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Tandem Mass Spectrometer (tandem + mass_spectrometer)
Selected AbstractsOccurrence and fate of micropollutants in the Vidy Bay of Lake Geneva, Switzerland.ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2010Part II: Micropollutant removal between wastewater, raw drinking water Abstract The occurrence and removal of 58 pharmaceuticals, endocrine disruptors, corrosion inhibitors, biocides, and pesticides, were assessed in the wastewater treatment plant (WWTP) of the city of Lausanne, Switzerland, as well as in the effluent-receiving water body, the Vidy Bay of Lake Geneva. An analytical screening method to simultaneously measure all of the 58 micropollutants was developed based on ultra performance liquid chromatography coupled to a tandem mass spectrometer (UPLC-MS/MS). The selection of pharmaceuticals was primarily based on a prioritization study, which designated them as environmentally relevant for the Lake Geneva region. Except for the endocrine disruptor 17,-ethinylestradiol, all substances were detected in 24-h composite samples of wastewater entering the WWTP or in the treated effluent. Of these compounds, 40% were also detected in raw drinking water, pumped from the lake 3,km downstream of the WWTP. The contributions of dilution and degradation to micropollutant elimination between the WWTP outlet and the raw drinking water intake were established in different model scenarios using hypothetical residence times of the wastewater in Vidy Bay of 1, 4, or 90 d. Concentration decrease due to processes other than dilution was observed for diclofenac, beta-blockers, several antibiotics, corrosion inhibitors, and pesticides. Measured environmental concentrations (MECs) of pharmaceuticals were compared to the predicted environmental concentrations (PECs) determined in the prioritization study and agreed within one order of magnitude, but MECs were typically greater than the corresponding PECs. Predicted no-effect concentrations of the analgesic paracetamol, and the two antibiotics ciprofloxacin and sulfamethoxazole, were exceeded in raw drinking water samples and therefore present a potential risk to the ecosystem. Environ. Toxicol. Chem. 2010; 29:1658,1668. © 2010 SETAC [source] Mass spectrometric detection of tyrosine sulfation in human pancreatic trypsinogens, but not in tumor-associated trypsinogenFEBS JOURNAL, Issue 2 2008Outi Itkonen Trypsinogen-1 and -2 are well-characterized enzymes that are expressed in the pancreas and also in several other tissues. Many cancers produce trypsinogen isoenzymes that differ from the pancreatic ones with respect to substrate specificity and isoelectric point. These tumor-associated trypsinogens play a pivotal role in cancer progression and metastasis. The differences between these and the pancreatic isoenzymes have been suggested to be caused by post-translational modification, either sulfation or phosphorylation of a tyrosine residue. We aimed to elucidate the cause of these differences. We isolated trypsinogens from pancreatic juice and conditioned medium from a colon carcinoma cell line. Intact proteins, and tryptic and chymotryptic peptides were characterized by electrospray ionization mass spectrometry. We also used immunoblotting with antibody against phosphotyrosine and N-terminal sequencing. The results show that pancreatic trypsinogen-1 and -2 are sulfated at Tyr154, whereas tumor-associated trypsinogen-2 is not. Detachment of a labile sulfogroup could be demonstrated by both in-source dissociation and low-energy collision-induced dissociation in a tandem mass spectrometer. Tyrosine sulfation is an ubiquitous protein modification occurring in the secretory pathway, but its significance is often underestimated due to difficulties in its analysis. Sulfation is an almost irreversible modification that is thought to regulate protein,protein interactions and the activity of proteolytic enzymes. We conclude that the previously known differences in charge, substrate specificity and inhibitor binding between pancreatic and tumor-associated trypsinogens are probably caused by sulfation of Tyr154 in pancreatic trypsinogens. [source] Organization of nucleobase-functionalized ,-peptides investigated by soft electrospray ionization mass spectrometryJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 5 2009Nicola Diezemann Abstract The development and validation of analytical methods is a key to succeed in investigating noncovalent interactions between biomolecules or between small molecules and biomolecules. Electrospray ionization mass spectrometry (ESI-MS) was applied with a Fourier transform ion cyclotron resonance mass spectrometer (FTICR-MS) as well as a quadrupole/time-of-flight tandem mass spectrometer (QqToF-MS) for a systematic investigation of noncovalent complexes based on