Peptide quantitation with methyl iodide isotopic tags and mass spectrometry

The Analyst ◽  
2010 ◽  
Vol 135 (6) ◽  
pp. 1456 ◽  
Author(s):  
Voislav Blagojevic ◽  
Nickholas Zhidkov ◽  
Samuel Tharmaratnam ◽  
Van Thong Pham ◽  
Harvey Kaplan ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Methyl Iodide ◽  
Peptide Quantitation

Monosaccharide permethylation products for gas chromatography - mass spectrometry: how reaction conditions can influence isomeric ratios

1997 ◽  
Vol 75 (10) ◽  
pp. 1385-1392 ◽  
Author(s):  
Daniel Derbie Asres ◽  
Hélène Perreault
Keyword(s):  
Mass Spectrometry ◽  
Methyl Iodide ◽  
Reaction Times ◽  
Membered Ring ◽  
Gas Chromatography Mass Spectrometry ◽  
Reaction Parameters ◽  
Methylation Analysis ◽  
Reaction Conditions ◽  
Starting Point

Methylation analysis has been widely used for determination of carbohydrate structures by mass spectrometry. Permethylation of monosaccharides yields mixtures of anomeric pyranosides and furanosides. This paper discusses the influence of some of the permethylation reaction parameters on the proportions of isomeric products obtained. The ratios of three five- and six-membered ring products obtained from two permethylated monosaccharides, D-galactose and L-fucose, have been determined as a function of reaction parameters. The method of Ciucanu and Kerek (1) (methyl iodide in dimethyl sulfoxide (DMSO) in the presence of sodium hydroxide (NaOH)) was used as a starting point. The "conventional" method consists of mixing all of the reagents with the substrate and allowing the reaction to proceed with stirring. Both D-galactose and L-fucose under these conditions produced two main permethylated isomers, a furanoside and a pyranoside, along with two other minor isomeric components. We have investigated the effect on the proportion of products obtained of mixing DMSO, substrate, and NaOH for various times prior to the addition of methyl iodide. Results for D-galactose showed that shorter times enhanced the formation of permethylated furanoside isomers, while reducing the proportion of pyranosides. In other sets of experiments, the time and temperature of reaction, following the addition of methyl iodide, were studied. The indication is that 15 min are sufficient to produce complete methylation, with longer reaction times yielding the same results. Again for D-galactose, low reaction temperatures (ca. 10 °C) favored formation of furanoside products. Higher temperatures yielded higher pyranoside/furanoside ratios. Higher quantities of NaOH also favored formation of the main galactopyranoside product. As for L-fucose, the ratio of the main furanoside vs. pyranoside products obtained by permethylation varied in a way similar to permethylated galactoside. Thus, higher temperatures and longer reaction times favored the main fucopyranoside product. Gentler conditions (i.e., shorter reaction times and lower temperatures) significantly favored the formation of the main fucofuranoside product. These results are interesting as they show the possibility of controlling the relative abundance of permethylated isomers of fucose and galactose. They also constitute a warning to chemists who use methylation procedures in their analyses, to the effect that permethylation products may vary considerably if the reaction conditions are not carefully controlled. Keywords: glucose, galactose, fucose, TLC, GC–MS, permethylation, monosaccharides.

scholarly journals Investigation of Elemental Mass Spectrometry in Pharmacology for Peptide Quantitation at Femtomolar Levels

PLoS ONE ◽  
2016 ◽  
Vol 11 (6) ◽  
pp. e0157943 ◽  
Author(s):  
Emmanuelle Cordeau ◽  
Carine Arnaudguilhem ◽  
Brice Bouyssiere ◽  
Agnès Hagège ◽  
Jean Martinez ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Peptide Quantitation ◽  
Elemental Mass ◽  
Elemental Mass Spectrometry

scholarly journals Structural investigation of the carbohydrate element of human pituitary follicle-stimulating hormone by methylation analysis

1972 ◽  
Vol 130 (2) ◽  
pp. 417-423 ◽  
Author(s):  
J. F. Kennedy ◽  
M. F. Chaplin
Keyword(s):  
Mass Spectrometry ◽  
Gas Phase ◽  
Methyl Iodide ◽  
Structural Investigation ◽  
Follicle Stimulating Hormone ◽  
Branch Points ◽  
Methylation Analysis ◽  
Human Pituitary ◽  
Hydrolysis Products ◽  
Stimulating Hormone

A preparation of human follicle-stimulating hormone has been subjected to methylation analysis by using the methyl sulphinyl carbanion–dimethyl sulphoxide–methyl iodide method. The hydrolysis products of the methylated glycoprotein were reduced, acetylated, analysed by gas-phase chromatography and mass spectrometry and identified by comparison with standards. Methylation analysis demonstrated that (1) the d-galactose, mannose, fucose and 2-amino-2-deoxyglucose units exist in the pyranose forms, (2) the 2-amino-2-deoxyglucose units are N-acetylated, (3) the fucopyranose units occupy terminal non-reducing positions, (4) the d-galactopyranose units are linked in the 1- and 2-positions, (5) the mannopyranose units exist in three forms, some as terminal non-reducing residues, some as 1,6-linked residues and some as 1,3,4-linked branch points, and (6) the 2-acetamido deoxyglucopyranose units are 1,6-linked. These structural assignments are compared with other data previously obtained for the carbohydrate moieties of follicle-stimulating hormone.

