A microengineered alignment bench for a nanospray ionization source

Hemoglobin (Hb) Neuilly-sur-Marne is a new α-chain variant found during a systematic screening. Electrospray mass measurements showed the presence of an abnormal α-chain displaying a shift of +315 u relative to the normal value. Tryptic cleavage of this chain and molecular weight determination of the peptides indicated that the 315 u shift was located into the αT-9 peptide, the molecular weight of which is higher than 3000 Da. High-energy collision spectra of MH+ ions generated by liquid secondary ion mass spectrometry from the normal and abnormal αT-9 afforded mainly amino-terminal containing ions. They indicated that these two peptides have an identical amino acid sequence from their 1st to 25th residues, the mass increase being thus located beyond this point. Too few ions were formed to establish reliably the sequence forward. It was hypothesized that this mass shift could result from a repeated sequence since the sum of the mass of the three residues—leucine, serine and aspartic acid—preceding position 25 is exactly 315 u. To get sequence information above position 25, decomposition of multicharged species was attempted. An ion trap fitted with a nanospray ionization source was used. It produced mainly triply- and quadruply-charged ions. Decomposition of the triply-charged ion afforded a series of singly-charged Y-ions in the expected region, giving a readily interpretable sequence. It confirmed the insertion of a Ser-Asp-Leu sequence above position 25. Surprisingly, decomposition of the quadruply-charged molecular ion gave too few ions to provide sequence information in the expected region. Spectra were dominated by some multicharged Y ions arising from cleavages close to the amino end. Tandem mass spectrometry experiments were performed on the abundant Y303+ ion and produced again a singly-charged Y ion series in the suitable domain which confirmed the above result. In Hb Neuilly-sur Marne this insertion of the Ser-Asp-Leu residues. between positions α-86 and α-87 is very likely due to a slipped strand mispairing mechanism.

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A Novel Combined Microstrip Resonator/Nanospray Ionization Source for Microwave-Assisted Trypsin Digestion of Proteins

Journal of the American Society for Mass Spectrometry ◽

10.1021/jasms.0c00115 ◽

2020 ◽

Vol 31 (8) ◽

pp. 1684-1696

Author(s):

Maria E. Rivera-Albarran ◽

Steven J. Ray

Keyword(s):

Trypsin Digestion ◽

Ionization Source ◽

Microstrip Resonator ◽

Microwave Assisted ◽

Nanospray Ionization

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The glycoproteomics of hawk and caiman tears

BMC Veterinary Research ◽

10.1186/s12917-021-03088-1 ◽

2021 ◽

Vol 17 (1) ◽

Author(s):

Ana Cláudia Raposo ◽

Carlito Lebrilla ◽

Ricardo Wagner Portela ◽

Gege Xu ◽

Arianne Pontes Oriá

Keyword(s):

Tear Film ◽

Molecular Function ◽

Ionization Source ◽

Schirmer Tear Test ◽

Reptile Species ◽

Endopeptidase Activity ◽

Adaptive Processes ◽

Nanospray Ionization ◽

The Stability ◽

Cellular Components

Abstract Background Glycoproteins are important tear components that participate in the stability of the ocular surface. However, the glycopeptides that are present in the tears of wild animals have not yet been described. This work aimed to describe the glycoproteomic profile of roadside hawk (Rupornis magnirostris) and caiman (Caiman latirostris) tears. Methods Tears collected from 10 hawks and 70 caimans using Schirmer tear test strips were used in this study. The samples were submitted to trypsin digestion and separated using a reverse-phase column coupled to a mass spectrometer associated to a nanospray ionization source. The glycoproteins were categorized as: cellular components, biological processes and molecular function, according to the UniProt Knowledgebase. Results As shown by the liquid chromatography–mass spectrometry, all glycopeptides found were classified as N-type. Of the 51 glycoproteins that were identified in the hawk tear film, the most abundant were ovotransferrin, globulins and complement system proteins. In the caiman tear film, 29 glycoproteins were identified. The most abundant caiman glycoproteins were uncharacterized proteins, ATPases, globulins and proteasome components. Ontological characterization revealed that the glycoproteins were extracellular, and the most identified molecular function was endopeptidase activity for both species. Conclusion Glycoproteins are abundant in the tear film of the bird and reptile species studied herein, and all these molecules were shown to have N-type modifications. Location at the extracellular space and an endopeptidase inhibitor activity were the main cell component and molecular function for both species, respectively. These profiles showed differences when compared to human tears, are possibly linked to adaptive processes and can be the basis for further studies on the search of disease biomarkers.