nucleobase pairing in an artificial and noncharged backbone topology. Synthetical ,-peptide helices covalently modified with nucleobases were organized by recognition of a sequence of four nucleobases. Specific duplexes of ,-peptide helices were obtained on the basis of hydrogen bonding base pair complementarity. Oligomer interactions were detected with defined stoichiometry and sensitivity for the respective duplex stability. FTICR-MS and QqToF-MS were used equally well to indicate double strand stabilities in agreement with the dissociation data determined by UV spectroscopy. Furthermore, the dissociation energies of gas phase ions of the noncovalent complexes were analyzed with collision induced dissociation (CID)-MS/MS and infrared multiphoton dissociation (IRMPD)-MS/MS. The CID conditions turned out to be too harsh for a differentiation of the duplex stabilities, whereas IRMPD might be developed as a technique to detect even small interaction energy differences. Copyright © 2009 John Wiley & Sons, Ltd. [source] Glycan side chains on naturally presented MHC class II ligandsJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 1 2005Jörn Dengjel Abstract The molecular characterization of unknown naturally presented major histocompatibility complex (MHC) class II glycopeptides carrying complex glycans has so far not been achieved, reflecting the different fragmentation characteristics of sugars and peptides in mass spectrometric analysis. Human leukocyte antigen (HLA)-DR-bound peptides were isolated by affinity purification, separated via high performance liquid chromatography and analyzed by matrix-assisted laser desorption/ionization and electrospray ionization mass spectrometry. We were able to identify two naturally processed MHC class II ligands, CD53122,136 and CD53121,136, carrying complex N -linked glycan side chains by a combination of in-source and collision-induced fragmentation on a quadrupole time-of-flight tandem mass spectrometer. Copyright © 2005 John Wiley & Sons, Ltd. [source] Using the protein chip interface with quadrupole time-of-flight mass spectrometry to directly identify peaks in SELDI profiles , initial evaluation using low molecular weight serum peaksPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 2 2009Jianhe Peng Abstract Mass spectrometric profiling, particularly in the form of SELDI, has been used in many studies, particularly in attempts to generate diagnostic serum profiles. Several studies have generated promising results but one of the limitations is the inability to identify easily potential discriminatory peaks. This may enable specific assays to be developed and increased biological insight. We describe the first systematic technical evaluation of the ProteinChip interface coupled to a tandem mass spectrometer which allows direct sequencing of peptides <6000,Da, and describe the direct sequence identification of 21 peaks commonly observed in serum samples. Additionally we describe for the first time the use of on-chip acetylation to assist in the validation of sequence identification. [source] Quantification of Greenland halibut serum vitellogenin: a trip from the deep sea to the mass spectrometerRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 7 2009Alejandro M. Cohen This paper focuses on the sequential steps involved in developing a technique for quantifying Greenland halibut vitellogenin, a serum protein biomarker, using a comprehensive mass spectrometric approach. In the first phase of this study, in-gel trypsin digestions of serum proteins separated by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) were analyzed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). A characteristic band around a molecular mass of 185,kDa, present in the mature female specimens, but absent in the male samples, was identified as vitellognin according to the peptide mass fingerprint obtained by MALDI-MS. Subsequently, MALDI and electrospray ionization tandem mass spectrometry (ESI-MS/MS) analyses were performed on the digest of the vitellogenin band for de novo sequencing. From these studies, a characteristic 'signature' peptide (sequence: FFGQEIAFANIDK) was selected from a list of candidate peptides as a surrogate analytical standard used for quantification purposes. Sample preparation for vitellogenin quantification consisted of a simple one-step overnight trypsin digestion. Samples were spiked with an isotopologue signature peptide standard and analyzed by high-performance liquid chromatography (HPLC) coupled in-line to an electrospray quadrupole-hexapole-quadrupole tandem mass spectrometer, operated in selective reaction monitoring mode. Transitions [(m/z 750.0,,,1020.4 and 750.0,,,1205.4) and (754.8,,,1028.6 and 754.8,,,1213.2)] were monitored for the signature peptide and the internal standard, respectively. Samples obtained