Gas-Liquid Chromatographic Analysis of N-(4-Chlorophenyl-N′-2,6-difluorobenzoyl)urea Insecticide After Chemical Derivatization

1976 ◽  
Vol 59 (4) ◽  
pp. 938-941
Author(s):  
James F Lawrence ◽  
Kanth M S Sundaram
Keyword(s):  
Mass Spectrometry ◽  
Electron Capture ◽  
Methyl Iodide ◽  
Chromatographic Analysis ◽  
Sodium Hydride ◽  
Full Scale ◽  
Chemical Derivatization ◽  
Liquid Chromatographic Analysis ◽  
Liquid Chromatographic ◽  
Full Scale Deflection

Abstract The gas-liquid chromatographic analysis of TH 6040 (N-(4-chlorophenyl)-N′-(2,6-difluorobenzoyl)urea) was carried out after the insecticide was converted to its N,N′-dimethyl analog (N-methyl-N-(4-chlorophenyl)-N′-methyl-N′-(2, 6-difluorobenzoyl)urea). The methylation was accomplished in DMSO with sodium hydride and methyl iodide. The derivative was thermally stable and chromatographed as a single peak on 3% OV-1 at 235°C. Support for the structure of the product was given by mass spectrometry. The sensitivity of the product to electrolytic conductivity detection was approximately 50 ng for 50% full-scale deflection in the nitrogen mode and 70 ng for the same response in the chloride (reductive) mode. About 0.25 ng was required for 50% full-scale deflection by electron capture (at 1 × 10−9 amp standing current). Foliage samples were analyzed for TH 6040, using the proposed method.

How SIMS microscopy can be used in medicine

1992 ◽  
Vol 50 (2) ◽  
pp. 1602-1603
Author(s):  
Philippe Fragu
Keyword(s):  
Mass Spectrometry ◽  
Biomedical Applications ◽  
Secondary Ion Mass Spectrometry ◽  
Chemical Elements ◽  
Biological Applications ◽  
The Past ◽  
Potential Source ◽  
Secondary Ion ◽  
Chemical Integrity ◽  
Scientific Endeavour

The identification, localization and quantification of intracellular chemical elements is an area of scientific endeavour which has not ceased to develop over the past 30 years. Secondary Ion Mass Spectrometry (SIMS) microscopy is widely used for elemental localization problems in geochemistry, metallurgy and electronics. Although the first commercial instruments were available in 1968, biological applications have been gradual as investigators have systematically examined the potential source of artefacts inherent in the method and sought to develop strategies for the analysis of soft biological material with a lateral resolution equivalent to that of the light microscope. In 1992, the prospects offered by this technique are even more encouraging as prototypes of new ion probes appear capable of achieving the ultimate goal, namely the quantitative analysis of micron and submicron regions. The purpose of this review is to underline the requirements for biomedical applications of SIMS microscopy.Sample preparation methodology should preserve both the structural and the chemical integrity of the tissue.

Imaging of Al-Li-Cu alloys with a Scanning Ion Microprobe

1990 ◽  
Vol 48 (2) ◽  
pp. 314-315
Author(s):  
K.K. Soni ◽  
D.B. Williams ◽  
J.M. Chabala ◽  
R. Levi-Setti ◽  
D.E. Newbury
Keyword(s):  
Mass Spectrometry ◽  
Secondary Ion Mass Spectrometry ◽  
Equilibrium Phase ◽  
Icosahedral Symmetry ◽  
Ion Microprobe ◽  
X Ray ◽  
Cu Alloys ◽  
Two Phases ◽  
The University ◽  
Secondary Ion

In contrast to the inability of x-ray microanalysis to detect Li, secondary ion mass spectrometry (SIMS) generates a very strong Li+ signal. The latter’s potential was recently exploited by Williams et al. in the study of binary Al-Li alloys. The present study of Al-Li-Cu was done using the high resolution scanning ion microprobe (SIM) at the University of Chicago (UC). The UC SIM employs a 40 keV, ∼70 nm diameter Ga+ probe extracted from a liquid Ga source, which is scanned over areas smaller than 160×160 μm2 using a 512×512 raster. During this experiment, the sample was held at 2 × 10-8 torr.In the Al-Li-Cu system, two phases of major importance are T1 and T2, with nominal compositions of Al2LiCu and Al6Li3Cu respectively. In commercial alloys, T1 develops a plate-like structure with a thickness <∼2 nm and is therefore inaccessible to conventional microanalytical techniques. T2 is the equilibrium phase with apparent icosahedral symmetry and its presence is undesirable in industrial alloys.

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