Chromatographic separation was performed by applying C18 column and a gradient elution. Analyses were carried out on a triple quadrupole mass spectrometer equipped with an electrospray ion source. The developed method was fully validated according to the international guidelines. The quantification range of the method was 5-1500 ng/mL, which corresponds to 1-300 mg/dL in urine. Limit of detection and quantitation were 2 and 5 ng/mL, respectively. Additionally, the comparison of creatinine determination by newly developed method to the colorimetric method was performed. The method enables the determination of creatinine in urine samples with a minimal sample preparation, excellent sensitivity and prominent selectivity. Since mass spectrometry allows to measure a number of compounds simultaneously, a future perspective would be to incorporate the determination of other clinically important compounds excreted in urine. PMID:27180423

  8. Decoding Split and Pool Combinatorial Libraries with Electron-Transfer Dissociation Tandem Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Sarkar, Mohosin; Pascal, Bruce D.; Steckler, Caitlin; Aquino, Claudio; Micalizio, Glenn C.; Kodadek, Thomas; Chalmers, Michael J.

    2013-07-01

    Screening of bead-based split and pool combinatorial chemistry libraries is a powerful approach to aid the discovery of new chemical compounds able to interact with, and modulate the activities of, protein targets of interest. Split and pool synthesis provides for large and well diversified chemical libraries, in this case comprised of oligomers generated from a well-defined starting set. At the end of the synthesis, each bead in the library displays many copies of a unique oligomer sequence. Because the sequence of the oligomer is not known at the time of screening, methods for decoding of the sequence of each screening "hit" are essential. Here we describe an electron-transfer dissociation (ETD) based tandem mass spectrometry approach for the decoding of mass-encoded split and pool libraries. We demonstrate that the newly described "chiral oligomers of pentenoic amides (COPAs)" yield non-sequence-specific product ions upon collisional activated dissociation; however, complete sequence information can be obtained with ETD. To aid in the decoding of libraries from MS and MS/MS data, we have incorporated 79Br/81Br isotope "tags" to differentiate N- and C-terminal product ions. In addition, we have created "Hit-Find," a software program that allows users to generate libraries in silico . The user can then search all possible members of the chemical library for those that fall within a user-defined mass error.

  9. Decoding Split and Pool Combinatorial Libraries with Electron Transfer Dissociation Tandem Mass Spectrometry

    PubMed Central

    Sarkar, Mohosin; Pascal, Bruce D.; Steckler, Caitlin; Aquino, Claudio; Micalizio, Glenn C.; Kodadek, Thomas; Chalmers, Michael J.

    2015-01-01

    Screening of bead-based split and pool combinatorial chemistry libraries is a powerful approach to aid the discovery of new chemical compounds able to interact with, and modulate the activities of, protein targets of interest. Split and pool synthesis provides for large and well diversified chemical libraries, in this case comprised of oligomers generated from a well-defined starting set. At the end of the synthesis, each bead in the library displays many copies of a unique oligomer sequence. Because the sequence of the oligomer is not known at the time of screening, methods for decoding of the sequence of each screening “hit” are essential. Here we describe an electron transfer dissociation (ETD) based tandem mass spectrometry approach for the decoding of mass-encoded split and pool libraries. We demonstrate that the newly described “chiral oligomers of pentenoic amides (COPAs)” yield non-sequence-specific product ions upon collisional activated dissociation; however, complete sequence information can be obtained with ETD. To aid in the decoding of libraries from MS and MS/MS data, we have incorporated 79Br/81Br isotope “tags” to differentiate N- and C-terminal product ions. In addition, we have created “Hit-Find,” a software program that allows users to generate libraries in silico. The user can then search all possible members of the chemical library for those that fall within a user-defined mass error. PMID:23636859

  10. Determination of nitrofuran and chloramphenicol residues by high resolution mass spectrometry versus tandem quadrupole mass spectrometry.

    PubMed

    Kaufmann, A; Butcher, P; Maden, K; Walker, S; Widmer, M

    2015-03-01

    An ultra-high performance liquid chromatography based method, coupled to high resolution mass spectrometry (UHPLC-HRMS), was developed to permit the detection and quantification of various nitrofuran and chloramphenicol residues in a number of animal based food products. This method is based on the hydrolysis of covalently bound metabolites and derivatization with 2-nitrobenzaldehyde. Clean-up is achieved by a liquid/liquid and a reversed phase/solid phase extraction. Not only are the four conventional nitrofurans (nitrofurantoin, furazolidone, nitrofurazone and furaltadone) detected, but also nifursol, nitrovin and nifuroxazide. Furthermore, an underivatizable nitrofuran (nifurpirinol) and another banned drug (chloramphenicol) can be quantified as well. The compounds are detected in the form of their precursor ions, [M+H](+) and [M-H](-), respectively. The mass resolving power of 70,000 FWHM, and the applied mass window ensure sufficient selectivity and sensitivity. Confirmation is obtained by monitoring the HRMS resolved product ions which were derived from the unit-mass resolved precursor ions. The multiplexing capability of the utilized Orbitrap instrument provides not only highly selective, but also sensitive confirmatory signals. This method has been validated according to the CD 2002/657/EC for the following matrices: muscle, liver, kidney, fish, honey, eggs and milk. PMID:25682427

  11. Simultaneous determination of albendazole and its metabolites in fish muscle tissue by stable isotope dilution ultra-performance liquid chromatography tandem mass spectrometry.

    PubMed

    Zhang, Xiaojun; Xu, Hanxiang; Zhang, Hong; Guo, Yuanming; Dai, Zhiyuan; Chen, Xuechang

    2011-08-01

    A rapid, specific, and sensitive method utilizing ultra-performance liquid chromatography tandem mass spectrometry was developed and validated to determine albendazole, albendazole sulfoxide, albendazole sulfone, and albendazole 2-aminosulfone in fish muscle tissue. The fish samples were extracted with ethyl acetate, then the organic phase was evaporated to dryness, and the residue was reconstituted in methanol-water solution and cleaned up by n-hexane. Reversed-phase separation of target compounds was achieved using a BEH C18 column and a gradient consisting of 0.2% (v/v) formic acid and methanol. Tandem mass spectrometry analyses were performed on a triple-quadrupole tandem mass spectrometer. In the whole procedure, the isotope-labeled internal standards were used to correct the matrix effect and variations associated with the analysis. The method was validated with respect to linearity, specificity, accuracy, and precision. The method exhibited a linear response from 0.1 to 20 ng mL(-1) (r(2) > 0.9985). The limit of quantitation for albendazole (ABZ), albendazole sulfoxide (ABZSO), albendazole sulfone (ABZSO(2)), and albendazole 2-aminosulfone (ABZ-2-NH(2)SO(2)) was 0.1, 0.1, 0.1, and 0.2 ng g(-1), respectively. The mean recoveries of ABZ, ABZSO, ABZSO(2), and ABZ-2-NH(2)SO(2) spiked at a level of 0.2-5.0 ng g(-1) were 95.3-113.7%, and the relative standard deviations of intra- and inter-day measurements were less than 6.38%. The method was later successfully applied to the determination of albendazole and its three metabolites in 60 fish samples collected from local markets. PMID:21633840

  12. Functional group composition of ambient and source organic aerosols determined by tandem mass spectrometry

    NASA Astrophysics Data System (ADS)

    Dron, J.; El Haddad, I.; Temime-Roussel, B.; Jaffrezo, J.-L.; Wortham, H.; Marchand, N.

    2010-08-01

    The functional group composition of various organic aerosols (OA) is investigated using a recently developed analytical approach based on atmospheric pressure chemical ionisation-tandem mass spectrometry (APCI-MS/MS). The determinations of three functional groups contents are performed quantitatively by neutral loss (carboxylic and carbonyl groups, R-COOH and R-CO-Ŕ respectively) and precursor ion (nitro groups, R-NO2) scanning modes of a tandem mass spectrometer. Major organic aerosol sources are studied: vehicular emission and wood combustion for primary aerosol sources; and a secondary organic aerosol (SOA) produced through photooxidation of o-xylene. The results reveal significant differences in the functional group contents of these source aerosols. The laboratory generated SOA is dominated by carbonyls while carboxylics are preponderate in the wood combustion particles. On the other hand, vehicular emissions are characterised by a strong nitro content. The total amount of the three functional groups accounts for 1.7% (vehicular) to 13.5% (o-xylene photooxidation) of the organic carbon. Diagnostic functional group ratios are then used to tentatively discriminate sources of particles collected in an urban background environment located in an Alpine valley (Chamonix, France) during a strong winter pollution event. The three functional groups under study account for a total functionalisation rate of 2.2 to 3.8% of the organic carbon in this ambient aerosol, which is also dominated by carboxylic moieties. In this particular case study of a deep alpine valley during winter, we show that the nitro- and carbonyl-to-carboxylic diagnostic ratios can be a useful tool to discriminate sources. In these conditions, the total OA concentrations are highly dominated by wood combustion OA. This result is confirmed by an organic markers source apportionment approach which assess a wood burning organic carbon contribution of about 60%. Finally, examples of functional group mass

  13. Simultaneous determination of guanidinosuccinic acid and guanidinoacetic acid in urine using high performance liquid chromatography/tandem mass spectrometry.

    PubMed

    Saigusa, Daisuke; Suzuki, Naoto; Takahashi, Mai; Shiba, Kanako; Tanaka, Satoshi; Abe, Takaaki; Hishinuma, Takanori; Tomioka, Yoshihisa

    2010-09-16

    We present a method for the simultaneous determination of guanidinosuccinic acid (GSA) and guanidinoacetic acid (GAA) from urine by protein precipitation and liquid chromatography/tandem mass spectrometry. The chromatographic separation was performed using a cation exchange column with an elution gradient of 0.1 mM and 20 mM ammonium acetate buffers. GSA was detected with the mass spectrometer in negative ion mode monitoring at m/z 174.1, and GAA, creatinine, arginine, and homoarginine were in positive ion mode monitoring at m/z 118.1, 114.1, 175.1, and 189.1, respectively. As an internal standard, L-arginine-(13)C(6) hydrochloride and creatinine-d(3) (methyl-d(3)) were used. The calibration ranges were 0.50-25.0 μg mL(-1), and good linearities were obtained for all compounds (r>0.999). The intra- and inter-assay accuracies (expressed as recoveries) and precisions at three concentration levels (1.00, 5.00 and 25.0 μg mL(-1)) were better than 83.8% and 7.41%, respectively. The analytical performance of the method was evaluated by determination of the compounds in urine from male C57BL/J Iar db/db diabetes mellitus (DM) mice. The values of GSA and GAA corrected by the ratios of the individual compounds to creatinine were significantly increased in DM mice compared with control mice. These results indicated that the newly developed method was useful for determining urinary guanidino compounds and metabolites of arginine. PMID:20837184

  14. Liquid chromatography-tandem mass spectrometric assay for ponatinib and N-desmethyl ponatinib in mouse plasma.

    PubMed

    Sparidans, Rolf W; Kort, Anita; Schinkel, Alfred H; Schellens, Jan H M; Beijnen, Jos H

    2016-06-15

    Ponatinib is a multi-targeted third generation BCR-ABL1 tyrosine-kinase inhibitor approved for specific types of leukemia. A bioanalytical assay for this drug and its N-desmethyl metabolite in mouse plasma was developed and validated using liquid chromatography-tandem mass spectrometric (LC-MS/MS) with liquid-liquid extraction as sample pre-treatment procedure. After extraction with tert-butyl methyl ether of both analytes with their isotopically labeled internal standards and evaporation and reconstitution of the extract, compounds were separated by reversed-phase liquid chromatography under alkaline conditions. After electrospray ionization, both compounds were quantified in the selected reaction monitoring mode of a triple quadrupole mass spectrometer. The linear assay was validated in the ranges 5-5000ng/ml for ponatinib and 1-1000ng/ml for N-desmethyl ponatinib. Within-run (n=18) and between-run (3 runs; n=18) precisions were 10% and 12% at the lower limit of quantification for the metabolite, all other precisions were ≤8% for the metabolite and ≤6% for ponatinib. Accuracies were between 92 and 108% for both compounds in the whole calibration range. The drug was sufficiently stable under most relevant analytical conditions, only ponatinib showed more than 15% hydrolytic degradation after storage for 6h and longer at ambient temperature in mouse plasma. Finally, the assay was successfully applied to determine plasma drug levels and study pharmacokinetics after oral administration of ponatinib to female FVB mice. PMID:27179188

  15. A novel method for quantification of human hemoglobin from dried blood spots by use of tandem mass spectrometry.

    PubMed

    Yu, Chaowen; Zhang, Juan; Yuan, Zhaojian; Liu, Hao; Wang, Xingbin; Wang, Ming; Zou, Lin

    2015-10-01

    Quantification of human hemoglobin (Hb) is essential for diagnosis of anemia, especially for screening for thalassemia and sickle cell disease. The main methods currently used for quantification of Hb, including spectrophotometry, fluorimetry, and electrochemical assays, are all based on the structural integrity of Hb, which could be affected by hemolysis and degradation. When used for disease screening, whole blood specimens cannot meet requirements for sample collecting, transport, and storage. Here, we report a novel MS-MS method for quantification of Hb from dried blood spots (DBS) by use of a triple-quadrupole mass spectrometer. Proteospecific peptides from α-globin chains were selected after tryptic digestion. The precursor → product ion transitions of representative peptides were studied to identify the best choice with regard to sensitivity and chromatographic properties. For quantification, stable isotope-labeled peptides were used as internal standards. The concentration of Hb in each sample was obtained by calculation on the basis of established equations. The precision of the method was within 15 % and accuracy was in the range -7 to 13.0 %. Compared with routine clinical results obtained by use of the automated hematology analyzer (AHA) assay, the correlation, r (2), was >0.993. When used for determination of anemia levels the sensitivity of the assay was 95.7 % and specificity 96.5 %. Our new approach for quantification of the concentration of Hb from DBS is feasible, and precision is acceptable. The method could be used for determination of anemia levels when screening for hemoglobin disorders. Graphical Abstract Quantification of human hemoglobin from digested dried blood spot samples using tandem mass spectrometry. PMID:26345440

  16. Derivatization of estrogens enhances specificity and sensitivity of analysis of human plasma and serum by liquid chromatography tandem mass spectrometry.

    PubMed

    Faqehi, Abdullah M M; Cobice, Diego F; Naredo, Gregorio; Mak, Tracy C S; Upreti, Rita; Gibb, Fraser W; Beckett, Geoffrey J; Walker, Brian R; Homer, Natalie Z M; Andrew, Ruth

    2016-05-01

    Estrogens circulate at concentrations less than 20pg/mL in men and postmenopausal women, presenting analytical challenges. Quantitation by immunoassay is unreliable at these low concentrations. Liquid chromatography tandem mass spectrometry (LC-MS/MS) offers greater specificity and sometimes greater sensitivity, but ionization of estrogens is inefficient. Introduction of charged moieties may enhance ionization, but many such derivatives of estrogens generate non-specific product ions originating from the "reagent" group. Therefore an approach generating derivatives with product ions specific to individual estrogens was sought. Estrogens were extracted from human plasma and serum using solid phase extraction and derivatized using 2-fluoro-1-methylpyridinium-p-toluenesulfonate (FMP-TS). Electrospray in positive mode with multiple reaction monitoring using a QTrap 5500 mass spectrometer was used to quantify "FMP" derivatives of estrogens, following LC separation. Transitions for the FMP derivatives of estrone (E1) and estradiol (E2) were compound specific (m/z 362→238 and m/z 364→128, respectively). The limits of detection and quantitation were 0.2pg on-column and the method was linear from 1-400pg/sample. Measures of intra- and inter-assay variability, precision and accuracy were acceptable (<20%). The derivatives were stable over 24h at 10°C (7-9% degradation). Using this approach, E1 and E2, respectively were detected in human plasma and serum: pre-menopausal female serum (0.5mL) 135-473, 193-722pmol/L; male plasma (1mL) 25-111, 60-180pmol/L and post-menopausal female plasma (2mL), 22-78, 29-50pmol/L. Thus FMP derivatization, in conjunction with LC-MS/MS, is suitable for quantitative analysis of estrogens in low abundance in plasma and serum, offering advantages in specificity over immunoassay and existing MS techniques. PMID:26946022

  17. Determination of Dicyandiamide in Powdered Milk Using Direct Analysis in Real Time Quadrupole Time-of-Flight Tandem Mass Spectrometry.

    PubMed

    Zhang, Liya; Yong, Wei; Liu, Jiahui; Wang, Sai; Chen, Qilong; Guo, Tianyang; Zhang, Jichuan; Tan, Tianwei; Su, Haijia; Dong, Yiyang

    2015-08-01

    The direct analysis in real time (DART) ionization source coupled with quadrupole time-of-flight tandem mass spectrometry (Q-TOF MS/MS) system has the capability to desorb analytes directly from samples without sample cleanup or chromatographic separation. In this work, a method based on DART/Q-TOF MS/MS has been developed for rapid identification of dicyandiamide (DCD) present in powdered milk. Simple sample extraction procedure employing acetonitrile-water (80:20, v/v) mixture was followed by direct, high-throughput determination of sample extracts spread on a steel mesh of the transmission module by mass spectrometry under ambient conditions. The method has been evaluated for both qualitative and quantitative analysis of DCD in powdered milk. Variables including experimental apparatus, DART gas heater temperature, sample presentation speed, and vacuum pressure were investigated. The quantitative method was validated with respect to linearity, sensitivity, repeatability, precision, and accuracy by using external standards. After optimization of these parameters, a limit of detection (LOD) of 100 μg kg(-1) was obtained for DCD with a linear working range from 100 to 10000 μg kg(-1) and a satisfactory correlation coefficient (R(2)) of 0.9997. Good recovery (80.08%-106.47%) and repeatability (RSD = 3.0%-5.4%) were achieved for DCD. The DART/Q-TOF MS/MS-based method provides a rapid, efficient, and powerful scheme to analyze DCD in powdered milk with limited sample preparation, thus reducing time and complexity of quality control. PMID:25930094

  18. Determination of Dicyandiamide in Powdered Milk Using Direct Analysis in Real Time Quadrupole Time-of-Flight Tandem Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Zhang, Liya; Yong, Wei; Liu, Jiahui; Wang, Sai; Chen, Qilong; Guo, Tianyang; Zhang, Jichuan; Tan, Tianwei; Su, Haijia; Dong, Yiyang

    2015-08-01

    The direct analysis in real time (DART) ionization source coupled with quadrupole time-of-flight tandem mass spectrometry (Q-TOF MS/MS) system has the capability to desorb analytes directly from samples without sample cleanup or chromatographic separation. In this work, a method based on DART/Q-TOF MS/MS has been developed for rapid identification of dicyandiamide (DCD) present in powdered milk. Simple sample extraction procedure employing acetonitrile-water (80:20, v/v) mixture was followed by direct, high-throughput determination of sample extracts spread on a steel mesh of the transmission module by mass spectrometry under ambient conditions. The method has been evaluated for both qualitative and quantitative analysis of DCD in powdered milk. Variables including experimental apparatus, DART gas heater temperature, sample presentation speed, and vacuum pressure were investigated. The quantitative method was validated with respect to linearity, sensitivity, repeatability, precision, and accuracy by using external standards. After optimization of these parameters, a limit of detection (LOD) of 100 μg kg-1 was obtained for DCD with a linear working range from 100 to 10000 μg kg-1 and a satisfactory correlation coefficient (R2) of 0.9997. Good recovery (80.08%-106.47%) and repeatability (RSD = 3.0%-5.4%) were achieved for DCD. The DART/Q-TOF MS/MS-based method provides a rapid, efficient, and powerful scheme to analyze DCD in powdered milk with limited sample preparation, thus reducing time and complexity of quality control.

  19. Quantification of anthocyanins and flavonols in milk-based food products by ultra performance liquid chromatography-tandem mass spectrometry.

    PubMed

    Nagy, Kornél; Redeuil, Karine; Bertholet, Raymond; Steiling, Heike; Kussmann, Martin

    2009-08-01

    The present article describes the development and validation of an ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for the comprehensive quantification of anthocyanin and flavonol constituents of milk-based food products. Protein precipitation by acidified methanol and ultrafiltration was utilized as sample preparation to preserve overall polyphenol composition but to eliminate milk proteins in order to comply with UPLC. Reversed-phase chromatography was optimized to achieve separation of 27 analytes in 10 min in order to reduce suppression effects, achieve a wide dynamic range, and most importantly, to resolve isomeric compounds. Positive-ion electrospray mass spectrometric detection and fragmentation of analytes was optimized, final transitions were selected for maximized selectivity, reliable quantification, and reduction of false positives. The quantitative performance of the method was validated, the main features include (1) range of lower limits of detection 0.3-30 ng/mL for glycosylated analytes, 10-300 ng/mL for aglycones, (2) lower limits of quantification 1-100 ng/mL for glycosylated analytes, 30-1,000 ng/mL for aglycones, (3) averaged intraday precision 9%, (4) calibrated range 2-180,000 ng/mL for glycosylated analytes, 60-600,000 ng/mL for aglycones, and (5) averaged accuracy 101%. Applications for yogurt and ice cream products are given. The presented data suggest that this method will help to better characterize the polyphenol composition of milk-based food products for quality control, for assessment of dietary intake, and for polyphenol bioavailability/bioefficacy studies. PMID:20337399

  20. Determination of ginsenoside compound K in human plasma by liquid chromatography–tandem mass spectrometry of lithium adducts

    PubMed Central

    Chen, Yunhui; Lu, Youming; Yang, Yong; Chen, Xiaoyan; Zhu, Liang; Zhong, Dafang

    2015-01-01

    Ginsenoside compound K (GCK), the main metabolite of protopanaxadiol constituents of Panax ginseng, easily produces alkali metal adduct ions during mass spectrometry particularly with lithium. Accordingly, we have developed a rapid and sensitive liquid chromatography–tandem mass spectrometric method for analysis of GCK in human plasma based on formation of a lithium adduct. The analyte and paclitaxel (internal standard) were extracted from 50 µL human plasma using methyl tert-butyl ether. Chromatographic separation was performed on a Phenomenex Gemini C18 column (50 mm×2.0 mm; 5 μm) using stepwise gradient elution with acetonitrile–water and 0.2 mmol/L lithium carbonate at a flow rate of 0.5 mL/min. Detection was performed in the positive ion mode using multiple reaction monitoring of the transitions at m/z 629→449 for the GCK-lithium adduct and m/z 860→292 for the adduct of paclitaxel. The assay was linear in the concentration range 1.00–1000 ng/mL (r2>0.9988) with intra- and inter-day precision of ±8.4% and accuracy in the range of −4.8% to 6.5%. Recovery, stability and matrix effects were all satisfactory. The method was successfully applied to a pharmacokinetic study involving administration of a single GCK 50 mg tablet to healthy Chinese volunteers. PMID:26579476

  1. Biomonitoring method for bisphenol A in human urine by ultra-high-performance liquid chromatography-tandem mass spectrometry

    PubMed Central

    Anderson, David J.; Brozek, Eric M.; Cox, Kyley J.; Porucznik, Christina A.; Wilkins, Diana G.

    2014-01-01

    An ultra-high-performance liquid chromatography-tandem mass spectrometry method for the measurement of total bisphenol A in human urine was developed and validated. The method utilized liquid/liquid extraction with 1-chlorobutane and a human urine aliquot size of 800 µL. Chromatography was performed on an Acquity UPLC® system with a Kinetex® Phenyl-Hexyl column. Mass spectrometric analysis was with negative electrospray ionization on a Quattro Premier XE™. The surrogate matrix method was used for the preparation of calibration standards in synthetic urine due to the presence of BPA in control human urine. The validated calibration range was 0.75 to 20 ng/mL with a limit of detection of 0.1 ng/mL. The internal standard was d16-bisphenol A. Method validation utilized quality control samples at three concentrations in both synthetic urine and human urine. Bisphenol A mono-glucuronide was fortified in synthetic urine in each analytical run to monitor the enzymatic conversion of the glucuronide conjugate to BPA by β-glucuronidase. Validated method parameters included linearity, accuracy, precision, integrity of dilution, selectivity, re-injection reproducibility, recovery/matrix effect, solution stability, and matrix stability in human urine. Acceptance criteria for analytical standards and QCs were ± 20% of nominal concentration. Matrix stability in human urine was validated after 24 hours at ambient temperature, after three freeze/thaw cycles, and after frozen storage at −20 °C and −80 °C for up to 218 days. The method has been applied to the analysis of over 1750 human urine samples from a biomonitoring study. The median and mean urine BPA concentrations were 2.71 ng/mL and 4.75 ng/mL, respectively. PMID:24594944

  2. A Novel Approach for Untargeted Post-translational Modification Identification Using Integer Linear Optimization and Tandem Mass Spectrometry*

    PubMed Central

    Baliban, Richard C.; DiMaggio, Peter A.; Plazas-Mayorca, Mariana D.; Young, Nicolas L.; Garcia, Benjamin A.; Floudas, Christodoulos A.

    2010-01-01

    A novel algorithm, PILOT_PTM, has been developed for the untargeted identification of post-translational modifications (PTMs) on a template sequence. The algorithm consists of an analysis of an MS/MS spectrum via an integer linear optimization model to output a rank-ordered list of PTMs that best match the experimental data. Each MS/MS spectrum is analyzed by a preprocessing algorithm to reduce spectral noise and label potential complimentary, offset, isotope, and multiply charged peaks. Postprocessing of the rank-ordered list from the integer linear optimization model will resolve fragment mass errors and will reorder the list of PTMs based on the cross-correlation between the experimental and theoretical MS/MS spectrum. PILOT_PTM is instrument-independent, capable of handling multiple fragmentation technologies, and can address the universe of PTMs for every amino acid on the template sequence. The various features of PILOT_PTM are presented, and it is tested on several modified and unmodified data sets including chemically synthesized phosphopeptides, histone H3-(1–50) polypeptides, histone H3-(1–50) tryptic fragments, and peptides generated from proteins extracted from chromatin-enriched fractions. The data sets consist of spectra derived from fragmentation via collision-induced dissociation, electron transfer dissociation, and electron capture dissociation. The capability of PILOT_PTM is then benchmarked using five state-of-the-art methods, InsPecT, Virtual Expert Mass Spectrometrist (VEMS), Modi, Mascot, and X!Tandem. PILOT_PTM demonstrates superior accuracy on both the small and large scale proteome experiments. A protocol is finally developed for the analysis of a complete LC-MS/MS scan using template sequences generated from SEQUEST and is demonstrated on over 270,000 MS/MS spectra collected from a total chromatin digest. PMID:20103568

  3. Simultaneous pharmacokinetic and pharmacodynamic analysis of 5α-reductase inhibitors and androgens by liquid chromatography tandem mass spectrometry.

    PubMed

    Upreti, Rita; Naredo, Gregorio; Faqehi, Abdullah M M; Hughes, Katherine A; Stewart, Laurence H; Walker, Brian R; Homer, Natalie Z M; Andrew, Ruth

    2015-01-01

    Benign prostatic hyperplasia and prostate cancer can be treated with the 5α-reductase inhibitors, finasteride and dutasteride, when pharmacodynamic biomarkers are useful in assessing response. A novel method was developed to measure the substrates and products of 5α-reductases (testosterone, 5α-dihydrotestosterone (DHT), androstenedione) and finasteride and dutasteride simultaneously by liquid chromatography tandem mass spectrometry, using an ABSciex QTRAP(®) 5500, with a Waters Acquity™ UPLC. Analytes were extracted from serum (500 µL) via solid-phase extraction (Oasis(®) HLB), with (13)C3-labelled androgens and d9-finasteride included as internal standards. Analytes were separated on a Kinetex C18 column (150 × 3 mm, 2.6 µm), using a gradient run of 19 min. Temporal resolution of analytes from naturally occurring isomers and mass +2 isotopomers was ensured. Protonated molecular ions were detected in atmospheric pressure chemical ionisation mode and source conditions optimised for DHT, the least abundant analyte. Multiple reaction monitoring was performed as follows: testosterone (m/z 289 → 97), DHT (m/z 291 → 255), androstenedione (m/z 287 → 97), dutasteride (m/z 529 → 461), finasteride (m/z 373 → 317). Validation parameters (intra- and inter-assay precision and accuracy, linearity, limits of quantitation) were within acceptable ranges and biological extracts were stable for 28 days. Finally the method was employed in men treated with finasteride or dutasteride; levels of DHT were lowered by both drugs and furthermore the substrate concentrations increased. PMID:25281165

  4. Determination of phosphodiesterase type V inhibitors in wastewater by direct injection followed by liquid chromatography coupled to tandem mass spectrometry.

    PubMed

    Causanilles, Ana; Emke, Erik; de Voogt, Pim

    2016-09-15

    A simple, fast and reliable analytical method for the determination of phosphodiesterase type V inhibitors in wastewater was developed and validated. The method was based on direct injection followed by liquid chromatography coupled to tandem mass spectrometry with triple quadrupole as mass analyzer. Transformation products and analogues were included in the target list besides the three active pharmaceutical ingredients (sildenafil, vardenafil and tadalafil). The method performance was thoroughly investigated, including the analyte stability in wastewater and matrix effect. All target compounds presented linear fits between their LOD and 500ng/L. The quantification limits ranged from 1.6 to 30ng/L for all compounds except for n-octylnortadalafil (LOQ: 100ng/L); precision calculated as intraday repeatability was lower than 30%; accuracy calculated as procedural recovery ranged successfully between 85 and 105% in all cases. The method was applied to samples collected during three week-long monitoring campaigns performed in 2013, 2014 and 2015 in three Dutch cities. Only sildenafil and its two metabolites, desmethyl- and desethylsildenafil, were present with normalized loads ranging from LOQ to 8.3, 11.8 and 21.6mg/day/1000 inh, respectively. Two additional week-long sets of samples were collected in Amsterdam at the time that a festival event took place, bringing around 350,000 visitors to the city. The difference in drug usage patterns was statistically studied: "weekday" versus "weekend", "normal" versus "atypical" week; and results discussed. The metabolite to parent drug concentration ratio evolution during consecutive years was discussed, leading to several possible explanations that should be further investigated. Finally, wastewater-based epidemiology approach was applied to back-calculate sildenafil consumption. PMID:27161135

  5. LipidBlast Templates As Flexible Tools for Creating New in-Silico Tandem Mass Spectral Libraries

    PubMed Central

    2015-01-01

    Tandem mass spectral libraries (MS/MS) are usually built by acquiring experimentally measured mass spectra from chemical reference compounds. We here show the versatility of in-silico or computer generated tandem mass spectra that are directly obtained from compound structures. We use the freely available LipidBlast development software to generate 15 000 MS/MS spectra of the glucuronosyldiacylglycerol (GlcADG) lipid class, recently discovered for the first time in plants. The generation of such an in-silico MS/MS library for positive and negative ionization mode took 5 h development time, including the validation of the obtained mass spectra. Such libraries allow for high-throughput annotations of previously unknown glycolipids. The publicly available LipidBlast templates are universally applicable for the development of MS/MS libraries for novel lipid classes. PMID:25340521

  6. Ultra performance liquid chromatography tandem mass spectrometry assay for determination of kukoamine B in human blood and urine.

    PubMed

    Zhao, Qian; Li, Lili; Wang, Zhenlei; Jiang, Ji; Dong, Kai; Chen, Shuai; Hu, Pei

    2016-09-15

    In this paper, we report a sensitive and rapid ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method which is capable of quantifying kukoamine B (KB) levels in human blood and urine. Following solid phase extraction and direct dilution process, the analyte and its internal standard (D5-KB) run on an Acquity UPLC(®) HSS T3 column (2.1×50mm i.d., 1.8μm) by using a gradient elution method (run time was 1.5min). The mass spectrometric analysis was performed by using an API-5500 mass spectrometer coupled with an electro-spray ionization source. The MRM transitions of m/z 531.3(+)→222.1(+) and 536.3(+)→222.1(+) were used to quantify KB and D5-KB respectively. This assay method has been fully validated in terms of selectivity, linearity, lower limit of quantification, precision, accuracy, stability, recovery and matrix effect. The concentration range of this method is 10.0-2000.0ngmL(-1) in blood and 0.5-500.0ngmL(-1) in urine. Linearity (R(2)) of calibration curves were 0.9964±0.0022 and 0.9935±0.0053 for blood and urine, respectively (regression equation: y=ax+b). The precision (RSD%) of quality control samples is less than 10.3% for blood and less than 10.5% for urine. The accuracy (RE%) is within -4.0-11.3% and -11.7-12.5% for blood and urine respectively. KB was stable after 4h in ice-water bath, 1 freeze/thaw cycles and 180days at -80°C for blood samples; and was stable after 3h at room temperature, 3 freeze/thaw cycles and 180days at -80°C for urine samples. Recoveries of KB were 4.7±0.9% in blood and 96.5±1.3% in urine, respectively. Additionally, the applicability of this method has been proved by analyzing clinical samples from pharmacokinetic study of KB in human. PMID:27447928

  7. A universal SI-traceable isotope dilution mass spectrometry method for protein quantitation in a matrix by tandem mass tag technology.

    PubMed

    Li, Jiale; Wu, Liqing; Jin, Youxun; Su, Ping; Yang, Bin; Yang, Yi

    2016-05-01

    Isotope dilution mass spectrometry (IDMS), an important metrological method, is widely used for absolute quantification of peptides and proteins. IDMS employs an isotope-labeled peptide or protein as an internal standard although the use of a protein provides improved accuracy. Generally, the isotope-labeled protein is obtained by stable isotope labeling by amino acids in cell culture (SILAC) technology. However, SILAC is expensive, laborious, and time-consuming. To overcome these drawbacks, a novel universal SI-traceable IDMS method for absolute quantification of proteins in a matrix is described with human transferrin (hTRF). The hTRF and a human serum sample were labeled with different tandem mass tags (TMTs). After mixing the TMT-labeled hTRF and serum sample together followed by digestion, the peptides were separated by nano-liquid chromatography and analyzed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Using the signature peptides, we calculated the ratios of reporter ions from the TMT-labeled peptides which, in turn, allowed determination of the mass fraction of hTRF. The recovery ranged from 97% to 105% with a CV of 3.9%. The LOD and LOQ were 1.71 × 10(-5) g/g and 5.69 × 10(-5) g/g of hTRF in human serum, respectively, and the relative expanded uncertainty was 4.7% with a mass fraction of 2.08 mg/g. For comparison, an enzyme-linked immunosorbent assay (ELISA) method for hTRF yielded a mass fraction of 2.03 mg/g. This method provides a starting point for establishing IDMS technology to accurately determine the mass fractions of protein biomarkers in a matrix with traceability to SI units. This technology should support the development of a metrological method useful for quantification of a wide variety of proteins. PMID:26942737

  8. Direct Measurement of Free Estradiol in Human Serum and Plasma by Equilibrium Dialysis-Liquid Chromatography-Tandem Mass Spectrometry.

    PubMed

    Ray, Julie A; Kushnir, Mark M; Rockwood, Alan L; Meikle, A Wayne

    2016-01-01

    We describe a direct method of measurement of free estradiol using equilibrium dialysis followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Serum aliquots and internal standards are extracted by liquid-liquid extraction using methyl-tert-butyl ether (MTBE) followed by derivatization with dansyl chloride. An API 5500 mass spectrometer operated in positive electrospray mode is used for detection. PMID:26602122

  9. Changes in Kicking Pattern: Effect of Experience, Speed, Accuracy, and Effective Striking Mass

    ERIC Educational Resources Information Center

    Southard, Dan L.

    2014-01-01

    Purpose: The purposes of this study were to: (a) examine the effect of experience and goal constraints (speed, accuracy) on kicking patterns; (b) determine if effective striking mass was independent of ankle velocity at impact; and (c) determine the accuracy of kicks relative to independent factors. Method: Twenty participants were recruited to…

  10. Validation of a liquid chromatography-tandem mass spectrometric assay for the quantitative determination of hydrastine and berberine in human serum.