from the field showed that vitellogenin levels were in accordance with fish maturity determined by macroscopic examination of the gonad, proving this technique suitable for measuring vitellogenin as a serum protein biomarker for reproductive maturity in female fish. Copyright © 2009 John Wiley & Sons, Ltd. [source] Precursor ion scan profiles of acylcarnitines by atmospheric pressure thermal desorption chemical ionization tandem mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 23 2008Giuseppe Paglia The fatty acyl esters of L-carnitine (acylcarnitines) are useful biomarkers for the diagnosis of some inborn errors of metabolism analyzed by liquid chromatography/tandem mass spectrometry. In this study the acylcarnitines were analyzed by atmospheric pressure thermal desorption chemical ionization using a commercial tandem mass spectrometer (APTDCI-MS/MS). The method is based on the precursor ion scan mode determination of underivatized acylcarnitines desorbed from samples by a hot desolvation gas flow and ionized by a corona pin discharge. During desorption/ionization step the temperature induces the degradation of acylcarnitines; nevertheless, the common fragment to all acylcarnitines [MH,59]+ is useful for analyzing their profile. APTDCI parameters, including angle of collection and incidence, gas flows and temperatures, were optimized for acylcarnitines. The experiments were performed drying 2,µL of an equimolar mixture of acylcarnitine standards on a glass slide. The specificity was evaluated by comparing product ion spectra and the precursor ion spectra of 85 m/z of acylcarnitines obtained by the APTDCI method and by electrospray ionization flow injection analysis (ESI-FIA). The method was also employed to analyze acylcarnitines extracted from a pathological dried blood spot and a control. The method enables analysis of biological samples and recognition of some acylcarnitines that are diagnostic markers of inherited metabolic diseases. The intrinsic high-throughput analysis of the ambient desorption ionization methods offers a new opportunity either for its potential application in clinical chemistry and for the expanded screening of some inborn errors of metabolism. Copyright © 2008 John Wiley & Sons, Ltd. [source] Gas-phase fragmentation study of novel synthetic 1,5-benzodiazepine derivatives using electrospray ionization tandem mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 14 2008Mohamed Rida The fragmentation patterns of a series of three novel synthesized 3-hydroxy-4-phenyl-tetrahydro-1,5-benzodiazepin-2-ones (1,3), possessing the same backbone structure, were investigated using electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry (MS/MS) techniques. A simple methodology, based on the use of ESI (positive ion mode) and by increasing the declustering potential in the atmospheric pressure/vacuum interface, collision-induced dissociation (CID), was used to enhance the formation of the fragment ions. In general, the novel synthetic 1,5-benzodiazepine derivatives afforded, in the gas phase, both protonated and sodiated molecules. This led to the confirmation of the molecular masses and chemical structures of the studied compounds. Exact accurate masses were measured using a high-resolution ESI-quadrupole orthogonal time-of-flight (QqToF)-MS/MS hybrid mass spectrometer instrument. The breakdown routes of the protonated molecules were rationalized by conducting low-energy collision CID-MS/MS analyses (product ion- and precursor ion scans) using a conventional quadrupole-hexapole-quadrupole (QhQ) tandem mass spectrometer. All the observed major fragmentations for the 1,5-benzodiazepines occurred in the saturated seven-membered ring containing the nitrogen atoms. These formed a multitude of product ions by different breakdown routes. All the major fragmentations involved cleavages of the N -1,C -2 andC -3,C -4 bonds. These occurred with concomitant eliminations of glyoxal, benzene and ethyl formate, forming the product ion at m/z 119, which was observed in all the studied compounds. In addition, an unique simultaneous CID-MS/MS fragmentation was noticed for the 1,5-benzodiazepines 1 and 3, which occurred by a pathway dictated by the substituent located on the N -1-position. It was evident that the aromatic ring portion of the 1,5-benzodiazepines was resistant to CID-MS/MS fragmentation. Re-confirmation of the various geneses of the product ions was achieved by conducting a series of precursor ion scans. ESI-MS and CID-MS/MS analyses have thus proven to be a specific and very sensitive method for the structural identification of these novel 1,5-benzodiazepine derivatives. Copyright © 2008 John Wiley & Sons, Ltd. [source] Mass spectral characterization of phloroglucinol derivatives hyperforin and adhyperforinRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 