Weak duality and the asymptotic determination of mass spectra

1970 ◽  
Vol 65 (4) ◽  
pp. 683-688
Author(s):  
D. Atkinson ◽  
K. Dietz
Keyword(s):  
Mass Spectra ◽  
Weak Duality ◽  
Asymptotic Determination

scholarly journals Новый подход к анализу фазового состава углеродсодержащих материалов методом времяпролетной вторично-ионной масс-спектрометрии

2019 ◽  
Vol 45 (2) ◽  
pp. 50
Author(s):  
М.Н. Дроздов ◽  
Ю.Н. Дроздов ◽  
А.И. Охапкин ◽  
С.А. Краев ◽  
М.А. Лобаев
Keyword(s):  
Mass Spectra ◽  
Secondary Ion Mass Spectrometry ◽  
Simple Algorithm ◽  
Cluster Ions ◽  
Two Phase ◽  
Depth Profiles ◽  
Secondary Cluster ◽  
Phase Systems ◽  
Secondary Ion

AbstractNew possibilities offered by the method of secondary ion mass spectrometry (SIMS) for analysis of the phase composition of carbon-containing materials are considered. Differences are established between the mass spectra of three carbon phases: diamond, diamond-like carbon (DLC), and graphite. A simple algorithm for the quantitative determination of different phases in two-phase systems diamond–graphite and DLC–graphite is proposed that is based on the measurement of relative intensities of secondary cluster ions such as C_8/C_5 and CsC_8/CsC_4. It is shown that nonuniform depth profiles of various carbon phases are formed in diamond structures upon laser cutting and in DLC structures upon thermal annealing.

scholarly journals Gas-Chromatographic Determination of the Trimethylsilyl Derivatives of Polyhydric Alcohol Humectants in Tobacco and in Tobacco Smoke

1971 ◽  
Vol 6 (2) ◽  
Author(s):  
N. Carugno ◽  
S. Rossi ◽  
G. Lionetti
Keyword(s):  
Gas Chromatography ◽  
Mass Spectra ◽  
Triethylene Glycol ◽  
Chromatographic Determination ◽  
Flame Ionization ◽  
Trimethylsilyl Derivatives ◽  
Gas Chromatographic Method ◽  
Derivatives Of ◽  
Quantitative Procedure

AbstractA qualitative and quantitative procedure has been developed for the determination of humectants in manufactured tobacco by gas-chromatographic method with a flame ionization detector. It consists of extraction with methanol, concentration of the extract and treatment with Tri-Sil reagents. The operating gas-chromatographic conditions are set forth. Samples of tobacco containing glycerine, propylene glycol, diethylene glycol, triethylene glycol, 1-3 butylene glycol and sorbitol have been analysed with recoveries, for the first five ones, in the range of 95-104 %. In order to verify that each chromatographic peak corresponded to the relative glycol, with no interference by other silylated compounds, the mass spectra were obtained through the combination of gas-chromatography with mass spectrometry. The results achieved confirm, as far as tobacco is concerned, that the procedure is accurate and precise. The same method for the determination of humectants was extended to cigarette smoke. Even though this involves morecomplicated problems, as compared to tobacco, because of the presence of silylated compounds, it was found that, for certain glycols, the gas-chromatography of the trimethyl derivatives can be also used as a method of analysis. The mass spectra of some polyhydric alcohols are shown

Mass Spectrometric Behaviour of Carboxylated Polyethylene Glycols and Carboxylated Octylphenol Ethoxylates

2003 ◽  
Vol 9 (3) ◽  
pp. 165-173 ◽  
Author(s):  
Magdalena Frańska ◽  
Agnieszka Zgoła ◽  
Joanna Rychłowska ◽  
Andrzej Szymański ◽  
Zenon Łukaszewski ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Alkali Metal ◽  
Mass Spectra ◽  
Secondary Ion Mass Spectrometry ◽  
Metal Cations ◽  
Mass Spectrometric ◽  
Polyethylene Glycols ◽  
Alkali Metal Cations ◽  
Secondary Ion

The mass spectrometric behaviour of mono- and di-carboxylated polyethylene glycols (PEGCs and CPEGCs) and carboxylated octylphenol ethoxylates (OPECs) is discussed. The tendency for ionisation (deprotonation, protonation and cationisation by alkali–metal cations) of carboxylated PEGs was compared with that of non-carboxylated analogues by using both secondary-ion mass spectrometry (SIMS) and electrospray ionisation (ESI). The fragmentation of the PEGCs and CPEGCs is discussed and also compared with their neutral analogues, PEGs. B/E linked-scan mass spectra were recorded, using secondary-ion mass spectrometry as a method for ion generation, for deprotonated and protonated molecules as well as for molecules cationised by alkali–metal cations. The fragmentation behaviour of PEGs is found to be different from that of CPEGCs, The presence of carboxyl groups may be confirmed not only by the determination of molecular weights of the ethoxylates studied, but also on the basis of the fragment ions formed. The metastable decomposition of the [OPEC-H]− ions proceeds through the cleavage of the bond between the octylphenol moiety and the ethoxylene chain and leads to the octylphenoxyl anions. It permits determination of the mass of the hydrophobic moiety of the studied carboxylated alkylphenol ethoxylate. ESI mass spectra recorded in the negative-ion mode were found to be more suitable than SI mass spectra for the determination of the average molecular weight of carboxylated ethoxylates.