    PubMed

    Gupta, Prem K; Hubbard, Martha; Gurley, Bill; Hendrickson, Howard P

    2009-05-01

    A high throughput liquid chromatography/tandem mass spectrometry (LC-MS/MS) method for the simultaneous determination of berberine and hydrastine in human serum, after oral administration of goldenseal (Hydrastis canadensis L.), was developed using simple acetonitrile treatment of serum samples. Noscapine served as the internal standard. Lower limit of quantification for both analytes was 0.1 ng mL(-1) using positive ion electrospray tandem mass spectrometry (MS/MS). The intra-day (n=5) accuracy and precision of the method for hydrastine was 82+/-8.8%, 97.9+/-2.4% and 96.2+/-3.3%, respectively. The inter-day (n=4) accuracy and precision for hydrastine was 90.0+/-15.17%, 99.9+/-7.1% and 98+/-6.54%, respectively. For berberine quantitation intra-day accuracy and precision was 96.0+/-8.4%, 92.5+/-4.7% and 94.4+/-3.7%, respectively. The respective values for inter-day quantitation were 91.0+/-8.4%, 94.3+/-4.7% and 94.4+/-3.7%. The analytical recovery for hydrastine was 82.4-96.2% and for berberine it was 94.4-96.0%. The analytes and noscapine were stable for 24h at room temperature (CV 5-10%). Matrix ion effects were studied by post-column infusion of hydrastine and berberine, calculation of calibration curve slope precision was obtained using serum from five different subjects, and by comparison of the response of methanol standards and extracted serum samples. The method was further validated by determination of serum pharmacokinetics of hydrastine and berberine after administration of a single oral dose of goldenseal extract containing 77 mg of hydrastine and 132 mg of berberine. PMID:19269122

  11. Planetary In Situ Sample Analysis with Tandem Two-Step Laser Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Brinckerhoff, W. B.; Getty, S. A.; Cornish, T. J.; Ecelberger, S. A.; Li, X.; Merrill Floyd, M. A.; Arevalo, R.; Elsila, J.; Callahan, M. P.

    2012-12-01

    -) and organic moieties. Second, by focusing a separate "post-ionization" laser pulse just above the sample surface, we can achieve two-step laser mass spectrometry, or L2MS, in the same highly-miniaturized TOF-MS. L2MS enables selective analysis of aromatic organics even in the presence of a complex mineral matrix. Finally, by introducing an ion optical gate in the flight path, we are able to take advantage of the broad focusing capabilities of the "curved field" reflectron at the core of the TOF-MS to achieve pseudo-tandem structural analysis of selected organics. The high-speed gate is used to admit only the molecular ion/s of interest into the reflectron. Diagnostic fragments of the ion/s obtained through metastable decay or active collision-induced dissociation (CID) remain in focus despite having widely variable velocities and masses. As such even molecular isomers with differing fragmentation pathways may be distinguished through a series of pseudo-tandem mass spectra that could be obtained in an automatic process during a mission. The "real-world" benefits of these enhancements are being fully characterized using a set of synthetic and natural standard samples as well as several planetary analogs and meteorites.

  12. Tandem mass spectrometry and ion mobility mass spectrometry for the analysis of molecular sequence and architecture of hyperbranched glycopolymers

    PubMed Central

    Liu, Xiumin; Cool, Lydia R.; Lin, Kenneth; Kasko, Andrea M.; Wesdemiotis, Chrys

    2015-01-01

    Multidimensional mass spectrometry techniques, combining matrix-assisted laser desorption/ionization (MALDI) or electrospray ionization (ESI) with tandem mass spectrometry (MS2), multistage mass spectrometry (MSn) or ion mobility mass spectrometry (IM-MS), have been employed to gain precise structural insight on the compositions, sequences and architectures of small oligomers of a hyperbranched glycopolymer, prepared by atom transfer radical copolymerization of an acrylate monomer (A) and an acrylate inimer (B), both carrying mannose ester pendants. The MS data confirmed the incorporation of multiple inimer repeat units, which ultimately lead to the hyperbranched material. The various possible structures of n-mers with the same composition were subsequently elucidated based on MS2 and MSn studies. The characteristic elimination of bromomethane molecule provided definitive information about the comonomer connectivity in the copolymeric AB2 trimer and A2B2 tetramer, identifying as present only one of the three possible trimeric isomers (viz. sequence BBA) and only two of the six possible tetrameric isomers (viz. sequences BBA2 and BABA). Complementary IM-MS studies confirmed that only one of the tetrameric structures is formed. Comparison of the experimentally determined collision cross-section of the detected isomer with those predicted by molecular simulations for the two possible sequences ascertained BBA2 as the predominant tetrameric architecture. The multidimensional MS approaches presented provide connectivity information at the atomic level without requiring high product purity (due to the dispersive nature of MS) and, hence, should be particularly useful for the microstructure characterization of novel glycopolymers and other types of complex copolymers. PMID:25519163

  13. Electrospray-assisted laser desorption/ionization and tandem mass spectrometry of peptides and proteins.

    PubMed

    Peng, Ivory X; Shiea, Jentaie; Ogorzalek Loo, Rachel R; Loo, Joseph A

    2007-01-01

    We have constructed an electrospray-assisted laser desorption/ionization (ELDI) source which utilizes a nitrogen laser pulse to desorb intact molecules from matrix-containing sample solution droplets, followed by electrospray ionization (ESI) post-ionization. The ELDI source is coupled to a quadrupole ion trap mass spectrometer and allows sampling under ambient conditions. Preliminary data showed that ELDI produces ESI-like multiply charged peptides and proteins up to 29 kDa carbonic anhydrase and 66 kDa bovine albumin from single-protein solutions, as well as from complex digest mixtures. The generated multiply charged polypeptides enable efficient tandem mass spectrometric (MS/MS)-based peptide sequencing. ELDI-MS/MS of protein digests and small intact proteins was performed both by collisionally activated dissociation (CAD) and by nozzle-skimmer dissociation (NSD). ELDI-MS/MS may be a useful tool for protein sequencing analysis and top-down proteomics study, and may complement matrix-assisted laser desorption/ionization (MALDI)-based measurements. PMID:17639579

  14. Tandem mass spectrometry and infrared spectroscopy as a tool to identify peptide oxidized residues.

    PubMed

    Scuderi, D; Ignasiak, M T; Serfaty, X; de Oliveira, P; Houée Levin, C

    2015-10-21

    The final products obtained by the oxidation of small model peptides containing the thioether function, either methionine or S-methyl cysteine, have been characterized by tandem mass spectrometry and IR Multiple Photon Dissociation (IRMPD) spectroscopy. The modified positions have been clearly identified by the CID-MS(2) fragmentation mass spectra with or without loss of sulfenic acid, as well as by the vibrational signature of the sulfoxide bond at around 1000 cm(-1). The oxidation of the thioether function did not lead to the same products in these model peptides. The sulfoxide and sulfone (to a lesser extent) have been clearly identified as final products of the oxidation of S-methyl-glutathione (GS-Me). Decarboxylation or hydrogen loss are the major oxidation pathways in GS-Me, while they have not been observed in tryptophan-methionine and methionine-tryptophan (Trp-Met and Met-Trp). Interestingly, tryptophan is oxidized in the dipeptide Met-Trp, while that is not the case in the reverse sequence (Trp-Met). PMID:26292724

  15. Modeling protein tandem mass spectrometry data with an extended linear regression strategy.

    PubMed

    Liu, Han; Bonner, Anthony J; Emili, Andrew

    2004-01-01

    Tandem mass spectrometry (MS/MS) has emerged as a cornerstone of proteomics owing in part to robust spectral interpretation algorithm. The intensity patterns presented in mass spectra are useful information for identification of peptides and proteins. However, widely used algorithms can not predicate the peak intensity patterns exactly. We have developed a systematic analytical approach based on a family of extended regression models, which permits routine, large scale protein expression profile modeling. By proving an important technical result that the regression coefficient vector is just the eigenvector corresponding to the least eigenvalue of a space transformed version of the original data, this extended regression problem can be reduced to a SVD decomposition problem, thus gain the robustness and efficiency. To evaluate the performance of our model, from 60,960 spectra, we chose 2,859 with high confidence, non redundant matches as training data, based on this specific problem, we derived some measurements of goodness of fit to show that our modeling method is reasonable. The issues of overfitting and underfitting are also discussed. This extended regression strategy therefore offers an effective and efficient framework for in-depth investigation of complex mammalian proteomes. PMID:17270923

  16. Determination of ten sulphonamides in egg by liquid chromatography-tandem mass spectrometry.

    PubMed

    Forti, A F; Scortichini, G

    2009-04-01

    A precise and reliable method for the determination of 10 sulphonamide antibiotics (sulfadiazine, sulfathiazole, sulfamerazine, sulfamethazine, sulfamethoxypyridazine, sulfachloropyridazine, sulfamethoxazole, sulfamonomethoxine, sulfadimethoxine and sulfaquinoxaline) in egg by liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed. Drugs were extracted using a mixture of dichloromethane/acetone (50:50, v/v), acidified with acetic acid and then cleaned-up on a cation-exchange solid-phase extraction (SPE) cartridge. The chromatographic separation was performed by gradient on a C(18) column with a mobile phase of methanol-water containing 0.1% formic acid and 5mM ammonium acetate, then sulphonamides were detected in a triple-quadrupole mass spectrometer operated in positive electrospray ionization mode (ESI(+)). The method was validated at 15, 30 and 45 microgkg(-1). These levels were much lower than the corresponding maximum residue limit of 100 microgkg(-1) set for sulphonamides in several matrices but not in eggs, where the presence of such residues is not permitted. Results were quantitated against the selected internal standard (13)C(6)-sulphamethazine and also according to the matrix-matched approach. The within-laboratory reproducibility, expressed as a relative standard deviation, never exceeded 21%. All decision limit (CCalpha) values lied in the range between 16.1 and 20.5 microgkg(-1) and the corresponding results for detection capability (CCbeta) were 16.9 and 25.7 microgkg(-1). Ruggedness was estimated according to the Youden robustness test. PMID:19286032

  17. Support Vector Machines for Improved Peptide Identification from Tandem Mass Spectrometry Database Search

    SciTech Connect

    Webb-Robertson, Bobbie-Jo M.

    2009-05-06

    Accurate identification of peptides is a current challenge in mass spectrometry (MS) based proteomics. The standard approach uses a search routine to compare tandem mass spectra to a database of peptides associated with the target organism. These database search routines yield multiple metrics associated with the quality of the mapping of the experimental spectrum to the theoretical spectrum of a peptide. The structure of these results make separating correct from false identifications difficult and has created a false identification problem. Statistical confidence scores are an approach to battle this false positive problem that has led to significant improvements in peptide identification. We have shown that machine learning, specifically support vector machine (SVM), is an effective approach to separating true peptide identifications from false ones. The SVM-based peptide statistical scoring method transforms a peptide into a vector representation based on database search metrics to train and validate the SVM. In practice, following the database search routine, a peptides is denoted in its vector representation and the SVM generates a single statistical score that is then used to classify presence or absence in the sample

  18. Quantitative analysis of mitragynine in human urine by high performance liquid chromatography-tandem mass spectrometry.

    PubMed

    Lu, Shijun; Tran, Buu N; Nelsen, Jamie L; Aldous, Kenneth M

    2009-08-15

    Mitragynine is the primary active alkaloid extracted from the leaves of Mitragyna speciosa Korth, a plant that originates in South-East Asia and is commonly known as kratom in Thailand. Kratom has been used for many centuries for their medicinal and psychoactive qualities, which are comparable to that of opiate-based drugs. Kratom abuse can lead to a detectable content of mitragynine residue in urine. Ultra trace amount of mitragynine in human urine was determined by a high performance liquid chromatography coupled to an electrospray tandem mass spectrometry (HPLC-ESI/MS/MS). Mitragynine was extracted by methyl t-butyl ether (MTBE) and separated on a HILIC column. The ESI/MS/MS was accomplished using a triple quadrupole mass spectrometer in positive ion detection and multiple reactions monitoring (MRM) mode. Ajmalicine, a mitragynine's structure analog was selected as internal standard (IS) for method development. Quality control (QC) performed at three levels 0.1, 1 and 5 ng/ml of mitragynine in urine gave mean recoveries of 90, 109, and 98% with average relative standard deviation of 22, 12 and 16%, respectively. The regression linearity of mitragynine calibration ranged from 0.01 to 5.0 ng/ml was achieved with correlation coefficient greater than 0.995. A detection limit of 0.02 ng/ml and high precision data within-day and between days analysis were obtained. PMID:19577523

  19. Silver complexation and tandem mass spectrometry for differentiation of isomeric flavonoid diglycosides.

    PubMed

    Zhang, Junmei; Brodbelt, Jennifer S

    2005-03-15

    For detection and differentiation of isomeric flavonoids, electrospray ionization mass spectrometry is used to generate silver complexes of the type (Ag + flavonoid)+. Collisionally activated dissociation (CAD) of the resulting 1:1 silver/flavonoid complexes allows isomer differentiation of flavonoids. Eighteen flavonoid diglycosides constituting seven isomeric series are distinguishable from each other based on the CAD patterns of their silver complexes. Characteristic dissociation pathways allow identification of the site of glycosylation, the type of disaccharide (rutinose versus neohesperidose), and the type of aglycon (flavonol versus flavone versus flavanone). This silver complexation method is more universal than previous metal complexation methods, as intense silver complexes are observed even for flavonoids that lack the typical metal chelation sites. To demonstrate the feasibility of using silver complexation and tandem mass spectrometry to characterize flavonoids in complex mixtures, flavonoids extracted from grapefruit juice are separated by high-performance liquid chromatography and analyzed via a postcolumn complexation ESI-MS/MS strategy. Diagnostic fragmentation pathways of the silver complexes of the individual eluting flavonoids allow successful identification of the six flavonoids in the extract. PMID:15762583

  20. Poiseuille flow-induced vibrations of two tandem circular cylinders with different mass ratios

    NASA Astrophysics Data System (ADS)

    Jiang, Ren-Jie; Lin, Jian-Zhong

    2016-06-01

    Flow-induced vibrations of two tandem circular cylinders with different mass ratios confined between two parallel walls are numerically studied via a lattice Boltzmann method. With fixed Reynolds number Re = 100 and blockage ratio β = 1/4, the effects of mass ratio m* = [0.0625, 16] and streamwise separation between two cylinders S/D = [1.125, 10] on the cylinder motions and vortex wake modes are investigated. A variety of distinct cylinder motion regimes involving the symmetric periodic vibration, biased quasi-periodic vibration, beating vibration, and steady regimes, with the corresponding wake structures, e.g., two rows of alternately rotating vortices, a single row of same-sign vortices, and steady wake, are observed. For each current case, the cylinder motion type is exclusive and in the binary oscillation regime, both cylinders always vibrate at a common primary frequency. The lighter cylinder usually oscillates at a larger amplitude than the heavier one, while the heavier cylinder undergoes larger lift force than the lighter one. The lift force and cylinder displacement always behave as an out-of-phase state. In the gap-interference region, large-amplitude oscillations could be produced extensively and in the wake-interference region, the cylinder motions and fluid flows are mainly dependent on the upstream cylinder. When the separation is large enough, both cylinders behave as two isolated ones. The mechanisms for the excitations of cylinder vibrations have also been analysed.

  1. Comparative Lipidomics of Caenorhabditis elegans Metabolic Disease Models by SWATH Non-Targeted Tandem Mass Spectrometry

    PubMed Central

    Prasain, Jeevan K.; Wilson, Landon; Hoang, Hieu D.; Moore, Ray; Miller, Michael A.

    2015-01-01

    Tandem mass spectrometry (MS/MS) with Sequential Window Acquisition of all Theoretical (SWATH) mass spectra generates a comprehensive archive of lipid species within an extract for retrospective, quantitative MS/MS analysis. Here we apply this new technology in Caenorhabditis elegans (C. elegans) to identify potential lipid mediators and pathways. The DAF-1 type I TGF-β and DAF-2 insulin receptors transmit endocrine signals that couple metabolic status to fertility and lifespan. Mutations in daf-1 and daf-2 reduce prostaglandin-endoperoxide synthase (i.e., Cox)-independent prostaglandin synthesis, increase triacylglyceride storage, and alter transcription of numerous lipid metabolism genes. However, the extent to which DAF-1 and DAF-2 signaling modulate lipid metabolism and the underlying mechanisms are not well understood. MS/MSALL with SWATH analysis across the groups identified significant changes in numerous lipids, including specific triacylglycerols, diacylglycerols, and phosphatidylinositols. Examples are provided, using retrospective neutral loss and precursor ion scans as well as MS/MS spectra, to help identify annotated lipids and search libraries for lipids of interest. As proof of principle, we used comparative lipidomics to investigate the prostaglandin metabolism pathway. SWATH data support an unanticipated model: Cox-independent prostaglandin synthesis may involve lysophosphatidylcholine and other lyso glycerophospholipids. This study showcases the power of comprehensive, retrospectively searchable lipid archives as a systems approach for biological discovery in genetic animal models. PMID:26569325

  2. De novo sequencing of peptides from top-down tandem mass spectra

    SciTech Connect

    Vyatkina, Kira; Wu, Si; Dekker, Leendert J.; vanDuijn, Martijn M.; Liu, Xiaowen; Tolic, Nikola; Dvorkin, Mikhail; Alexandrova, Sonya; Luider, Theo N.; Pasa-Tolic, Ljiljana; Pevzner, Pavel A.

    2015-09-28

    De novo sequencing of proteins and peptides is one of the most important problems in mass spectrometry-driven proteomics. A variety of methods have been developed to accomplish this task from a set of bottom-up tandem (MS/MS) mass spectra. However, a more recently emerged top-down technology, now gaining more and more popularity, opens new perspectives for protein analysis and characterization, implying a need in efficient algorithms for processing this kind of MS/MS data. Here we describe a method that allows to retrieve from a set of top-down MS/MS spectra long and accurate sequence fragments of the proteins contained in a sample. To this end, we outline a strategy for generating high-quality sequence tags from top-down spectra, and introduce the concept of a T-Bruijn graph by adapting to the case of tags the notion of an A-Bruijn graph widely used in genomics. The output of the proposed approach represents the set of amino acid strings spelled out by optimal paths in the connected components of a T-Bruijn graph. We illustrate its performance on top-down datasets acquired from carbonic anhydrase 2 (CAH2) and the Fab region of alemtuzumab.

  3. Analysis of Amadori compounds by high-performance cation exchange chromatography coupled to tandem mass spectrometry.

    PubMed

    Davidek, Tomas; Kraehenbuehl, Karin; Devaud, Stéphanie; Robert, Fabien; Blank, Imre

    2005-01-01

    High-performance cation exchange chromatography coupled to tandem mass spectrometry or electrochemical detection was found to be an efficient tool for analyzing Amadori compounds derived from hexose and pentose sugars. The method allows rapid separation and identification of Amadori compounds, while benefiting from the well-known advantages of mass spectrometry, such as specificity and sensitivity. Glucose- and xylose-derived Amadori compounds of several amino acids, such as glycine, alanine, valine, leucine/isoleucine, methionine, proline, phenylalanine, and glutamic acid, were separated or discriminated using this new method. The method is suitable for the analysis of both model reaction mixtures and food products. Fructosylglutamate was found to be the major Amadori compound in dried tomatoes (approximately 1.5 g/100 g) and fructosylproline in dried apricots (approximately 0.2 g/100 g). Reaction of xylose and glycine at 90 degrees C (pH 6) for 2 h showed rapid formation of xylulosylglycine (approximately 12 mol %, 15 min) followed by slow decrease over time. Analysis of pentose-derived Amadori compounds is shown for the first time, which represents a major breakthrough in studying occurrence, formation, and decomposition of these labile Maillard intermediates. PMID:15623289

  4. Profiling pneumococcal type 3-derived oligosaccharides by high resolution liquid chromatography-tandem mass spectrometry

    PubMed Central

    Li, Guoyun; Li, Lingyun; Xue, Changhu; Middleton, Dustin; Linhardt, Robert J.; Avci, Fikri Y.

    2015-01-01

    Pneumococcal type-3 polysaccharide (Pn3P) is considered a major target for the development of a human vaccine to protect against Streptococcus pneumonia infection. Thus, it is critical to develop methods for the preparation and analysis of Pn3P-derived oligosaccharides to better understand its immunological properties. In this paper, we profile oligosaccharides, generated by the free radical depolymerization of Pn3P, using liquid chromatography (LC)-tandem mass spectrometry (MS/MS). Hydrophilic liquid interaction chromatography (HILIC)-mass spectrometry (MS) revealed a series of oligosaccharides with an even- and odd-number of saccharide residues, ranging from monosaccharide, degree of polymerization (dp1) to large oligosaccharides up to dp 20, generated by free radical depolymerization. Isomers of oligosaccharides with an even number of sugar residues were easily separated on a HILIC column, and their sequences could be distinguished by comparing MS/MS of these oligosaccharides and their reduced alditols. Fluorescent labeling with 2-aminoacridone (AMAC) followed by reversed phase (RP)-LC-MS/MS was applied to analyze and sequence poorly separated product mixtures, as RP-LC affords higher resolution of AMAC-labeled oligosaccharides than does HILIC-based separation. The present methodology can be potentially applied to profiling other capsular polysaccharides. PMID:25913329

  5. Does deamidation cause protein unfolding? A top-down tandem mass spectrometry study

    PubMed Central

    Soulby, Andrew J; Heal, Jack W; Barrow, Mark P; Roemer, Rudolf A; O'Connor, Peter B

    2015-01-01

    Deamidation is a nonenzymatic post-translational modification of asparagine to aspartic acid or glutamine to glutamic acid, converting an uncharged amino acid to a negatively charged residue. It is plausible that deamidation of asparagine and glutamine residues would result in disruption of a proteins' hydrogen bonding network and thus lead to protein unfolding. To test this hypothesis Calmodulin and B2M were deamidated and analyzed using tandem mass spectrometry on a Fourier transform ion cyclotron resonance mass spectrometer (FTICR-MS). The gas phase hydrogen bonding networks of deamidated and nondeamidated protein isoforms were probed by varying the infra-red multi-photon dissociation laser power in a linear fashion and plotting the resulting electron capture dissociation fragment intensities as a melting curve at each amino acid residue. Analysis of the unfolding maps highlighted increased fragmentation at lower laser powers localized around heavily deamidated regions of the proteins. In addition fragment intensities were decreased across the rest of the proteins which we propose is because of the formation of salt-bridges strengthening the intramolecular interactions of the central regions. These results were supported by a computational flexibility analysis of the mutant and unmodified proteins, which would suggest that deamidation can affect the global structure of a protein via modification of the hydrogen bonding network near the deamidation site and that top down FTICR-MS is an appropriate technique for studying protein folding. PMID:25653127

  6. Analysis of aristolochic acids, aristololactams and their analogues using liquid chromatography tandem mass spectrometry.

    PubMed

    Yu, Jie; Ma, Chao-Mei; Wang, Xuan; Shang, Ming-Ying; Hattori, Masao; Xu, Feng; Jing, Yu; Dong, Shi-Wen; Xu, Yu-Qiong; Zhang, Cui-Ying; Cai, Shao-Qing

    2016-08-01

    More than 80 aristolochic acids (AAs) and aristololactams (ALs) have been found in plants of the Aristolochiaceae family, but relatively few have been fully studied. The present study aimed at developing and validating a liquid chromatography tandem mass spectrometry (LC/MS(n)) for the analysis of these compounds. We characterized the fragmentation behaviors of 31 AAs, ALs, and their analogues via high performance liquid chromatography coupled with electrospray ionization mass spectrometry. We summarized their fragmentation rules and used these rules to identify the constituents contained in Aristolochia contorta, Ar. debilis, Ar. manshurensis, Ar. fangchi, Ar. cinnabarina, and Ar. mollissima. The AAs and ALs showed very different MS behaviors. In MS(1) of AAs, the characteristic pseudomolecular ions were [M + NH4](+), [M + H](+), and [M + H - H2O](+). However, only [M + H](+) was found in the MS(1) of ALs, which was simpler than that of AAs. Distinct MS(n)fragmentation patterns were found for AAs and ALs, showing the same skeleton among the different substituent groups. The distribution of the 31 constituents in the 6 species of Aristolochia genus was reported for the first time. 25 Analogues of AAs and ALs were detected in this genus. A hierarchical schemes and a calculating formula of the molecular formula of these nitrophenanthrene carboxylic acids and their lactams were proposed. In conclusion, this method could be applied to identification of similar unknown constituents in other plants. PMID:27608953

  7. Drug screening of whole blood by ultra-performance liquid chromatography-tandem mass spectrometry.

    PubMed

    Oiestad, Elisabeth Leere; Johansen, Unni; Oiestad, Ase Marit Leere; Christophersen, Asbjørg Solberg

    2011-06-01

    An ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS-MS) method for screening of drugs in whole blood has been developed and validated. Samples were prepared by supported liquid-liquid extraction on ChemElute(®) columns with ethyl acetate/heptane (4:1). LC separation was achieved with an Acquity HSS T3-column (2.1 100 mm, 1.8-μm particle). Mass detection was performed by positive ion mode electrospray MS-MS and included the following drugs/metabolites: morphine, codeine, ethyl morphine, oxycodone, buprenorphine, methadone, cocaine, methylphenidate, amphetamine, methamphetamine, 3,4-methylenedioxymethamphetamine (MDMA), Δ(9)-tetrahydrocannabinol (THC), fentanyl, alprazolam, bromazepam, clonazepam, diazepam, nordiazepam, 3-OH-diazepam, fenazepam, flunitrazepam, lorazepam, nitrazepam, oxazepam, zopiclone, zolpidem, carisoprodol, and meprobamate. The cycle time was 9 min, and within- and between-day relative coefficients of variation varied from 1% to 33% and 2% to 58%, respectively. Extraction recoveries from whole blood were > 50% except for morphine and THC. The limit of quantitation was 0.1 to 521 ng/mL, depending on the drug. PMID:21619723

  8. Isomerization of 4-vinylcyclohexene radical cation. A tandem mass spectrometry study

    SciTech Connect

    Vollmer, D.; Rempel, D.L.; Gross, M. L. ); Williams, F. )

    1995-02-08

    Investigation by matrix-isolation ESR has shown that 4-vinylcyclohexene, 1, surprisingly undergoes isomerization to the bicyclo[3.2.1]oct-2-ene ion, 3. Here we demonstrate the occurrence of this isomerization in the gas phase by use of tandem (MS/MS) sector and Fourier transform (FT) mass spectrometries. The radical cations of 4-vinylcyclohexene (IE = 8.93 eV) or bicyclo[3.2.1]oct-2-ene (approximately 14 kcal/mol more stable than that of 4-vinylcyclohexene) were formed, in separate trials, in a chemical ionization (CI) source by electron ionization (EI). The radical cations were then studied by obtaining their collisionally activated decomposition (CAD) spectra. The CAD spectra are similar, indicating that the isomerization has occurred. Both the sector and the FT mass spectrometer results reflect those obtained in the matrix-isolation ESR investigation. That is isomerizes to 3 at high internal energy, but is stable at low internal energy. Two mechanisms explain this rearrangement. The second mechanism is questionable because the most stable olefin radical cation formed from 5 is that of bicyclo[2.2.2]-2-octene, which gives different ESR and CAD spectra than those of 1 or 3. The CAD spectrum of bicyclo[2.2.2]-2-octene radical cation indicates that the retro-Diels-Alder loss of ethylene is more facile than that from 1 or 3. 18 refs., 3 figs.

  9. Fast methods for screening of trichothecenes in fungal cultures using gas chromatography-tandem mass spectrometry.

    PubMed

    Nielsen, K F; Thrane, U

    2001-09-21

    The paper presents a fast method for trichothecene profiling and chemotaxonomic studies in species of Fusarium, Stachybotrys. Trichoderma and Memnoniella. Micro scale extracted crude Fusarium extracts were derivatised using pentafluoropropionic anhydride and analysed by gas chromatography with simultaneous full scan and tandem mass spectrometric detection. It was possible to monitor for up to four compounds simultaneous, making detection of acetyl T-2 toxin, T-2 toxin, HT-2 toxin, T-2 triol. T-2 tetraol, neosolaniol, iso-neosolaniol, scirpentriol, 4,15-diacetoxyscirpenol, 15-acetoxyscirpenol, 4-acetoxyscirpentriol, nivalenol, fusarenon-X, deoxynivalenol, 15-acetyl-deoxynivalenol and 3-acetyldeoxynivalenol possible during a 23-min GC run. A slightly modified method could detect trichothecenes produced by Stachybotrys, Memnoniella and Trichoderma, by hydrolysing crude extracts prior to derivatisation with heptafluorobuturyl imidazole. All types of derivatised extracts could be reanalysed using negative ion chemical ionisation (NICI) GC-MS for molecular mass determination and verification purposes. A retention time index could be used for correction in retention time drifts between sequences and worked both in EI+ and NICI mode. PMID:11594405

  10. Improved protein identification using automated high mass measurement accuracy MALDI FT-ICR MS peptide mass fingerprinting

    NASA Astrophysics Data System (ADS)

    Horn, David M.; Peters, Eric C.; Klock, Heath; Meyers, Andrew; Brock, Ansgar

    2004-11-01

    A comparison between automated peptide mass fingerprinting systems using MALDI-TOF and MALDI FT-ICR MS is presented using 86 overexpressed proteins from Thermotoga maritima. The high mass measurement accuracy of FT-ICR MS greatly reduces the probability of an incorrect assignment of a protein in peptide mass fingerprinting by significantly decreasing the score and peptide sequence coverage of the highest ranked random protein match from the database. This improved mass accuracy led to the identification of all 86 proteins with the FT-ICR data versus 84 proteins using the TOF data against the T. maritima database. The beneficial effect of mass accuracy becomes much more evident with the addition of variable modifications and an increase in the size of the database used in the search. A search of the same data against the T. maritima database with the addition of a variable modification resulted in 77 identifications using MALDI-TOF and 84 identifications using MALDI FT-ICR MS. When searching the NCBInr database, the FT-ICR based system identified 82 of 86 proteins while the TOF based system could only identify 73. The MALDI FT-ICR based system has the further advantage of producing fewer unassigned masses in each peptide mass fingerprint, resulting in greatly reduced sequence coverage and score for the highest ranked random match and improving confidence in the correctly assigned top scoring protein. Finally, the use of rms error as a measure for instrumental mass accuracy is discussed.

  11. Screening of anabolic steroids in horse urine by liquid chromatography-tandem mass spectrometry.

    PubMed

    Yu, Nola H; Ho, Emmie N M; Leung, David K K; Wan, Terence S M

    2005-04-29

    Anabolic steroids have the capability of improving athletic performance and are banned substances in the Olympic games as well as in horseracing and equestrian competitions. The control of their abuse in racehorses is traditionally performed by detecting the presence of anabolic steroids and/or their metabolite(s) in urine samples using gas chromatography-mass spectrometry (GC-MS). However, this approach usually requires tedious sample processing and chemical derivatisation steps and could be very insensitive in detecting certain steroids. This paper describes a high performance liquid chromatography-tandem mass spectrometry (HPLC-MS-MS) method for the detection of anabolic steroids that are poorly covered by GC-MS. Enzyme-treated urine was processed by solid-phase extraction (SPE) using a Bond Elut Certify cartridge, followed by a base wash for further cleanup. Separation of the steroids was carried out on a reversed-phase DB-8 column using 0.1% acetic acid and methanol as the mobile phase in a gradient elution programme. The mass spectrometer for the detection of the steroids was operated in the positive electrospray ionisation (ESI) mode with multiple reaction monitoring (MRM). Urine samples fortified with 15 anabolic steroids (namely, androstadienone, 1-androstenedione, bolasterone, boldione, 4-estrenedione, gestrinone, methandrostenolone, methenolone, 17alpha-methyltestosterone, norbolethone, normethandrolone, oxandrolone, stenbolone, trenbolone and turinabol) at low ng/mL levels were consistently detected. No significant matrix interference was observed at the retention times of the targeted ion masses in blank urine samples. The method specificity, sensitivity, precision, recoveries, and the performance of the enzyme hydrolysis step were evaluated. The successful application of the method to analyse methenolone acetate administration urine samples demonstrated that the method could be effective in detecting anabolic steroids and their metabolites in horse

  12. Characterization of wheat gliadin proteins by combined two-dimensional gel electrophoresis and tandem mass spectrometry.

    PubMed

    Mamone, Gianfranco; Addeo, Francesco; Chianese, Lina; Di Luccia, Aldo; De Martino, Alessandra; Nappo, Annunziata; Formisano, Annarita; De Vivo, Pasqualina; Ferranti, Pasquale

    2005-07-01

    A proteomics-based approach was used for characterizing wheat gliadins from an Italian common wheat (Triticum aestivum) cultivar. A two-dimensional gel electrophoresis (2-DE) map of roughly 40 spots was obtained by submitting the 70% alcohol-soluble crude protein extract to isoelectric focusing on immobilized pH gradient strips across two pH gradient ranges, i.e., 3-10 or pH 6-11, and to sodium dodecyl sulfate-polyacrylamide electrophoresis in the second dimension. The chymotryptic digest of each spot was characterized by matrix-assisted laser desorption/ionization-time of flight mass spectrometry and nano electrospray ionization-tandem mass spectrometry (MS/MS) analysis, providing a "peptide map" for each digest. The measured masses were subsequently sought in databases for sequences. For accurate identification of the parent protein, it was necessary to determine de novo sequences by MS/MS experiments on the peptides. By partial mass fingerprinting, we identified protein molecules such as alpha/beta-, gamma-, omega-gliadin, and high molecular weight-glutenin. The single spots along the 2-DE map were discriminated on the basis of their amino acid sequence traits. alpha-Gliadin, the most represented wheat protein in databases, was highly conserved as the relative N-terminal sequence of the components from the 2-DE map contained only a few silent amino acid substitutions. The other closely related gliadins were identified by sequencing internal peptide chains. The results gave insight into the complex nature of gliadin heterogeneity. This approach has provided us with sound reference data for differentiating gliadins amongst wheat varieties. PMID:15952231

  13. A validated liquid chromatography-tandem mass spectrometry method for the quantitative determination of 4β-hydroxycholesterol in human plasma.

    PubMed

    van de Merbel, Nico C; Bronsema, Kees J; van Hout, Mischa W J; Nilsson, Ralf; Sillén, Henrik

    2011-07-15

    A novel liquid chromatography-tandem mass spectrometry method is described for the quantitative determination of the endogenous CYP 3A4/5 marker 4β-hydroxycholesterol in human K(2)-EDTA plasma. It is based on alkaline hydrolysis to convert esterified to free 4β-hydroxycholesterol, followed by analyte extraction from plasma by hexane and purification of the hexane extract by normal-phase solid-phase extraction. The analyte is chromatographically separated from endogenous isobaric plasma oxysterols and excess cholesterol by a 16-min reversed-phase gradient on a C18 column; detection is performed by atmospheric pressure photoionization tandem mass spectrometry in the positive ion mode, using toluene as a dopant. Using 400μl of plasma, 4β-hydroxycholesterol can be quantified in the concentration range 10.0-250nM. Validation results show that the method is sufficiently selective towards endogenous plasma sterols and capable of quantifying the analyte with good precision and accuracy. The analyte is sufficiently stable in all relevant matrices and solvents; the addition of the anti-oxidant butylated hydroxytoluene to prevent in vitro formation of 4β-hydroxycholesterol from cholesterol during storage or analysis is not necessary, provided that long-term frozen storage of plasma occurs at -70°C. PMID:21507593

  14. Dynamic Biodistribution of Icaritin and Its Phase-II Metabolite in Rat Tissues by Ultra-High Performance Liquid Chromatography-Tandem Mass Spectrometry.