18 2006Lekha Sleno Active phloroglucinol constituents of Hypericum perforatum (St. John's wort) extracts, hyperforin and adhyperforin, have been studied following ion activation using tandem mass spectrometry (MS/MS) and complemented by accurate mass measurements. These two compounds were readily analyzed as protonated and deprotonated molecules with electrospray ionization. MS/MS and MS3 data from a quadrupole-linear ion trap tandem mass spectrometer were employed to elucidate fragmentation pathways. Fourier transform ion cyclotron resonance measurements afforded excellent mass accuracies for the confirmation of elemental formulae of product ions formed via infrared multiphoton dissociation and sustained off-resonance irradiation collision-induced dissociation. Fragmentation schemes have been devised for the dissociation of hyperforin and adhyperforin in negative and positive ion modes. This information is expected to be especially valuable for the characterization of related compounds, such as degradation products, metabolites and novel synthetic analogs of hyperforin. Copyright © 2006 John Wiley & Sons, Ltd. [source] Quantitative determination of dipyridamole in human plasma by high-performance liquid chromatography,tandem mass spectrometry and its application to a pharmacokinetic studyBIOMEDICAL CHROMATOGRAPHY, Issue 3 2010Ting Qin Abstract Dipyridamole is a classic platelet inhibitor which has been a key medicine in clinical therapy of thrombosis and cerebrovascular disease. A rapid, selective and convenient method using high-performance liquid chromatography,tandem mass spectrometry (HPLC-MS/MS) was developed for determination of dipyridamole in human plasma. After protein precipitation of 200 ,L plasma with methanol, dipyridamole and diazepam (internal standard) were chromatographed on an UltimateÔ XB-C18 (50 × 2.1 mm i.d, 3 ,) column with the mobile phase consisting of methanol,ammonium acetate (5 mM; 80 : 20, v/v) at a flow rate of 0.25 mL/min. The detection was performed on a triple quadrupole tandem mass spectrometer by multiple reaction monitoring mode via positive eletrospray ionization source (ESI+). The retention times of dipyridamole and diazepam were 1.4 and 1.2 min, respectively. The method was validated over a concentration range of 0.0180,4.50 ,g/mL (r2 , 0.99) with a lower limit of quantitation (LLOQ) of 0.0180 ,g/mL for dipyridamole. The intra- and inter-day precisions (RSD) of the assay at all three QC levels were 1.6,12.7% with an accuracy (RE) of ,4.3,1.9%, which meets the requirements of the FDA guidance. The HPLC-MS/MS method herein described was proved to be suitable for pharmacokinetic study of sustained-release dipyridamole tablet in volunteers after oral administration. Copyright © 2009 John Wiley & Sons, Ltd. [source] Liquid chromatography,mass spectrometry for analysis of a novel ,2 -adrenoceptor agonist trantinterol and its metabolites in beagle dog urineBIOMEDICAL CHROMATOGRAPHY, Issue 3 2010Yanjuan Wang Abstract A liquid chromatography,tandem mass spectrometry method was developed for the identification of metabolites of trantinterol, a novel ,2 -adrenoceptor agonist, in beagle dog urine. The separation of metabolites was performed on a reversed-phase C8 column using 0.1% formic acid in water and methanol (70 : 30, v/v) as the mobile phase. The structural information and elemental information of metabolites were acquired by an electrospray ionization tandem mass spectrometer and a quadrupole time-of-flight mass spectrometer, respectively. A total of 13 metabolites were detected and characterized on the basis of their tandem MS/MS fragmentation patterns. The accurate masses of nine metabolites were determined and two metabolites were further confirmed by comparing with reference standards. The metabolic pathways of trantinterol in beagle dog are proposed. Copyright © 2009 John Wiley & Sons, Ltd. [source] Solid-phase extraction and analysis of paroxetine in human plasma by ultra performance liquid chromatography,electrospray ionization mass spectrometryBIOMEDICAL CHROMATOGRAPHY, Issue 2 2010Mitesh Bhatt Abstract A rapid, sensitive and rugged solid-phase extraction ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was developed for determination of paroxetine in human plasma. The procedure for sample preparation includes simple SPE extraction procedure coupled with Hypersil Gold C18 column (100 mm , 2.1 mm, i.d., 1.9 ,m) with isocratic elution at a flow-rate of 0.350 mL/min and fluoxetine was used as the internal standard. The analysis was performed on a triple-quadrupole tandem mass spectrometer by multiple reactions monitoring mode via electrospray ionization. Using 500 ,L plasma, the methods were validated over the concentration range 0.050,16.710 ng/mL for paroxetine, with a lower limit of quantification of 0.050 ng/mL. The intra- and