Mass spectrometric analysis of prenyl phosphates and their glycosylated forms.

Three different mass spectrometric method suitable for the analysis of polyprenyl and dolichyl phosphates and their glycosylated forms are described. Fast atom bombardment mass spectrometry (FAB MS) of glycosyl monophosphopolyprenols produces negative ions characteristic of the intact molecule. Tandem mass spectrometry of (M-H)- anions allows the determination of masses of both glycosyl and lipid moieties. Thus, for example, FAB-MS/MS of a mixture of native glycosyl monophosphopolyprenols isolated from ethambutol-treated Mycobacterium smegmatis enabled us to detect two novel pentosyl monophosphopolyprenols. Two other methods are proposed for the analysis of prenyl phosphates, as these compounds do not produce fragments in FAB-MS/MS at low collisional energy. By Desorption Electron Impact ionization (DEI) an intense (M-H3PO4)+ ion as well as fragments corresponding to the successive loss of isoprene residues (68 Da) can be observed. Alternatively, Desorption Chemical Ionization yields ions corresponding to the loss of 66, 78 and 98 Da (i.e. of a part or the entire phosphate moiety) of a prenyl phosphate molecule. Tandem mass spectrometry of the (M-H-98)- ion gives a series of intense fragments differing by 68 mass units over the whole mass range.

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Microprobe two-step laser mass spectrometry as an analytical tool for meteoritic samples

Symposium - International Astronomical Union ◽

10.1017/s0074180900009451 ◽

1997 ◽

Vol 178 ◽

pp. 305-320 ◽

Cited By ~ 11

Author(s):

Simon J. Clemett ◽

Richard N. Zare

Keyword(s):

Mass Spectrometry ◽

Rapid Heating ◽

Multiphoton Ionization ◽

Mass Spectrometric ◽

Spectrometric Method ◽

Spectrometric Analysis ◽

Laser Mass Spectrometry ◽

Mass Spectrometric Method ◽

Complex Materials ◽

Spot Area

Microprobe two-step laser mass spectrometry (μL2MS) is a new mass spectrometric method in which the two essential steps of any mass spectrometric analysis, vaporization and ionization, are carried out using two independent laser sources. In the first step, the output of a pulsed infrared laser is focused on the sample to cause rapid heating in the spot area illuminated, which is typically 40 μm by 40 μm. In the second step, the output of a pulsed ultraviolet laser causes (1+1) resonance-enhanced multiphoton ionization (REMPI) of those desorbed neutral molecules that (1) are able to absorb this UV wavelength and (2) whose ionization potential is less than the energy of two photons of this UV wavelength. The resulting ions are then mass analyzed in a reflectron time-of-flight apparatus. Under suitable conditions fragmentation can be avoided in both the vaporization and ionization steps so that μL2MS can be applied to the analysis of a mixture of molecules. Applications of μL2MS to meteorite samples are presented as a means of detecting trace amounts of certain organic molecules present in complex materials without prior sample preparation, extraction, purification, and separation steps. Moreover, this analysis can be carried out with micrometer spatial resolution so that in favorable cases the presence or absence of certain molecules can be correlated to mineralogical features of the sample.

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Rapid diagnosis of phenylketonuria by quantitative analysis for phenylalanine and tyrosine in neonatal blood spots by tandem mass spectrometry

Clinical Chemistry ◽

10.1093/clinchem/39.1.66 ◽

1993 ◽

Vol 39 (1) ◽

pp. 66-71 ◽

Cited By ~ 233

Author(s):

D H Chace ◽

D S Millington ◽

N Terada ◽

S G Kahler ◽

C R Roe ◽

...

Keyword(s):

Mass Spectrometry ◽

Tandem Mass Spectrometry ◽

Neonatal Screening ◽

Screening Method ◽

Dried Blood Spots ◽

Spectrometric Method ◽

Tandem Mass ◽

Mass Spectrometric Method ◽

Blood Spots ◽

Minimal Sample

Abstract A new method for quantifying specific amino acids in small volumes of plasma and whole blood has been developed. Based on isotope-dilution tandem mass spectrometry, the method takes only a few minutes to perform and requires minimal sample preparation. The accurate assay of both phenylalanine and tyrosine in dried blood spots used for neonatal screening for phenylketonuria in North Carolina successfully differentiated infants who had been classified as normal, affected, and falsely positive by current fluorometric methods. Because the mass-spectrometric method also recognizes other aminoacidemias simultaneously and is capable of automation, it represents a useful development toward a broad-spectrum neonatal screening method.

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Discovery of Unexpected Sphingolipids in Almonds and Pistachios with an Innovative Use of Triple Quadrupole Tandem Mass Spectrometry

Foods ◽

10.3390/foods9020110 ◽

2020 ◽

Vol 9 (2) ◽

pp. 110 ◽

Cited By ~ 3

Author(s):

Federico Maria Rubino ◽

Michele Dei Cas ◽

Monica Bignotto ◽

Riccardo Ghidoni ◽

Marcello Iriti ◽

...