    PubMed

    Zhang, Shuang-Qing

    2016-01-01

    Icaritin (ICT), a major component in herb Epimedium brevicornum Maxim., shows beneficial effects for the treatment of osteoporosis and various cancers, and is predominantly metabolized to glucuronidated icaritin (GICT). Although clinical trials of ICT have exhibited good safety and tolerance, the dynamic bioditributions of ICT and GICT have not been reported. In the present study, the chemical structure of GICT was firstly reported, and a reliable ultra-high performance liquid chromatography-tandem mass spectrometry method (UHPLC-MS/MS) was firstly established for the simultaneous quantifications of ICT and GICT in rat tissues. The dynamic distribution of ICT and GICT in rat tissues and their pharmacokinetic parameters have been reported for the first time. ICT, GICT and the internal standard coumestrol were separated on a C18 column with a gradient mobile phase of acetonitrile and water containing ammonium formate and formic acid at a flow rate of 0.3 mL min(-1). The analytes were quantified by a triple quadrupole tandem mass spectrometer in the negative ionization mode. The lower limit of quantification values for ICT and GICT were 0.2 and 2 ng mL(-1), respectively. Good selectivity, linearity, accuracy, precision and recovery were achieved, and no significant matrix effect was observed. The UHPLC-MS/MS was firstly applied to a dynamic biodistribution study of ICT and GICT in rats, following an intraperitoneal administration of ICT at a dose of 10 mg kg(-1). PMID:27302583

  15. Microfluidic chip based nano liquid chromatography coupled to tandem mass spectrometry for the determination of abused drugs and metabolites in human hair.

    PubMed

    Zhu, Kevin Y; Leung, K Wing; Ting, Annie K L; Wong, Zack C F; Ng, Winki Y Y; Choi, Roy C Y; Dong, Tina T X; Wang, Tiejie; Lau, David T W; Tsim, Karl W K

    2012-03-01

    A microfluidic chip based nano-HPLC coupled to tandem mass spectrometry (nano-HPLC-Chip-MS/MS) has been developed for simultaneous measurement of abused drugs and metabolites: cocaine, benzoylecgonine, cocaethylene, norcocaine, morphine, codeine, 6-acetylmorphine, phencyclidine, amphetamine, methamphetamine, MDMA, MDA, MDEA, and methadone in the hair of drug abusers. The microfluidic chip was fabricated by laminating polyimide films and it integrated an enrichment column, an analytical column and a nanospray tip. Drugs were extracted from hairs by sonication, and the chromatographic separation was achieved in 15 min. The drug identification and quantification criteria were fulfilled by the triple quardropule tandem mass spectrometry. The linear regression analysis was calibrated by deuterated internal standards with all of the R(2) at least over 0.993. The limit of detection (LOD) and the limit of quantification (LOQ) were from 0.1 to 0.75 and 0.2 to 1.25 pg/mg, respectively. The validation parameters including selectivity, accuracy, precision, stability, and matrix effect were also evaluated here. In conclusion, the developed sample preparation method coupled with the nano-HPLC-Chip-MS/MS method was able to reveal the presence of drugs in hairs from the drug abusers, with the enhanced sensitivity, compared with the conventional HPLC-MS/MS. PMID:22281681

  16. Simultaneous Determination and Pharmacokinetic Study of Protocatechuic Aldehyde and Its Major Active Metabolite Protocatechuic Acid in Rat Plasma by Liquid Chromatography-Tandem Mass Spectrometry.

    PubMed

    Wang, Xiangyang; Yan, Kaijing; Ma, Xiaohui; Li, Wei; Chu, Yang; Guo, Jiahua; Li, Shuming; Zhou, Shuiping; Zhu, Yonghong; Liu, Changxiao

    2016-05-01

    A very simple and selective high-performance liquid chromatography electrospray ionization tandem mass spectrometry (LC-MS-MS) method was developed for simultaneous determination and pharmacokinetic study of protocatechuic aldehyde (PAL) and its active metabolite protocatechuic acid (PCA). The method involves a simple liquid-liquid extraction with ethyl acetate. The separation was performed on a Hypersil GOLD C18column (2.1 × 150 mm, 3.0 µm; particle, Thermo, USA) with isocratic elution using a mobile phase consisted of methanol and water (containing 0.1% formic acid) at a flow rate of 0.2 mL/min. The detection of target compounds was done by using low-energy collision dissociation tandem mass spectrometry (CID-MS-MS) using the selective reaction monitoring scan mode. The method was linear for all analytes over the investigated range for all correlation coefficients greater than 0.9950. The lower limits of quantification were 2.0 ng/mL for PAL and PCA. The intra- and interday precisions (relative standard deviation, RSD %) were <6.84 and 5.54%, and the accuracy (relative error, RE %) was between -2.85 and 0.74% (n= 6). The developed method was applied to study the pharmacokinetics of PAL and its major active metabolite PCA in rat plasma after oral and intravenous administration of PAL. PMID:26969682

  17. In vivo pharmacokinetics of and tissue distribution study of physalin B after intravenous administration in rats by liquid chromatography with tandem mass spectrometry.

    PubMed

    Zheng, Yunliang; Chen, Jing; Liu, Lin; Liang, Xingguang; Hong, Dongsheng

    2016-08-01

    A rapid and sensitive liquid chromatography tandem mass spectrometry quantitative analysis method was established for the pharmacokinetics and tissue distribution study of physalin B in rat. Physalin B and physalin H (internal standard, IS) were separated on an Agilent Eclips XDB C8 column. MS detection was performed on a triple quadrupole tandem mass spectrometer in the multiple reaction monitoring mode with a positive eletrospray ionization source. The assay was validated in the concentration ranges of 22.6-22600 ng/mL for heart and lung and 4.52-4520 ng/mL for other tissues. The intra- and inter-day precisions (RSD) were ≤9.23 and ≤12.51%, respectively, with accuracy (%) in the range of 88.07-113.2%. A pharmacokinetic study showed that physalin B has a long dwell time with a half-life of 321.2 ± 29.5 min and clearance of 175.4 ± 25.7 mL/min/kg after intravenous administration. Additionally, physalin B showed a wide tissue distribution with a special higher penetration in lung. The data presented in this study could provide useful information for the further study of physalin B. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26714262

  18. Liquid Chromatography-Tandem Mass Spectrometry Method for Determination of Homocysteine in Rat Plasma: Application to the Study of a Rat Model for Tauopathies.

    PubMed

    Kovac, Andrej; Svihlova, Katarina; Michalicova, Alena; Novak, Michal

    2015-07-01

    Hyperhomocysteinemia is a common occurrence in many neurodegenerative diseases, including tauopathies. We developed and validated a simple and sensitive liquid chromatography-tandem mass spectrometry method for the analysis of homocysteine (Hcy) in rat plasma. Hcy was analyzed using ultra-performance liquid chromatography on a C8 column with detection by positive ESI tandem mass spectrometry. For optimal retention and separation, we used ion-pair reagent-heptafluorobutyric acid. The method utilizes heavy labeled internal standard and does not require any derivatization or extraction step. The procedure was validated in compliance with the European Medicines Agency guideline. The limit of detection was 0.15 µmol/L and the limit of quantification was 0.5 µmol/L. The method showed excellent linearity with regression coefficients higher than 0.99. The accuracy was in the range of 93-98%. The inter-day precision (n = 5 days), expressed as % relative standard deviation, was in the range 3-8%. Using this method, we analyzed plasma samples from two transgenic lines of the rat model for tauopathies. PMID:25466230

  19. Data supporting the rat brain sample preparation and validation assays for simultaneous determination of 8 neurotransmitters and their metabolites using liquid chromatography–tandem mass spectrometry

    PubMed Central

    Wojnicz, Aneta; Ortiz, José Avendaño; Casas, Ana I.; Freitas, Andiara E.; López, Manuela G.; Ruiz-Nuño, Ana

    2016-01-01

    The data presented in this article supports the rat brain sample preparation procedure previous to its injection into the liquid chromatography–tandem mass spectrometry (LC–MS/MS) system to monitor levels of adrenaline, noradrenaline, glutamic acid, γ-aminobutyric acid, dopamine, 5-hydroxytryptamine, 5-hydroxyindole acetic acid, and 3-methoxy-4-hydroxyphenylglycol. In addition, we describe the method validation assays (such as calibration curve, lower limit of quantification, precision and accuracy intra- and inter-day, selectivity, extraction recovery and matrix effect, stability, and carry-over effect) according to the United States Food and Drug Administration and European Medicine Agency to measure in one step different neurotransmitters and their metabolites. The data supplied in this article is related to the research study entitled: “Simultaneous determination of 8 neurotransmitters and their metabolite levels in rat brain using liquid chromatography in tandem with mass spectrometry: application to the murine Nrf2 model of depression” (Wojnicz et al. 2016) [1]. PMID:27054183

  20. Determination of parabens in urine samples by microextraction using packed sorbent and ultra-performance liquid chromatography coupled to tandem mass spectrometry.

    PubMed

    Cristina Jardim, Valeria; de Paula Melo, Lidervan; Soares Domingues, Diego; Costa Queiroz, Maria Eugênia

    2015-01-01

    A simple, sensitive, and selective method using ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) was developed and validated for simultaneous determination of parabens [methyl paraben (MeP), ethyl paraben (EtP), propyl paraben (PrP), butyl paraben (BuP), and benzyl paraben (BzP)] in human urine samples. After microextraction by packed sorbent (MEPS) using a C18 phase, the parabens were separated on a Kinetex C18 column (100 mm × 2.1 mm × 1.7 μm) within 4.6 min using isocratic elution. These compounds were detected on a triple quadrupole tandem mass spectrometer using the multiple reactions monitoring (MRM) mode via an electrospray ionization source operating in the negative ionization mode. Important factors that influence MEPS performance were evaluated, such as the sample pH, draw-eject sample volume, clean-up step, and desorption conditions. The proposed MEPS/UPLC-MS/MS method presented a linear range from 0.5 ng mL(-1) (limit of quantification - LOQ) to 50 ng mL(-1), and interassay precision with coefficients of variation lower than 15%, and relative standard error values of the accuracy ranged from -8.8% to 15%. The MEPS/UPLC-MS/MS method was applied successfully to determine parabens in urine samples from 30 postpartum volunteers, enabling assessment of human exposure to these compounds. PMID:25463195

  1. Ultrapressure liquid chromatography-tandem mass spectrometry assay using atmospheric pressure photoionization (UPLC-APPI-MS/MS) for quantification of 4-methoxydiphenylmethane in pharmacokinetic evaluation.

    PubMed

    Farhan, Nashid; Fitzpatrick, Sean; Shim, Yun M; Paige, Mikell; Chow, Diana Shu-Lian

    2016-09-01

    4-Methoxydiphenylmethane (4-MDM), a selective augmenter of Leukotriene A4 Hydrolase (LTA4H), is a new anti-inflammatory compound for potential treatment of chronic obstructive pulmonary disease (COPD). Currently, there is no liquid chromatography tandem mass spectrometric (LC-MS/MS) method for the quantification of 4-MDM. A major barrier for developing the LC-MS/MS method is the inability of electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) to ionize 4-MDM due to its hydrophobicity and lack of any functional group for ionization. With the advent of atmospheric pressure photoionization (APPI) technique, many hydrophobic compounds have been demonstrated to ionize by charge transfer reactions. In this study, a highly sensitive ultrapressure liquid chromatography tandem mass spectrometry assay using atmospheric pressure photoionization (UPLC-APPI-MS/MS) for the quantifications of 4-MDM in rat plasma has been developed and validated. 4-MDM was extracted from the plasma by solid phase extraction (SPE) and separated chromatographically using a reverse phase C8 column. The photoionization (PI) was achieved by introducing anisole as a dopant to promote the reaction of charge transfer. The assay with a linear range of 5 (LLOQ)-400ngmL(-1) met the regulatory requirements for accuracy, precision and stability. The validated assay was employed to quantify the plasma concentrations of 4-MDM after an oral dosing in Sprague Dawley (SD) rats. PMID:27232150

  2. Determination of dexmedetomidine in human plasma using high performance liquid chromatography coupled with tandem mass spectrometric detection: application to a pharmacokinetic study.

    PubMed

    Li, Wenjing; Zhang, Zunjian; Wu, Lili; Tian, Yuan; Feng, Shudan; Chen, Yun

    2009-12-01

    A rapid, sensitive and selective high performance liquid chromatography-electrospray ionization-tandem mass spectrometry method (HPLC-ESI-MS/MS) was developed and validated for the determination and pharmacokinetic investigation of dexmedetomidine (DMED) in human plasma. Dexmedetomidine and the internal standard (ondansetron) were extracted in a single step with diethyl-ether from 1.0 mL of alkalinized plasma. The mobile phase was a mixture of acetonitrile and 0.5% formic acid solution (30:70, v/v) at a flow rate of 0.2 mL min(-1). The detection was performed on a triple quadrupole tandem mass spectrometer in the selected reaction monitoring (SRM) mode using the respective [M+H]+ ions m/z 201.0-->95.1 for DMED and m/z 294.1-->170.1 for the IS. The assay exhibited a linear dynamic range of 5-5000 pg mL(-1) with the correlation coefficient above 0.9995. The lower limit of quantification (LLOQ) was 5 pg mL(-1) with a relative standard deviation of less than 15%. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. The validated HPLC-MS/MS method has been successfully applied to study the pharmacokinetics of three level doses of DMED in Chinese healthy volunteers. PMID:19577876

  3. Rapid simultaneous analysis of 17 haloacetic acids and related halogenated water contaminants by high-performance ion chromatography-tandem mass spectrometry.

    PubMed

    Xue, Runmiao; Donovan, Ariel; Shi, Honglan; Yang, John; Hua, Bin; Inniss, Enos; Eichholz, Todd

    2016-09-01

    Haloacetic acids (HAAs), which include chloroacetic acids, bromoacetic acids, and emerging iodoacetic acids, are toxic water disinfection byproducts. General screening methodology is lacking for simultaneously monitoring chloro-, bromo-, and iodoacetic acids. In this study, a rapid and sensitive high-performance ion chromatography-tandem mass spectrometry method for simultaneous determination of chloro-, bromo-, and iodo- acetic acids and related halogenated contaminants including bromate, bromide, iodate, and iodide was developed to directly analyze water samples after filtration, eliminating the need for preconcentration, and chemical derivatization. The resulting method was validated in both untreated and treated water matrices including tap water, bottled water, swimming pool water, and both source water and drinking water from a drinking water treatment facility to demonstrate application potential. Satisfactory accuracies and precisions were obtained for all types of tested samples. The detection limits of this newly developed method were lower or comparable with similar techniques without the need for extensive sample treatment requirement and it includes all HAAs and other halogenated compounds. This provides a powerful methodology to water facilities for routine water quality monitoring and related water research, especially for the emerging iodoacetic acids. Graphical abstract High performance ion chromatography-tandem mass spectrometry method for detection of haloacetic acids in water. PMID:27422643

  4. Determination of Drugs in Plasma Samples by High-Performance Liquid Chromatography-Tandem Mass Spectrometry for Therapeutic Drug Monitoring of Schizophrenic Patients.

    PubMed

    Domingues, Diego Soares; Pinto, Mônia Aparecida Lemos; de Souza, Israel Donizeti; Hallak, Jaime Eduardo Cecilio; Crippa, José Alexandre de Souza; Queiroz, Maria Eugênia Costa

    2016-01-01

    This work describes the development of a simple, sensitive and selective method based on high-performance liquid chromatography coupled to tandem mass spectrometry (LC-MS-MS) to determine antipsychotics (olanzapine, quetiapine, clozapine, haloperidol and chlorpromazine) along with antidepressants (mirtazapine, paroxetine, citalopram, sertraline, imipramine, clomipramine and fluoxetine), anticonvulsants (carbamazepine and lamotrigine) and anxiolytics (diazepam and clonazepam) in plasma samples obtained from schizophrenic patients. The samples were prepared by protein precipitation. The target drugs were separated on an XSelect SCH C18 column (100 mm × 2.1 mm × 2.5 µm) within 8.0 min by means of gradient elution. The drugs were then detected on a quadrupole tandem mass spectrometer equipped with an electrospray ionization source, operating in the multiple reactions monitoring mode and in the positive ionization mode. The LC-MS-MS method was linear range from subtherapeutic to toxic concentrations with lower limit of quantification values ranged from 0.2 to 5.0 ng mL(-1), precision with coefficient of variation values lower than 12%, and accuracy ranged from 90 to 108%. The developed method enabled successful analysis of the target drugs in plasma samples obtained from 51 schizophrenic patients. Therapeutic drug monitoring revealed that many of the evaluated schizophrenic patients presented altered plasma concentrations of the analyzed drugs. These altered concentrations resulted from pharmacokinetic interactions among the medications prescribed to treat schizophrenia. PMID:26333987

  5. Analysis of drugs in plasma samples from schizophrenic patients by column-switching liquid chromatography-tandem mass spectrometry with organic-inorganic hybrid cyanopropyl monolithic column.

    PubMed

    Domingues, Diego Soares; Souza, Israel Donizeti de; Queiroz, Maria Eugênia Costa

    2015-07-01

    This study reports on the development of a rapid, selective, and sensitive column-switching liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to analyze sixteen drugs (antidepressants, anticonvulsants, anxiolytics, and antipsychotics) in plasma samples from schizophrenic patients. The developed organic-inorganic hybrid monolithic column with cyanopropyl groups was used for the first dimension of the column-switching arrangement. This arrangement enabled online pre-concentration of the drugs (monolithic column) and their subsequent analytical separation on an XSelect SCH C18 column. The drugs were detected on a triple quadrupole tandem mass spectrometer (multiple reactions monitoring mode) with an electrospray ionization source in the positive ion mode. The developed method afforded adequate linearity for the sixteen target drugs; the coefficients of determination (R(2)) lay above 0.9932, the interassay precision had coefficients of variation lower than 6.5%, and the relative standard error values of the accuracy ranged from -14.0 to 11.8%. The lower limits of quantification in plasma samples ranged from 63 to 1250pgmL(-1). The developed method successfully analyzed the target drugs in plasma samples from schizophrenic patients for therapeutic drug monitoring (TDM). PMID:25984963

  6. Classification of the medicinal plants of the genus Atractylodes using high-performance liquid chromatography with diode array and tandem mass spectrometry detection combined with multivariate statistical analysis.

    PubMed

    Cho, Hyun-Deok; Kim, Unyong; Suh, Joon Hyuk; Eom, Han Young; Kim, Junghyun; Lee, Seul Gi; Choi, Yong Seok; Han, Sang Beom

    2016-04-01

    Analytical methods using high-performance liquid chromatography with diode array and tandem mass spectrometry detection were developed for the discrimination of the rhizomes of four Atractylodes medicinal plants: A. japonica, A. macrocephala, A. chinensis, and A. lancea. A quantitative study was performed, selecting five bioactive components, including atractylenolide I, II, III, eudesma-4(14),7(11)-dien-8-one and atractylodin, on twenty-six Atractylodes samples of various origins. Sample extraction was optimized to sonication with 80% methanol for 40 min at room temperature. High-performance liquid chromatography with diode array detection was established using a C18 column with a water/acetonitrile gradient system at a flow rate of 1.0 mL/min, and the detection wavelength was set at 236 nm. Liquid chromatography with tandem mass spectrometry was applied to certify the reliability of the quantitative results. The developed methods were validated by ensuring specificity, linearity, limit of quantification, accuracy, precision, recovery, robustness, and stability. Results showed that cangzhu contained higher amounts of atractylenolide I and atractylodin than baizhu, and especially atractylodin contents showed the greatest variation between baizhu and cangzhu. Multivariate statistical analysis, such as principal component analysis and hierarchical cluster analysis, were also employed for further classification of the Atractylodes plants. The established method was suitable for quality control of the Atractylodes plants. PMID:26888213

  7. Sensitive liquid chromatography positive electrospray tandem mass spectrometry method for the quantitation of tegaserod in human plasma using liquid-liquid extraction.

    PubMed

    Nirogi, Ramakrishna; Kandikere, Vishwottam; Mudigonda, Koteshwara

    2009-02-01

    A sensitive and rapid high-performance liquid chromatography-positive ion electrospray tandem mass spectrometry method is developed and validated for the quantitation of tegaserod in human plasma. Following liquid-liquid extraction, the analytes are separated using an isocratic mobile phase on a reversed-phase column and analyzed by tandem mass spectrometry in the multiple reaction monitoring mode using the respective (M+H)+ ions, m/z 302 to 173 for tegaserod and m/z 409 to 228 for the internal standard. The assay exhibits a linear dynamic range of 100-10000 pg/mL for tegaserod in human plasma. The lower limit of quantitation is 100 pg/mL with a relative standard deviation of less than 7%. Acceptable precision and accuracy are obtained for concentrations over the standard curve range. A run time of 2.0 min for each sample makes it possible to analyze more than 250 human plasma samples per day. The validated method is successfully used to analyze human plasma samples for application in pharmacokinetic, bioavailability, or bioequivalence studies. PMID:19222925

  8. Simultaneous determination of four secoiridoid and iridoid glycosides in rat plasma by ultra performance liquid chromatography-tandem mass spectrometry and its application to a comparative pharmacokinetic study.

    PubMed

    Wu, Yun; Ai, Yu; Wang, Fenrong; Ma, Wen; Bian, Qiaoxia; Lee, David Y-W; Dai, Ronghua

    2016-02-01

    A simple, reliable and rapid ultra-performance liquid chromatography-tandem mass spectrometry method was developed and validated for the simultaneous quantification of four secoiridoid (gentiopicroside, swertiamarin, sweroside) and iridoid glycosides (loganic acid), the bio-active ingredients in rat plasma. After liquid-liquid extraction, chromatographic separation was accomplished on a Shim-pack XR-ODS column with a mobile phase consisting of methanol and 0.1% formic acid in water. A triple quadrupole tandem mass spectrometry equipped with an electrospray ionization source was used as detector operating both in positive and negative ionization mode and operated by multiple-reaction monitoring scanning. The lower limits of quantitation were 0.25-30 ng/mL for all the analytes. Both intra-day and inter-day precision and accuracy of analytes were well within acceptance criteria (±15%). The mean extraction recoveries of analytes and internal standard (amygdalin) from rat plasma were all >71.4%. The validated method was successfully applied to a comparative pharmacokinetic study of four analytes in rat plasma between normal and arthritic rats after oral administration of Huo Luo Xiao Ling Dan and Gentiana macrophylla extract, respectively. Results showed significant differences in pharmacokinetic properties of the analytes among the different groups. PMID:26014753

  9. Simultaneous determination of Δ9-tetrahydrocannabinol, cannabidiol, cannabinol and 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid in hair using liquid chromatography-tandem mass spectrometry.

    PubMed

    Dulaurent, S; Gaulier, J M; Imbert, L; Morla, A; Lachâtre, G

    2014-03-01

    For several years, hair analyses have become a powerful tool to investigate past exposure towards xenobiotics. In the case of illicit drugs and more precisely of cannabis exposure, four compounds are usually investigated: Δ(9)-tetrahydrocannabinol (THC), the main active compound of cannabis, one of its metabolites [11-nor-Δ(9)-tetrahydrocannabinol-9-carboxylic acid (THC-COOH)] and two cannabinoids (cannabinol and cannabidiol). Up until now, the hair determination of the carboxylic metabolite of THC, which has been described as the only marker allowing distinguishing consumption and passive exposure, has been performed using a gas chromatography-tandem mass spectrometry method. The aim of this study was to develop a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the simultaneous quantitative determination of the four markers. The sample preparation was based on an alkaline hydrolysis of hair samples followed by a liquid-liquid extraction of compounds in acidic conditions using a hexane/ethyl acetate mixture. The method was validated and the results were satisfactory: intra- and inter-assay accuracies below 9% and relative standard deviation below 15% for the four compounds. Moreover, the limit of quantification for THC-COOH, the most challenging compound, was validated at 0.2 pg/mg. This concentration is in accordance with the recommendations made by a scientific society which specializes in hair testing. It makes it possible to distinguish the kind of exposure to cannabis. PMID:24529787

  10. Quantification of 1-(13) C-L-methionine in rat serum with hydrophilic interaction liquid chromatography coupled with tandem mass spectrometry and its application in pharmacokinetic study.

    PubMed

    Xu, Ying; Huang, Xiao; Nie, Xiuli; Yang, Li; Yan, Weili; Wang, Zhengtao; Wang, Changhong; Hu, Zhibi

    2011-09-01

    A rapid, selective and sensitive hydrophilic interaction liquid chromatography (HILIC) coupled with tandem mass spectrometry (MS/MS) method was developed to determine 1-(13) C-l-methionine in rat serum. Proteins in serum were precipitated using acetonitrile and the supernatant was separated after centrifugation. 1-(13) C-l-phenylalnine was used as the internal standard. HILIC-tandem mass spectrometry analysis was performed on a hydrophilic interaction silica column (TSK-GEL AMIDE-80) using a linear gradient elution system, acetonitrile-5 mm ammonium acetate containing 0.1% formic acid and multiple reaction monitoring mode for 1-(13) C-l-methionine and 1-(13) C-l-phenylalnine. The assay was validated with a linear range between 10 and 150 ng mL(-1) (r ≥ 0.99) and a lower limit of quantification of 10 ng mL(-1) , calculated with weighted (1/x(2) ) least squares linear regression. The RSD of intra-day precision was smaller than 3.6% and the inter-day RSD less than 6.5%, while the average recovery was 100.48% with an RSD of accuracy within 2.9%, determined from quality control samples. The HILIC-MS/MS method was fully validated and successfully applied to the in vivo pharmacokinetic study of stable-isotope 1-(13) C-l-methionine in rats. PMID:21287581

  11. Determination of chrysotoxine in rat plasma by liquid chromatography-tandem mass spectrometry and its application to a rat pharmacokinetic study.

    PubMed

    Fan, Jingjing; Guan, Li; Kou, Zeqi; Feng, Feng; Zhang, Yanbo; Liu, Wenyuan

    2014-09-15

    Chrysotoxine (CTX), a naturally occurring bibenzyl compound isolated from Dendrobium species, has been reported to have neuroprotective effects. To evaluate its pharmacokinetics in rats, a rapid, sensitive and specific high performance liquid chromatography-tandem mass spectrometric (HPLC-MS/MS) method has been developed and validated for the quantification of CTX in rat plasma. Samples were pretreated using a simple liquid-liquid extraction with ethyl acetate and the chromatographic separation was performed on a C18 column with acetonitrile-water (90:10, v/v) as the mobile phase. CTX and the internal standard (wogonin) were detected using a tandem mass spectrometer in positive multiple reaction monitoring mode. Method validation revealed excellent linearity over the range 0.5-1000 ng/mL together with satisfactory intra- and inter-day precision, accuracy and recovery. Stability testing showed that CTX spiked into rat plasma was stable for 8 h at room temperature, for up to two weeks at -20 °C, and during three freeze-thaw cycles. Extracted samples were also observed to be stable over 24 h in an auto-sampler. The method was successfully used to investigate the pharmacokinetic profile of CTX after oral (100 mg/kg) and intravenous (25 mg/kg) administration in rats. CTX showed rapid excretion and low bioavailability in rats. PMID:25069096

  12. High-accuracy peptide mass fingerprinting using peak intensity data with machine learning.

    PubMed

    Yang, Dongmei; Ramkissoon, Kevin; Hamlett, Eric; Giddings, Morgan C

    2008-01-01

    For MALDI-TOF mass spectrometry, we show that the intensity of a peptide-ion peak is directly correlated with its sequence, with the residues M, H, P, R, and L having the most substantial effect on ionization. We developed a machine learning approach that exploits this relationship to significantly improve peptide mass fingerprint (PMF) accuracy based on training data sets from both true-positive and false-positive PMF searches. The model's cross-validated accuracy in distinguishing real versus false-positive database search results is 91%, rivaling the accuracy of MS/MS-based protein identification. PMID:17914788

  13. Analysis of tacrolimus and creatinine from a single dried blood spot using liquid chromatography tandem mass spectrometry

    PubMed Central

    Koop, Dennis R.; Bleyle, Lisa A.; Munar, Myrna; Cherala, Ganesh; Al-Uzri, Amira

    2014-01-01

    Long term therapeutic drug monitoring and assessment of renal function are required in renal transplant recipients on immunosuppressant therapy such as tacrolimus. Dry blood spots (DBS) have been used successfully in the clinic for many years and offers a convenient, simple and non-invasive method for repeated blood tests. We developed and performed a preliminary validation of a method for the analysis of tacrolimus and creatinine from a single DBS using liquid chromatography-tandem mass spectrometric (LC–MS/MS). Tacrolimus and creatinine were extracted from a 6 mm punch with a mixture of methanol/acetonitrile containing ascomycin and deuterated creatinine as internal standards. A 10 μl aliquot of the extract was analyzed directly after dilution for creatinine with normal phase high performance liquid chromatography and multiple reaction monitoring. The remainder of the extract was processed and analyzed for tacrolimus. The lower limit of quantification for tacrolimus was 1 ng/ml with accuracy of 0.34% bias and precision (CV) of 11.1%. The precision ranged from 1.33% to 7.68% and accuracy from −4.44% to 11.6% bias for the intra- and inter-day analysis. The lower limit of quantification of creatinine was 0.01 mg/dL with precision of 7.94%. Accuracy was based on recovery of additional creatinine spiked into whole blood samples and ranged from −2.45% bias at 5 mg/dL to 3.75% bias at 0.5 mg/dL. Intra- and inter-day precision was from 3.48 to 4.11%. The assay was further validated with DBS prepared from pediatric renal transplant recipients. There was excellent correlation between the levels of tacrolimus and creatinine obtained from the clinical laboratory and the DBS method developed. After additional validation, this assay may have a significant impact on compliance with medication intake as well as potentially lowering the cost associated with intravenous blood draws in clinical laboratories. PMID:23548676

  14. Analysis of isomeric forms of oxidized triacylglycerols using ultra-high-performance liquid chromatography and tandem mass spectrometry.

    PubMed

    Suomela, Jukka-Pekka; Leskinen, Heidi; Kallio, Heikki

    2011-08-10

    Detailed studies on the regioisomeric structures of oxidized species of triacylglycerols (TAG), formed in food during storage and processing, have not been published thus far. In this study, an analytical approach based on efficient ultra-high-performance liquid chromatographic (UHPLC) separation of different isomers of oxidized TAG species and their tandem mass spectrometric analysis was created. A linear solvent gradient based on acetonitrile and acetone was used in the UHPLC method. A novel method utilizing positive ion ESI using ammonia supplemented in the nebulizer gas was used to produce ammonium adduct ions for mass spectrometric analysis. With the UHPLC method used, different regioisomers of TAG species containing oxidized linoleic or oleic acid could be efficiently resolved. Differences in the fragmentation patterns of many of the oxidized TAG isomers could be demonstrated by the tandem mass spectrometric method. On the basis of the results, the approach enables regiospecific analysis of oxidized TAG molecules. PMID:21702477

  15. Matrix effect on the determination of synthetic corticosteroids and diuretics by liquid chromatography-tandem mass spectrometry

    NASA Astrophysics Data System (ADS)

    Dikunets, M. A.; Appolonova, S. A.; Rodchenkov, G. M.

    2009-04-01

    This work presents a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) procedure for selective and reliable screening of corticosteroids and diuretics in human urine. Sample preparation included the extraction, evaporation of the organic extract under nitrogen, and solution of the dry residue. The extract was analyzed by HPLC combined with tandem mass spectrometry using electro-spraying ionization at atmospheric pressure with negative ion recording. The mass spectra of all compounds were recorded, and the characteristic ions, retention times, and detection limits were determined. The procedure was validated by evaluating the degree of the matrix suppression of ionization, extraction of analytes from human biological liquid, and the selectivity and specificity of determination.

  16. Design and performance of an instrument for electron impact tandem mass spectrometry and action spectroscopy of mass/charge selected macromolecular ions stored in RF ion trap*

    NASA Astrophysics Data System (ADS)

    Ranković, Milos Lj.; Giuliani, Alexandre; Milosavljević, Aleksandar R.

    2016-05-01

    A new apparatus was designed, coupling an electron gun with a linear quadrupole ion trap mass spectrometer, to perform m/z (mass over charge) selected ion activation by electron impact for tandem mass spectrometry and action spectroscopy. We present in detail electron tracing simulations of a 300 eV electron beam inside the ion trap, design of the mechanical parts, electron optics and electronic circuits used in the experiment. We also report examples of electron impact activation tandem mass spectra for Ubiquitin protein, Substance P and Melittin peptides, at incident electron energies in the range from 280 eV to 300 eV. Contribution to the Topical Issue "Advances in Positron and Electron Scattering", edited by Paulo Limao-Vieira, Gustavo Garcia, E. Krishnakumar, James Sullivan, Hajime Tanuma and Zoran Petrovic.

  17. Construction of an Ultrahigh Pressure Liquid Chromatography-Tandem Mass Spectral Library of Plant Natural Products and Comparative Spectral Analyses.

    PubMed

    Lei, Zhentian; Jing, Li; Qiu, Feng; Zhang, Hua; Huhman, David; Zhou, Zhiqin; Sumner, Lloyd W

    2015-07-21

    A plant natural product tandem mass spectral library has been constructed using authentic standards and purified compounds. Currently, the library contains 1734 tandem mass spectra for 289 compounds, with the majority (76%) of the compounds being plant phenolics such as flavonoids, isoflavonoids, and phenylpropanoids. Tandem mass spectra and chromatographic retention data were acquired on a triple quadrupole mass spectrometer coupled to an ultrahigh pressure liquid chromatograph using six different collision energies (CEs) (10-60 eV). Comparative analyses of the tandem mass spectral data revealed that the loss of ring substituents preceded the C-ring opening during the fragmentation of flavonoids and isoflavonoids. At lower CE (i.e., 10 and 20 eV), the flavonoids and isoflavonoid central ring structures typically remained intact, and fragmentation was characterized by the loss of the substituents (i.e., methyl and glycosyl groups). At higher CE, the flavonoid and isoflavonoid core ring systems underwent C-ring cleavage and/or rearrangement depending on the structure, particularly hydroxylation patterns. In-source electrochemical oxidation was observed for phenolics that had ortho-diphenol moieties (i.e., vicinal hydroxyl groups on the aromatic rings). The ortho-diphenols were oxidized to ortho-quinones, yielding an intensive and, in most cases, a base ion peak corresponding to a [(M - 2H) - H](-) ion in their mass spectra. The library also contains reverse-phase retention times, allowing for the construction, validation, and testing of an artificial neural network retention prediction of other flavonoids and isoflavonoids not contained within the library. The library is freely available for nonprofit, academic use and it can be downloaded at http://www.noble.org/apps/Scientific/WebDownloadManager/DownloadArea.aspx. PMID:26107650

  18. Quantitative analysis of positional isomers of triacylglycerols via electrospray ionization tandem mass spectrometry of sodiated adducts.