inter-day precision and accuracy of the quality control samples were within 10.0%. The recovery was 69.2 and 74.4% for paroxetine and fluoxetine respectively. Total run time was only 1.9 min. The method was highly reproducible and gave peaks with excellent chromatography properties. Copyright © 2009 John Wiley & Sons, Ltd. [source] Determination of teniposide in rat plasma by ultra performance liquid chromatography electrospray ionization tandem mass spectrometry after intravenous administrationBIOMEDICAL CHROMATOGRAPHY, Issue 9 2009Jing Wang Abstract A novel, specific and rapid ultra performance liquid chromatography electrospray ionization tandem mass spectrometry method has been developed and validated for determination of teniposide in rat plasma. A one-step liquid,liquid extraction method was used and the separation was carried out on an Acquity UPLCTM BEH C18 column with gradient elution using a mobile phase composed of acetonitrile and water (containing 0.1% formic acid) at a flow rate of 0.20 mL/min. A triple quadrupole tandem mass spectrometer in multiple-reaction monitoring mode via an electrospray ionization interface was used for the detection of teniposide. The detection was complete within 3.0 min. A linear calibration curve was obtained over the concentration range 10,10,000 ng/mL for teniposide, with a lower limit of quantification of 10 ng/mL. The intra-day precision and inter-day precision (relative standard deviation) were less than 10.23 and 13.09%, respectively. The developed method was applied for the first time to the pharmacokinetic study of teniposide in rats following a single intravenous administration of 4.5 mg/kg teniposide. Copyright © 2009 John Wiley & Sons, Ltd. [source] A sensitive and specific liquid chromatography/tandem mass spectrometry method for determination of echinacoside and its pharmacokinetic application in ratsBIOMEDICAL CHROMATOGRAPHY, Issue 6 2009Hao Yang Abstract A rapid and sensitive method based on liquid chromatography/tandem mass spectrometry (LC/MS/MS) for the determination of echinacoside in rat plasma was established and fully validated. A single step of liquid,liquid extraction with n -butanol was utilized. Chromatographic separation of the analyte and the internal standard (IS), chlorogenic acid, from the sample matrix was performed using a Capcell-MG C18 analytical column (100 2.0 mm × 5 µm), with a gradient of acetonitrile and water containing 0.1% acetic acid as the mobile phase. Detection was performed on a triple quadrupole tandem mass spectrometer equipped with electrospray ionization source operated in negative ion selected reaction monitoring mode. The method was linear in the concentration range 10,2500 ng/mL. The deviations of both intra- and inter-day precisions (RSD) were 7.1% and the assay accuracies were within 99.2,106.5%. Echinacoside proved to be stable during sample storage, preparation and analysis when an antioxidant solution was used. The method was successfully applied to a pharmacokinetic study in rats after an intragastric administration of echinacoside (100 mg/kg). With the lower limit of quantification at 10 ng/mL, this method proved to have sufficient selectivity, sensitivity and reproducibility for the pharmacokinetic study of echinacoside. Copyright © 2009 John Wiley & Sons, Ltd. [source] Determination of quinapril and quinaprilat in human plasma by ultraperformance liquid chromatography,electrospray ionization mass spectrometryBIOMEDICAL CHROMATOGRAPHY, Issue 5 2009Bhavesh Dasandi Abstract A novel, specific and sensitive ultraperformance liquid chromatography tandem mass spectrometry (UPLC,MS/MS) method was developed for the simultaneous determination of quinapril and its active metabolite quinaprilat in human plasma. The method involves a simple, one-step extraction procedure coupled with an Acquity UPLCÔ BEH C18 column (100 × 2.1 mm, i.d., 1.7 µm) with isocratic elution at a flow-rate of 0.2 mL/min and lisinopril as the internal standard. Detection was performed on a triple-quadrupole tandem mass spectrometer in multiple reaction monitoring mode via electrospray ionization. Using 250 µL plasma, the methods were validated over the concentration range 5.010,500.374 ng/mL for quinapril and 10.012,1000 ng/mL for quinaprilat, with a lower limit of quantification of 5.010 ng/mL for quinapril and 10.012 ng/mL for quinaprilat. The intra- and inter-day precision and accuracy were within 10.0%. The recovery was 85.8, 62.6 and 61.3% for quinapril, quinaprilat and lisinopril, respectively. Total run time was 3.0 min only. Copyright © 2008 John Wiley & Sons, Ltd. [source] Determination of huperzine A in human plasma by liquid chromatography,electrospray tandem mass spectrometry: application to a bioequivalence study on Chinese volunteersBIOMEDICAL CHROMATOGRAPHY, Issue 4 2008Wei Li Abstract A