scholarly journals 4-t-Butylbenzylation of carboxylic acid for GC–MS analysis

2020 ◽  
Vol 2 (5) ◽  
Author(s):  
Shinji Tsunoi ◽  
Nao Yamamoto ◽  
Tomohiro Yasuhisa ◽  
Riko Akehi ◽  
Itaru Suzuki ◽  
...  
Keyword(s):  
Carboxylic Acid ◽  
Carboxylic Acids ◽  
Water Samples ◽  
Mass Spectra ◽  
Molecular Ions ◽  
Good Sensitivity ◽  
Good Reproducibility ◽  
Methyl Radical ◽  
Microwave Reactor

Abstract We report a 4-t-butylbenzyl derivatization for the analysis of carboxylic acids by GC–MS (EI). Carboxylic acids were analyzed as a 4-t-butylbenzyl ester after the derivatization with 4-t-butylbenzyl bromide. On the mass spectra of 4-t-butylbenzyl ester, [M-15]+ ions were observed with high intensity. These ions were tertiary benzyl cations generated by the elimination of a methyl radical from molecular ions. After optimization of the 4-t-butylbenzyl derivatization conditions using microwave reactor, we established a method for the determination of the carboxylic acids in water samples. The method showed good sensitivity and good reproducibility, and was successfully applied to the analysis of rain water samples.

Mass spectral analysis of acetylated peptides: Implications in proteomics

2019 ◽  
Vol 26 (1) ◽  
pp. 36-45
Author(s):  
Deepika Chandra ◽  
P Gayathri ◽  
Mudita Vats ◽  
R Nagaraj ◽  
MK Ray ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Pseudomonas Syringae ◽  
Mass Spectra ◽  
De Novo ◽  
Spectral Quality ◽  
Tryptic Peptides ◽  
Mass Spectral ◽  
Human Proteins ◽  
Terminal Amino

Sequence determination of peptides using mass spectrometry plays a crucial role in the bottom-up approaches for the identification of proteins. It is crucially important to minimise false detection and validate sequence of the peptides in order to correctly identify a protein. Chemical modification of peptides followed by mass spectrometry is an option for improving the spectral quality. In silico-derived tryptic peptides with different N-terminal amino acids were designed from human proteins and synthesized. The effect of acetylation on the fragmentation of peptides was studied. N-terminal acetylation of the tryptic peptides was shown to form b1-ions, improve the abundance and occurrence of b-ions. In some cases, the intensity and occurrence of some y-ions also varied. Thus, it is demonstrated that acetylation plays an important role in improving the de novo sequencing efficiency of the peptides. The acetylation method was extended to tryptic peptides generated from the proteome of an Antarctic bacterium Pseudomonas syringae Lz4W using the proteomics work flow and mass spectra of the peptides were analysed. Comparison of the MS/MS spectra of the acetylated and unacetylated peptides revealed that acetylation helped in improving the spectral quality and validated the peptide sequences. Using this method, 673 proteins of the 1070 proteins identified were validated.

Gas-Liquid Chromatographic Determination of Chlordene Epoxide in Catfish

1978 ◽  
Vol 61 (1) ◽  
pp. 01-04
Author(s):  
Gabriel D Castillo ◽  
Marshall T Jeffus ◽  
Charles T Kenner
Keyword(s):  
Mass Spectra ◽  
Chromatographic Determination ◽  
Gas Liquid Chromatography ◽  
Edible Portion ◽  
The Third ◽  
Chemical Residues ◽  
Fish Samples ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract Chlordene epoxide was detected in the range of 0.04 to 0.27 ppm in the edible portion of 3 catfish samples during the analysis of 36 fish samples by electron capture gas-liquid chromatography (GLC) for pesticide and industrial chemical residues. Two of these catfish samples were from suppliers in Louisiana and the third was from a Texas supplier. Chlordene was also present; the amount of chlordene epoxide in the 3 samples averaged 46% of the amount of chlordene present. The epoxide was identified by comparison of the mass spectra and the CLC retention times of the samples with reference material prepared in this laboratory.

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