    PubMed

    Herrera, Lisandra Cubero; Potvin, Michael A; Melanson, Jeremy E

    2010-09-01

    Herein we report a reversed-phase high-performance liquid chromatography tandem mass spectrometry (RP-HPLC/MS/MS) method for the analysis of positional isomers of triacylglycerols (TAGs) in vegetable oils. The fragmentation behavior of [M + X](+) ions (X = NH(4), Li, Na or Ag) was studied on a quadrupole-time-of-flight (Q-TOF) mass spectrometer under low-energy collision-induced dissociation (CID) conditions. Mass spectra that were dependent on the X(+) ion and the nature and position of the acyl substituents were observed for four pairs of 'AAB/ABA'-type TAGs, namely PPO/POP, OOP/OPO, LLO/LOL and OOL/OLO (where P is 16:0, palmitic acid; O is 18:1, oleic acid; and L is 18:2, linoleic acid). For the majority of [M + X](+) adducts, the loss of the fatty acid in the outer positions (sn-1 or sn-3) was favored over the loss in the central position (sn-2), which enabled the determination of the fractional abundance of the isomers. Ratios of the intensity of fragment ions at various AAB/ABA compositions produced linear calibration curves with positive slopes, comparable to those obtained traditionally by ESI-MS/MS of [M + NH(4)](+) adducts. The only exceptions were the [M + Ag](+) adducts of the PPO/POP system, which produced calibration curves with negative slopes. Sodium adducts provided the most consistent level of isomeric discrimination for the TAGs studied and also offered the most convenience in that they required no additive to the mobile phase. Therefore, calibration curve data derived from [M + Na](+) adducts were applied to the quantification of TAG regioisomers in sunflower and olive oils. The regiospecific analysis showed that palmitic acid was typically located at positions sn-1 or sn-3, whereas unsaturated fatty acids, oleic and linoleic acids were mostly found at the sn-2 position. PMID:20814981

  19. Characterization of N-Succinylation of L-Lysylphosphatidylglycerol in Bacillus subtilis Using Tandem Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Atila, Metin; Katselis, George; Chumala, Paulos; Luo, Yu

    2016-08-01

    Phospholipids generally dominate in bacterial lipids. The negatively charged nature of phospholipids renders bacteria susceptible to cationic antibiotic peptides. In comparison with Gram-negative bacteria, Gram-positive bacteria in general have much less zwitterionic phosphatidylethanolamine. However, they are known for producing aminoacylated phosphatidylglycerol (PG), especially positively charged uc(l)-lysyl-PG, which is catalyzed by lysyl-PG synthase MprF, which appears to have a broad range of specificity for uc(l)-aminoacyl transfer RNAs. In addition, many Gram-positive bacteria also have a dlt-gene-coded uc(d)-alanylation pathway for lipoteichoic acids and wall teichoic acids covalently attached to a glycolipid or peptidoglycan. uc(d)-Alanylation also masks the dominant negative charge of the phosphate-rich polymers of teichoic acids. Using mass spectrometry, we have recently observed that precursor scans in negative mode for deprotonated amino acid fragments were most sensitive for ester-linked amino acids. Such a scan for precursors generating an m/z 145 lysyl anion revealed lysyl-PG as well as an additional species 100 m/z units greater than lysyl-PG. This unexpected species corresponded precisely to the expected mass of N-succinylated lysyl-PG. Tandem mass spectrometry revealed a precise match to the fragmentation pattern of this putative new species. PG, lysyl-PG, and N-succinyl-lysyl-PG may form a complete loop of charge reversal from -1 to +1 and then back to -1. Analogous charge reversal by N-succinylation of lysine residues in the bacterial as well as eukaryotic proteomes has been recently discovered as a major posttranslational modification. Such modification in bacterial lipids is possibly catalyzed by an enzyme homologous to the enzymes that modify lysine residues in proteins.

  20. Investigation of silver binding to polyamidoamine (PAMAM) dendrimers by ESI tandem mass spectrometry.

    PubMed

    Mazzitelli, Carolyn L; Brodbelt, Jennifer S

    2006-05-01

    Electrospray ionization tandem mass spectrometry (ESI-MS/MS) was used to probe the binding of silver ions and reduced silver species with polyamidoamine generation 1 amine-terminated (PAMAMG1NH2) and generation 2 hydroxyl-terminated (PAMAMG2OH) dendrimers. At Ag(+)/PAMAMG2OH molar ratios of 1, 2:1 and low abundance 3:1 complexes emerge. Similar results were observed for PAMAMG1NH2. The collisional activated dissociation (CAD) patterns of the dendrimer ions are characterized by losses of amidoamine branches resulting largely from hydrogen migration and cleavage reactions. Ag+/dendrimer complexes are characterized by the loss of a dendrimer branch from the complex, with the silver ion remaining bound to a dendrimer fragment. When the Ag+-bound dendrimer complexes are reduced by hydrazine, low abundance complexes, whose m/z values are consistent with ones containing zerovalent silver species, are observed in the mass spectra. Complexes with three silver atoms are observed in the spectrum containing PAMAMG1NH2, and complexes with four and five silver atoms are observed with PAMAMG2OH. The CAD fragmentation patterns of the complexes formed after the silver reduction are different than those observed for complexes containing one silver ion and are characterized by the ejection of all silver species, possibly as a cluster, leaving the intact dendrimer ion. Experiments with Cu+, Cu2+, and Pt2+ binding to PAMAMG2OH were also done, but reduced metal clusters were not observed in the mass spectra after the addition of hydrazine. PMID:16516486

  1. Quantitative, Multidrug Pain Medication Testing by Liquid Chromatography: Tandem Mass Spectrometry (LC-MS/MS).

    PubMed

    Bodor, Geza S

    2016-01-01

    Chronic pain is often treated with narcotic analgesics. The most commonly used narcotic analgesics are the opiates (natural or modified compounds of the poppy plant) or opioids (synthetic chemicals that act on opiate receptors). While opiates and opioids are excellent analgesics, they can also have significant side effects that include respiratory depression, coma, or death. Tolerance, physical dependence, and addiction (psychological dependence) are other severe side effects of opioid use. Patients who develop dependence or addiction often times abuse other, non-opioid narcotics and may trade their prescription medication for illegal street drugs (called "diversion"). In order to minimize side effects, detect possible multidrug abuse and prove diversion, simultaneous monitoring of numerous prescription and illicit drugs is required. The method described in this chapter is for the quantitative measurement of 43 different drugs in urine. The panel includes narcotic pain medications, benzodiazepines, NIDA drugs, and other, commonly abused medications. The analytes of interests are injected in the presence of deuterated internal standards to correct for possible extraction inefficiencies, ion suppression, or other interferences. The sample is prepared by adding dilution buffer with the deuterated internal standards to the sample, followed by reversed-phase, gradient HPLC separation on a Phenyl-Hexyl column using water and methanol as mobile phases. Detection of the analytes of interest is done by isotope-dilution mass spectrometry on a triple-quadrupole tandem mass spectrometer following electrospray ionization in the positive mode. Mass spectrometric (MS) data are collected in the scheduled MRM (sMRM) mode. Two MRM transitions are monitored for each analyte and one MRM transition is monitored for each IS. Quantitation of the unknown analytes is achieved by comparing the peak area ratios of the analytes to that of the internal standards and reading the unknown

  2. Determination of phentermine, N-hydroxyphentermine and mephentermine in urine using dilute and shoot liquid chromatography-tandem mass spectrometry.

    PubMed

    Choi, Yun Jeong; Sim, Arum; Kim, Min Kyung; Suh, Sunglll; In, Moon Kyo; Kim, Jin Young

    2016-09-01

    Nonmedical use of prescription stimulants such as phentermine (PT) has been regulated by law enforcement authorities due to its euphorigenic and relaxing effects. Due to high potential for its abuse, reliable analytical methods were required to detect and identify PT and its metabolite in biological samples. Thus a dilute and shoot liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed and validated for simultaneous determination of PT, N-hydroxyphentermine (NHOPT) and mephentermine (MPT) in urine. A 5μL aliquot of diluted urine was injected into the LC-MS/MS system. Chromatographic separation was performed by reversed-phase C18 column with gradient elution for all analytes within 5min. Identification and quantification were based on multiple reaction monitoring (MRM) detection. Linear least-squares regression with a 1/x(2) weighting factor was used to generate a calibration curve and the assay was linear from 50 to 15000ng/mL (PT and MPT) and 5 to 750ng/mL (NHOPT). The intra- and inter-day precisions were within 8.9% while the intra- and inter-day accuracies ranged from -6.2% to 11.2%. The limits of quantification were 3.5ng/mL (PT), 1.5ng/mL (NHOPT) and 1.0ng/mL (MPT). Method validation requirements for selectivity, dilution integrity, matrix effect and stability were satisfied. The applicability of the developed method was examined by analyzing urine samples from drug abusers. PMID:27398632

  3. Simultaneous quantitative analysis of eight vitamin D analogues in milk using liquid chromatography-tandem mass spectrometry.

    PubMed

    Gomes, Fabio P; Shaw, P Nicholas; Whitfield, Karen; Hewavitharana, Amitha K

    2015-09-01

    Milk is an important source of nutrients for various risk populations, including infants. The accurate measurement of vitamin D in milk is necessary to provide adequate supplementation advice for risk groups and to monitor regulatory compliance. Currently used liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods are capable of measuring only four analogues of vitamin D in unfortified milk. We report here an accurate quantitative analytical method for eight analogues of vitamin D: Vitamin D2 and D3 (D2 and D3), 25-hydroxy D2 and D3, 24,25-dihydroxy D2 and D3, and 1,25-dihydroxyD2 and D3. In this study, we compared saponification and protein precipitation for the extraction of vitamin D from milk and found the latter to be more effective. We also optimised the pre-column derivatisation using 4-phenyl-l,2,4-triazoline-3,5-dione (PTAD), to achieve the highest sensitivity and accuracy for all major vitamin D forms in milk. Chromatography was optimised to reduce matrix effects such as ion-suppression, and the matrix effects were eliminated using co-eluting stable isotope labelled internal standards for the calibration of each analogue. The analogues, 25-hydroxyD3 (25(OH)D3) and its epimer (3-epi-25(OH)D3) were chromatographically resolved, to prevent over-estimation of 25(OH)D3. The method was validated and subsequently applied for the measurement of total vitamin D levels in human, cow, mare, goat and sheep milk samples. The detection limits, repeatability standard deviations, and recovery ranges were from 0.2 to 0.4 femtomols, 6.30-13.5%, and 88.2-105%, respectively. PMID:26388380

  4. Pharmacokinetic study of ACT-132577 in rat plasma by ultra performance liquid chromatography-tandem mass spectrometry

    PubMed Central

    Zhang, Jin; Geng, Peiwu; Luo, Xinhua; Zhou, Genzhi; Lin, Yingying; Zhang, Lijing; Wang, Shuanghu; Wen, Congcong; Ma, Jianshe; Ding, Ting

    2015-01-01

    It was reported that macitentan was metabolized predominantly by cytochrome P450 3A4, and ACT-132577, its pharmacologically active metabolite, is fivefold less potent at blocking ET receptors than macitentan. In this work, a sensitive and selective ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for determination of ACT-132577 in rat plasma was developed and validated. After addition of diazepam as an internal standard (IS), protein precipitation by acetonitrile was used to prepare samples. Chromatographic separation was achieved on a UPLC BEH C18 column (2.1 mm × 100 mm, 1.7 μm) with 0.2% formic acid and methanol as the mobile phase with gradient elution. An electrospray ionization source was applied and operated in positive ion mode; multiple reactions monitoring (MRM) mode was used for quantification using target fragment ions m/z 546.9→200.6 for ACT-132577, and m/z 285.1→193.1 for IS. Calibration plots were linear throughout the range 10-4000 ng/mL for ACT-132577 in rat plasma. Mean recovery of ACT-132577 in rat plasma ranged from 82.6% to 90.6%, matrix effect of ACT-132577 in rat plasma ranged from 101.4% to 115.2%. RSD of intra-day and inter-day precision were both less than 11%. The accuracy of the method ranged from 96.1% to 103.5%. The method was successfully applied to pharmacokinetic study of ACT-132577 after oral and intravenous administration of macitentan. PMID:26770447

  5. Simultaneous determination of azilsartan and chlorthalidone in rat and human plasma by liquid chromatography-electrospray tandem mass spectrometry.

    PubMed

    Ramakrishna, Rachumallu; Puttrevu, Santosh Kumar; Bhateria, Manisha; Bala, Veenu; Sharma, Vishnu L; Bhatta, Rabi Sankar

    2015-05-15

    Azilsartan medoxomil (AZM), an ester prodrug of azilsartan (AZ), and chlorthalidone (CLT) have recently been approved as a combination therapy for the management of hypertension. This is the first report which described a selective and sensitive method for the simultaneous quantification of AZ and CLT in rat and human plasma using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). AZ and CLT were extracted from plasma by liquid-liquid extraction technique and separated on a C18 reverse phase column using ammonium acetate (10mM, pH 4)-mixture of methanol and acetonitrile (8:92, v/v) as a mobile phase at a flow rate of 0.7mL/min. Detection was performed by electrospray ionization (ESI) operated in negative multiple reaction monitoring (MRM) mode. The lower limit of quantitation (LLOQ) of this method was 1ng/mL and the calibration curves were linear (r(2)≥0.995) over the concentration range of 1-4000ng/mL for both the analytes. The intra- and inter-day precision and accuracy were well within the acceptable limits. The mean extraction recoveries were found to be about 80% and no matrix effect was observed. AZ and CLT were found to be stable under all relevant storage conditions. The method was successfully applied to the oral pharmacokinetic study of AZM and CLT in rats. Further, the sensitivity of the method enabled the determination of protein binding of AZ and CLT in human plasma. PMID:25899870

  6. Fluoroquinolone residues in compost by green enhanced microwave-assisted extraction followed by ultra performance liquid chromatography tandem mass spectrometry.

    PubMed

    Speltini, Andrea; Sturini, Michela; Maraschi, Federica; Viti, Simona; Sbarbada, Davide; Profumo, Antonella

    2015-09-01

    A novel, simple and straightforward method for determination of fluoroquinolones (FQs) in compost has been developed. The procedure entails a low-pressurized microwave-assisted extraction (MAE) carried out by a high performance instrument, in alkaline aqueous solution containing magnesium ions as FQs complexing agent, followed by ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS). Ciprofloxacin (CIP), Enrofloxacin (ENR), Levofloxacin (LEV) and Norfloxacin (NOR), four widely used FQ antibiotics, were simultaneously extracted from compost by a single MAE cycle (20min, 135°C). The method was validated in terms of linearity, selectivity, sensitivity and accuracy. Quantitative absolute recovery (70-112%, n=3) and suitable precision (RSD<15%, n=3) were observed, at concentration levels ranging from 25 ng g(-1) to 2500 ng g(-1). Analytes were separated in a 10min chromatographic run and quantified/confirmed in single reaction monitoring (SRM) mode. UPLC coupled to SRM-MS detection allowed to achieve improved sensitivity, and selective detection. Method detection and quantification limits, MDLs and MQLs, were in the range 2.2-3.0 ng g(-1) and 6.6-9.0 ng g(-1), respectively. The high-performance microwave system here used strongly improved the extraction efficiency with respect to a conventional apparatus. The procedure proved to be simpler, less expensive, faster, and more green with respect to the few methods currently described in literature, providing at the same time suitable recovery and reproducibility. The analytical method has been applied to the analysis of actual compost samples, wherein FQs have been quantified at concentrations up to 88 ng g(-1). PMID:26250963

  7. Quantitative determination of trimebutine maleate and its three metabolites in human plasma by liquid chromatography-tandem mass spectrometry.

    PubMed

    Wang, Hongyun; Zhou, Hui; Horimoto, Shingo; Jiang, Ji; Mayumi, Tsuyoshi; Hu, Pei

    2002-11-01

    A sensitive and selective HPLC-MS-MS method was developed for the determination of trimebutine maleate (TM) and its major metabolites N-monodemethyltrimebutine (TM-MPB), N-didemethyltrimebutine (APB) and 3,4,5-trimethoxybenzoic acid (TMBA) in human plasma. The analytes were extracted from plasma samples by liquid-liquid extraction and chromatographed on a YMC J'sphere C(18) column. The mobile phase consisted of 2 mM ammonium acetate buffer (pH 6.5)-methanol (20:80, v/v), and at a flow-rate of 0.2 ml/min. Detection was carried out on a triple quadrupole tandem mass spectrometer in multiple reactions monitoring (MRM) mode using positive-negative switching electrospray ionization (ESI). The method was validated over the concentration range of 1-100 ng/ml for trimebutine maleate and APB, 1-500 ng/ml for MPB, and 50-10,000 ng/ml for TMBA. Inter- and intra-day precision (RSD%) for trimebutine maleate and its three metabolites were all within +/-15% and the accuracy was within 85-115%. The limit of quantitation was 1 ng/ml for trimebutine maleate, TM-MPB and APB, and 50 ng/ml for TMBA. The extraction recovery was on average 58.2% for trimebutine maleate, 69.6% for MPB, 51.2% for APB and 62.5% for TMBA. The method was applied to the pharmacokinetic study of trimebutine maleate and its metabolites in healthy Chinese volunteers. PMID:12361732

  8. Highly sensitive and selective measurement of underivatized methylmalonic acid in serum and plasma by liquid chromatography-tandem mass spectrometry.

    PubMed

    Yuan, Chao; Gabler, Jessica; El-Khoury, Joe M; Spatholt, Regina; Wang, Sihe

    2012-07-01

    Methylmalonic acid (MMA) is a functional biomarker of vitamin B12 deficiency. Measurement of plasma MMA is challenging due to its small molecular weight and hydrophilic nature. Several liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods have been developed for measuring plasma MMA. However, these methods involve lengthy sample preparation, long chromatographic run time, inadequate sensitivity, or interference from succinic acid (SA). Here we report a novel LC-MS/MS method for quantitation of underivatized MMA in serum or heparinized plasma with high sensitivity and selectivity. Sample preparation involved only strong anion exchange solid phase extraction. The extract was purified by online turbulent flow and analyzed on an Organic Acids column. MS/MS analysis was performed in negative electrospray mode, and the analytical time was 6 min. The use of ion ratio confirmation in combination with chromatographic resolution from SA greatly enhanced the selectivity. No interference was observed. This method was linear from 26.2 to 26,010.0 nM with an accuracy of 98-111 %. Total coefficient of variation was less than 4.6 % for three concentration levels tested. Comparison with a reference laboratory LC-MS/MS method using leftover patient serum specimens (n = 48) showed a mean bias of -2.3 nM (-0.61 %) with a Deming regression slope of 1.016, intercept of -6.6 nM, standard error of estimate of 25.3 nM, and a correlation coefficient of 0.9945. In conclusion, this LC-MS/MS method offers highly sensitive and selective quantitation of MMA in serum and plasma with simple sample preparation. PMID:22618327

  9. Quantification of vincristine and its major metabolite in human plasma by high-performance liquid chromatography/tandem mass spectrometry.

    PubMed

    Dennison, Jennifer B; Renbarger, Jamie L; Walterhouse, David O; Jones, David R; Hall, Stephen D

    2008-06-01

    An analytical method using electrospray ionization and high-performance liquid chromatography/tandem mass spectrometry (LC/ESI-MS/MS) was developed to quantify vincristine and M1, the CYP3A-mediated metabolite of vincristine, in human plasma. Vinblastine (internal standard), vincristine, and M1 in plasma were extracted in methylene chloride after acidification with TCAA. The analytes were separated on an Inertsil ODS-3 C18 column (2.1 x 150 mm) with a 5-mum particle size using a gradient elution with a run time of 20 min. The initial mobile phase composition was 0.2% formic acid/water (80:20, v/v) with a final composition of 0.2% formic acid/water (20:80, v/v). Detection was accomplished with multiple reaction monitoring for vinblastine (m/z 406.3--> 271.7), vincristine (m/z 413.2--> 362.2), and M1 (m/z 397.3 --> 376.2). At three concentrations of vincristine and M1, the inter-day and intra-day accuracy and precision were within the acceptable limits for validation (106.8 +/- 9.6% for intra-day, n = 5 each concentration; 90.9 +/- 10.9% for inter-day, n = 4 each concentration). For both vincristine and M1, the concentration limits of quantification and detection were 12 pg/mL and 6 pg/mL, respectively. Stability studies indicated that 80% of M1 degraded in plasma after 15 hours at room temperature (n = 3, high and low QC concentrations). Therefore, short plasma processing times (<30 min) are recommended. The assay was used successfully to quantify vincristine and M1 in pediatric plasma samples up to 24 hours after vincristine administration. Vincristine and M1 concentrations were within the limits of quantification for all patient plasma samples. PMID:18520608

  10. [Determination of 5 polyether antibiotics in chicken tissues by liquid chromatography-electrospray ionization tandem mass spectrometry].

    PubMed

    Liang, Chunlai; Cheng, Linli; Shen, Jianzhong; Zhang, Yujie; Zhang, Suxia

    2009-11-01

    A liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI MS/MS) method for the determination of 5 polyether antibiotics (lasalocid, salinomycin, monensin, narasin and maduramicin) in chicken tissues was developed. The polyether antibiotics were extracted from chicken tissues with methanol. The extract was evaporated to dry, and redissolved in hexane, then cleaned up on a Sep-Pak Silica solid-phase extraction cartridge. The target drugs were eluted with 6 mL methylene chloride-methanol (90:10, v/v), and the eluate was collected and dried under a gentle stream of nitrogen gas, then the residue was dissolved with 1 mL acetonitrile (containing 0.1% formic acid) and analyzed by LC-MS/MS. The LC separation was performed on a Symmetry Shield reversed phase C18 bonded silica column with acetonitrile (containing 0.1% formic acid)-0.1% formic acid (97:3, v/v) as mobile phase. The quantification was carried out by positive electrospray ionization and multiple reaction monitoring (MRM) mode. The validation was carried out on spiked chicken muscle (spiked at 0.1 -1500 microg/kg) and chicken liver (spiked at 0.2-4500 microg/kg), the average recoveries of target drugs ranged from 71.6%-99.1% with intra-day relative standard deviations (RSDs) of 3.2%-10.7% and inter-day RSDs of 4.6%-14.7%. The limits of quantification (LOQs) in chicken muscle and liver were 0.1-1.0 kg/kg. The results demonstrated that the sensitivity, accuracy and precision of this method meet the requirements of veterinary drug residue analysis. The method is applicable to detect 5 polyether antibiotics in chicken muscle and liver. PMID:20352937

  11. Determination of albendazole and metabolites in silkworm Bombyx mori hemolymph by ultrafast liquid chromatography tandem triple quadrupole mass spectrometry.

    PubMed

    Li, Li; Xing, Dong-Xu; Li, Qing-Rong; Xiao, Yang; Ye, Ming-Qiang; Yang, Qiong

    2014-01-01

    Albendazole is a broad-spectrum parasiticide with high effectiveness and low host toxicity. No method is currently available for measuring albendazole and its metabolites in silkworm hemolymph. This study describes a rapid, selective, sensitive, synchronous and reliable detection method for albendazole and its metabolites in silkworm hemolymph using ultrafast liquid chromatography tandem triple quadrupole mass spectrometry (UFLC-MS/MS). The method is liquid-liquid extraction followed by UFLC separation and quantification in an MS/MS system with positive electrospray ionization in multiple reaction monitoring mode. Precursor-to-product ion transitions were monitored at 266.100 to 234.100 for albendazole (ABZ), 282.200 to 208.100 for albendazole sulfoxide (ABZSO), 298.200 to 159.100 for albendazole sulfone (ABZSO2) and 240.200 to 133.100 for albendazole amino sulfone (ABZSO2-NH2). Calibration curves had good linearities with R2 of 0.9905-0.9972. Limits of quantitation (LOQs) were 1.32 ng/mL for ABZ, 16.67 ng/mL for ABZSO, 0.76 ng/mL for ABZSO2 and 5.94 ng/mL for ABZSO2-NH2. Recoveries were 93.12%-103.83% for ABZ, 66.51%-108.51% for ABZSO, 96.85%-105.6% for ABZSO2 and 96.46%-106.14% for ABZSO2-NH2, (RSDs <8%). Accuracy, precision and stability tests showed acceptable variation in quality control (QC) samples. This analytical method successfully determined albendazole and its metabolites in silkworm hemolymph in a pharmacokinetic study. The results of single-dose treatment suggested that the concentrations of ABZ, ABZSO and ABZSO2 increased and then fell, while ABZSO2-NH2 level was low without obvious change. Different trends were observed for multi-dose treatment, with concentrations of ABZSO and ABZSO2 rising over time. PMID:25255321

  12. Determination of polyphenolic profiles by liquid chromatography-electrospray-tandem mass spectrometry for the authentication of fruit extracts.

    PubMed

    Puigventós, Lidia; Navarro, Meritxell; Alechaga, Élida; Núñez, Oscar; Saurina, Javier; Hernández-Cassou, Santiago; Puignou, Lluis

    2015-01-01

    Liquid chromatography-electrospray-tandem mass spectrometry (LC-ESI-MS/MS) was applied to the analysis and authentication of fruit-based products and fruit-based pharmaceutical preparations. A Kinetex C18 reversed-phase column under gradient elution with 0.1 % formic acid aqueous solution and methanol mobile phases was used for the simultaneous determination of 26 polyphenols, allowing an acceptable separation in less than 22 min. Instrumental quality parameters such as limits of detection (LOD, values between 12 and 14 μg/L for 19 of the 26 analyzed polyphenols), linearity (r (2) > 0.991), run-to-run and day-to-day precisions (relative standard deviation (RSD) values lower than 9.9 and 13.5 %, respectively), and accuracy (relative errors lower than 8 %) were established. A simple extraction method, consisting of a sample sonication with acetone/water/hydrochloric acid (70:29.9:0.1 v/v/v) and centrifugation, was proposed. Two calibration procedures, external calibration using standards prepared in water and standard addition, were evaluated for polyphenol quantification in several grape and cranberry fruits and processed fruit products. For a 95 % confidence level, no statistical differences were observed between the two calibration methods (p values between 0.06 and 0.95), denoting that external calibration was suitable enough for the quantitative analysis of polyphenols in fruit-based products. The proposed LC-ESI-MS/MS method was then applied to the analysis of polyphenols in 23 grape-based and cranberry-based natural products and pharmaceutical preparations. Polyphenolic concentration data was then analyzed by principal component analysis (PCA) to extract information of the most significant profile data contributing to authentication of natural extracts according to their fruit of origin. PMID:25370163

  13. A liquid chromatography-electrospray ionization-tandem mass spectrometry study of ethanolamines in high salinity industrial wastewaters.

    PubMed

    Campo, Pablo; Suidan, Makram T; Chai, Yunzhou; Davis, John

    2010-01-15

    The detection and quantitation of four ethanolamines, tris(2-hydroxyethyl)amine (triethanolamine, TEA), N,N-bis(2-hydroxyethyl)methylamine (methyldiethanolamine, MDEA), N-(2-aminoethyl)ethanolamine (AEA), and N,N-diethylethanolamine (DEA), were achieved in wastewaters from two aerobic activated sludge bioreactors located in an industrial wastewater treatment plant. The streams had salt concentrations of approximately 3% and 7% by weight in Reactor 1 and Reactor 2, respectively. The use of liquid chromatography-electrospray ionization-tandem mass spectrometry avoided the need for some sample preparation steps such as extraction, concentration, and derivatization. Ion suppression in the electrospray, attributable to the presence of sodium clusters, was attenuated by a 10-fold dilution of the wastewaters with acetonitrile. A matrix-matched calibration model averted other potential interferences. For the compounds analyzed in selected reaction monitoring mode (TEA, MDEA, and DEA), the calibration curves presented linearity in a range of 10-1000microg/L with corresponding detection limits ranging from 2 to 11microg/L, depending upon the specific analyte and aqueous matrix. AEA was calibrated in selected ion monitoring mode (100-1000microg/L), with corresponding detection limits in the two wastewaters of 74.6 and 85.3microg/L, respectively. Overall good precision (<10%) and accuracy (97-110%) were achieved for both matrices, which fell within-laboratory reproducibility. Finally, the amines were introduced into six mixed liquor samples from both reactors and quantified following the reported protocol. Again, recoveries were close to 100% with a relative standard deviation of less than 10% in all cases. PMID:20006060

  14. Simultaneous determination of opiates, methadone, buprenorphine and metabolites in human urine by superficially porous liquid chromatography tandem mass spectrometry.

    PubMed

    Lin, Huei-Ru; Chen, Chin-Lun; Huang, Chieh-Liang; Chen, Shao-Tsu; Lua, Ahai-Chuang

    2013-04-15

    For monitoring compliance of methadone or buprenorphine maintenance patient, a method for the simultaneous determination of methadone, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), buprenorphine, norbuprenorphine, opiates (morphine, codeine, 6-monoacetylmorphine) in urine by superficially porous liquid chromatography tandem mass spectrometry was developed and validated. After enzyme digestion and liquid-liquid extraction, reverse-phase separation was achieved in 5.2 min and quantification was performed by multiple reaction monitoring. Chromatographic separation was performed at 40 °C on a reversed phase Poroshell column with gradient elution. The mobile phase consisted of water and methanol, each containing 0.1% formic acid, at a flow rate of 0.32 mL/min. Intra-day and inter-day precision were less than 12.1% and accuracy was between -9.8% and 13.7%. Extraction efficiencies were more than 68%. Although ion suppression was detected, deuterated internal standards compensated for these effects. Carryover was minimal, less than 0.20%. All analytes were stable at room temperature for 16 h, 4 °C for 72 h, and after three freeze-thaw cycles. The assay also fulfilled compound identification criteria in accordance with the European Commission Decision 2002/657/EC. We analyzed 62 urine samples from patients received maintenance therapy and found that 54.8% of the patient samples tested were detected for morphine, codeine, or 6-monoacetylmorphine. This method provides a reliable and simultaneous quantification of opiates, maintenance drugs, and their metabolites in urine samples. It facilitates the routine monitoring in individuals prescribed the drug to ensure compliance and help therapeutic process. PMID:23507455

  15. Simultaneous determination of trantinterol and its metabolites in rat urine and feces by liquid chromatography-tandem mass spectrometry.

    PubMed

    Li, Kunjie; Wang, Yanjuan; Zhang, Lili; Qin, Feng; Guo, Xingjie; Li, Famei

    2013-09-01

    A highly selective and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the simultaneous determination of trantinterol (SPFF) and its major metabolites for the first time. The analytes were extracted from rat urine and feces samples by liquid-liquid extraction (LLE) and determined in multiple reaction monitoring (MRM) mode with clenbuterol as the internal standard. Chromatographic separation was achieved on a Venusil ASB C8 column (2.1mm×100mm, 3μm), with the mobile phase consisted of methanol-0.2% formic acid (30:70, v/v) at the flow rate of 0.2mL/min. Each sample was chromatographed within 5min. This method has a lower limit of quantification (LLOQ) of 0.450, 1.05, 1.35, 0.904 and 1.36ng/mL for trantinterol (SPFF), arylhydroxylamine trantinterol (N-OH-SPFF), tert-butyl hydroxylated trantinterol (Tert-OH-SPFF), 1-carbonyl trantinterol (SPFF-COOH) and 3-methyl sulfone-dechloro-trantinterol (SPFF-SO2CH3) in rat urine, and 0.450, 1.35 and 0.904ng/mL for SPFF, Tert-OH-SPFF and SPFF-COOH in rat feces, respectively. The linear correlation coefficients were greater than 0.990. The intra- and inter-day precision (relative standard deviation, RSD) values were below 15% and the accuracy (relative error, RE) was -9.9% to 11% at three quality control levels. The method has been successfully applied to the excretion study following an oral administration of 1mg/kg trantinterol to rats. PMID:23911540

  16. Pharmacokinetics in rats and tissue distribution in mouse of magnoflorine by ultra performance liquid chromatography-tandem mass spectrometry

    PubMed Central

    Bao, Shihui; Geng, Peiwu; Wang, Shuanghu; Zhou, Yunfang; Hu, Lufeng; Yang, Xuezhi

    2015-01-01

    Magnoflorine is one of the most widespread aporphine alkaloids. In this work, a sensitive and selective ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for the determination of magnoflorine in rat plasma and mouse tissue have been developed and validated. After addition of nuciferine as an internal standard (IS), protein precipitation by acetonitrile-methanol (9:1, v/v) was used for samples treatment. Chromatographic separation was achieved on a UPLC BEH C18 column (2.1 mm×100 mm, 1.7 μm) with 0.1% formic acid and acetonitrile as the mobile phase with gradient elution. An electrospray ionization source was applied and operated in positive ion mode; multiple reactions monitoring (MRM) mode was used for quantification using target fragment ions m/z 342.8→298.2 for magnoflorine and m/z 296.0→265.1 for IS. Calibration plots were linear throughout the range 2-2000 ng/mL for magnoflorine in rat plasma and tissue. Mean recoveries of magnoflorine in rat plasma were better than 83.0%. RSD of intra-day and inter-day precision were both less than 9%. The accuracy of the method was between 95.5% and 107.5%. The method was successfully applied to pharmacokinetics and tissue distribution study of magnoflorine. The absolute bioavailability of magnoflorine was reported as 22.6%. The magnoflorine underwent a rapid and wide distribution to tissues; the level of magnoflorine in liver is highest, then followed by heart, spleen and lung. Based on tissue distribution data, a back-propagation artificial neural network (BP-ANN) method was developed and it could be used to predict the concentrations of magnoflorine in tissues. PMID:26884929

  17. Rapid quantification of miglustat in human plasma and cerebrospinal fluid by liquid chromatography coupled with tandem mass spectrometry.

    PubMed

    Guitton, Jérôme; Coste, Sylvie; Guffon-Fouilhoux, Nathalie; Cohen, Sabine; Manchon, Monique; Guillaumont, Marc

    2009-01-15

    Miglustat (OGT 918) is an iminosugar recently introduced in therapeutic as potential alternative therapy in disorders found in several diseases such as Tay-Sachs, Gaucher or Niemann-Pick diseases. A highly sensitive liquid-chromatography-electrospray tandem mass spectrometry (LC-MS/MS) assay was developed for the quantification of miglustat in human plasma and cerebrospinal fluid (CSF). The sample preparation consists in a simple protein precipitation with a mixture of acetonitrile/methanol (75/25) which yields 100% recovery. The isocratic separation utilizes an Atlantis Hilic (3 microm, 150 mm x 2.1 mm) column, with a mobile phase of acetonitrile/water/ammonium acetate buffer (75/10/15, v/v/v) delivered at 230 microl/min. Selected reaction monitoring (SRM) mode was used with the transitions m/z 220-->158 for the miglustat and m/z 208-->m/z 146 for the miglitol (internal standard). Good linearity was observed in a range from 125 to 2500 ng/ml and from 50 to 1000 ng/ml, for plasma and CSF, respectively. The within-run precision of the assay was less than 6%, and the between-run run precision was less than 6.5%, for six replicates at each of three concentrations and evaluated on three separated days for both plasma and CSF mediums. Assay accuracy was in the range of 98-106.5%. Stability of miglustat was reported under a variety of storage conditions. The miglustat concentrations in two children are presented to demonstrate the clinical interest of this new method. PMID:19095507

  18. Determination of afloqualone in human plasma using liquid chromatography/tandem mass spectrometry: Application to pharmacokinetic studies in humans.

    PubMed

    Yun, Hwi-Yeol; Lee, Seo-Pan; Jeong, Hae Hum; Yoon, Young-Ran; Sohn, Soo Jung; Kim, Sang Kyum; Kang, Wonku; Kwon, Kwang-Il

    2007-10-15

    Two methods for determining the central-acting muscle relaxant afloqualone in human plasma were developed and compared using API2000 and API4000 liquid chromatography tandem mass spectrometry (LC/MS/MS) systems. In the API2000 LC/MS/MS system, afloqualone and the internal standard methaqualone were extracted from plasma using a methyl-tertiary ether. After drying the organic layer, the residue was reconstituted in a mobile phase (0.1% formic acid-acetonitrile:0.1% formic acid buffer, 80:20 v/v) and injected onto a reversed-phase C(18) column. The isocratic mobile phase was eluted at 0.2ml/min. The ion transitions monitored in multiple reaction-monitoring mode were m/z 284-->146 and 251-->117 for afloqualone and methaqualone, respectively. Sample preparation for the API4000LC/MS/MS system involved simple protein precipitation with an organic mixture (methanol:10% ZnSO(4)=8:2). The ion transitions monitored in multiple reaction-monitoring mode were m/z 284-->146 and 251-->131 for afloqualone and methaqualone, respectively. In both assays, the coefficient of variation of the precision was less than 11.8%, the accuracy exceeded 91.5%, the limit of quantification was 0.5ng/ml, and the limit of detection was 0.1ng/ml for afloqualone. Two methods were used to measure the plasma afloqualone concentration in healthy subjects after a single oral 20-mg dose of afloqualone. During subsequent application of the methods, we observed that high-concentration plasma samples (>7ng/ml) prepared using the protein precipitation method resulted in about 20% higher afloqualone concentrations than with plasma samples prepared using the liquid-liquid extraction method. We believe that this phenomenon was related to the cleanness of the sample and its chemical nature. PMID:19073082

  19. Tandem Native Mass-Spectrometry on Antibody-Drug Conjugates and Submillion Da Antibody-Antigen Protein Assemblies on an Orbitrap EMR Equipped with a High-Mass Quadrupole Mass Selector.