simple, sensitive and selective LC-MS-MS method has been developed for the quantification of huperzine A in human plasma. Huperzine A and pseudoephedrine hydrochloride (internal standard) were isolated from human plasma by extraction with ethyl acetate, chromatographed on a C18 column with a mobile phase consisting of 0.2% formic acid,methanol (15:85, v/v) and detected using a tandem mass spectrometer with an electrospray ionization interface. The lower limit of quantification was 0.0508 ng/mL, and the assay exhibited a linear range of 0.0508,5.08 ng/mL (r = 0.9998). The method was successfully applied to investigate the bioequivalence between two kinds of tablets (test vs reference product) in 18 healthy male Chinese volunteers. After a single 0.2 mg dose for the test and reference product, the resulting means of major pharmacokinetic parameters such as AUC0,24, AUC0,,, Cmax, Tmax and t1/2 of huperzine A were 16.35 ± 3.42 vs 16.38 ± 3.61 ng h/mL, 17.53 ± 3.80 vs 17.70 ± 3.97 ng h/mL, 2.47 ± 0.49 vs 2.51 ± 0.51 ng/mL, 1.3 ± 0.4 vs 1.2 ± 0.3 h and 5.92 ± 0.75 vs 6.18 ± 0.66 h, respectively, indicating that these two kinds of tablets were bioequivalent. Copyright © 2007 John Wiley & Sons, Ltd. [source] Simple determination of huperzine A in human plasma by liquid chromatographic,tandem mass spectrometric methodBIOMEDICAL CHROMATOGRAPHY, Issue 1 2007Yun-Xia Li Abstract Huperzine A is a potent, reversible acetylcholinesterase inhibitor. In the present work, a rapid and sensitive LC,MS,MS method for the determination of huperzine A in human plasma using codeine phosphate as internal standard has been developed and validated. The analyte and internal standard were extracted from plasma using ethyl acetate, chromatographed on a C18 column (5 µm, 150 × 4.6 mm i.d.) with a mobile phase consisting of 1% formic acid,methanol (40:60, v/v), and detected using a tandem mass spectrometer with a TurboIonSpray ionization interface. The run time was only 2 min. Good linearity was achieved in the range 0.126 -25.2 ng/mL and the limit of detection in plasma was 0.064 ng/mL. The average recovery for huperzine A was 83.4% from plasma. The analytical sensitivity and accuracy of this assay is adequate for characterization of huperzine A in human plasma. Copyright © 2006 John Wiley & Sons, Ltd. [source] Mass spectrometric determination of insulins and their degradation products in sports drug testingMASS SPECTROMETRY REVIEWS, Issue 1 2008Mario Thevis Abstract Insulins' anabolic and anti-catabolic properties have supposedly led to its misuse in sport. Hence, doping control assays were developed to allow the unequivocal identification of synthetic insulin analogs and metabolic products derived from human insulin and its artificial counterparts in urine and plasma specimens. Analyses were based on immunoaffinity purification and subsequent characterization of target analytes by top-down sequencing-based approaches, which were conducted with hybrid tandem mass spectrometers that consisted of either quadrupole-linear ion trap or linear ion trap-orbitrap analyzers. Diagnostic product ions and analytical strategies are presented and discussed in light of the need to unambiguously identify misused drugs in urine and plasma specimens for doping control. © 2007 Wiley Periodicals, Inc., Mass Spec Rev 27:35,50, 2008 [source] Comparison of negative ion electrospray mass spectra measured by seven tandem mass analyzers towards library formationRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 2 2008ina Volná A library of negative ion electrospray ionization mass spectra and tandem mass spectra (MS/MS) of sulfonated dyes has been developed for fast identification purposes. The uniform protocol has been elaborated and applied to the measurements of more than 50 anionic dyes. Three collision energies are selected in our protocol which ensures that at least one of them provides a suitable ratio of product ions to the precursor ion. The robustness is investigated with altered values of tuning parameters (e.g. the pressure of the nebulizing gas, the temperature and the flow rate of drying gas, and the mobile phase composition). The results of the inter-laboratory comparison of product ion mass spectra recorded on seven different tandem mass spectrometers (three ion traps, two triple quadrupoles and two hybrid quadrupole time of flight instruments) are presented for four representative anionic dyes , azo dye Acid Red 118, anthraquinone dye Acid Violet 43, triphenylmethane dye Acid Blue 1 and Al(III) metal-complex azo dye. The fragmentation patterns are almost identical for all tandem mass analyzers, only the ratios of product ions differ somewhat which confirms the possibility of spectra transfer among different mass analyzers with the goal of library formation. Copyright © 2007 John Wiley & Sons, Ltd. [source] | ||||||||||