Keyword(s):

Mass Spectrometry ◽

Tandem Mass Spectrometry ◽

Neutral Loss ◽

Spectrometric Method ◽

Total Lipid Extract ◽

Tandem Mass ◽

Mass Spectrometric Method ◽

Triple Quadrupole ◽

Loss Experiment ◽

Long Chain

The densely packed storage of valuable nutrients (carbohydrates, lipids, proteins, micronutrients) in the endosperm of nuts and seeds makes the study of their complex composition a topic of great importance. Ceramides in the total lipid extract of some ground almonds and pistachios were searched with a systematic innovative discovery precursor ion scan in a triple quadrupole tandem mass spectrometry, where iso-energetic collision activated dissociation was performed. Five descriptors were used to search components with different C18 long chain bases containing different structural motifs (d18:0, d18:1, d18:2, t18:0, t18:1). The presence of hexoside unit was screened with a specific neutral loss experiment under iso-energetic collision activated dissociation conditions. The discovery scans highlighted the presence of two specific hexosyl-ceramides with a modified sphingosine component (d18:2) and C16:0 or C16:0 hydroxy-fatty acids. The hexosyl-ceramide with the non-hydroxylated fatty acid seemed specific of pistachios and was undetected in almonds. The fast and comprehensive mass spectrometric method used here can be useful to screen lipid extracts of several more seeds of nutraceutical interest, searching for unusual and/or specific sphingosides with chemically decorated long chain bases.

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A Novel Simultaneous Estimation of Sofosbuvir and Velpatasvir in Human Plasma by Liquid Chromatography Tandem-Mass Spectrometry after Protein Precipitation Method

Current Pharmaceutical Analysis ◽

10.2174/1573412914666180910102353 ◽

2019 ◽

Vol 15 (7) ◽

pp. 710-715

Author(s):

S.T. Narenderan ◽

Basuvan Babu ◽

T. Gokul ◽

Subramania Nainar Meyyanathan

Keyword(s):

Mass Spectrometry ◽

Tandem Mass Spectrometry ◽

Human Plasma ◽

Multiple Reaction Monitoring ◽

Simultaneous Estimation ◽

Pharmacokinetic Studies ◽

Tandem Mass ◽

Mass Spectrometric Method ◽

Highly Sensitive ◽

Tandem Mass Spectrometric

Objective: The aim of the present work is to achieve a novel highly sensitive chromatographic method for the simultaneous determination of hepatitis C agents, sofosbuvir and velpatasvir from human plasma using ritonavir as an internal standard. Methods: Chromatographic separation was achieved using Hypersil C18 column (50mm x 4.6mm, 3μm) with an isocratic elution mode using the mobile phase composition 10 mM ammonium formate buffer (pH 5.0): acetonitrile (20:80 v/v) pumped at a flow rate of 0.5 ml/min. The detection was carried out by tandem mass spectrometry using Multiple Reaction Monitoring (MRM) positive Electrospray Ionization (ESI) with proton adducts at m/z 530.10 > 243.10, 883.40 > 114.0 and 721.25 > 197.0. Results: The method validated as per USFDA guidelines with respect to linearity, accuracy, and precision was found to be acceptable over the concentration range of 0.2–2000 ng/ml and 5-2000 ng/ml for sofosbuvir and velpatasvir respectively and the method was found to be highly sensitive and selective. Conclusion: The developed tandem mass spectrometric method is robust and can be applied for the monitoring of plasma levels of the analyzed drug in preclinical and clinical pharmacokinetic studies.

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Vitamin D analyses in veterinary feeds by gas chromatography-tandem mass spectrometry

European Journal of Mass Spectrometry ◽

10.1177/14690667211000244 ◽

2021 ◽

pp. 146906672110002

Author(s):

Andreas Lehner ◽

Margaret Johnson ◽

Alan Zimmerman ◽

Justin Zyskowski ◽

John Buchweitz

Keyword(s):

Mass Spectrometry ◽

Vitamin D ◽

Gas Chromatography ◽

Liquid Chromatography ◽

Tandem Mass Spectrometry ◽

Vitamin D3 ◽

Mass Spectrometric ◽

Chromatographic Behavior ◽

Tandem Mass ◽

Chromatography Tandem Mass Spectrometry

This report examines the feasibility of determination of Vitamin D3, D2 and their 25-hydroxy metabolites utilizing Gas Chromatography Tandem Mass Spectrometry (GC/MS/MS) as a potential alternative to popular Liquid Chromatography Tandem Mass Spectrometric (LC/MS/MS) methodologies. The GC/MS/MS approach was found to operate reasonably well despite long-standing concerns that gas-liquid chromatography of vitamin D compounds invoke thermal rearrangements owing to the relatively high inlet and capillary column temperatures used. The workup procedure involved incubation of feed samples with concentrated potassium hydroxide for overnight fat saponification, extraction of D Vitamins in n-hexane and reaction with N,O-bis(trimethylsilyl)trifluoroacetamide at 70 °C for 30 mins. In addition to parent compounds, small amounts of pyro-, isopyro-, and iso-vitamin D and isotachysterol3 variants were obtained from each Vitamin D-related compound upon extraction and GC/MS/MS analysis. Mass spectral and chromatographic behavior of these compounds are herein described and interpreted. Multiple Reaction Monitoring settings on GC/MS/MS included m/z 456→351 for Vitamin D3 and m/z 486→363 for Vitamin D2. Trimethylsilylation enabled single predominant peaks for Vitamins D3 and D2, and sample workup in the presence of deuterated Vitamin D analogs enabled accurate and precise sensitivity to 1 ppb (ng/g) in feeds. The method could be extended with reasonable accuracy to 25-hydroxy (25OH) compounds, but accuracies would be significantly improved by inclusion of respective 25OH-specific deuterated internal standards. The method was applied to 27 submissions of suspect dog foods of which 22% were discovered elevated and 44% were discovered to contain toxic levels of Vitamin D3. The described method was thus discovered to provide a suitable mass spectrometric approach for Vitamin D, proving itself here specifically of value in detection of ergocalciferol and cholecalciferol in animal feeds. The specificity and sensitivity of the tandem quadrupole approach can enable suitable applicability to serum determination if desired.

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