    PubMed

    Dyachenko, Andrey; Wang, Guanbo; Belov, Mike; Makarov, Alexander; de Jong, Rob N; van den Bremer, Ewald T J; Parren, Paul W H I; Heck, Albert J R

    2015-06-16

    Native mass spectrometry is emerging as a powerful tool for the characterization of intact antibodies and antibody-based therapeutics. Here, we demonstrate new possibilities provided by the implementation of a high mass quadrupole mass selector on the recently introduced Orbitrap Exactive EMR mass spectrometer. This configuration allows precursor ion selection, and thus tandem mass spectrometry experiments, even on analytes with masses in the hundreds of kilodaltons. We apply tandem mass spectrometry to localize the drug molecules in the therapeutic antibody-drug conjugate brentuximab vedotin, which displays a heterogeneous drug load. Our tandem MS data reveal that drug conjugation takes place nonhomogeneously to cysteine residues both on the light and heavy chains. Next, we analyzed how many antigens bind to IgG hexamers, based on a recently described antibody mutant IgG1-RGY that forms hexamers and activates complement in solution. The fully saturated IgG1-RGY-antigen complexes displayed a stoichiometry of IgG:CD38 of 6:12, possessing a molecular weight of about 1.26 MDa and demonstrating that IgG assembly does not hamper antigen binding. Through tandem MS experiments, we retrieve information about the spatial arrangement and stoichiometry of the subunits within this complex. These examples underscore the potential of this further modified Orbitrap-EMR instrument especially for the in-depth characterization by native tandem mass spectrometry of antibodies and antibody-based constructs. PMID:25978613

  20. Confirmatory analysis of acetylgestagens in plasma using liquid chromatography-tandem mass spectrometry.

    PubMed

    Mortensen, Sarah Kelly; Pedersen, Mikael

    2007-03-14

    A confirmatory method has been developed and validated for the determination of chlormadinone acetate (CMA), megestrol acetate (MGA), melengestrol acetate (MLA) and medroxyprogesterone acetate (MPA) in bovine and porcine plasma. Analytes are extracted from plasma samples using matrix-assisted liquid-liquid extraction (LLE) on Extrelut NT columns followed by C18 solid-phase extraction (SPE). Analytes were analysed using liquid chromatography-tandem mass spectrometry (LC-MS/MS), and quantification was performed using matrix-matched calibration standards in combination with deuterated internal standards. In accordance with Commission Decision 2002/657/EC, two ion transitions were monitored for each analyte. Decision limits (CCalpha) were estimated by analysing 20 blank plasma samples and ranged from 0.1 to 0.2 ng mL(-1). Detection capabilities (CCbeta) were estimated using 20 plasma samples fortified at 0.5 ng mL(-1) and were <0.5 ng mL(-1). In the range 0.5-2 ng mL(-1), the mean intra-laboratory reproducibility of the analytes ranged from 6 to 18% (%R.S.D.). Analytes were shown to be stable in fortified plasma samples for >8 months when stored at -20 degrees C. PMID:17386714

  1. Determination of gestagens in kidney fat by liquid chromatography tandem mass spectrometry.

    PubMed

    Lõhmus, Madis; Kender, Tiia

    2007-03-14

    The use of gestagens in animal fattening is prohibited within the European Union. Recently, the use of spectrometric methods for the detection and confirmation of banned substances was made obligatory. Therefore, conventional high-performance liquid chromatographic (HPLC) methods have been superseded. It has been possible to couple a previously described HPLC method for the determination of acetyl-gestagens in kidney fat to tandem mass spectrometry (LC-MS/MS). The decision limits CCalpha and the detection capability CCbeta are found to be below the minimum required performance limit (MRPL) established for medroxyprogesterone acetate (MPA) at 1 microg kg(-1). The calculated values for CCalpha are as follows: megestrol acetate (MGA)--0.15 microg kg(-1), melengesterol acetate (MLA)--0.15 microg kg(-1), chlormadinone acetate (CMA)--0.37 microg kg(-1) and for medroxyprogesterone acetate (MPA)--0.24 microg kg(-1). The CCbeta values for these compounds have been determined as 0.19, 0.19, 0.47 and 0.32 microg kg(-1), respectively. PMID:17386717

  2. Simultaneous determination of seven gestagens in kidney fats by Ultra Performance Convergence Chromatography tandem mass spectrometry.

    PubMed

    Tao, Yanfei; Paula, Rutgers; Stolker, A A M; Chen, Dongmei; Yuan, Zonghui

    2015-04-15

    An ultra-performance convergence chromatography (UPC2) system coupled tandem mass spectrometry was successfully utilised to analyse chlormadinone acetate, delmadinone acetate, fluorogestone acetate, medroxyprogesterone acetate, megestrol acetate, melengestrol acetate, chlortestasterone acetate in bovine and porcine kidney fat. This novel approach obtained an improved resolution in comparison to previously reported chromatographic methods combined with MS detector in a shorter analytical time. All the acetylgestagen compounds were well separated on a ACQUITY UPC(2) HSS C18 column (3.0 × 100 mm, 1.7 μm) by applying methanol and carbon dioxide (2/98). The LOQ of delmadinone acetate, melengestrol acetate, medroxyprogesterone acetate and megestrol acetate are 0.5 μg/kg, fluorogestone acetate, chlormadinone acetate and chlortestasterone acetate 1.0 μg/kg. The recoveries of gestagens spiked in kidney fats at a concentration range of 0.5 to 4 μg/kg were above 86.1% with relative standard deviations (RSD) less than 13.1%. These rapid and reliable methods can be used to efficiently separate, characterize and quantify the residues of gestagens in kidney fats with advantages of shorter time, more sensitive and environmental friendly. PMID:25777477

  3. Human embryonic stem cell phosphoproteome revealed by electron transfer dissociation tandem mass spectrometry

    PubMed Central

    Swaney, Danielle L.; Wenger, Craig D.; Thomson, James A.; Coon, Joshua J.

    2009-01-01

    Protein phosphorylation is central to the understanding of cellular signaling, and cellular signaling is suggested to play a major role in the regulation of human embryonic stem (ES) cell pluripotency. Here, we describe the use of conventional tandem mass spectrometry-based sequencing technology—collision-activated dissociation (CAD)—and the more recently developed method electron transfer dissociation (ETD) to characterize the human ES cell phosphoproteome. In total, these experiments resulted in the identification of 11,995 unique phosphopeptides, corresponding to 10,844 nonredundant phosphorylation sites, at a 1% false discovery rate (FDR). Among these phosphorylation sites are 5 localized to 2 pluripotency critical transcription factors—OCT4 and SOX2. From these experiments, we conclude that ETD identifies a larger number of unique phosphopeptides than CAD (8,087 to 3,868), more frequently localizes the phosphorylation site to a specific residue (49.8% compared with 29.6%), and sequences whole classes of phosphopeptides previously unobserved. PMID:19144917

  4. Differentiating Isobaric Steroid Hormone Metabolites Using Multi-Stage Tandem Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Tedmon, Lauren; Barnes, Jeremy S.; Nguyen, Hien P.; Schug, Kevin A.

    2013-03-01

    Steroid hormones and their metabolites are currently undergoing clinical trials as potential therapeutics for traumatic brain injury (TBI). To support this work, it is necessary to develop improved procedures for differentiating isobaric species in this compound class. Equilin sulfate (E-S), estrone sulfate (E1-S), 17α-dihydroequilin sulfate (ADHE-S), and 17β-dihydroequilin sulfate (BDHE-S) are primary constituents in hormone replacement therapies, such as Premarin, which are among pharmaceuticals being investigated for TBI treatment. The latter three compounds are isomers and can be difficult to differentiate in trace analytical determinations. In this work, a systematic study of the fragmentation of ADHE-S, BDHE-S, E1-S, and E-S under different stages of higher order tandem mass spectrometry (MSn) and variation of collision energy, allowed optimization of conditions for distinguishing the isomeric structures. For epimeric variants (e.g., ADHE-S versus BDHE-S; α- versus β-stereoisomerization in the C-17 position), differentiation was achieved at MS4 and fragmentation was demonstrated through MS5. Computational analysis was performed to further explore differences in the fragmentation pathways due to changes in stereochemistry.

  5. Rapid extraction of melamine in powdered milk for direct electrospray ionization tandem mass spectrometry analysis.

    PubMed

    Domingo, Elisângela do Carmo; Tireli, Aline Auxiliadora; Nunes, Cleiton Antonio; Batista, Alexandre Vieira; Guerreiro, Mário César; Pinto, Sandra Maria

    2015-01-01

    A combination of a simple pretreatment for melamine extraction and direct analysis in electrospray ionization tandem mass spectrometry (ESI-MS/MS) is proposed. Three pretreatments were evaluated. The first was based on suppressing interference using acetonitrile. The second used sulphuric acid and trichloroacetic acid to suppress interference and for melamine extraction, respectively. The third used sulphuric acid to suppress milk interference, trichloroacetic acid for melamine precipitation, and ethyl acetate for melamine extraction. However, only the last pretreatment suppressed milk interference in melamine detection and a good linearity (R(2)=0.99) was obtained. The presence of MS/MS 85 on melamine fragmentation spectrum showed the selectivity of this method. The limit of detection and limit of quantification were 0.269 µg L(-1) and 0.897 µg L(-1), respectively. The recoveries and relative standard deviation (RDS) of method were lower than 114% and 7.86%, respectively. Further, the research was extended to elucidate the nature of the melamine in the extract through infrared spectroscopy and microscopy analyses. The precipitate was characterized as melaminium bis(trichloroacetate) dihydrate, which is generated through hydrogen bound formation in an interaction between melamine and trichloroacetic acid. Therefore, a simple, fast, and easy method for melamine extraction and direct ESI-MS/MS analysis was developed. PMID:25476341

  6. Accelerator mass spectrometry and radioisotope detection at the Argonne FN tandem facility

    SciTech Connect

    Henning, W.; Kutschera, W.; Paul, M.; Smither, R.K.; Stephenson, E.J.; Yntema, J.L.

    1980-01-01

    The Argonne FN tandem accelerator and standard components of its experimental heavy-ion research facility, have been used as a highly-sensitive mass spectrometer to detect several long-lived radioisotopes and measure their concentration by counting of accelerated ions. Background beams from isobaric nuclei have been eliminated by combining the dispersion from the energy loss in a uniform Al foil stack with the momentum resolution of an Enge split-pole magnetic spectrograph. Radioisotope concentrations in the following ranges have been measured: /sup 14/C//sup 12/C = 10/sup -12/ to 10/sup -13/, /sup 26/Al//sup 27/Al = 10/sup -10/ to 10/sup -12/, /sup 32/Si/Si = 10/sup -8/ to 10/sup -14/, /sup 36/Cl/Cl = 10/sup -10/ to 10/sup -11/. Particular emphasis was put on exploring to what extent the technique of identifying and counting individual ions in an accelerator beam can be conveniently used to determine nuclear quantities of interest when their measurement involves very low radioisotope concentrations. The usefulness of this method can be demonstrated by measuring the /sup 26/Mg(p,n)/sup 26/Al(7.2 x 10/sup 5/ yr) cross section at proton energies in the astrophysically interesting range just above threshold, and by determining the previously poorly known half life of /sup 32/Si.

  7. Glycerophospholipid analysis of Eastern red bat (Lasiurus borealis) hair by electrospray ionization tandem mass spectrometry.

    PubMed

    Pannkuk, Evan L; McGuire, Liam P; Gilmore, David F; Savary, Brett J; Risch, Thomas S

    2014-03-01

    Pilosebaceous units found in the mammalian integument are composed of a hair follicle, the proximal portion of the hair shaft, a sebaceous gland, and the erector pili muscle. Pilosebaceous units release protective oils, or sebum, by holocrine secretion onto skin and hair through rupturing of sebocytes. Sebum is composed largely of polar and neutral lipids including glycerolipids, free fatty acids, sterols, wax esters, sterol esters, and squalene. In addition to these lipid classes, there is a small proportion of ionic/anionic glycerophospholipids (GPs). Composition of GPs on hair is rarely addressed despite their broad biological activities as signaling molecules and membrane stability. Furthermore, knowledge on GP composition in bats is lacking. Bat GP composition is important to document due to GP roles ranging from decreasing drag during migration to interaction with the integumentary microbiome. In this study, we analyzed GP molecular composition with liquid chromatography electrospray ionization tandem mass spectrometry and compared GP content to previous literature. A total of 152 GPs were detected. Broad GP classes identified include lysophosphatidylcholine, phosphatidylcholine (PC), lysophosphatidylethanolamine, phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, phosphatidic acid, and phosphatidylglycerol, with PC being the most abundant class. The acyl components were consistent with fatty acid methyl esters and triacylglyceride moieties found in Eastern red bat sebum. Glycerophospholipid proportions of the hair surface were different from a previous study on bat lung surfactants. This study determined the broad class and molecular species of bat sebum GPs that may be used in future ecological studies in vespertilionid bats. PMID:24532214

  8. A method for profiling gangliosides in animal tissues using electrospray ionization-tandem mass spectrometry.

    PubMed

    Tsui, Zhao-Chun; Chen, Qi-Rui; Thomas, Michael J; Samuel, Michael; Cui, Zheng

    2005-06-15

    Gangliosides are critical in many functions of mammalian cells but present as a minor lipid component with many molecular species of subtle differences. Conventional strategies for profiling gangliosides suffer from poor reproducibility, low sensitivity, and low-throughput capacity. Prior separation of gangliosides by thin-layer chromatography and/or high-performance liquid chromatography not only was laborious and tedious but also could introduce uneven losses of molecular species. We developed a new strategy of using electrospray ionization-tandem mass spectrometry (ESI-MS/MS) to profile gangliosides with high-throughput potential. This strategy involves three new findings: (i) collision-induced fragmentation of gangliosides gave rise to a common ion of m/z 290, a derivative of N-acetylneuraminic acid; (ii) phospholipids exert a profound suppression of ganglioside detection in ESI-MS/MS to prevent a direct detection in total cellular lipid extracts; and (iii) enrichment of gangliosides in the aqueous phase from total cellular lipid extracts eliminates the damping effect of phospholipids and permits direct precursor scan. PMID:15907870

  9. Global Analysis of the Membrane Subproteome of Pseudomonas aeruginosa using Liquid Chromatography-Tandem Mass Spectrometry

    SciTech Connect

    Blonder, Josip; Goshe, Michael B.; Xiao, Wenzhong; Camp, David G.; Wingerd, Mark A.; Davis, Ronald W.; Smith, Richard D.

    2004-05-30

    Pseudomonas aeruginosa is one of the most significant opportunistic bacterial pathogens in humans causing infections and premature death in patients with cystic fibrosis, AIDS, severe burns, organ transplants or cancer. Liquid chromatography coupled online with tandem mass spectrometry (LC-MS/MS) was used for the large-scale proteomic analysis of the P. aeruginosa membrane subproteome. Concomitantly, an affinity labeling technique, using iodoacetyl-PEO biotin to tag cysteinyl-containing proteins, permitted the enrichment and detection of lower abundance membrane proteins. The application of these approaches resulted in the identification of 786 proteins. A total of 333 proteins (42%) had a minimum of one transmembrane domain (TMD; ranging from 1 to 14) and 195 proteins were classified as hydrophobic based on their positive GRAVY values (ranging from 0.01 to 1.32). Key integral inner and outer membrane proteins involved in adaptation and antibiotic resistance were conclusively identified, including the detection of 53% of all predicted opr-type porins (outer integral membrane proteins) and all the components of the mexA-mexB-oprM transmembrane protein complex. This work represents the most comprehensive qualitative proteomic analysis of the membrane subproteome of P. aeruginosa and for prokaryotes in general to date.

  10. Determination of sulfonamides in beeswax by liquid chromatography coupled to tandem mass spectrometry.

    PubMed

    Mitrowska, Kamila; Antczak, Maja

    2015-12-01

    The manuscript presents the development of a new method for the quantification of 16 sulfonamides in beeswax. Different sample preparation techniques were tested and modified to maximise the recovery of the target analytes and minimise the amount of coeluted impurities under conditions that provide reproducible results. The proposed method consisted of melting and dilution of beeswax in a mixture of n-hexane and isopropanol followed by extraction with 2% acetic acid. The extract was cleaned up by solid-phase extraction using strong cation exchange phase. Determination of the sulfonamides was achieved by liquid chromatography coupled to tandem mass spectrometry with the use of a pentafluorophenyl analytical column and applying a gradient elution with acetonitrile and 0.01% acetic acid as mobile phases. The limits of detection and limits of quantification ranged from 1 to 2μg/kg and from 2 to 5μg/kg, respectively. The recoveries varied between 65.2% and 117.8% while coefficient of variation of the method was less than 24.2% under intermediate precision conditions. Finally, the method was applied to the analysis of real samples of beeswax from beekeepers and commercial foundations manufacturers. PMID:26554312

  11. Determination of melatonin in Acyrthosiphon pisum aphids by liquid chromatography-tandem mass spectrometry.

    PubMed

    Escrivá, Laura; Manyes, Lara; Barberà, Miquel; Martínez-Torres, David; Meca, Guiseppe

    2016-03-01

    Melatonin is a hormone mainly involved in the regulation of circadian and seasonal rhythms in both invertebrates and vertebrates. Despite the identification of melatonin in many insects, its involvement in the insect seasonal response remains unclear. A liquid chromatography tandem mass spectrometry (LC-MS/MS) method has been developed for melatonin analysis in aphids (Acyrthosiphon pisum) for the first time. After comparing two different procedures and five extraction solvents, a sample preparation procedure with a mixture of methanol/water (50:50) was selected for melatonin extraction. The method was validated by analyzing melatonin recovery at three spiked concentrations (5, 50 and 100 pg/mg) and showed satisfactory recoveries (75-110%), and good repeatability, expressed as relative standard deviation (<10%). Limits of detection (LOD) and quantitation (LOQ) were 1 pg/mg and 5 pg/mg, respectively. Eight concentration levels were used for constructing the calibration curves which showed good linearity between LOQ and 200 times LOQ. The validated method was successfully applied to 26 aphid samples demonstrating its usefulness for melatonin determination in insects. This is -to our knowledge- the first identification of melatonin in aphids by LC-MS/MS. PMID:26778054

  12. [Determination of 25 quinolones in cosmetics by liquid chromatography-tandem mass spectrometry].

    PubMed

    Lin, Li; Zhang, Yi; Tu, Xiaoke; Xie, Liqi; Yue, Zhenfeng; Kang, Haining; Wu, Weidong; Luo, Yao

    2015-03-01

    An analytical method was developed for the simultaneous determination of 25 quinolones, including danofloxacin mesylate, enrofloxacin, flumequine, oxloinic acid, ciprofloxacin, sarafloxacin, nalidixic acid, norfloxacin, and ofloxacin etc in cosmetics using direct extraction and liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). Cosmetic sample was extracted by acidified acetonitrile, defatted by n-hexane and separated on Poroshell EC-C18 column with gradient elution program using acetonitrile and water (both containing 0. 1% formic acid) as the mobile phases and analyzed by LC-ESI-MS/MS under the positive mode using multiple reaction monitoring (MRM). The interference of matrix was reduced by the matrix-matched calibration standard curve. The method showed good linearities over the range of 1-200 mg/kg for the 25 quinolones with good linear correlation coefficients (r ≥ 0.999). The method detection limit of the 25 quinolones was 1.0 mg/kg, and the recoveries of all analytes in lotion, milky and cream cosmetics matrices ranged from 87.4% to 105% at the spiked levels of 1, 5 and 10 mg/kg with the relative standard deviations (RSD) of 4.54%-19.7% (n = 6). The results indicated that this method is simple, fast and credible, and suitable for the simultaneous determination of the quinolones in the above three types of cosmetics. PMID:26182469

  13. Affinity chromatographic selection of carbonylated proteins followed by identification of oxidation sites using tandem mass spectrometry.

    PubMed

    Mirzaei, Hamid; Regnier, Fred

    2005-04-15

    It has been shown that oxidatively modified forms of proteins accumulate during oxidative stress, aging, and in some age-related diseases. One of the unique features of a wide variety of routes by which proteins are oxidized is the generation of carbonyl groups. This paper reports a method for the isolation of oxidized proteins, which involves (1) biotinylation of oxidized proteins with biotin hydrazide and (2) affinity enrichment using monomeric avidin affinity chromatography columns. The selectivity of the method was validated by adding in vitro oxidized biotinylated BSA to a yeast lysate and showing that the predominant protein recovered was BSA. This method was applied to the question of whether large doses of 2-nitropropane produce oxidized proteins. A study of rat liver homogenates showed that animals dosed with 2-nitropropane produced 17 times more oxidized protein than controls in 6 h. Tryptic digestion of these oxidized proteins followed by reversed-phase chromatography and tandem mass spectrometry led to the identification of 14 peptides and their parent proteins. Nine of the 14 identified peptides were found to carry 1 or 2 oxidation sites and 5 of the 9 peptides were biotinylated. The significance of this affinity method is that it allows the isolation of oxidized proteins from the rest of the proteome and facilitates their identification. In some cases, it is even possible to identify the site of oxidation. PMID:15828771

  14. GLYCEROPHOSPHOLIPID ANALYSIS OF EASTERN RED BAT (Lasiurus borealis) HAIR BY ELECTROSPRAY IONIZATION TANDEM MASS SPECTROMET

    PubMed Central

    Pannkuk, Evan L.; McGuire, Liam P.; Gilmore, David F.; Savary, Brett J.; Risch, Thomas S.

    2014-01-01

    Pilosebaceous units found in the mammalian integument are composed of a hair follicle, the proximal portion of the hair shaft, a sebaceous gland, and the erector pili muscle. Pilosebaceous units release protective oils, or sebum, by holocrine secretion onto skin and hair through rupturing of sebocytes. Sebum is largely composed of polar and neutral lipids including glycerolipids, free fatty acids, sterols, wax esters, sterol esters, and squalene. In addition to these lipid classes, there is a small proportion of ionic/anionic glycerophospholipids (GPs). Composition of GPs on hair is rarely addressed despite their broad biological activities as signaling molecules and membrane stability. Furthermore, knowledge on GP composition in bats is lacking. Bat GP composition is important to document due to GP roles ranging from decreasing drag during migration to interaction with the integumentary microbiome. In this study, we analyzed GP molecular composition with liquid chromatography electrospray ionization tandem mass spectrometry and compared GP content to previous literature. A total of 152 GPs were detected. Broad GP classes identified include lysophosphatidylcholine, phosphatidylcholine (PC), lysophosphatidylethanolamine, phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, phosphatidic acid, and phosphatidylglycerol, with PC being the most abundant class. The acyl components were consistent with fatty acid methyl esters and triacylglyceride moieties found in Eastern red bat sebum. GP proportions of the hair surface were different from a previous study on bat lung surfactants. This study determined the broad class and molecular species of bat sebum GPs that may be used in future ecological studies in vespertilionid bats. PMID:24532214

  15. Determination of cosmogenic Ca-41 in a meteorite with tandem accelerator mass spectrometry

    NASA Technical Reports Server (NTRS)

    Kubik, P. W.; Elmore, D.; Conard, N. J.; Nishiizumi, K.; Arnold, J. R.

    1986-01-01

    The first use of tandem accelerator mass spectrometry (TAMS) to measure the content of Ca-41 in a natural sample, the iron Bogou meteorite, is reported. Ca in the samples was extracted by hydroxide precipitation and purified by means of a caution exchange resin (AG 50W-X8). After adding 4 percent ammonium oxide, the precipitate was ignited to CaO in a quartz vial at about 1100 C. The Ca-41/Ca ratios were determined following acceleration by alternate measurements of the Ca-40 beam current in an image Faraday cup. Ca-41 particles were also measured using a gas counter. The measured Ca-41/Ca ratio was 3.8 + or -0.6 x 10 to the 12th, which corresponds to a Ca-41 activity of 6.9 + or -1.1 d.p.m. per kg. Calculation of the half-life of Ca-41 in the Bogou meteorite yielded an age of 103,000 years.

  16. Creatinine measurements in 24 h urine by liquid chromatography--tandem Mass Spectrometry.

    PubMed

    Park, Eun-Kee; Watanabe, Takaho; Gee, Shirley J; Schenker, Marc B; Hammock, Bruce D

    2008-01-23

    A simple, sensitive, and specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for determining urinary creatinine was developed and used to evaluate 24 h urine samples collected during an exposure study. Urine (1 microL) was diluted with methanol and then directly applied to LC-MS/MS. Under electrospray ionization (ESI) conditions, the transition molecules of creatinine and creatinine- d3 were observed at m/ z 114 > 44 and m/ z 117 > 47, respectively. The retention time of creatinine was 0.59 min. The linear range was 1-2000 ng/mL, with a detection limit in urine of 1 ng/mL. LC-MS/MS and colorimetric end-point methods were significantly associated ( R2 = 0.8785, p < 0.0001). The LC-MS/MS method to determine creatinine in 24 h urine samples had shorter retention times, was more sensitive, reliable, reproducible, simple, selective, and used a smaller sample size than other LC-MS/MS or commercial methods. PMID:18092755

  17. Determination of pyrolysis products of smoked methamphetamine mixed with tobacco by tandem mass spectrometry.

    PubMed

    Lee, M R; Jeng, J; Hsiang, W S; Hwang, B H

    1999-01-01

    This study examines the pyrolysis products of smoked methamphetamine mixed with tobacco that was trapped with a C8 adsorbent cartridge and then detected by gas chromatography-tandem mass spectrometry. According to the results, the mainstream smoke contains 2-methylpropyl-benzene, 2-chloropropyl-benzene, 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one, 3-ethyl-phenol, methamphetamine, dimethylamphetamine, hydroquinone, 3-methyl-5-(1-methylethyl)-methylcarbamate phenol, N-methyl-N-(2-phenylethyl)-acetamide, 4-(3-hydroxy-1-butenyl)-3,5,5-trimethyl-2-cyclohexene-1-one, propanoic acid, N-acetylmethamphetamine, phenyl ester, and furfurylmethylamphetamine. In addition, the compounds in sidestream smoke are 2-propenyl benzene, phenylacetone, methamphetamine, dimethylamphetamine, benzyl methyl ketoxime, 3,4-dihydro-2-naphthalenone, N-folmyamphetamine, N-acetylamphetamine, bibenzyl, N-folmylmethamphetamine, N-acetylmethamphetamine, N-propionymethamphetamine, and furfurylmethylamphetamine. Moreover, the presence of methamphetamine promotes the oxidation of the tobacco components. PMID:10022208

  18. Determination of ractopamine in pig hair using liquid chromatography with tandem mass spectrometric detection.

    PubMed

    Wu, Junlin; Liu, Xiaoyun; Peng, Yunping

    2014-01-01

    A quantitative analytical procedure for the determination of ractopamine in pig hair has been developed and validated. The hair samples were washed and incubated at 75°C with isoxuprine and hair extraction buffer. The drug present was quantified using mixed solid-phase extraction and liquid chromatography with tandem mass spectrometric detection. The limit of quantization (LOQ) was 10pg/mg and the intra-day precision at 25pg/mg and 750pg/mg was 0.49% and 2.8% respectively. Inter-day precision was 0.88% and 3.52% at the same concentrations. The hair extraction percentage recovery at 25pg/mg and 50ng/mL was 99.47% and 103.83% respectively. The extraction percentage recovery at 25pg/mg and 50ng/mg was 93.52% and 100.26% respectively. Our results showed that ractopamine residues persist in hair in 24days of withdrawal and also showed the possibility to test ractopamine from pig hair samples. PMID:24548851

  19. Antibiotic toxicity and absorption in zebrafish using liquid chromatography-tandem mass spectrometry.

    PubMed

    Zhang, Fan; Qin, Wei; Zhang, Jing-Pu; Hu, Chang-Qin

    2015-01-01

    Evaluation of drug toxicity is necessary for drug safety, but in vivo drug absorption is varied; therefore, a rapid, sensitive and reliable method for measuring drugs is needed. Zebrafish are acceptable drug toxicity screening models; we used these animals with a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method in a multiple reaction monitoring mode to quantify drug uptake in zebrafish to better estimate drug toxicity. Analytes were recovered from zebrafish homogenate by collecting supernatant. Measurements were confirmed for drugs in the range of 10-1,000 ng/mL. Four antibiotics with different polarities were tested to explore any correlation of drug polarity, absorption, and toxicity. Zebrafish at 3 days post-fertilization (dpf) absorbed more drug than those at 6 h post-fertilization (hpf), and different developmental periods appeared to be differentially sensitive to the same compound. By observing abnormal embryos and LD50 values, zebrafish embryos at 6 hpf were considered to be suitable for evaluating embryotoxicity. Also, larvae at 3 dpf were adapted to measure acute drug toxicity in adult mammals. Thus, we can exploit zebrafish to study drug toxicity and can reliably quantify drug uptake with LC-MS/MS. This approach will be helpful for future studies of toxicology in zebrafish. PMID:25938774

  20. Direct Tandem Mass Spectrometric Profiling of Sulfatides in Dry Urinary Samples for Screening of Metachromatic Leukodystrophy

    PubMed Central

    Kuchař, Ladislav; Asfaw, Befekadu; Poupětová, Helena; Honzíková, Jitka; Tureček, František; Ledvinová, Jana

    2013-01-01

    Background Prediagnostic steps in suspected metachromatic leukodystrophy (MLD) rely onclinical chemical methods other than enzyme assays. We report a new diagnostic method which evaluates changes in the spectrum of molecular types of sulfatides (3-O-sulfogalactosyl ceramides) in MLD urine. Methods The procedure allows isolation of urinary sulfatides by solid-phase extraction on DEAE-cellulose membranes, transportation of a dry membrane followed by elution and tandem mass spectrometry (MS/MS) analysis in the clinical laboratory. Major sulfatide isoforms are normalized to the least variable component of the spectrum, which is the indigenous C18:0 isoform. This procedure does not require the use of specific internal standards and minimizes errors caused by sample preparation and measurement. Results Urinary sulfatides were analyzed in a set of 21 samples from patients affected by sulfatidosis. The combined abundance of the five most elevated isoforms, C22:0, C22:0-OH, C24:0, C24:1-OH, and C24:0-OH sulfatides, was found to give the greatest distinction between MLD-affected patients and a control group. Conclusions The method avoids transportation of liquid urine samples and generates stable membrane-bound sulfatide samples that can be stored at ambient temperature. MS/MS sulfatide profiling targeted on the most MLD-representative isoforms is simple with robust results and is suitable for screening. PMID:23838369

  1. Metabolism profiles of nuciferine in rats using ultrafast liquid chromatography with tandem mass spectrometry.

    PubMed

    Ye, Lin-Hu; Xiao, Bing-Xin; Liao, Yong-Hong; Liu, Xin-Min; Pan, Rui-Le; Chang, Qi

    2016-08-01

    Nuciferine (NF) is one of the main aporphine alkaloids existing in the traditional Chinese medicine Folium Nelumbinis (lotus leaves). Modern pharmacological studies have demonstrated that NF has a broad spectrum of bioactivities, such as anti-HIV and anti-hyperlipidemic effects, and has been recommended as a leading compound for new drug development. However, the metabolites and biotransformation pathway of NF in vivo have not yet been comprehensively investigated. The present study was performed to identify the metabolites of NF for exploring in vivo fates. Rat plasma and urine samples were collected after oral administration and prepared by liquid-liquid extraction with ethyl acetate. A method based on ultrafast liquid chromatography with tandem mass spectrometry was applied to identify the metabolites. Q1 (first quadrupole) full scan combined with a multiple reaction monitoring (MRM) survey scan were used for the detection of metabolites. MRM-information-dependent acquisition of enhanced product ions was used for the structural identification of detected metabolites. A total of 10 metabolites were identified, including phase I (demethylation, oxidation and dehydrogenation) and phase II (glucuronidation, sulfation and glutathione) biotransformation products. Demethylation is the main metabolic pathway of NF in the body. These results can help in improving understanding of the disposition and pharmacological mechanism of NF in the body. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26682724

  2. Characterization and identification of pradimicin analogs from Actinomadura hibisca using liquid chromatography-tandem mass spectrometry.

    PubMed

    Park, Je Won; Park, Sung Ryeol; Han, Ah Reum; Ban, Yeon Hee; Yoo, Young Ji; Kim, Eunji; Kim, Beom Seok; Sohng, Jae Kyung; Yoon, Yeo Joon

    2011-04-22

    Microbial cultures produce complex and potentially interesting mixtures of biosynthetic intermediates and derivatives of metabolites. These mixtures' reliable identification is important and so too is the development of techniques for their analysis. Here, a simple and highly selective method of detecting the biosynthetic congeners involved in the pentangular polyphenol pradimicin (PR) pathway from Actinomadura hibisca fermentation was developed. Solid-phase extraction (SPE) cleanup using an OASIS HLB cartridge was a simple and reliable tool for the extraction of PRs from a fermentation broth. The separation of each natural PR analog--eluted with a gradient system of aqueous acetonitrile through a reversed-phase C(18) column containing ammonium acetate and acetic acid as additives--allowed their simultaneous profiling. The combined use of SPE cleanup and chromatographic separation, coupled with electrospray ionization-tandem mass spectrometry (ESI-MS/MS) detection was demonstrated to be sufficiently accurate and reliable to analyze the natural PR analogs produced from A. hibisca. Ten natural PRs were identified: four alanine-containing (PRA, PRC, PRL, and PRB), two glycine-substituted (PRD and PRE), and four serine-substituted (PRFA-1, PRFA-2, PRFL, and PRFB). This report demonstrates the first use of both SPE cleanup and HPLC-ESI-MS/MS to profile a wide range of structurally closely related PRs in a bacterial fermentation broth. PMID:21376331

  3. [Determination of pesticides in Chinese dumplings using liquid chromatography-tandem mass spectrometry].

    PubMed

    Okamoto, You; Takatori, Satoshi; Kitagawa, Yoko; Okihashi, Masahiro; Fukui, Naoki; Murata, Hiroshi; Sumimoto, Tatsuo; Tanaka, Yukio; Obana, Hirotaka

    2009-02-01

    A rapid and easy multiresidue method for determination of pesticide residues in Chinese dumplings using liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed. Pesticide residues were extracted with ethyl acetate in the presence of anhydrous magnesium sulfate in a disposable tube using a homogenizer. The extract was concentrated and reconstituted in hexane, followed by acetonitrile-hexane partition to remove lipids. The acetonitrile layer was purified with a double-layered cartridge column (graphite carbon black/primary secondary amine silica gel). After removal of the solvent, the extract was resolved in methanol/water and analyzed with LC-MS/MS. Recovery tests of 99 pesticide residues from Chinese dumpling were performed at 20 and 100 ng/g, and 72 pesticides exhibited acceptable recoveries (70-120%) with low relative standard deviations (<20%) at both concentrations. The time for sample preparation with 12 samples to test solutions was approximately 6 hr. This method could be useful for determination of pesticide residues in the Chinese dumplings. PMID:19325220

  4. [Determination of gossypol in edible vegetable oil with high performance liquid chromatography-tandem mass spectrometry].