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Effect of Work Parameters for Surface Ionization Source on Ion Mobility Spectrum

CHINESE JOURNAL OF ANALYTICAL CHEMISTRY (CHINESE VERSION) ◽

10.3724/sp.j.1096.2011.01491 ◽

2012 ◽

Vol 39 (10) ◽

pp. 1491-1495

Author(s):

De-Xin ZHANG ◽

Xiao-Guang GAO ◽

Jian JIA ◽

Xiu-Li HE ◽

Jian-Ping LI

Keyword(s):

Ion Mobility ◽

Surface Ionization ◽

Ionization Source ◽

Mobility Spectrum

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A novel and sensitive LC-MS/MS method for the quantitation of ceftiofur in pharmaceutical preparations and milk samples

Combinatorial Chemistry & High Throughput Screening ◽

10.2174/1386207323999201110192558 ◽

2020 ◽

Vol 23 ◽

Author(s):

Serkan Levent ◽

Saniye Özcan ◽

Aysun Geven ◽

Nafiz Öncü Can

Keyword(s):

Quantitative Estimation ◽

Signal To Noise Ratio ◽

Multiple Reaction Monitoring ◽

Pharmaceutical Preparations ◽

Calibration Method ◽

Negative Ion ◽

Cow Milk ◽

Tandem Mass ◽

Ionization Source ◽

Liquid Chromatography Tandem Mass

Introduction:: In the present study, a sensitive and selective liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was described for the determination of ceftiofur (CEF) in cow milk and pharmaceutical preparations. CEF is an antibiotic compound, which is commonly used in the treatment of animal diseases such as respiratory system, soft tissue, and foot infections, as well as postpartum acute puerperal metritis. One of the critical features of CEF is its prescription while breastfeeding of cows; in accordance, its quantitative estimation is essential to assess its residual amounts. Methods:: In the method reported herein, after simple protein precipitation using acetonitrile, the pre-treated samples were introduced in to an LC-MS/MS instrument equipped with a Chromolith® High-Resolution RP-18 series HPLC column (100 mm × 4.6 mm from Merck KGaA, Germany). Electrospray ionization was employed as the ionization source in the triplequadrupole tandem mass spectrometer. Results:: For the calibration method using solvent-based standards; LOQ was 3.038 ng/mL, 12.15 ng/mL, and LOD was 1.215 ng/mL and 6.076 ng/mL for ESI+ and ESI- modes, respectively. On the other hand, for the method of matrix-matched standards; LOQ was 1.701 ng/mL, 10.13 ng/mL, and LOD was 0.486 ng/mL and 5.929 ng/mL for ESI+ and ESI- modes, respectively as obtained from signal to noise ratio. Conclusion:: Applicability of both positive and negative ion modes was tested, and the analyte was detected via multiple reaction monitoring. The distorting effects of the milk matrix on the MS ionization and quantitation of CEF were overcome by using matrix-matched calibration for the first time.

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A Rapid and Sensitive Method for the Pharmacokinetic Study of Janumet (Sitagliptin and Metformin) Tablets by LC-MS/MS Coupled with Ion-Pair Solid Phase Extraction

Current Pharmaceutical Analysis ◽

10.2174/1573412914666181011141714 ◽

2019 ◽

Vol 15 (7) ◽

pp. 776-784

Author(s):

Xiaonian Han ◽

Jing Wang ◽

Jing Huang ◽

Lirong Peng

Keyword(s):

Solid Phase Extraction ◽

Pharmacokinetic Study ◽

Solid Phase ◽

Multiple Reaction Monitoring ◽

Ion Pair ◽

Phase Extraction ◽

Plasma Samples ◽

Ionization Source ◽

Tandem Mass Spectrometric

Background: As first-line treatments for diabetes, sitagliptin and metformin have been widely prescribed as a combination to enhance the therapeutic effect. Objective: To establish a methodology to simultaneously monitor the two drugs in vivo by a reversedphase Liquid Chromatography-Tandem Mass Spectrometric (LC-MS/MS) method. Methods: The two drugs were extracted from 50 μl human plasma by ion-pair solid phase extraction. The separation of the plasma samples was implemented on an Agilent Zorbax SB-CN column (150×4.6 mm, 5.0 µm). The mobile phase was the mixture (80:20, v/v) of methanol and 5.0 mM ammonium formate in water (pH 4.5). An ion trap spectrometer equipped with an electrospray ionization source was utilized to detect the elution in positive mode. Quantification of the analytes was achieved by Multiple Reaction Monitoring (MRM) using the transitions of m/z 408.3→235.1 for sitagliptin and m/z 130.1→ 60.2 for metformin. Results: Sitagliptin and metformin demonstrated good linearity among the range of 1.00-1000 ng/mL and 5.00-4000 ng/mL. The intra-day and inter-day investigations displayed precisions of ≤ 3.6% and an accuracy range of -7.5% to 6.0% for the two drugs. The mean recovery of the two drugs was 96.0% and 98.5%. Under mandatory storage conditions, both the drugs gave an acceptable stability. The throughput of the assay was found to be more than 100 plasma samples per day ascribed to the run time of 3.0 min for each sample. Conclusion: The developed method was successfully applied to a pharmacokinetic study for a fixeddose tablet formulation containing 50 mg sitagliptin and 500 mg metformin in 12 healthy volunteers.

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