    PubMed

    Zhang, Wenhua; Huang, Chaoqun; Xie, Wen; Shen, Li

    2014-06-01

    A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the determination of gossypol in edible vegetable oil. The sample was extracted with ethyl alcohol by vortex-excited oscillation. The extract was cleaned up by 0.22 microm filter membrane and centrifuged for 5 min at 4 000 r/min after standing in a fridge at 4 degrees C for 30 min. The compound was separated on a C18 column (100 mm x 2.1 mm, 3.5 microm) with acetonitrile and 1% (v/v) formic acid aqueous solution as mobile phase. The detection of gossypol was carried out by LC-MS/MS with positive electrospray ionization under multiple reaction monitoring (MRM) mode using external standard method. The limits of quantification (S/N > 10) of gossypol in edible vegetable oil was 1 mg/kg. The recoveries were from 87.4% to 100% at the spiked levels of 1, 2, 200 mg/kg of gossypol in edible vegetable oil with the relative standard deviations (RSDs) between 3.9% and 12.2%. The method, with high sensitivity, good precision and high recovery, was suitable for the confirmation and quantification of gossypol residue in edible vegetable oil. PMID:25269254

  5. Formation of prostamides from anandamide in FAAH knockout mice analyzed by HPLC with tandem mass spectrometry.

    PubMed

    Weber, Allan; Ni, Jinsong; Ling, Kah-Hiing John; Acheampong, Andrew; Tang-Liu, Diane D-S; Burk, Robert; Cravatt, Benjamin F; Woodward, David

    2004-04-01

    We investigated the formation of PGF(2alpha) 1-ethanolamide, PGE(2) 1-ethanolamide, and PGD(2) 1-ethanolamide (prostamides F(2alpha), E(2), and D(2), respectively) in liver, lung, kidney, and small intestine after a single intravenous bolus administration of 50 mg/kg of anandamide to normal and fatty acid amide hydrolase knockout (FAAH -/-) male mice. One group of three normal mice was not dosed (naïve) while another group of three normal mice received a bolus intravenous injection of 50 mg/kg of anandamide. Three FAAH -/- mice also received an intravenous injection of 50 mg/kg of anandamide. After 30 min, the lung, liver, kidney, and small intestine were harvested and processed by liquid-liquid extraction. The concentrations of prostamide F(2alpha), prostamide E(2), prostamide D(2), and anandamide were determined by HPLC-tandem mass spectrometry. Prostamide F(2alpha) was detected in tissues in FAAH -/- mice after administration of anandamide. Concentrations of anandamide, prostamide E(2), and prostamide D(2) in liver, kidney, lung, and small intestine were much higher in the anandamide-treated FAAH -/- mice than those of the anandamide-treated control mice. This report demonstrates that prostamides, including prostamide F(2alpha), were formed in vivo from anandamide, potentially by the cyclooxygenase-2 pathway when the competing FAAH pathway is lacking. PMID:14729864

  6. Proteomic analysis of endodontic infections by liquid chromatography–tandem mass spectrometry

    PubMed Central

    Nandakumar, R.; Madayiputhiya, N.; Fouad, A.F.

    2009-01-01

    Introduction Endodontic infections are very prevalent and have a polymicrobial etiology characterized by complex interrelationships between endodontic microorganisms and the host defenses. Proteomic analysis of endodontic infections can provide global insights into the invasion, pathogenicity mechanisms, and multifactorial interactions existing between root canal bacteria and the host in the initiation and progression of apical periodontitis. The purpose of this study was to apply proteomic techniques such as liquid chromatography–tandem mass spectrometry (LC–MS/MS) for the identification of proteins of bacterial origin present in endodontic infections. Methods Endodontic specimens were aseptically obtained from seven patients with root canal infections. Protein mixtures were subjected to tryptic in-solution digestion and analysed by reverse-phase nano-LC–MS/MS followed by a database search. Results Proteins, mainly of cell wall or membrane origin, from endodontic bacteria especially Enterococcus faecalis, Enterococcus faecium, Porphyromonas gingivalis, Fusobacterium nucleatum, and Treponema denticola were identified from all the samples tested. Identified proteins included adhesins, autolysins, proteases, virulence factors, and antibiotic-resistance proteins. Conclusions LC–MS/MS offers a sensitive analytical platform to study the disease processes in the root canal environment. The array of proteins expressed in endodontic infections reflects the complex microbial presence and highlights the bacterial species involved in the inflammatory process. PMID:19572900

  7. Axial Imidazole Binding Strengths in Porphyrinoid Cobalt(III) Complexes as Studied by Tandem Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Mishra, Ekta; Worlinsky, Jill L.; Gilbert, Thomas M.; Brückner, Christian; Ryzhov, Victor

    2012-06-01

    The Co(II) complexes of twelve meso-tetraaryl-porphyrins, -chlorins, and chlorin analogues containing non-pyrrolic heterocycles were synthesized and converted in situ to the corresponding Co(III) complexes coordinated to one or two imidazoles. Electrospray ionization tandem mass spectrometry (ESI-MS/MS) in conjunction with the energy-variable collision-induced dissociation (CID) technique was used to compare the relative gas-phase binding strength of the axially coordinated imidazoles to the octahedral and square planar Co(III) porphyrinoid complex ions. The observed binding energies of these ligands were rationalized in terms of the effects of porphyrinoid core structure and meso-substitution on the electron density on the central Co(III) centers. Some of these trends were supported by DFT-based computational studies. The study highlights to which extend porphyrins vary from chlorins and chlorin analogues in their coordination abilities and to which extraordinary degree meso-thienyl-substituents influence the electronic structure of porphyrins. The study also defines further the scope and limits CID experiments can be used to interrogate the electronic structures of metalloporphyrin complexes.

  8. Selective extraction and determination of neonicotinoid insecticides in wine by liquid chromatography-tandem mass spectrometry.

    PubMed

    Rodríguez-Cabo, T; Casado, J; Rodríguez, I; Ramil, M; Cela, R

    2016-08-19

    A simplified, high throughput procedure for the determination of five neonicotinoid insecticides in red and white wines, using liquid chromatography (LC)-tandem mass spectrometry (MS/MS), is presented. The effects of different experimental parameters (extraction sorbent, solvent elution and clean-up conditions) in the efficiency and the selectivity of the sample preparation process were assessed through calculation of the extraction yields and the matrix effects (MEs). Wines (10mL) were concentrated using OASIS HLB cartridges, on-line connected to Florisil clean-up cartridges, with acetonitrile serving as the elution solvent. The extract (5mLvol) was concentrated to 1mL and injected in the LC-ESI-MS/MS system. The optimized procedure provided quantitative extraction yields at the same time that the efficiency of ESI ionization remained unchanged between standards and sample extracts. Overall recoveries, calculated against authentic standards in ACN, varied between 77 and 119% and the attained limits of quantification remained below 0.2ngmL(-1). Analysis of commercial wines revealed imidacloprid residues in more than 50% of processed samples, with a maximum level of 14ngmL(-1). PMID:27425763

  9. Comprehensive characterization of anticoagulant rodenticides in sludge by liquid chromatography-tandem mass spectrometry.

    PubMed

    Gómez-Canela, Cristian; Lacorte, Silvia

    2016-08-01

    The occurrence of 10 commonly used anticoagulant rodenticides in centrifuged sludge of 27 wastewater treatment plants was evaluated using solid-liquid extraction (SLE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). Activated carbon, alumina, and Florisil cartridges with methanol/dichloromethane as eluting solvents were tested in combination with primary-secondary amine (PSA) to optimize an efficient sample cleanup. PSA in combination with Florisil was the best methodology to extract anticoagulant rodenticides in sludge providing recoveries between 42 ± 0.5 and 100 ± 2 %. Warfarin, bromadiolone, ferulenol, and coumachlor were the most ubiquitous compounds in sludge at concentrations up to 84.2 ng g(-1) for the latter. Coumatetralyl, dicoumarol, and brodifacoum were detected sporadically at levels between 6.1 and 17.4 ng g(-1). On the contrary, acenocoumarol, difenacoum, and flocoumafen were not detected in any sample. Finally, we estimated the amount of anticoagulant rodenticides discharged via sludge in order to determine the potential impact to agricultural soil according to different sludge usage practices in the region investigated. This study demonstrates that anticoagulant rodenticides are accumulated in sludge during activated sludge treatment and that the application of sludge as fertilizers may pose a future environmental risk, if not controlled. PMID:27146526

  10. Unusual fragmentation of β-linked peptides by ExD tandem Mass Spectrometry

    PubMed Central

    Sargaeva, Nadezda P.; Lin, Cheng; O’Connor, Peter B.

    2015-01-01

    Ion-electron reaction based fragmentation methods (ExD) in tandem mass spectrometry (MS), such as Electron Capture Dissociation (ECD) and Electron Transfer Dissociation (ETD) represent a powerful tool for biological analysis ExD methods have been used to differentiate the presence of the isoaspartate (isoAsp) from the aspartate (Asp) in peptides and proteins. IsoAsp is a β3-type amino acid that has an additional methylene group in the backbone, forming a Cα-Cβ bond within the polypeptide chain. Cleavage of this bond provides specific fragments that allow differentiation of the isomers. The presence of a Cα-Cβ bond within the backbone is unique to β-amino acids, suggesting a similar application of ExD toward the analysis of peptides containing other β-type amino acids. In the current study, ECD and ETD analysis of several β-amino acid containing peptides was performed. It was found that N-Cβ and Cα-Cβ bond cleavages were rare, providing few c and z• type fragments, which was attributed to the instability of the Cβ radical. Instead, the electron capture resulted primarily in the formation of a• and y fragments, representing an alternative fragmentation pathway, likely initiated by the electron capture at a backbone amide nitrogen protonation site within the beta amino acid residues. PMID:21472566

  11. Determination of porphyrins in oral bacteria by liquid chromatography electrospray ionization tandem mass spectrometry.

    PubMed

    Fyrestam, Jonas; Bjurshammar, Nadja; Paulsson, Elin; Johannsen, Annsofi; Östman, Conny

    2015-09-01

    Biofilms in the oral cavity can be visualized by fluorescence and a common assumption is that the endogenously produced porphyrins in certain bacteria give rise to this fluorescence. Porphyrin content in oral bacteria has been sparingly investigated, and non-selective detection techniques such as utilizing the Soret fluorescence band of porphyrins are often used. In the present study, a quantitative and selective method for the determination of porphyrins in oral bacteria has been developed and validated using high performance liquid chromatography-tandem mass spectrometry. Lysis of bacteria using Tris-EDTA buffer together with ultrasonication showed high microbial killing efficiency ≥99.98%, and sample clean-up using C18-solid phase extraction resulted in low matrix effects ≤14% for all analytes. Using this method, the porphyrin content was determined in the two oral pathogens Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis, as well as for baker's yeast, Saccharomyces cerevisiae. Uroporphyrin, 7-carboxylporphyrin, 6-carboxylporphyrin, coproporphyrin, and protoporphyrin IX were identified in the investigated microorganisms, and it was shown that the porphyrin profile differs between the two bacteria, as well as for S. cerevisiae. To our knowledge, this is the first time the porphyrin profile has been determined for the bacterium A. actinomycetemcomitans. PMID:26168965

  12. Learning score function parameters for improved spectrum identification in tandem mass spectrometry experiments

    PubMed Central

    Spivak, Marina; Bereman, Michael S.; MacCoss, Michael J.; Noble, William Stafford

    2012-01-01

    The identification of proteins from spectra derived from a tandem mass spectrometry experiment involves several challenges: matching each observed spectrum to a peptide sequence, ranking the resulting collection of peptide-spectrum matches, assigning statistical confidence estimates to the matches, and identifying the proteins. The present work addresses algorithms to rank peptide-spectrum matches. Many of these algorithms, such as PeptideProphet, IDPicker, or Q-ranker, follow similar methodology that includes representing peptide-spectrum matches as feature vectors and using optimization techniques to rank them. We propose a richer and more flexible feature set representation that is based on the parametrization of the SEQUEST XCorr score and that can be used by all of these algorithms. This extended feature set allows a more effective ranking of the peptide-spectrum matches based on the target-decoy strategy, in comparison to a baseline feature set devoid of these XCorr-based features. Ranking using the extended feature set gives 10–40% improvement in the number of distinct peptide identifications relative to a range of q-value thresholds. While this work is inspired by the model of the theoretical spectrum and the similarity measure between spectra used specifically by SEQUEST, the method itself can be applied to the output of any database search. Further, our approach can be trivially extended beyond XCorr to any linear operator that can serve as similarity score between experimental spectra and peptide sequences. PMID:22866926

  13. Aflatoxin M1 determination in cheese by liquid chromatography-tandem mass spectrometry.

    PubMed

    Cavaliere, Chiara; Foglia, Patrizia; Guarino, Chiara; Marzioni, Francesca; Nazzari, Manuela; Samperi, Roberto; Laganà, Aldo

    2006-12-01

    A new method for determining aflatoxin M1 (AFM1) in cheese by liquid chromatography-tandem mass spectrometry has been developed. Two methodologies were compared for sample extraction. The first one involves sample extraction with dichloromethane for hard, aged cheese or acetone for fresh cheese and includes a preliminary matrix solid-phase dispersion-extraction step before solid-phase extraction (SPE) clean-up by a Carbograph-4 cartridge. The second method uses a water/methanol solution (90:10, v/v) extraction at 150 degrees C before clean-up. The average recoveries of AFM1 from samples spiked at levels of 0.25-0.45 microg/kg, were 81-92% and the precision (RSD) ranged from 3 to 7% with the first method, whilst the average recoveries were 79-84%, and RSD ranged from 7 to 15% for the second method. Due to different matrix effect, the quantification limits were 0.019-0.025 microg/kg in the first case and 0.048-0.143 microg/kg in the second one, depending on cheese typology. PMID:17056052

  14. Multiresidue analysis of environmental pollutants in edible vegetable oils by gas chromatography-tandem mass spectrometry.

    PubMed

    Zhou, Rui-Ze; Jiang, Jie; Mao, Ting; Zhao, Ya-Song; Lu, Yong

    2016-09-15

    A novel multiresidue determination of polycyclic aromatic hydrocarbons (PAHs), phthalate esters (PAEs) and alkylphenols (APs) in edible vegetable oils was developed. The samples were extracted with hexane-saturated acetonitrile, and after concentration, the extract was directly qualitatively and quantitatively analyzed by gas chromatography-tandem mass spectrometry (GC-MS/MS) with multiple reaction monitoring (MRM) in positive ion mode. The calibration curve displayed good linearity in the range of 2-100 μg/L, with correlation coefficients greater than 0.99. The mean recoveries were 70.0-110.8% by analysis of spiked oil, and the relative standard deviations (RSDs) were 2.1-10.2% (n=6), respectively. The limits of detection (LODs) for the 23 PAHs, 17 PAEs and 3 APs were 0.1-1.0 μg/kg, 0.1-4.0 μg/kg and 1.2-3.0 μg/kg, respectively. The established method effectively avoided interference from large amounts of lipids and pigments. It was applied to real sample and shown to be a rapid and reliable alternative for determination and confirmation in routine analysis. PMID:27080878

  15. Simultaneous determination of cosmetics ingredients in nail products by fast gas chromatography with tandem mass spectrometry.

    PubMed

    Zhou, Wanlong; Wang, Perry G; Wittenberg, James B; Rua, Diego; Krynitsky, Alexander J

    2016-05-13

    A rapid and sensitive gas chromatography with tandem mass spectrometry (GC-MS/MS) method has been developed and validated to quantitatively determine cosmetic ingredients, such as toluene, N-methylpyrrolidone, 2,4-dihydroxybenzophenone (benzophenone-1, BP-1), and diethylene glycol dimethacrylate, in nail products. In this procedure, test portions were extracted with acetone, followed by vortexing, sonication, centrifugation, and filtration. During the extraction procedure, BP-1 was derivatized making it amenable to GC-MS analysis, using N,O-​bis(trimethylsilyl)​trifluoroacetamide. The four ingredients were quantified by GC-MS/MS in an electron ionization mode. Four corresponding stable isotopically labeled analogues were selected as internal standards, which were added at the beginning of the sample preparation to correct for recoveries and matrix effects. The validated method was used to screen 34 commercial nail products for these four cosmetic ingredients. The most common ingredients detected in the nail products were toluene and BP-1. Toluene was detected in 26 products and ranged from 1.36 to 173,000μg/g. BP-1 ranged from 18.3 to 2,370μg/g in 10 products. PMID:27083261

  16. Fate and occurrence of alkylphenolic compounds in sewage sludges determined by liquid chromatography tandem mass spectrometry.

    PubMed

    Koh, Y K K; Chiu, T Y; Paterakis, N; Boobis, A; Scrimshawe, M D; Lester, J N; Cartmell, E

    2009-12-01

    An analytical method has been developed and applied to determine the concentrations of the nonionic alkylphenol polyethoxylate surfactants and their metabolites, alkylphenoxy carboxylates and alkyphenols, in sewage sludges. The compounds were extracted with methanol/acetone (1:1 v/v) from sludge, and concentrated extracts were cleaned by silica solid-phase extraction prior to determination by liquid chromatography tandem mass spectrometry. The recoveries, determined by spiking sewage sludge at two concentrations, ranged from 51% to 89% with method detection limits from 6 microg kg(-1) to 60 microg kg(-1). The methodology was subsequently applied to sludge samples obtained from a carbonaceous activated sludge plant, a nitrifying/denitrifying activated sludge plant and a nitrifying/ denitrifying activated sludge plant with phosphorus removal. Concentrations of nonylphenolic compounds were two to three times higher than their octyl analogues. Long-chain nonylphenol polyethoxylates (NP3-12EO) ranged from 16 microg kg(-1) to 11754 microg kg(-1). The estrogenic metabolite nonylphenol was present at concentrations ranging from 33 microg kg(-1) to 6696 microg kg(-1). PMID:20088206

  17. Determination of antibiotics in Brazilian surface waters using liquid chromatography-electrospray tandem mass spectrometry.

    PubMed

    Locatelli, Marco Antonio F; Sodré, Fernando F; Jardim, Wilson F

    2011-04-01

    A liquid chromatography-electrospray tandem mass spectrometry (LC-MS/MS) method for the determination of antibiotics in water was developed and applied to Brazilian surface waters. Amoxicillin, ampicillin, cefalexin (CEF), ciprofloxacin (CIP), norfloxacin (NOR), sulfamethoxazole, tetracycline (TET), and trimethoprim were selected as target compounds due to their high consumption pattern in Brazil. LC and MS conditions were optimized to produce the maximum analytic response for each compound. Anion exchange and polymeric solid-phase extraction cartridges, in series, were employed during the extraction procedures. Recovery, linear range, limit of detection (LOD), and limit of quantification were calculated. LOD varied from 0.13 ng L(-1) for CIP and NOR to 0.76 ng L(-1) for TET. Surface water samples from the Atibaia watershed (São Paulo State, Brazil) were analyzed. Results showed that seasonal and anthropogenic aspects dictated the levels of antibiotics in the samples. An overall frequency of detection of 55% was observed during the rainy period, whereas a higher percentage (88%) was noticed for samples collected during the dry season. In the Atibaia River, sample concentrations ranged from 29 ng L(-1) for CEF to 0.5 ng L(-1) for NOR. In a sewage-affected stream, however, concentrations up to 2422 ng L(-1) CEF were found. PMID:20535610

  18. Development of a high-performance liquid chromatography - Tandem mass spectrometry urinary pterinomics workflow.

    PubMed

    Burton, Casey; Shi, Honglan; Ma, Yinfa

    2016-07-13

    Pteridines have evoked considerable interest from the scientific community owing to their prominent roles in human health and disease. The availability of analytical methodologies suitable for comprehensive pteridine profiling, termed here as "pterinomics", has been limited by inconsistent sample preparation and the exclusion of lesser studied pteridine derivatives. In response, the present study describes a new pterinomics workflow using a high-performance liquid chromatography - tandem mass spectrometry (HPLC-MS/MS) methodology for the simultaneous analysis of 15 pteridine derivatives including four structural isomers, marking the largest quantitative pteridine panel that has been studied to-date. The validated method possessed excellent sensitivity with method detection limits (0.025 μg L(-1) to 0.5 μg L(-1)) that were comparable or superior to existing techniques. Spiked recovery studies demonstrated the technique was both accurate (88-112%) and precise (RSD: 0-6%). A comparative study of commonly used oxidative pretreatments, including triiodide, permanganate, and manganese dioxide, revealed that the oxidative mechanisms were inefficient, complex, and concentration dependent. Finally, 50 clinical urine specimens were examined with the new technique wherein 10 pteridine derivatives were quantified and population ranges have been given. This technique can be used to examine pteridine molecular epidemiology and biochemistry to support related research applications, and may further be readily extended to include additional pteridine derivatives and biological matrices for specific applications. PMID:27237839

  19. An iterative algorithm to quantify factors influencing peptide fragmentation during tandem mass spectrometry.

    PubMed

    Yu, Chungong; Lin, Yu; Sun, Shiwei; Cai, Jinjin; Zhang, Jingfen; Bu, Dongbo; Zhang, Zhuo; Chen, Runsheng

    2007-04-01

    In protein identification by tandem mass spectrometry, it is critical to accurately predict the theoretical spectrum for a peptide sequence. To date, the widely-used database searching methods adopted simple statistical models for predicting. For some peptide, these models usually yield a theoretical spectrum with a significant deviation from the experimental one. In this paper, in order to derive an improved predicting model, we utilized a non-linear programming model to quantify the factors impacting peptide fragmentation. Then, an iterative algorithm was proposed to solve this optimization problem. Upon a training set of 1803 spectra, the experimental result showed a good agreement with some known principles about peptide fragmentation, such as the tendency to cleave at the middle of peptide, and Pro's preference of the N-terminal cleavage. Moreover, upon a testing set of 941 spectra, comparison of the predicted spectra against the experimental ones showed that this method can generate reasonable predictions. The results in this paper can offer help to both database searching and de novo methods. PMID:17589963

  20. Quantification of X. laevis vitellogenin by liquid chromatography tandem mass spectrometry.

    PubMed

    Luna, Leah G; Coady, Katherine

    2016-02-01

    Over the last several decades, there has been an increase in public awareness and regulatory activity in regard to the presence of emerging contaminants in the environment that may have the potential to interact with the endocrine system of exposed wildlife. Alterations in vitellogenin (VTG), a high density yolk precursor protein, can indicate endocrine activity in oviparous species, including many fish and amphibians. While various methodologies and experiments have been performed to characterize baseline VTG concentrations among commonly studied fish species, fewer methodologies for accurately quantifying amphibian VTG are available. Since there is relatively little information available on background VTG levels in male and female frogs, the present investigation set out to quantify baseline levels of VTG in juvenile as well as adult male and female African clawed frogs (Xenopus laevis) using a newly developed liquid chromatography tandem mass spectrometry method. This new methodology for quantifying VTG in X. laevis frog blood plasma can be applied in mechanistic and toxicity studies with X. laevis to better characterize potential endocrine modes of action. PMID:26562177

  1. Enrichment of Integral Membrane Proteins for Proteomic Analysis Using Liquid Chromatography-Tandem Mass Spectrometry

    SciTech Connect

    Blonder, Josip; Goshe, Michael B.; Moore, Ronald J.; Pasa-Tolic, Liljiana; Masselon, Christophe D.; Lipton, Mary S.; Smith, Richard D.

    2002-04-01

    Currently, most proteomic studies rely on liquid chromatography-tandem mass spectrometry (LC-MS/MS) to detect and identify constituent peptides of enzymatically digested proteins obtained from various organisms and cell types. However, sample preparation methods for isolating membrane proteins typically involve the use of detergents, chaotropes, or reducing reagents that often interfere with electrospray ionization (ESI). To increase the identification of integral membrane proteins by LC-ESI-MS/MS, a sample preparation method combining carbonate extraction and surfactant-free organics solvent-assisted solubilization and proteolysis was developed and used to target the membrane subproteome of Deinococcus radiodurans. Out of 503 proteins identified, 135 were recognized as hydrophobic based on their positive grand average of hydropathicity values that covers 15% of the theoretical hydrophobic proteome. Using the PSORT algorithm, 268 identified proteins were recognized as integral membrane proteins covering 21% and 43% of the predicted integral cytoplasmic and outer membrane proteins, respectively. Of the integral cytoplasmic membrane proteins containing four or more predicted transmembrane domains (TMDs), 65% were identified by detecting at least one peptide spanning a TMD using LC-MS/MS. The extensive identification of highly hydrophobic proteins containing multiple TMDs confirms the efficacy of the described sample preparation protocol to isolate and solubilize integral membrane proteins and validates the method for large-scale analysis of bacterial membrane subproteomes using LC-ESI-MS/MS.

  2. Antibiotic Toxicity and Absorption in Zebrafish Using Liquid Chromatography-Tandem Mass Spectrometry

    PubMed Central

    Zhang, Fan; Qin, Wei; Zhang, Jing-Pu; Hu, Chang-Qin

    2015-01-01

    Evaluation of drug toxicity is necessary for drug safety, but in vivo drug absorption is varied; therefore, a rapid, sensitive and reliable method for measuring drugs is needed. Zebrafish are acceptable drug toxicity screening models; we used these animals with a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method in a multiple reaction monitoring mode to quantify drug uptake in zebrafish to better estimate drug toxicity. Analytes were recovered from zebrafish homogenate by collecting supernatant. Measurements were confirmed for drugs in the range of 10–1,000 ng/mL. Four antibiotics with different polarities were tested to explore any correlation of drug polarity, absorption, and toxicity. Zebrafish at 3 days post-fertilization (dpf) absorbed more drug than those at 6 h post-fertilization (hpf), and different developmental periods appeared to be differentially sensitive to the same compound. By observing abnormal embryos and LD50 values, zebrafish embryos at 6 hpf were considered to be suitable for evaluating embryotoxicity. Also, larvae at 3 dpf were adapted to measure acute drug toxicity in adult mammals. Thus, we can exploit zebrafish to study drug toxicity and can reliably quantify drug uptake with LC-MS/MS. This approach will be helpful for future studies of toxicology in zebrafish. PMID:25938774

  3. A Derivative Method with Free Radical Oxidation to Predict Resveratrol Metabolites by Tandem Mass Spectrometry

    PubMed Central

    Liu, Wangta; Shiue, Yow-Ling; Lin, Yi-Reng; Lin, Hugo You-Hsien; Liang, Shih-Shin

    2015-01-01

    In this study, we demonstrated an oxidative method with free radical to generate 3,5,4′-trihydroxy-trans-stilbene (trans-resveratrol) metabolites and detect sequentially by an autosampler coupling with liquid chromatography electrospray ionization tandem mass spectrometer (LC-ESI–MS/MS). In this oxidative method, the free radical initiator, ammonium persulfate (APS), was placed in a sample bottle containing resveratrol to produce oxidative derivatives, and the reaction progress was tracked by autosampler sequencing. Resveratrol, a natural product with purported cancer preventative qualities, produces metabolites including dihydroresveratrol, 3,4′-dihydroxy-trans-stilbene, lunularin, resveratrol monosulfate, and dihydroresveratrol monosulfate by free radical oxidation. Using APS free radical, the concentrations of resveratrol derivatives differ as a function of time. Besides simple, convenient and time- and labor saving, the advantages of free radical oxidative method of its in situ generation of oxidative derivatives followed by LC-ESI–MS/MS can be utilized to evaluate different metabolites in various conditions.

  4. Investigation of the biotransformation of osthole by liquid chromatography/tandem mass spectrometry.

    PubMed

    Li, Jie; Chan, Wan

    2013-02-23

    Osthole is an active ingredient and one of the major coumarin compounds that were identified in the genus Cnidium moonnieri (L.) Cussion, the fruit of which was used as traditional Chinese medicine to treat male impotence, ringworm infection and blood stasis conventionally. Recent studies revealed that osthole has diverse pharmacological effects, such as improving male sexual dysfunction, anti-diabetes, and anti-hypertentions. The inhibition of thrombosis and platelet aggregation and protection of central nerve were also observed. On the other hand, the metabolism of osthole has not yet been investigated thoroughly. Herein the biotransformation of osthole in rat was investigated after oral administration of osthole by using efficient and sensitive ultra-performance liquid chromatography-tandem quadrupole-time of flight mass spectrometry (UPLC-QTOF/MS). Eighteen osthole metabolites and the parent drug were detected and identified in rat urine. Fourteen metabolites of osthole were identified and characterized for the first time. Structures of metabolites of osthole were elucidated by comparing fragment pattern under MS/MS scan and change of molecular weight with those of osthole. The main phase I metabolic pathways were summed as 7-demethylation, 8-dehydrogenation, hydroxylation on coumarin and 3,4-epoxide. Sulfate conjugates were detected as phase II metabolites of osthole. PMID:23245246

  5. Identification of Microorganisms by High Resolution Tandem Mass Spectrometry with Accurate Statistical Significance.

    PubMed

    Alves, Gelio; Wang, Guanghui; Ogurtsov, Aleksey Y; Drake, Steven K; Gucek, Marjan; Suffredini, Anthony F; Sacks, David B; Yu, Yi-Kuo

    2016-02-01

    Correct and rapid identification of microorganisms is the key to the success of many important applications in health and safety, including, but not limited to, infection treatment, food safety, and biodefense. With the advance of mass spectrometry (MS) technology, the speed of identification can be greatly improved. However, the increasing number of microbes sequenced is challenging correct microbial identification because of the large number of choices present. To properly disentangle candidate microbes, one needs to go beyond apparent morphology or simple 'fingerprinting'; to correctly prioritize the candidate microbes, one needs to have accurate statistical significance in microbial identification. We meet these challenges by using peptidome profiles of microbes to better separate them and by designing an analysis method that yields accurate statistical significance. Here, we present an analysis pipeline that uses tandem MS (MS/MS) spectra for microbial identification or classification. We have demonstrated, using MS/MS data of 81 samples, each composed of a single known microorganism, that the proposed pipeline can correctly identify microorganisms at least at the genus and species levels. We have also shown that the proposed pipeline computes accurate statistical significances, i.e., E-values for identified peptides and unified E-values for identified microorganisms. The proposed analysis pipeline has been implemented in MiCId, a freely available software for Microorganism Classification and Identification. MiCId is available for download at http://www.ncbi.nlm.nih.gov/CBBresearch/Yu/downloads.html . Graphical Abstract ᅟ. PMID:26510657

  6. Determination of ethyl glucuronide in human hair by hydrophilic interaction liquid chromatography-tandem mass spectrometry.

    PubMed

    Yaldiz, Fadile; Daglioglu, Nebile; Hilal, Ahmet; Keten, Alper; Gülmen, Mete Korkut

    2013-10-01

    Ethyl glucuronide (EtG) is a direct metabolite of ethanol and has been utilized as a marker for alcohol intake. This study presents development, validation and application of a new hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS) method for the analysis of EtG in human hair samples. The linearity was assessed in the range of 5-2000 pg/mg hair, with a correlation coefficient of >0.99. The method was selective and sensitive, with a limit of detection (LOD) and limit of quantitation (LOQ) of 0.05 pg/mg and 0.18 pg/mg in hair, respectively. Differently from the extraction procedures in the literature, a fast and simple liquid-liquid method was used and highest recoveries and cleanest extracts were obtained. The method was successfully applied to 30 human hair samples which were taken from those who state they consume alcohol. EtG concentrations in the hair samples of alcohol users participated in this study, ranged between 1.34 and 82.73 pg/mg. From the concentration of EtG in hair strands 20 of the 30 subjects can be considered regular moderate drinkers. PMID:24112322

  7. Metabolism study of boldenone in human urine by gas chromatography-tandem mass spectrometry.

    PubMed

    Wu, Xinchen; Gao, Feng; Zhang, Wenxin; Ni, Jian

    2015-11-10

    Boldenone (BOLD), an anabolic steroid, is likely to be abused in livestock breeding and in sports. Although some of BOLD metabolites in human urine, such as 5β-adrost-1-en-17β-ol-3-one (BM1), have been detected, investigations on their excretion patterns for both genders are insufficient. Moreover, little research on 17α-BOLD glucuronide as a metabolite in human urine has been reported. The aim of this study is to make a contribution to the knowledge of 17β-BOLD metabolism in humans. Three male and three female volunteers were orally administrated with 30mg 17β-BOLD. Urine samples were collected and analyzed with gas chromatography-tandem mass spectrometry. The data proved that 17β-BOLD, BM1, and 17α-BOLD were excreted in urine in both free and glucuronic conjugated forms after administration of 17β-BOLD. For most subjects, the urinary concentrations of BM1 were higher than that of 17β-BOLD. 17α-BOLD was excreted in small amounts. 17α-BOLD, 17β-BOLD, and BM1 were present naturally in urine with low concentrations. Administration of 30mg 17β-BOLD could not influence the excretion profiles of urinary androsterone, etiocholanolone, and testosterone/epitestosterone ratio. There were no differences in BOLD metabolic patterns between man and woman. PMID:26319750

  8. Tandem Mass Spectrometry for Characterization of Covalent Adducts of DNA with Anti-cancer Therapeutics

    PubMed Central

    Silvestri, Catherine; Brodbelt, Jennifer S.

    2012-01-01

    The chemotherapeutic activities of many anticancer and antibacterial drugs arise from their interactions with nucleic acid substrates. Some of these ligands interact with DNA in a way that causes conformational changes or damage to the nucleic acid targets, ultimately altering recognition by key DNA-specific enzymes, interfering with DNA transcription or prohibiting replication, and terminating cell growth and proliferation. The design and synthesis of ligands that bind to nucleic acids remains a dynamic field in medicinal chemistry and pharmaceutical research. The quest for more selective and efficacious DNA-interactive anti-cancer chemotherapeutics has likewise catalyzed the need for sensitive analytical methods that can provide structural information about the nature of the resulting DNA adducts and provide insight into the mechanistic pathways of the DNA/drug interactions and the impact on the cellular processes in biological systems. This review focuses on the array of tandem mass spectrometric strategies developed and applied for characterization of covalent adducts formed between DNA and anti-cancer ligands. PMID:23150278

  9. [Determination of five synthetic sweeteners in wines using high performance liquid chromatography-tandem mass spectrometry].

    PubMed

    Ji, Chao; Feng, Feng; Chen, Zhengxing; Sun, Li; Chu, Xiaogang

    2010-08-01

    A high performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI MS/MS) method for the determination of five synthetic sweeteners (acesulfame, sodium saccharin, sodium cyclamate, aspartame and neotame) in wines has been developed. The HPLC separation was carried out on an Ultimate C18 column (100 mm x 2.1 mm, 3 microm). Several parameters, including the composition and pH of the mobile phase, column temperature and the monitor ions, were optimized for improving the chromatographic performance and the sensitivity of determination. The results demonstrated that the separation can be completed in less than 5 min by gradient elution with 20 mmol/L ammonium formate and 0.1% (v/v) formic acid (pH 3.8) and methanol as the mobile phase. The column temperature was kept at 45 degrees C. When the analytes were detected by ESI -MS/MS under multiple reaction monitoring mode, the detection limits were 0.6, 5, 1, 0.8 and 0.2 microg/L for acesulfame, sodium saccharin, sodium cyclamate, aspartame and neotame, respectively. The average recoveries ranged from 87.2% to 103%. The relative standard deviations were not more than 1.2%. This method is rapid, accurate, highly sensitive and suitable for the quality control of low concentration of the synthetic sweeteners, which are illegally added to wines and other foods with complex matrices. PMID:21261041

  10. Endogenous glucocorticoid analysis by liquid chromatography-tandem mass spectrometry in routine clinical laboratories.

    PubMed

    Hawley, James M; Keevil, Brian G

    2016-09-01

    Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is a powerful analytical technique that offers exceptional selectivity and sensitivity. Used optimally, LC-MS/MS provides accurate and precise results for a wide range of analytes at concentrations that are difficult to quantitate with other methodologies. Its implementation into routine clinical biochemistry laboratories has revolutionised our ability to analyse small molecules such as glucocorticoids. Whereas immunoassays can suffer from matrix effects and cross-reactivity due to interactions with structural analogues, the selectivity offered by LC-MS/MS has largely overcome these limitations. As many clinical guidelines are now beginning to acknowledge the importance of the methodology used to provide results, the advantages associated with LC-MS/MS are gaining wider recognition. With their integral role in both the diagnosis and management of hypo- and hyperadrenal disorders, coupled with their widespread pharmacological use, the accurate measurement of glucocorticoids is fundamental to effective patient care. Here, we provide an up-to-date review of the LC-MS/MS techniques used to successfully measure endogenous glucocorticoids, particular reference is made to serum, urine and salivary cortisol. PMID:27208627

  11. Multiresidue Analysis of Pesticides in Straw Roughage by Liquid Chromatography-Tandem Mass Spectrometry.

    PubMed

    Zhang, Zihao; Feng, Mengyuan; Zhu, Kechen; Han, Lijun; Sapozhnikova, Yelena; Lehotay, Steven J

    2016-08-10

    A multiresidue analytical method using a modification of the "quick, easy, cheap, effective, rugged, and safe" (QuEChERS) sample preparation approach combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis was established and validated for the rapid determination of 69 pesticides at different levels (1-100 ng/g) in wheat and rice straws. In the quantitative analysis, the recoveries ranged from 70 to 120%, and consistent RSDs ≤ 20% were achieved for most of the target analytes (53 pesticides in wheat straw and 58 in rice straw). Almost all of the analytes achieved good linearity with R(2) > 0.98, and the limit of validation levels (LVLs) for diverse pesticides ranged from 1 to 10 ng/g. Different extraction and cleanup conditions were evaluated in both types of straw, leading to different options. The use of 0.1% formic acid or not in extraction with acetonitrile yielded similar final outcomes, but led to the use of a different sorbent in dispersive solid-phase extraction. Both options are efficient and useful for the multiresidue analysis of targeted pesticides in wheat and rice straw samples. PMID:26881844

  12. Residue analysis of orthosulfamuron herbicide in fatty rice using liquid chromatography–tandem mass spectrometry

    PubMed Central

    Lee, Young-Jun; Choi, Jeong-Heui; Abd El-Aty, A.M.; Im, So Jeong; Musfiqur Rahman, Md.; Kim, Sung-Woo; Shim, Jae-Han

    2014-01-01

    In the present study, orthosulfamuron residues were extracted from fatty (unpolished) rice and rice straw using a modified QuEChERS method and analyzed using liquid chromatography–tandem mass spectrometry. The matrix-matched calibration was linear over the concentration ranges of 0.01–2.0 mg/kg with determination coefficient (R2) ⩾ 0.997. The recovery rates at two fortification levels (0.1 and 0.5 mg/kg) were satisfactory and ranged between 88.1% and 100.6%, with relative standard deviation (RSD) <8%. The limit of quantitation, 0.03 mg/kg, was lower than the maximum residue limit, 0.05 mg/kg, set by the Ministry of Food and Drug Safety in the Republic of Korea. The developed method was applied successfully to field samples harvested at 116 days and none of the samples were positive for the residue. PMID:26257949

  13. Analysis of the Glycoproteome of Toxoplasma gondii using Lectin Affinity Chromatography and Tandem Mass Spectrometry

    PubMed Central

    Luo, Qilie; Upadhya, Rajendra; Zhang, Hong; Madrid-Aliste, Carlos; Nieves, Edward; Kim, Kami; Angeletti, Ruth Hogue; Weiss, Louis M.

    2011-01-01

    Glycoproteins are involved in many important molecular recognition processes including invasion, adhesion, differentiation, and development. To identify the glycoproteins of Toxoplasma gondii, a proteomic analysis was undertaken. T. gondii proteins were prepared and fractioned using lectin affinity chromatography. The proteins in each fraction were then separated using SDS-PAGE and identified by tryptic in gel digestion followed by tandem mass spectrometry. Utilizing these methods 132 proteins were identified. Among the identified proteins were 17 surface proteins, 9 microneme proteins, 15 rhoptry proteins, 11 heat shock proteins (HSP), and 32 hypothetical proteins. Several proteins had 1 to 5 transmembrane domains (TMD) with some being as large as 608.3 kDa. Both lectin-fluorescence labeling and lectin blotting were employed to confirm the presence of carbohydrates on the surface or cytoplasm of T. gondii parasites. PCR demonstrated that selected hypothetical proteins were expressed in T. gondii tachyzoites. This is data provides a large scale analysis of the T. gondii glycoproteome. Studies of the function of glycosylation of these proteins may help elucidate mechanism(s) involved in invasion improving drug therapy as well as identify glycoproteins that may prove to be useful as vaccine candidates. PMID:21920448

  14. Interdomain conformational changes in Akt activation revealed by chemical cross-linking and tandem mass spectrometry.

    PubMed

    Huang, Bill X; Kim, Hee-Yong

    2006-06-01

    Akt, a serine/threonine kinase, plays a critical role in cell survival. Upon growth factor receptor stimulation, cytosolic Akt is recruited to the plasma membrane by phospholipid binding and activated through phosphorylation at Thr(308) and Ser(473). Although crystal structures for the parts of Akt have been reported, neither the three-dimensional structure of the whole molecule nor sequential conformational changes during activation have been demonstrated. In this study, we demonstrated that Akt undergoes dramatic interdomain conformational changes during activation processes by probing the three-dimensional structure of full-length Akt in solution using chemical cross-linking and tandem mass spectrometry. The cross-linking results not only provided new structural information but also revealed distinctive spatial arrangements of individual domains in the Akt molecule in resting, membrane-interacted, phosphorylated, and substrate-bound states. Our data allowed a new model for stepwise interdomain conformational changes in Akt activation sequence, setting a stage for the further investigation on Akt-membrane, Akt-protein, and/or Akt-drug interactions in solution to understand molecular mechanisms involved in physiological and pathophysiological processes of cell survival. PMID:16531397

  15. Fully automated screening of veterinary drugs in milk by turbulent flow chromatography and tandem mass spectrometry

    PubMed Central

    Stolker, Alida A. M.; Peters, Ruud J. B.; Zuiderent, Richard; DiBussolo, Joseph M.

    2010-01-01

    There is an increasing interest in screening methods for quick and sensitive analysis of various classes of veterinary drugs with limited sample pre-treatment. Turbulent flow chromatography in combination with tandem mass spectrometry has been applied for the first time as an efficient screening method in routine analysis of milk samples. Eight veterinary drugs, belonging to seven different classes were selected for this study. After developing and optimising the method, parameters such as linearity, repeatability, matrix effects and carry-over were studied. The screening method was then tested in the routine analysis of 12 raw milk samples. Even without internal standards, the linearity of the method was found to be good in the concentration range of 50 to 500 µg/L. Regarding repeatability, RSDs below 12% were obtained for all analytes, with only a few exceptions. The limits of detection were between 0.1 and 5.2 µg/L, far below the maximum residue levels for milk set by the EU regulations. While matrix effects—ion suppression or enhancement—are obtained for all the analytes the method has proved to be useful for screening purposes because of its sensitivity, linearity and repeatability. Furthermore, when performing the routine analysis of the raw milk samples, no false positive or negative results were obtained. PMID:20379812

  16. Acrylamide levels in Finnish foodstuffs analysed with liquid chromatography tandem mass spectrometry.

    PubMed

    Eerola, Susanna; Hollebekkers, Koen; Hallikainen, Anja; Peltonen, Kimmo

    2007-02-01

    Sample clean-up and HPLC with tandem mass spectrometric detection (LC-MS/MS) was validated for the routine analysis of acrylamide in various foodstuffs. The method used proved to be reliable and the detection limit for routine monitoring was sensitive enough for foods and drinks (38 microg/kg for foods and 5 microg/L for drinks). The RSDs for repeatability and day-to-day variation were below 15% in all food matrices. Two hundred and one samples which included more than 30 different types of food and foods manufactured and prepared in various ways were analysed. The main types of food analysed were potato and cereal-based foods, processed foods (pizza, minced beef meat, meat balls, chicken nuggets, potato-ham casserole and fried bacon) and coffee. Acrylamide was detected at levels, ranging from nondetectable to 1480 microg/kg level in solid food, with crisp bread exhibiting the highest levels. In drinks, the highest value (29 microg/L) was found in regular coffee drinks. PMID:17230586

  17. Identification of Microorganisms by High Resolution Tandem Mass Spectrometry with Accurate Statistical Significance

    NASA Astrophysics Data System (ADS)

    Alves, Gelio; Wang, Guanghui; Ogurtsov, Aleksey Y.; Drake, Steven K.; Gucek, Marjan; Suffredini, Anthony F.; Sacks, David B.; Yu, Yi-Kuo

    2016-02-01

    Correct and rapid identification of microorganisms is the key to the success of many important applications in health and safety, including, but not limited to, infection treatment, food safety, and biodefense. With the advance of mass spectrometry (MS) technology, the speed of identification can be greatly improved. However, the increasing number of microbes sequenced is challenging correct microbial identification because of the large number of choices present. To properly disentangle candidate microbes, one needs to go beyond apparent morphology or simple `fingerprinting'; to correctly prioritize the candidate microbes, one needs to have accurate statistical significance in microbial identification. We meet these challenges by using peptidome profiles of microbes to better separate them and by designing an analysis method that yields accurate statistical significance. Here, we present an analysis pipeline that uses tandem MS (MS/MS) spectra for microbial identification or classification. We have demonstrated, using MS/MS data of 81 samples, each composed of a single known microorganism, that the proposed pipeline can correctly identify microorganisms at least at the genus and species levels. We have also shown that the proposed pipeline computes accurate statistical significances, i.e., E-values for identified peptides and unified E-values for identified microorganisms. The proposed analysis pipeline has been implemented in MiCId, a freely available software for Microorganism Classification and Identification. MiCId is available for download at http://www.ncbi.nlm.nih.gov/CBBresearch/Yu/downloads.html.

  18. Measurement of phthalates diesters in food using gas chromatography-tandem mass spectrometry.

    PubMed

    Cariou, Ronan; Larvor, Frédéric; Monteau, Fabrice; Marchand, Philippe; Bichon, Emmanuelle; Dervilly-Pinel, Gaud; Antignac, Jean-Philippe; Le Bizec, Bruno

    2016-04-01

    An analytical strategy dedicated to 4 major phthalate diesters (DiBP, DnBP, BBzP and DEHP) monitoring in food items has been developed and validated according to normalized guidelines. The method has been applied to a wide range of foodstuffs (n=54) to generate first-ever occurrence data at the French level. This method involves separation and detection using gas chromatography coupled to tandem mass spectrometry, in electron ionisation with highly specific selected reaction monitoring, quantification being performed according to the isotope dilution principle. A particular attention has been paid to background contamination management at any stage of the analytical process, from the sampling to the expression of the results. Limits of reporting, defined as statistically different from background contamination, were found to be 2.7, 0.53, 0.18 and 3.4 μg kg(-1), and relative combined uncertainties were finally found to be 7.6%, 12.2%, 12.0% and 14.1%, for DiBP, DnBP, BBzP and DEHP, respectively. PMID:26593485

  19. Multiclass analysis of antibiotic residues in honey by ultraperformance liquid chromatography-tandem mass spectrometry.

    PubMed

    Vidal, Jose Luis Martínez; Aguilera-Luiz, María Del Mar; Romero-González, Roberto; Frenich, Antonia Garrido

    2009-03-11

    A method has been developed and validated for the simultaneous analysis of different veterinary drug residues (macrolides, tetracyclines, quinolones, and sulfonamides) in honey. Honey samples were dissolved with Na(2)EDTA, and veterinary residues were extracted from the supernatant by solid-phase extraction (SPE), using OASIS HLB cartridges. The separation and determination was carried out by ultraperformance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS), using an electrospay ionization source (ESI) in positive mode. Data acquisition under MS/MS was achieved by applying multiple reaction monitoring (MRM) of two ion transitions per compound to provide a high degree of sensitivity and specificity. The method was validated, and mean recoveries were evaluated at three concentration levels (10, 50, and 100 microg/kg), ranging from 70 to 120% except for doxycycline, erythromycin, and tylmicosin with recovery higher than 50% at the three levels assayed. Relative standard deviations (RSDs) of the recoveries were less than 20% within the intraday precision and less than 25% within the interday precision. The limits of quantification (LOQs) were always lower than 4 microg/kg. The developed procedure was applied to 16 honey samples, and erythromycin, sarafloxacin, and tylosin were found in a few samples. PMID:19195999

  20. Determination of 76 pharmaceutical drugs by liquid chromatography-tandem mass spectrometry in slaughterhouse wastewater.

    PubMed

    Shao, Bing; Chen, Dong; Zhang, Jing; Wu, Yongning; Sun, Chengjun

    2009-11-20

    A multi-residue method for the analysis of 76 pharmaceutical agents of nine classes of drugs (tetracyclines, macrolides, fluoroquinolones, beta-agonists, beta-blockers, diuretics, sedatives, sulfonamides and chloramphenicol) in slaughterhouse wastewater and a receiving river is presented. After simultaneous extraction with an Oasis HLB solid-phase extraction (SPE) cartridge and further purification using an amino SPE cartridge, analytes were detected by liquid chromatography-electrospray ionization-tandem mass spectrometry in positive or negative ion mode. Standard addition was used for quantification to overcome unavoidable matrix effects during ESI-MS analysis. Recoveries for most analytes based on matrix-matched calibration in different test matrices were >60%. The method quantification limits of 76 pharmaceuticals were in the range 0.2-30 ng/L. Nineteen compounds of 76 drugs were found in raw and treated slaughterhouse wastewater from four main slaughterhouses in Beijing. Sulfanamides (sulfanilamide, sulfameter), fluoroquenones (ofloxacin, pefloxacin, norfloxacin, ciprofloxacin, enrofloxacin), tetracyclines (tetracycline, oxytetracycline) and macrolides (kitasamycin, tylosin, erythromycin) were most frequently detected, with the highest levels up to approximately 3 microg/L in slaughterhouse wastewater and approximately 1 microg/L in treated wastewater. Illicit drugs for animal feeding such as clenbuterol and diazepam were commonly detected in slaughterhouse wastewater. These analytes were also observed in a river receiving slaughterhouse wastewater, with a highest level of up to 0.2 microg/L. PMID:19825501

  1. Silymarin in liposomes and ethosomes: pharmacokinetics and tissue distribution in free-moving rats by high-performance liquid chromatography-tandem mass spectrometry.

    PubMed

    Chang, Li-Wen; Hou, Mei-Ling; Tsai, Tung-Hu

    2014-12-01

    The aim of this study was to prepare silymarin formulations (silymarin entrapped in liposomes and ethosomes, formulations referred to as LSM and ESM, respectively) to improve oral bioavailability of silymarin and evaluate its tissue distribution by liquid chromatography with tandem mass spectrometry (LC-MS/MS) in free-moving rats. Silibinin is the major active constituent of silymarin, which is the main component to be analyzed. A rapid, sensitive, and repeatable LC-MS/MS method was developed and validated in terms of precision, accuracy, and extraction recovery. Furthermore, the established method was applied to study the pharmacokinetics and tissue distribution of silymarin in rats. The size, ζ potential, and drug release of the formulations were characterized. These results showed that the LSM and ESM encapsulated formulations of silymarin may provide more efficient tissue distribution and increased oral bioavailability, thus improving its therapeutic bioactive properties in the body. PMID:25375210

  2. SMART Digest™ compared with pellet digestion for analysis of human immunoglobulin G1 in rat serum by liquid chromatography tandem mass spectrometry.

    PubMed

    Lanshoeft, Christian; Heudi, Olivier; Cianférani, Sarah

    2016-05-15

    The newly developed SMART Digest™ kit was applied for the sample preparation of human immunoglobulin G1 (hIgG1) in rat serum prior to qualitative and quantitative analyses by liquid chromatography tandem mass spectrometry (LC-MS/MS). The sequence coverages obtained for the light and heavy chains of hIgG1A were 50 and 76%, respectively. The calibration curve was linear from 1.00 to 1000 μg/ml for three of four generic peptides. Overall, the SMART Digest™ kit resulted in similar quantitative data (linearity, sensitivity, accuracy, and precision) compared with the pellet digestion protocol. However, the SMART Digest™ required only 2 h of sample preparation with fewer reagents. PMID:26893107

  3. Diagnostic application of the exponentially modified Gaussian model for peak quality and quantitation in high-throughput liquid chromatography-tandem mass spectrometry.

    PubMed

    Zabell, Adam P R; Foxworthy, Tyler; Eaton, Kimberly Napoli; Julian, Randall K

    2014-11-21

    Typical area calculation for a chromatographic peak assumes the observed signal strength at every measurement is an exactly accurate count of the signal. We compared that approach to one using the exponentially modified Gaussian (EMG) in an automated, clinical production setting. Peak areas in a 47 analyte high throughput clinical production liquid chromatography-tandem mass spectrometry assay were compared across four months of production data to determine trends over the lifespan of a chromatographic column. The EMG parameters were superior to traditional quality control methods for monitoring data reproducibility, accuracy and precision. Because the EMG calculations are performed for every peak in the system, a constant monitor of system health is integrated into the operational workflow. Parameter trends confirmed the need for column replacement, and indicated the opportunity for a reduced schedule of preventive and routine maintenance. PMID:25441075

  4. Quantitation of Cotinine and its Metabolites in Rat Plasma and Brain Tissue by Hydrophilic Interaction Chromatography Tandem Mass Spectrometry (HILIC-MS/MS)

    PubMed Central

    Li, Pei; Beck, Wayne D.; Callahan, Patrick M.; Terry, Alvin V.; Bartlett, Michael G.

    2014-01-01

    In this work, we developed a sensitive method to quantify cotinine (COT), norcotinine (NCOT), trans-3′-hydroxycotinine (OHCOT) and cotinine-N-oxide (COTNO) in rat plasma and brain tissue, using solid phase extraction (SPE), hydrophilic interaction liquid chromatography (HILIC) and tandem mass spectrometry (MS/MS). The linear range was 1–100 ng/ml for each analyte in rat plasma and brain homogenate (3–300 ng/g brain tissue). The method was validated with precision within 15% relative standard deviation (RSD) and accuracy within 15% relative error (RE). Stable isotope-labeled internal standards (IS) were used for all the analytes to achieve good reproducibility, minimizing the influence of recovery and matrix effects. This method can be used in future studies to simultaneously determine the concentrations of COT and three major metabolites in rat plasma and brain tissue. PMID:23022114

  5. Development of a multiresidue method for the determination of endocrine disrupters in fish fillet using gas chromatography-triple quadrupole tandem mass spectrometry.

    PubMed

    Munaretto, Juliana S; Ferronato, Giovana; Ribeiro, Lucila C; Martins, Manoel L; Adaime, Martha B; Zanella, Renato

    2013-11-15

    Endocrine Disrupter Compounds (EDCs) are responsible for alterations in the endocrine system functions. Aquatic organisms are able to accumulate EDCs residues, being the major source of contamination for top predators and human consumers. This study aimed to develop and validate a method for the determination of 40 EDCs in fish fillet using modified QuEChERS and Gas Chromatography coupled with Mass Spectrometry in tandem (GC-MS/MS). A factorial design was used to optimize the extraction procedure. Method validation presented recoveries from 70.1% to 120.0% with RSD<20% and method limit of detection ranged from 0.3 to 7.5 µg kg(-1), showing good accuracy and precision. This method was successfully applied to the analysis of fish fillet from different species and residues of bisphenol A, chlorpyrifos and bifenthrin were detected. The proposed method proved to be effective for the determination of EDCs in fish fillet at very low concentration levels. PMID:24148481

  6. Ultrahigh-Performance Liquid Chromatography (UHPLC)-Tandem Mass Spectrometry (MS/MS) Quantification of Nine Target Indoles in Sparkling Wines.

    PubMed

    Tudela, Rebeca; Ribas-Agustí, Albert; Buxaderas, Susana; Riu-Aumatell, Montserrat; Castellari, Massimo; López-Tamames, Elvira

    2016-06-15

    An ultrahigh-performance liquid chromatography (UHPLC)-tandem mass spectrometry (MS/MS) method was developed for the simultaneous determination of nine target indoles in sparkling wines. The proposed method requires minimal sample pretreatment, and its performance parameters (accuracy, repeatability, LOD, and matrix effect) indicate that it is suitable for routine analysis. Four indoles were found at detectable levels in commercial Cava samples: 5-methoxytryptophol (5MTL), tryptophan (TRP), tryptophan ethyl ester (TEE), and N-acetylserotonin (NSER). Two of them, NSER and 5MTL, are reported here for the first time in sparkling wines, with values of 0.3-2 and 0.29-29.2 μg/L, respectively. In the same samples, the contents of melatonin (MEL), serotonin (SER), 5-hydroxytryptophan (5-OHTRP), 5-hydroxyindole-3-acetic acid (5OHIA), and 5-methoxy-3-indoleacetic acid (5MIA) were all below the corresponding limits of detection. PMID:27148823

  7. Liquid chromatography-electrospray tandem mass spectrometric method for quantification of monensin in plasma and edible tissues of chicken used in pharmacokinetic studies: applying a total error approach.

    PubMed

    Chéneau, Estelle; Henri, Jérôme; Pirotais, Yvette; Abjean, Jean-Pierre; Roudaut, Brigitte; Sanders, Pascal; Laurentie, Michel

    2007-05-01

    A liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed and validated for use in pharmacokinetic studies in order to determine the concentrations of monensin in plasma and edible tissues of chicken. Two sample preparations were performed, one for determining monensin concentrations in plasma using acetonitrile for protein precipitation and another one for determining monensin concentrations in muscle, liver, and fat using methanol-water followed by a clean up on a solid-phase extraction cartridge. Sample extracts were injected into the LC-MS/MS system, and a gradient elution was performed on a C18 column. Narasin was used as internal standard. The LC-MS/MS method was validated using an approach based on accuracy profiles, and applicability of the method was demonstrated for the determination of monensin in chicken plasma, muscle, liver, and fat in a pharmacokinetic study. PMID:17141581

  8. Simultaneous enantioselective quantification of fluoxetine and norfluoxetine in human milk by direct sample injection using 2-dimensional liquid chromatography-tandem mass spectrometry.

    PubMed

    Alvim-Jr, Joel; Lopes, Bianca Rebelo; Cass, Quezia Bezerra

    2016-06-17

    A two-dimensional liquid chromatography system coupled to triple quadrupole tandem mass spectrometer (2D LC-MS/MS) was employed for the simultaneously quantification of fluoxetine (FLX) and norfluoxetine (NFLX) enantiomers in human milk by direct injection of samples. A restricted access media of bovine serum albumin octadecyl column (RAM-BSAC18) was used in the first dimension for the milk proteins depletion, while an antibiotic-based chiral column was used in the second dimension. The results herein described show good selectivity, extraction efficiency, accuracy, and precision with limits of quantification in the order of 7.5ngmL(-1)for the FLX enantiomers and 10.0ngmL(-1) for NFLX enantiomers. Furthermore, it represents a practical tool in terms of sustainability for the sample preparation of such a difficult matrix. PMID:27208983

  9. Development and validation of a high-throughput online solid phase extraction - Liquid chromatography - Tandem mass spectrometry method for the detection of tetrodotoxin in human urine.

    PubMed

    Coleman, Rebecca; Lemire, Sharon W; Bragg, William; Garrett, Alaine; Ojeda-Torres, Geovannie; Hamelin, Elizabeth; Johnson, Rudolph C; Thomas, Jerry

    2016-09-01

    Tetrodotoxin (TTX) is an extremely potent paralytic toxin responsible for yearly illness and death around the world. A clinical measurement is necessary to confirm exposure because symptoms of TTX intoxication cannot be distinguished from other paralytic toxins. Our group has developed an online solid phase extraction hydrophilic interaction liquid chromatography (HILIC) method for the analysis of TTX in human urine with tandem mass spectrometry. The reportable range for the method was 2.80 - 249 ng/mL in urine with precision and accuracy within 15% as determined for all quality control samples. No isotopically-labeled internal standard is available for TTX; thus a surrogate internal standard, voglibose, was investigated to compensate for matrix effects and ionization suppression. However, upon evaluation, voglibose was ineffective for this purpose. This new online method rapidly identifies TTX, facilitating the work of public health authorities and providing support to monitoring programs worldwide. PMID:27212629

  10. Performance characterization of a quantitative liquid chromatography-tandem mass spectrometric method for 12 macrolide and lincosamide antibiotics in salmon, shrimp and tilapia.

    PubMed

    Dickson, Leslie C

    2014-09-15

    This paper describes an extension and performance characterization of a quantitative confirmatory multi-residue liquid chromatography-tandem mass spectrometric method for residues of macrolide and lincosamide antibiotics, originally validated for application to bovine kidney tissues, to tissues of salmon, shrimp and tilapia. The 12 analytes include clindamycin, erythromycin A, gamithromycin, josamycin, lincomycin, neospiramycin 1, oleandomycin, pirlimycin, spiramycin 1, tildipirosin, tilmicosin and tylosin A. The limit of detection was 0.5 μg/kg. Within-laboratory precision evaluated over the analytical range of 5.0-50.0 μg/kg ranged from 4 to 17%. The accuracy of the method ranged from 80 to 112%. Recoveries ranged from 47 to 99% with all but one recovery above 60%. This is the first report of a quantitative confirmatory method for gamithromycin, pirlimycin and tildipirosin in fish and shrimp. PMID:25125397

  11. A high-performance liquid chromatographic-atmospheric pressure chemical ionization-tandem mass spectrometric method for determination of risperidone and 9-hydroxyrisperidone in human plasma.

    PubMed

    Moody, David E; Laycock, John D; Huang, Wei; Foltz, Rodger L

    2004-09-01

    Risperidone, a benzisoxazole derivative, is an antipsychotic agent used for the treatment of schizophrenia. We developed a liquid chromatographic-atmospheric pressure chemical ionization-tandem mass spectrometric (LC-APCI-MS-MS) method with improved sensitivity, selectivity, and dynamic range for determination of risperidone and 9-hydroxyrisperidone in human plasma. A structural analogue of risperidone, RO68808 (5 ng/mL), is added as the internal standard to 1 mL of human plasma. Plasma is made basic, extracted with pentane/methylene chloride (3:1), the organic phase evaporated to dryness, and the residue is reconstituted in water with 0.1% formic acid/acetonitrile (20:1). For LC-MS-MS analysis, a Metachem Inertsel HPLC column (2.1 x 150 mm, 5-microm particle size) is connected to a Finnigan TSQ7000 tandem MS via the Finnigan API interface. Both electrospray (ESI) and APCI produced predominantly MH(+) ions for the two analytes and the internal standard. Ions detected by selected reaction monitoring correspond to the following transitions: m/z 411 to 191 for risperidone, m/z 427 to 207 for 9-hydroxyrisperidone, and m/z 421 to 201 for the internal standard. APCI provided a larger dynamic range (0.1 to 25 ng/mL) and better precision and accuracy than ESI. Intrarun accuracy and precision determined at 0.1, 0.25, 2.5, and 15 ng/mL were within 12% of target with %CVs not exceeding 10.9%. Interrun accuracy and precision determined at the same concentrations were within 9.6% of target with %CVs not exceeding 6.7%. Analytes were stable in plasma after 24 h at room temperature, 2 freeze-thaw cycles, and 490 days at -20 degrees C. PMID:15516302

  12. Analysis of Mammalian Sphingolipids by Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS) and Tissue Imaging Mass Spectrometry (TIMS)

    PubMed Central

    Sullards, M. Cameron; Liu, Ying; Chen, Yanfeng; Merrill, Alfred H.

    2011-01-01

    Sphingolipids are a highly diverse category of molecules that serve not only as components of biological structures but also as regulators of numerous cell functions. Because so many of the structural features of sphingolipids give rise to their biological activity, there is a need for comprehensive or “sphingolipidomic” methods for identification and quantitation of as many individual subspecies as possible. This review defines sphingolipids as a class, briefly discusses classical methods for their analysis, and focuses primarily on liquid chromatography tandem mass spectrometry (LC-MS/MS) and tissue imaging mass spectrometry (TIMS). Recently, a set of evolving and expanding methods have been developed and rigorously validated for the extraction, identification, separation, and quantitation of sphingolipids by LC-MS/MS. Quantitation of these biomolecules is made possible via the use of an internal standard cocktail. The compounds that can be readily analyzed are free long-chain (sphingoid) bases, sphingoid base 1-phosphates, and more complex species such as ceramides, ceramide 1-phosphates, sphingomyelins, mono- and di-hexosylceramides sulfatides, and novel compounds such as the 1-deoxy- and 1-(deoxymethyl)-sphingoid bases and their N-acyl-derivatives. These methods can be altered slightly to separate and quantitate isomeric species such as glucosyl/galactosylceramide. Because these techniques require the extraction of sphingolipids from their native environment, any information regarding their localization in histological slices is lost. Therefore, this review also describes methods for TIMS. This technique has been shown to be a powerful tool to determine the localization of individual molecular species of sphingolipids directly from tissue slices. PMID:21749933

  13. Mass spectrometric characterization of tamoxifene metabolites in human urine utilizing different scan parameters on liquid chromatography/tandem mass spectrometry.

    PubMed

    Mazzarino, Monica; de la Torre, Xavier; Di Santo, Roberto; Fiacco, Ilaria; Rosi, Federica; Botrè, Francesco

    2010-03-01

    Different liquid chromatographic/tandem mass spectrometric (LC/MS/MS) scanning techniques were considered for the characterization of tamoxifene metabolites in human urine for anti-doping purpose. Five different LC/MS/MS scanning methods based on precursor ion scan (precursor ion scan of m/z 166, 152 and 129) and neutral loss scan (neutral loss of 72 Da and 58 Da) in positive ion mode were assessed to recognize common ions or common losses of tamoxifene metabolites. The applicability of these methods was checked first by infusion and then by the injection of solution of a mixture of reference standards of four tamoxifene metabolites available in our laboratory. The data obtained by the analyses of the mixture of the reference standards showed that the five methods used exhibited satisfactory results for all tamoxifene metabolites considered at a concentration level of 100 ng/mL, whereas the analysis of blank urine samples spiked with the same tamoxifene metabolites at the same concentration showed that the neutral loss scan of 58 Da lacked sufficient specificity and sensitivity. The limit of detection in urine of the compounds studied was in the concentration range 10-100 ng/mL, depending on the compound structure and on the selected product ion. The suitability of these approaches was checked by the analysis of urine samples collected after the administration of a single dose of 20 mg of tamoxifene. Six metabolites were detected: 4-hydroxytamoxifene, 3,4-dihydroxytamoxifene, 3-hydroxy-4-methoxytamoxifene, N-demethyl-4-hydroxytamoxifene, tamoxifene-N-oxide and N-demethyl-3-hydroxy-4-methoxytamoxifene, which is in conformity to our previous work using a time-of-flight (TOF) mass spectrometer in full scan acquisition mode. PMID:20187079

  14. Measurement of oxidative stress parameters using liquid chromatography-tandem mass spectroscopy (LC-MS/MS)

    SciTech Connect

    Winnik, Witold M. Kitchin, Kirk T.

    2008-11-15

    There is increasingly intense scientific and clinical interest in oxidative stress and the many parameters used to quantify the degree of oxidative stress. However, there remain many analytical limitations to currently available assays for oxidative stress markers. Recent improvements in software, hardware, and instrumentation design have made liquid chromatography and tandem mass spectroscopy (LC-MS/MS) methods optimal choices for the determination of many oxidative stress markers. In particular, LC-MS/MS often provides the advantages of higher specificity, higher sensitivity, and the capacity to determine multiple analytes (e.g. 4-11 oxidative stress markers per LC run) when compared to other available methods, such as gas chromatography-MS, immunoassays, spectrophotometric or flourometric assays. LC-MS/MS methods are also compatible with cleanup and sample preparation methods including prior solid phase extraction or automated two dimensional LC/LC chromatography followed by MS/MS. LC-MS/MS provides three analytical filtering functions: (1) the LC column provides initial separation as each analyte elutes from the column. (2) The first MS dimension isolates ions of a particular mass-to-charge (m/z) ratio. (3) The selected precursor ion is fragmented into product ions that provide structural information about the precursor ion. Quantitation is achieved based on the abundances of the product ions. The sensitivity limits for LC-MS/MS usually lie within the range of fg-pg of analyte per LC on-column injection. In this article, the present capabilities of LC-MS/MS are briefly presented and some specific examples of the strengths of these LC-MS/MS assays are discussed. The selected examples include methods for isoprostanes, oxidized proteins and amino acids, and DNA biomarkers of oxidative stress.

  15. An improved method for measuring metaldehyde in surface water using liquid chromatography tandem mass spectrometry

    PubMed Central

    Schumacher, Melanie; Castle, Glenn; Gravell, Anthony; Mills, Graham A.; Fones, Gary R.

    2016-01-01

    The molluscicide metaldehyde (2,4,6,8-tetramethyl-1,3,5,7-tetraoxocanemetacetaldehyde) is an emerging pollutant. It is frequently detected in surface waters, often above the European Community Drinking Water Directive limit of 0.1 μg/L for a single pesticide. Gas chromatography mass spectrometry (GC–MS) can be used to determine metaldehyde in environmental waters, but this method requires time consuming extraction techniques prior to instrumental analysis. Use of liquid chromatography-tandem mass spectrometry (LC–MS/MS) can overcome this problem. We describe a novel LC–MS/MS method, using a methylamine mobile phase additive, coupled with on-line sample enrichment that allows for the rapid and sensitive measurement of metaldehyde in surface water. Only the methylamine adduct of metaldehyde was formed with other unwanted alkali metal adducts and dimers being suppressed. As considerably less collision energy is required to fragment the methylamine adduct, a five-fold improvement in method sensitivity, compared to a previous method using an ammonium acetate buffer mobile phase was achieved. This new approach offers: • A validated method that meets regulatory requirements for the determination of metaldehyde in surface water. • Improved reliability of quantification over existing LC–MS/MS methods by using stable precursor ions for multiple reaction monitoring. • Low limits of quantification for tap water (4 ng/L) and river water (20 ng/L) using only 800 μL of sample; recoveries > 97%. PMID:27054094

  16. An improved method for measuring metaldehyde in surface water using liquid chromatography tandem mass spectrometry.

    PubMed

    Schumacher, Melanie; Castle, Glenn; Gravell, Anthony; Mills, Graham A; Fones, Gary R

    2016-01-01

    The molluscicide metaldehyde (2,4,6,8-tetramethyl-1,3,5,7-tetraoxocanemetacetaldehyde) is an emerging pollutant. It is frequently detected in surface waters, often above the European Community Drinking Water Directive limit of 0.1 μg/L for a single pesticide. Gas chromatography mass spectrometry (GC-MS) can be used to determine metaldehyde in environmental waters, but this method requires time consuming extraction techniques prior to instrumental analysis. Use of liquid chromatography-tandem mass spectrometry (LC-MS/MS) can overcome this problem. We describe a novel LC-MS/MS method, using a methylamine mobile phase additive, coupled with on-line sample enrichment that allows for the rapid and sensitive measurement of metaldehyde in surface water. Only the methylamine adduct of metaldehyde was formed with other unwanted alkali metal adducts and dimers being suppressed. As considerably less collision energy is required to fragment the methylamine adduct, a five-fold improvement in method sensitivity, compared to a previous method using an ammonium acetate buffer mobile phase was achieved. This new approach offers: •A validated method that meets regulatory requirements for the determination of metaldehyde in surface water.•Improved reliability of quantification over existing LC-MS/MS methods by using stable precursor ions for multiple reaction monitoring.•Low limits of quantification for tap water (4 ng/L) and river water (20 ng/L) using only 800 μL of sample; recoveries > 97%. PMID:27054094

  17. Neutron-encoded signatures enable product ion annotation from tandem mass spectra.

    PubMed

    Richards, Alicia L; Vincent, Catherine E; Guthals, Adrian; Rose, Christopher M; Westphall, Michael S; Bandeira, Nuno; Coon, Joshua J

    2013-12-01

    We report the use of neutron-encoded (NeuCode) stable isotope labeling of amino acids in cell culture for the purpose of C-terminal product ion annotation. Two NeuCode labeling isotopologues of lysine, (13)C6(15)N2 and (2)H8, which differ by 36 mDa, were metabolically embedded in a sample proteome, and the resultant labeled proteins were combined, digested, and analyzed via liquid chromatography and mass spectrometry. With MS/MS scan resolving powers of ~50,000 or higher, product ions containing the C terminus (i.e. lysine) appear as a doublet spaced by exactly 36 mDa, whereas N-terminal fragments exist as a single m/z peak. Through theory and experiment, we demonstrate that over 90% of all y-type product ions have detectable doublets. We report on an algorithm that can extract these neutron signatures with high sensitivity and specificity. In other words, of 15,503 y-type product ion peaks, the y-type ion identification algorithm correctly identified 14,552 (93.2%) based on detection of the NeuCode doublet; 6.8% were misclassified (i.e. other ion types that were assigned as y-type products). Searching NeuCode labeled yeast with PepNovo(+) resulted in a 34% increase in correct de novo identifications relative to searching through MS/MS only. We use this tool to simplify spectra prior to database searching, to sort unmatched tandem mass spectra for spectral richness, for correlation of co-fragmented ions to their parent precursor, and for de novo sequence identification. PMID:24043425

  18. Neutron-encoded Signatures Enable Product Ion Annotation From Tandem Mass Spectra*

    PubMed Central

    Richards, Alicia L.; Vincent, Catherine E.; Guthals, Adrian; Rose, Christopher M.; Westphall, Michael S.; Bandeira, Nuno; Coon, Joshua J.

    2013-01-01

    We report the use of neutron-encoded (NeuCode) stable isotope labeling of amino acids in cell culture for the purpose of C-terminal product ion annotation. Two NeuCode labeling isotopologues of lysine, 13C615N2 and 2H8, which differ by 36 mDa, were metabolically embedded in a sample proteome, and the resultant labeled proteins were combined, digested, and analyzed via liquid chromatography and mass spectrometry. With MS/MS scan resolving powers of ∼50,000 or higher, product ions containing the C terminus (i.e. lysine) appear as a doublet spaced by exactly 36 mDa, whereas N-terminal fragments exist as a single m/z peak. Through theory and experiment, we demonstrate that over 90% of all y-type product ions have detectable doublets. We report on an algorithm that can extract these neutron signatures with high sensitivity and specificity. In other words, of 15,503 y-type product ion peaks, the y-type ion identification algorithm correctly identified 14,552 (93.2%) based on detection of the NeuCode doublet; 6.8% were misclassified (i.e. other ion types that were assigned as y-type products). Searching NeuCode labeled yeast with PepNovo+ resulted in a 34% increase in correct de novo identifications relative to searching through MS/MS only. We use this tool to simplify spectra prior to database searching, to sort unmatched tandem mass spectra for spectral richness, for correlation of co-fragmented ions to their parent precursor, and for de novo sequence identification. PMID:24043425

  19. Analysis of methylcitrate in dried blood spots by liquid chromatography-tandem mass spectrometry.

    PubMed

    Al-Dirbashi, Osama Y; McIntosh, Nathan; McRoberts, Christine; Fisher, Larry; Rashed, Mohamed S; Makhseed, Nawal; Geraghty, Michael T; Santa, Tomofumi; Chakraborty, Pranesh

    2014-01-01

    Accumulation of propionylcarnitine (C3) in neonatal dried blood spots (DBS) is indicative of inborn errors of propionate metabolism including propionic acidemia (PA), methylmalonic aciduria (MMA), and cobalamin (Cbl) metabolic defects. Concentrations of C3 in affected newborns overlap with healthy individuals rendering this marker neither specific nor sensitive. While a conservative C3 cutoff together with relevant acylcarnitines ratios improve screening sensitivity, existing mass spectrometric methods in newborn screening laboratories are inadequate at improving testing specificity. Therefore, using the original screening DBS, we sought to measure 2-methylcitric acid (MCA), a pathognomonic hallmark of C3 disorders to decrease the false positive rate and improve the positive predictive value of C3 disorders. MCA was derivatized with 4-[2-(N,N-dimethylamino)ethylaminosulfonyl]-7-(2-aminoethylamino)-2,1,3-benzoxadiazole (DAABD-AE). No separate extraction step was required and derivatization was performed directly using a 3.2-mm disc of DBS as a sample (65°C for 45 min). The reaction mixture was analyzed by liquid chromatography tandem mass spectrometry. MCA was well separated and eluted at 2.3 min with a total run time of 7 min. The median and (range) of MCA of 0.06 μmol/L (0-0.63) were in excellent agreement with the literature. The method was applied retrospectively on DBS samples from established patients with PA, MMA, Cbl C, Cbl F, maternal vitamin B12 deficiency (n = 20) and controls (n = 337). Comparison with results obtained by another method was satisfactory (n = 252). This method will be applied as a second tier test for samples which trigger positive PA or MMA results by the primary newborn screening method. PMID:24997714

  20. A Machine Learning Based Approach to de novo Sequencing of Glycans from Tandem Mass Spectrometry Spectrum.

    PubMed

    Kumozaki, Shotaro; Sato, Kengo; Sakakibara, Yasubumi

    2015-01-01

    Recently, glycomics has been actively studied and various technologies for glycomics have been rapidly developed. Currently, tandem mass spectrometry (MS/MS) is one of the key experimental tools for identification of structures of oligosaccharides. MS/MS can observe MS/MS peaks of fragmented glycan ions including cross-ring ions resulting from internal cleavages, which provide valuable information to infer glycan structures. Thus, the aim of de novo sequencing of glycans is to find the most probable assignments of observed MS/MS peaks to glycan substructures without databases. However, there are few satisfiable algorithms for glycan de novo sequencing from MS/MS spectra. We present a machine learning based approach to de novo sequencing of glycans from MS/MS spectrum. First, we build a suitable model for the fragmentation of glycans including cross-ring ions, and implement a solver that employs Lagrangian relaxation with a dynamic programming technique. Then, to optimize scores for the algorithm, we introduce a machine learning technique called structured support vector machines that enable us to learn parameters including scores for cross-ring ions from training data, i.e., known glycan mass spectra. Furthermore, we implement additional constraints for core structures of well-known glycan types including N-linked glycans and O-linked glycans. This enables us to predict more accurate glycan structures if the glycan type of given spectra is known. Computational experiments show that our algorithm performs accurate de novo sequencing of glycans. The implementation of our algorithm and the datasets are available at http://glyfon.dna.bio.keio.ac.jp/. PMID:26671799

  1. Using total error concept for the validation of a liquid chromatography-tandem mass spectrometry method for the determination of budesonide epimers in human plasma.

    PubMed

    Streel, B; Cahay, B; Klinkenberg, R

    2009-08-01

    A robust, sensitive and selective method to quantify budesonide epimers in human plasma using solid-phase extraction and liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed and fully validated. The drug was first isolated from the biological matrix by automated solid-phase extraction (SPE) on disposable extraction cartridges (C-2). The methanolic eluate was then collected and evaporated to dryness. The residue was dissolved in mobile phase and an aliquot was injected onto a Phenomenex Luna octadecylsilica (C-18) column (50 mm x 4.6 mm i.d., 3 microm). The mobile phase is composed of water containing 10 mM ammonium acetate adjusted to pH 3.2 with glacial acetic acid and acetonitrile (65:35, v/v). The flow-rate was 1.00 ml/min. Hydrocortisone acetate was used as internal standard (IS). Detection of the analytes was achieved using negative atmospheric pressure chemical ionization (APCI) tandem mass spectrometry in selected reaction monitoring (SRM) mode. The MS/MS ion transitions monitored were m/z 489.3-->357.3 and 463.3-->403.2 for budesonide epimers and hydrocortisone, respectively. The method was validated using SFSTP (2003) proposal based on total measurement error and accuracy profiles as a decision tool. The most appropriate regression model for the response function as well as the limit of quantitation was first selected during the prevalidation step. These latter criteria were then assessed during the formal validation step. The limit of quantitation (LOQ) was around 50 pg/ml for budesonide epimers. The method was validated with respect to stability, recovery, linearity, precision, trueness and accuracy. Risk and uncertainty were also evaluated. The validated method was finally applied successfully to investigate the plasma concentration of budesonide epimers in a pharmacokinetic study. PMID:19249257

  2. Direct tandem mass spectrometric analysis of amino acids in plasma using fluorous derivatization and monolithic solid-phase purification.

    PubMed

    Tamashima, Erina; Hayama, Tadashi; Yoshida, Hideyuki; Imakyure, Osamu; Yamaguchi, Masatoshi; Nohta, Hitoshi

    2015-11-10

    In this study, we developed a novel direct tandem mass spectrometric method for rapid and accurate analysis of amino acids utilizing a fluorous derivatization and purification technique. Amino acids were perfluoroalkylated with 2H,2H,3H,3H-perfluoroundecan-1-al in the presence of 2-picoline borane via reductive amination. The derivatives were purified by perfluoroalkyl-modified silica-based monolithic solid-phase extraction (monolithic F-SPE), and directly analyzed by tandem mass spectrometry using electrospray ionization without liquid chromatographic separation. The perfluoroalkyl derivatives could be sufficiently distinguished from non-fluorous compounds, i.e. the biological matrix, due to their fluorous interaction. Thus, rapid and accurate determination of amino acids was accomplished. The method was validated with human plasma samples and applied to the analysis of amino acids in the plasma of mice with maple syrup urine disease or phenylketonuria. PMID:26222276

  3. Relationship between Leg Mass, Leg Composition and Foot Velocity on Kicking Accuracy in Australian Football

    PubMed Central

    Hart, Nicolas H.; Nimphius, Sophia; Spiteri, Tania; Cochrane, Jodie L.; Newton, Robert U.

    2016-01-01

    Kicking a ball accurately over a desired distance to an intended target is arguably the most important skill to acquire in Australian Football. Therefore, understanding the potential mechanisms which underpin kicking accuracy is warranted. The aim of this study was to examine the relationship between leg mass, leg composition and foot velocity on kicking accuracy in Australian Football. Thirty-one Australian Footballers (n = 31; age: 22.1 ± 2.8 years; height: 1.81 ± 0.07 m; weight: 85.1 ± 13.0 kg; BMI: 25.9 ± 3.2) each performed ten drop punt kicks over twenty metres to a player target. Athletes were separated into accurate (n = 15) and inaccurate (n = 16) kicking groups. Leg mass characteristics were assessed using whole body DXA scans. Foot velocity was determined using a ten-camera optoelectronic, three-dimensional motion capture system. Interactions between leg mass and foot velocity evident within accurate kickers only (r = -0.670 to -0.701). Relative lean mass was positively correlated with kicking accuracy (r = 0.631), while no relationship between foot velocity and kicking accuracy was evident in isolation (r = -0.047 to -0.083). Given the evident importance of lean mass, and its interaction with foot velocity for accurate kickers; future research should explore speed-accuracy, impulse-variability, limb co-ordination and foot-ball interaction constructs in kicking using controlled with-in subject studies to examine the effects of resistance training and skill acquisition programs on the development of kicking accuracy. Key points Accurate kickers expressed a very strong inverse relationship between leg mass and foot velocity. Inaccurate kickers were unable to replicate this, with greater volatility in their performance, indicating an ability of accurate kickers to mediate foot velocity to compensate for leg mass in order to deliver the ball over the required distance. Accurate kickers exhibited larger quantities of relative lean mass and lower

  4. Relationship between Leg Mass, Leg Composition and Foot Velocity on Kicking Accuracy in Australian Football.

    PubMed

    Hart, Nicolas H; Nimphius, Sophia; Spiteri, Tania; Cochrane, Jodie L; Newton, Robert U

    2016-06-01

    Kicking a ball accurately over a desired distance to an intended target is arguably the most important skill to acquire in Australian Football. Therefore, understanding the potential mechanisms which underpin kicking accuracy is warranted. The aim of this study was to examine the relationship between leg mass, leg composition and foot velocity on kicking accuracy in Australian Football. Thirty-one Australian Footballers (n = 31; age: 22.1 ± 2.8 years; height: 1.81 ± 0.07 m; weight: 85.1 ± 13.0 kg; BMI: 25.9 ± 3.2) each performed ten drop punt kicks over twenty metres to a player target. Athletes were separated into accurate (n = 15) and inaccurate (n = 16) kicking groups. Leg mass characteristics were assessed using whole body DXA scans. Foot velocity was determined using a ten-camera optoelectronic, three-dimensional motion capture system. Interactions between leg mass and foot velocity evident within accurate kickers only (r = -0.670 to -0.701). Relative lean mass was positively correlated with kicking accuracy (r = 0.631), while no relationship between foot velocity and kicking accuracy was evident in isolation (r = -0.047 to -0.083). Given the evident importance of lean mass, and its interaction with foot velocity for accurate kickers; future research should explore speed-accuracy, impulse-variability, limb co-ordination and foot-ball interaction constructs in kicking using controlled with-in subject studies to examine the effects of resistance training and skill acquisition programs on the development of kicking accuracy. Key pointsAccurate kickers expressed a very strong inverse relationship between leg mass and foot velocity. Inaccurate kickers were unable to replicate this, with greater volatility in their performance, indicating an ability of accurate kickers to mediate foot velocity to compensate for leg mass in order to deliver the ball over the required distance.Accurate kickers exhibited larger quantities of relative lean mass and lower quantities

  5. Rapid determination of benzodiazepines, zolpidem and their metabolites in urine using direct injection liquid chromatography-tandem mass spectrometry.

    PubMed

    Jeong, Yu-Dong; Kim, Min Kyung; Suh, Sung Ill; In, Moon Kyo; Kim, Jin Young; Paeng, Ki-Jung

    2015-12-01

    Benzodiazepines and zolpidem are generally prescribed as sedative, hypnotics, anxiolytics or anticonvulsants. These drugs, however, are frequently misused in drug-facilitated crime. Therefore, a rapid and simple liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed for identification and quantification of benzodiazepines, zolpidem and their metabolites in urine using deuterium labeled internal standards (IS). Urine samples (120 μL) mixed with 80 μL of the IS solution were centrifuged. An aliquot (5 μL) of the sample solution was directly injected into the LC-MS/MS system for analysis. The mobile phases consisted of water and acetonitrile containing 2mM ammonium trifluoroacetate and 0.2% acetic acid. The analytical column was a Zorbax SB-C18 (100 mm × 2.1 mm i.d., 3.5 μm, Agilent). The separation and detection of 18 analytes were achieved within 10 min. Calibration curves were linear over the concentration ranges of 0.5-20 ng/mL (zolpidem), 1.0-40 ng/mL (flurazepam and temazepam), 2.5-100 ng/mL (7-aminoclonazepam, 1-hydroxymidazolam, midazolam, flunitrazepam and alprazolam), 5.0-200 ng/mL (zolpidem phenyl-4-carboxylic acid, α-hydroxyalprazolam, oxazepam, nordiazepam, triazolam, diazepam and α-hydroxytriazolam), 10-400 ng/mL (lorazepam and desalkylflurazepam) and 10-100 ng/mL (N-desmethylflunitrazepam) with the coefficients of determination (r(2)) above 0.9971. The dilution integrity of the analytes was examined for supplementation of short linear range. Dilution precision and accuracy were tested using two, four and ten-folds dilutions and they ranged from 3.7 to 14.4% and -12.8 to 12.5%, respectively. The process efficiency for this method was 63.0-104.6%. Intra- and inter-day precisions were less than 11.8% and 9.1%, while intra- and inter-day accuracies were less than -10.0 to 8.2%, respectively. The lower limits of quantification were lower than 10 ng/mL for each analyte. The applicability of the developed method was successfully

  6. Simultaneous analysis of mono-, di-, and tri-ethanolamine in cosmetic products using liquid chromatography coupled tandem mass spectrometry.

    PubMed

    Shin, Kyong-Oh; Lee, Yong-Moon

    2016-01-01

    Alkanolamines such as monoethanolamine (MEA), diethanolamine (DEA), and triethanolamine (TEA) are used as wetting agents in shampoos, lotions, creams, and other cosmetics. DEA is widely used to provide lather in shampoos and maintain a favorable consistency in lotions and creams. Although DEA is not harmful, it may react with other ingredients in the cosmetic formula after extended storage periods to form an extremely potent carcinogen called nitrosodiethanolamine (NDEA), which is readily absorbed through the skin and has been linked to the development of stomach, esophagus, liver, and bladder cancers. The purpose of this study was to develop a simultaneous quantification method for measurement of MEA, DEA, and TEA in cosmetic products. Liquid chromatography coupled tandem mass spectrometry (LC-MS/MS) was performed using a hydrophilic interaction liquid chromatography (HILIC) column with isocratic elution containing acetonitrile and 5 mM ammonium formate in water (88:12, v/v). Identification and quantification of alkanolamines were performed using MS/MS monitoring to assess the transition from precursor to product ion of MEA (m/z, 61.1 → 44.0), DEA (m/z, 106.1 → 88.0), TEA (m/z, 150.1 → 130.0), and the internal standard triethylamine (m/z, 102.2 → 58.0). Alkanolamines extractions were simplified using a single extraction with acetonitrile in the cosmetic matrix. Performance of the method was evaluated with quality parameters such as specificity, carry-over, linearity and calibration, correlation of determination (R(2)), detection limit, precision, accuracy, and recovery. Calibration curves of MEA (2.9-1000 ppb), DEA (1-1000 ppb), and TEA (1-1000 ppb) were constructed by plotting concentration versus peak-area ratio (analyte/internal standard with a correlation coefficient greater than 0.99). The intra- and inter-assay accuracy ranged from 92.92 to 101.15 % for all analytes. The intra- and inter-assay precision for MEA, DEA, and TEA showed all

  7. Quantification of nimesulide in human plasma by high-performance liquid chromatography/tandem mass spectrometry. Application to bioequivalence studies.

    PubMed

    Barrientos-Astigarraga, R E; Vannuchi, Y B; Sucupira, M; Moreno, R A; Muscará, M N; De Nucci, G

    2001-12-01

    A method based on liquid chromatography with negative ion electrospray ionization and tandem mass spectrometry is described for the determination of nimesulide in human plasma. Liquid-liquid extraction using a mixture of diethyl ether and dichloromethane was employed and celecoxib was used as an internal standard. The chromatographic run time was 4.5 min and the weighted (1/x) calibration curve was linear in the range 10.0-2000 ng x ml(-1). The limit of quantification was 10 ng x ml(-1), the intra-batch precision was 6.3, 2.1 and 2.1% and the intra-batch accuracy was 3.2, 0.3 and 0.1% for 30, 300 and 1200 ng x ml(-1) respectively. The inter-batch precision was 2.3, 2.8 and 2.7% and the accuracy was 3.3, 0.3 and 0.1% for 30, 300 and 1200 ng x ml(-1) respectively. This method was employed in a bioequivalence study of one nimesulide drop formulation (nimesulide 50 mg x ml(-1) drop, Medley S/A Indústria Farmacêutica, Brazil) against one standard nimesulide drop formulation (Nisulid, 50 mg x ml(-1) drop, Astra Médica, Brazil). Twenty-four healthy volunteers (both sexes) took part in the study and received a single oral dose of nimesulide (100 mg, equivalent to 2 ml of either formulation) in an open, randomized, two-period crossover way, with a 2-week washout interval between periods. The 90% confidence interval (CI) for geometric mean ratios between nimesulide and Nisulid were 93.1-109.6% for C(max), 87.7-99.8% for AUC(last) and 88.1-99.7% for AUC(0-infinity). Since the 90% CI for the above-mentioned parameters were included in the 80-125% interval proposed by the US Food and Drug Administration, the two formulations were considered bioequivalent in terms of both rate and extent of absorption. PMID:11754119

  8. Rare disorders of metabolism with elevated butyryl- and isobutyryl-carnitine detected by tandem mass spectrometry newborn screening.

    PubMed

    Koeberl, Dwight D; Young, Sarah P; Gregersen, Niels S; Vockley, Jerry; Smith, Wendy E; Benjamin, Daniel Kelly; An, Yan; Weavil, Susan D; Chaing, Shu H; Bali, Deeksha; McDonald, Marie T; Kishnani, Priya S; Chen, Y-T; Millington, David S

    2003-08-01

    Tandem mass spectrometry was adopted for newborn screening by North Carolina in April 1999. Since then, three infants with short-chain acyl-CoA dehydrogenase (SCAD) and one with isobutyryl-CoA dehydrogenase deficiency were detected on the basis of elevated butyrylcarnitine/isobutyrylcarnitine (C4-carnitine) concentrations in newborn blood spots analyzed by tandem mass spectrometry. For three SCAD-deficient infants, biochemical evaluation included a plasma acylcarnitine profile with markedly elevated C4-carnitine, urine organic acid analysis with markedly elevated ethylmalonic and 2-methylsuccinic acids, and markedly elevated [U-13C]butyrylcarnitine concentrations in medium from fibroblasts incubated with [U-13C]palmitic acid and excess l-carnitine, consistent with classic SCAD deficiency. Two of three infants diagnosed with classic SCAD deficiency remained asymptomatic; however, the third infant presented with seizures and a cerebral infarct at 10 wk of age. All three infants had putatively inactivating mutations in both alleles of the SCAD gene. The highly elevated plasma C4-carnitine levels in the three infants detected by newborn screening tandem mass spectrometry differentiated them from infants and children who were homozygous or compound heterozygous for one of two SCAD gene susceptibility variations; for the latter group the C4-carnitine levels were normal. Isobutyryl-CoA dehydrogenase deficiency in a fourth infant was confirmed after isolated elevation of C4-carnitine in the acylcarnitine profile. PMID:12736383

  9. Binomial probability distribution model-based protein identification algorithm for tandem mass spectrometry utilizing peak intensity information.

    PubMed

    Xiao, Chuan-Le; Chen, Xiao-Zhou; Du, Yang-Li; Sun, Xuesong; Zhang, Gong; He, Qing-Yu

    2013-01-01

    Mass spectrometry has become one of the most important technologies in proteomic analysis. Tandem mass spectrometry (LC-MS/MS) is a major tool for the analysis of peptide mixtures from protein samples. The key step of MS data processing is the identification of peptides from experimental spectra by searching public sequence databases. Although a number of algorithms to identify peptides from MS/MS data have been already proposed, e.g. Sequest, OMSSA, X!Tandem, Mascot, etc., they are mainly based on statistical models considering only peak-matches between experimental and theoretical spectra, but not peak intensity information. Moreover, different algorithms gave different results from the same MS data, implying their probable incompleteness and questionable reproducibility. We developed a novel peptide identification algorithm, ProVerB, based on a binomial probability distribution model of protein tandem mass spectrometry combined with a new scoring function, making full use of peak intensity information and, thus, enhancing the ability of identification. Compared with Mascot, Sequest, and SQID, ProVerB identified significantly more peptides from LC-MS/MS data sets than the current algorithms at 1% False Discovery Rate (FDR) and provided more confident peptide identifications. ProVerB is also compatible with various platforms and experimental data sets, showing its robustness and versatility. The open-source program ProVerB is available at http://bioinformatics.jnu.edu.cn/software/proverb/ . PMID:23163785

  10. Investigation of Scrambled Ions in Tandem Mass Spectra, Part 2. On the Influence of the Ions on Peptide Identification

    NASA Astrophysics Data System (ADS)

    Dong, Nai-ping; Liang, Yi-zeng; Yi, Lun-zhao; Lu, Hong-mei

    2013-06-01

    A comprehensive investigation was performed to understand the influence of sequence scrambling in peptide ions on peptide identification results. To achieve this, four tandem mass spectrometry datasets with scrambled ions included and with them excluded were analyzed by Crux, X!Tandem, SpectraST, Lutefisk, and PepNovo. While the different algorithms differed in their performance, an increase in the number of correctly identified peptides was generally observed when removing scrambled ions, with the exception of the SpectraST algorithm. However, the variation of the match scores upon removal was unpredictable. Following these investigations, an interpretation was given on how the scrambled ions affect peptide identification. Lastly, a simulated theoretical mass spectral library derived from the NIST peptide Libraries was constructed and searched by SpectraST to study whether scrambled ions in predicted mass spectra could affect peptide identification. Consistent with the peptide library search results, no significant variations for dot product scores as well as peptide identification results were observed when these ions were included in the theoretical MS/MS spectra. From the five adopted algorithms, the SpectraST and Crux provided the most robust results, whereas X!Tandem, PepNovo, and Lutefisk were sensitive to the existence of the scrambled ions, especially the latter two de novo sequencing algorithms.

  11. A simple algorithm improves mass accuracy to 50-100 ppm for delayed extraction linear MALDI-TOF mass spectrometry

    SciTech Connect

    Hack, Christopher A.; Benner, W. Henry

    2001-10-31

    A simple mathematical technique for improving mass calibration accuracy of linear delayed extraction matrix assisted laser desorption ionization time-of-flight mass spectrometry (DE MALDI-TOF MS) spectra is presented. The method involves fitting a parabola to a plot of Dm vs. mass data where Dm is the difference between the theoretical mass of calibrants and the mass obtained from a linear relationship between the square root of m/z and ion time of flight. The quadratic equation that describes the parabola is then used to correct the mass of unknowns by subtracting the deviation predicted by the quadratic equation from measured data. By subtracting the value of the parabola at each mass from the calibrated data, the accuracy of mass data points can be improved by factors of 10 or more. This method produces highly similar results whether or not initial ion velocity is accounted for in the calibration equation; consequently, there is no need to depend on that uncertain parameter when using the quadratic correction. This method can be used to correct the internally calibrated masses of protein digest peaks. The effect of nitrocellulose as a matrix additive is also briefly discussed, and it is shown that using nitrocellulose as an additive to a CHCA matrix does not significantly change initial ion velocity but does change the average position of ions relative to the sample electrode at the instant the extraction voltage is applied.

  12. Identification of Tryptic Peptides from Large Databases using Multiplexed Tandem Mass Spectrometry: Simulations and Experimental Results

    SciTech Connect

    Masselon, Christophe D. ); Pasa-Tolic, Ljiljana ); Lee, Sang-Won ); Li, Lingjun; Anderson, Gordon A. ); Harkewicz, Richard ); Smith, Richard D. )

    2003-07-01

    Multiplexed MS/MS was recently demonstrated as a means to increase the throughput of peptides identification in LC-MS/MS experiments. In this approach, a set of parent species is dissociated simultaneously and measured in a single spectrum (in the same manner that a single parent ion is conventionally studied), providing a gain in sensitivity and throughput proportional to the number of species that can be simultaneously addressed. In the present work, simulations performed using the Caenorhabditis elegans predicted proteome database show that multiplexed MS/MS data allow the identification of tryptic peptides from mixtures of up to 10 peptides from a single dataset with only 3 y or b fragments per peptide and a mass accuracy of 2.5 to 5 ppm. At this level of database and data complexity, 98% of the 500 peptides considered in the simulation were correctly identified. This compares favorably with the rates obtained for classical MS/MS at more modest mass measurement accuracy. LC-multiplexed FTICR MS/MS data obtained from a 66 kDa protein (bovine serum albumin) tryptic digest sample are presented to illustrate the approach, and confirm that peptides can be effectively identified from the C. elegans database to which the protein sequence had been appended.

  13. Improved 6-Plex Tandem Mass Tags Quantification Throughput Using a Linear Ion Trap-High-Energy Collision Induced Dissociation MS(3) Scan.

    PubMed

    Liu, Jane M; Sweredoski, Michael J; Hess, Sonja

    2016-08-01

    The use of tandem mass tags (TMT) as an isobaric labeling strategy is a powerful method for quantitative proteomics, yet its accuracy has traditionally suffered from interference. This interference can be largely overcome by selecting MS(2) fragment precursor ions for high-energy collision induced dissociation (HCD) MS(3) analysis in an Orbitrap scan. While this approach minimizes the interference effect, sensitivity suffers due to the high AGC targets and long acquisition times associated with MS(3) Orbitrap detection. We investigated whether acquiring the MS(3) scan in a linear ion trap with its lower AGC target would increase overall quantification levels with a minimal effect on precision and accuracy. Trypsin-digested proteins from Saccharomyces cerevisiae were tagged with 6-plex TMT reagents. The sample was subjected to replicate analyses using either the Orbitrap or the linear ion trap for the HCD MS(3) scan. HCD MS(3) detection in the linear ion trap vs Orbitrap increased protein identification by 66% with minor loss in precision and accuracy. Thus, the use of a linear ion trap-HCD MS(3) scan during a 6-plex TMT experiment can improve overall identification levels while maintaining the power of multiplexed quantitative analysis. PMID:27377715

  14. Validation of a tandem mass spectrometry method using combined extraction of 37 oxylipins and 14 endocannabinoid-related compounds including prostamides from biological matrices.

    PubMed

    Gouveia-Figueira, Sandra; Nording, Malin L

    2015-09-01

    There is a clinical need for more relevant coverage of bioactive lipids using smaller sample volumes. Therefore, we have validated a tandem mass spectrometry method for combined solid phase extraction of 37 compounds in the oxylipin (OxL) and 14 in the endocannabinoid (eCB) metabolome, as well as prostamides. The limits of quantification (LOQ) for compounds in the eCB metabolome were in the range 0.5-1000 fg on column, intraday accuracy and precision ranges (%) were 83-125 and 0.3-17, respectively, and interday accuracy and precision ranges (%) were 80-119 and 1.2-20, respectively, dependent upon the compound and the concentration studied. Corresponding values for OxL were 0.5 fg-4.2 pg on column (LOQ), 85-115% (inter- and intraday accuracy) and <5% (precision). The combined extraction method was successfully applied to tissues, cell extracts, human plasma and milk samples. A deeper study of levels in elk, pig and cow brain, as well as cow heart and liver revealed tissue and species-specific elevation of eicosanoids: arachidonate diols, 20-HETE and 12(S)-HEPE (cow liver), LTB4 (cow brain), and monohydroxy metabolites (HETEs), epoxides and 5-oxo-ETE in elk brain, which might be caused by factors of stress and/or post-mortem reactions in the tissues. PMID:26115647

  15. ANALYSIS FOR B-LACTAM ANTIBIOTICS IN KIDNEY TISSUE BY LIQUID CHROMATOGRAPHY WITH ELECTROSPRAY IONIZATION AND SELECTIVE REACTION MONITORING/TANDEM ION TRAP MASS SPECTROMETRY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Eleven B-lactams antibiotics were analyzed in fortified and incurred beef kidney tissue using high-performance liquid chromatography/selective reaction monitoring/tandem ion trap mass spectrometry. The analytes included: deacetylcephapirin, amoxicillin, cephapirin, desfuroylceftiofur cysteine disul...

  16. MEASUREMENT OF PYRETHROID RESIDUES IN ENVIRONMENTAL AND FOOD SAMPLES BY ENHANCED SOLVENT EXTRACTION/SUPERCRITICAL FLUID EXTRACTION COUPLED WITH GAS CHROMATOGRAPHY-TANDEM MASS SPECTROMETRY

    EPA Science Inventory

    The abstract summarizes pyrethorid methods development research. It provides a summary of sample preparation and analytical techniques such as supercritical fluid extraction, enhance solvent extraction, gas chromatography and tandem mass spectrometry.

  17. Dynamic Modeling Accuracy Dependence on Errors in Sensor Measurements, Mass Properties, and Aircraft Geometry

    NASA Technical Reports Server (NTRS)

    Grauer, Jared A.; Morelli, Eugene A.

    2013-01-01

    A nonlinear simulation of the NASA Generic Transport Model was used to investigate the effects of errors in sensor measurements, mass properties, and aircraft geometry on the accuracy of dynamic models identified from flight data. Measurements from a typical system identification maneuver were systematically and progressively deteriorated and then used to estimate stability and control derivatives within a Monte Carlo analysis. Based on the results, recommendations were provided for maximum allowable errors in sensor measurements, mass properties, and aircraft geometry to achieve desired levels of dynamic modeling accuracy. Results using other flight conditions, parameter estimation methods, and a full-scale F-16 nonlinear aircraft simulation were compared with these recommendations.

  18. Detection and identification of alkylphosphonic acids by positive electrospray ionization tandem mass spectrometry using a tricationic reagent.

    PubMed

    Tak, Vijay; Pardasani, Deepak; Purohit, Ajay; Dubey, D K

    2011-11-30

    The retrospective detection and identification of degradation products of chemical warfare agents are of immense importance in order to prove their spillage and use. A highly sensitive liquid chromatography/electrospray ionization tandem mass spectrometric (LC/ESI-MS/MS) method--using an imidazolium-based tricationic reagent--was developed for the detection and identification of the anionic degradation products of nerve agents. A commercially available solution of 1,3-imidazolium-bis-(1-hexylbenzylimidazolium) trifluoride (IBHBI) formed adducts with alkylphosphonic acids (APAs), allowing detection of the APAs by positive mode ESI-MS. Tandem mass spectrometry was used for the unambiguous identification of the APAs. Parameters influencing the formation and stability of these adduct during mass spectrometric analysis, such as solvent composition, concentration of IBHBI, effect of pH and interferences by salts, were optimized. The absolute limits of detection (0.1 ng) for achieved for the APAs were better than those previously reported, and linear dynamic ranges of 10-2000 ng mL(-1) were achieved. The method was repeatable with a relative standard deviation ≤7.3%. APAs present in aqueous samples provided by the Organization for the Prohibition of Chemical Weapons during the 22(nd) and 24(th) Official Proficiency tests were detected and identified as IBHBI adducts. The added advantage of this method is that low-mass analytes are detected at higher mass, thus obviating the problem with background noise at low mass. PMID:22002694

  19. A liquid chromatography and tandem mass spectrometry method for the determination of potential biomarkers of cardiovascular disease.

    PubMed

    Magiera, Sylwia; Baranowska, Irena; Kusa, Jacek; Baranowski, Jacek

    2013-03-01

    A simple, accurate and sensitive liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed and validated for the quantitation of α-ketoglutaric acid (α-KG), L-carnitine (L-CAR) and acetyl-L-carnitine (acetyl-L-CAR) in human urine as potential biomarkers of cardiovascular disease. The separation was performed using an isocratic elution of 0.1% formic acid in water and acetonitrile (97:3, v/v) on an Acclaim 120 C8 column (150 mm × 4.6 mm, 3.0 μm). The flow rate of the mobile phase was 1.2 mL/min and the total assay run time was 3 min. Detection was performed on a triple-quadrupole mass spectrometer in selected reaction monitoring (SRM) mode via an electrospray ionization (ESI) source in positive and negative ion modes. This method covered a linearity range of 0.1-500 ng/mL for L-CAR and acetyl-L-CAR and 1-1000 ng/mL for α-KG with lower limits of quantification (LLOQ) of 0.08 ng/mL for L-CAR, 0.04 ng/mL for acetyl-L-CAR and 0.8 ng/mL for α-KG. The intra-day and inter-day precision and accuracy of the quality control samples exhibited relative standard deviations of less than 5.54% and relative error values from -5.95% to 3.11%. Analyte stability was evaluated under various sample preparation, analysis and storage conditions and varied from -9.89% to -0.47%. A two-step solid-phase extraction (SPE) procedure using silica gel and quaternary amine cartridges was used for urine sample cleanup. The average recoveries for all analyzed compounds were better than 86.64% at three concentrations. The method was successfully applied for the quantitation of α-KG, L-CAR and acetyl-L-CAR in human urine samples. PMID:23411015

  20. Derivatization of estrogens enhances specificity and sensitivity of analysis of human plasma and serum by liquid chromatography tandem mass spectrometry

    PubMed Central

    Faqehi, Abdullah M.M.; Cobice, Diego F.; Naredo, Gregorio; Mak, Tracy C.S.; Upreti, Rita; Gibb, Fraser W.; Beckett, Geoffrey J.; Walker, Brian R.; Homer, Natalie Z.M.; Andrew, Ruth

    2016-01-01

    Estrogens circulate at concentrations less than 20 pg/mL in men and postmenopausal women, presenting analytical challenges. Quantitation by immunoassay is unreliable at these low concentrations. Liquid chromatography tandem mass spectrometry (LC–MS/MS) offers greater specificity and sometimes greater sensitivity, but ionization of estrogens is inefficient. Introduction of charged moieties may enhance ionization, but many such derivatives of estrogens generate non-specific product ions originating from the “reagent” group. Therefore an approach generating derivatives with product ions specific to individual estrogens was sought. Estrogens were extracted from human plasma and serum using solid phase extraction and derivatized using 2-fluoro-1-methylpyridinium-p-toluenesulfonate (FMP-TS). Electrospray in positive mode with multiple reaction monitoring using a QTrap 5500 mass spectrometer was used to quantify “FMP” derivatives of estrogens, following LC separation. Transitions for the FMP derivatives of estrone (E1) and estradiol (E2) were compound specific (m/z 362→238 and m/z 364→128, respectively). The limits of detection and quantitation were 0.2 pg on-column and the method was linear from 1–400 pg/sample. Measures of intra- and inter-assay variability, precis