Correlation Between GC Retention Data and Relative Molecular Weight of N,N-Bis(2,2,2-trifluoroethyl)dithiocarbamates of Some Divalent Metals

1996 ◽  
Vol 61 (11) ◽  
pp. 1609-1614 ◽  
Author(s):  
Ján Hrouzek ◽  
Ján Krupčík ◽  
Ivan Skačáni
Keyword(s):  
Molecular Weight ◽  
Correlation Coefficients ◽  
Retention Indices ◽  
Chromatographic Retention ◽  
Retention Data ◽  
Capillary Gc ◽  
Data Retention ◽  
Divalent Metals ◽  
Relative Molecular Weight ◽  
Linear Retention Indices

The correlation of gas-chromatographic retention data (retention times and linear retention indices) and relative molecular weight was examined for N,N-bis(2,2,2-trifluoroethyl)dithiocarbamate chelates of some divalent metals. Regression analysis of data obtained by capillary GC on a non-polar column heated by applying a dual-ramp temperature programme gave linear dependences possessing reasonable correlation coefficients.

scholarly journals The separation and sequencing of permethylated peptides by mass spectrometry directly coupled to gas-liquid chromatography

1976 ◽  
Vol 157 (3) ◽  
pp. 777-780 ◽  
Author(s):  
J D Priddle ◽  
K Rose ◽  
R E Offord
Keyword(s):  
Mass Spectrometry ◽  
Molecular Weight ◽  
Chemical Ionization ◽  
Chromatographic Retention ◽  
Gas Liquid Chromatography ◽  
Retention Data ◽  
Primary Sequence ◽  
Peptide Derivatives ◽  
Derivatives Of

The use of g.l.c. coupled to mass spectrometry to separate and sequence permethylated acetyl- and trifluoroacetyl-peptides in a single operation is described. Both electron impact and chemical ionization were used to induce fragmentation, and the latter was found to be more sensitive. Chromatographic retention data are presented which suggest that peptide derivatives of molecular weight of at least 750 are accessible to the technique. The application of our methods to the determination of the primary sequence of proteins is discussed.

Dependence of Gas Chromatographic Retention Data of Hydrocarbons on the Film Thickness of the Polydimethylsiloxane Stationary Phase

1994 ◽  
Vol 59 (11) ◽  
pp. 2390-2396
Author(s):  
Ján Krupčík ◽  
Ivan Skačáni ◽  
Eva Benická ◽  
Pat Sandra
Keyword(s):  
Film Thickness ◽  
Stationary Phase ◽  
Aromatic Hydrocarbons ◽  
Active Sites ◽  
Capillary Columns ◽  
Retention Indices ◽  
Chromatographic Retention ◽  
Gas Liquid Chromatography ◽  
Retention Data ◽  
Phase Retention

Kovats indices of cyclic and aromatic hydrocarbons, separated by capillary gas liquid chromatography on polydimethylsiloxane capillary columns, were found to increase with increasing stationary phase film thickness. This effect is explained in terms of adsorption of the stationary phase on the active sites of the inner surface of the capillary column. Since the number of active sites is limited, the overall polarity of the polydimethylsiloxane stationary phase is better defined in columns with thick stationary phase films. Interlaboratory reproducibility of retention indices of cyclic and aromatic hydrocarbons is therefore also better when using capillary columns with thick films of the polydimethylsiloxane stationary phase. Retention data obtained on such thick-film columns are influenced by adsorption of the stationary phase on the column walls to a lesser extent than in columns with thinner films.

A new approach to the prediction of gas chromatographic retention indices from physico-chemical constants

1991 ◽  
Vol 56 (10) ◽  
pp. 2042-2054 ◽  
Author(s):  
Igor G. Zenkevich ◽  
Lyudmila M. Kuznetsova
Keyword(s):  
Molecular Weight ◽  
Stationary Phases ◽  
Retention Indices ◽  
Molar Refraction ◽  
Boiling Temperature ◽  
Chromatographic Retention ◽  
New Approach ◽  
Physico Chemical ◽  
Gas Chromatographic Retention Indices ◽  
Chromatographic Retention Indices

A general approach is proposed to the calculation of gas chromatographic retention indices (RI) of organic compounds on standard polydimethylsiloxane stationary phases based on their principal physico-chemical constants such as the boiling temperature, molar refraction or molecular weight. A combination of logical criteria was established for comparing functions of the above parameters for the identification of substances whose RI values are only determined by their boiling temperatures. It is demonstrated that within homologous series, the dependence of the RI value on the boiling temperature or any additive molecular parameter (molecular weight, molar refraction, number of carbon atoms in the molecule, etc.) is nonlinear. If this dependence is taken into account, the RI value of any organic compound can be predicted with a precision comparable to the standard deviation of the statistically processed values determined in nonequivalent conditions.

Gas-Chromatographic Identification of Urinary Carbohydrates Isolated by Anion-Exchange Chromatography

1970 ◽  
Vol 16 (8) ◽  
pp. 722-725 ◽  
Author(s):  
W C Butts ◽  
R L Jolley
Keyword(s):  
Molecular Weight ◽  
Anion Exchange ◽  
Anion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Chromatographic Retention ◽  
Retention Data ◽  
Methylene Unit ◽  
Trimethylsilyl Derivatives ◽  
Chromatographic Peaks ◽  
Anion Exchange Separation

Abstract More than 40 chromatographic peaks representing carbohydrates have been separated from human urine by a carbohydrate analyzer that makes use of anion-exchange chromatography. Ten of these separated carbohydrates have been identified by gas chromatography of their trimethylsilyl derivatives, which were formed by reaction with N-trimethylsilylimidazole. The borate buffer from the anion-exchange separation was removed from the samples before the derivatives were made. Gas-chromatographic retention data have been determined for 37 carbohydrates, including pentoses, hexoses, hexosamines, disaccharides, and trisaccharides, and are tabulated as methylene unit (MU) values. These various classes of carbohydrates elute within distinct MU regions, generally in the order of increasing molecular weight. More than one peak is obtained for those sugars existing in more than one anomeric form.

scholarly journals Quantitative structure-gas chromatographic retention index relationship of long-chain esters: The case of Scandix pecten-veneris L. essential-oil constituents

2016 ◽  
Vol 14 (2) ◽  
pp. 97-104 ◽  
Author(s):  
Marko Mladenovic ◽  
Niko Radulovic
Keyword(s):  
Essential Oil ◽  
Retention Index ◽  
Retention Indices ◽  
Chromatographic Retention ◽  
Retention Data ◽  
Chromatographic Property ◽  
Gas Chromatographic Retention Indices ◽  
Chromatographic Retention Indices ◽  
Relationship Of ◽  
Long Chain

Motivated by a recent identification of two homologous series of branched butanoates and pentanoates in S. pecten-veneris essential oil, with an apparently regular change of their retention index (RI) values, we decided to examine the generality of such structure-chromatographic property relationship. Based on the experimentally obtained retention data (RI values of in total 20 compounds) of hexyl, decyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, heneicosyl and tricosyl isobutanoates and 3-methylbutanoates and selected 2-methylbutanoates, a model was built up that correlates the total number of carbon atoms, Wiener (WI), Balaban (BI) and molecular topological (MTI) indices of the mentioned esters and their RI data (RI = 240.5 + 91.2 x C + 2.94 x WI + 4.6 x 10-5 x BI - 0.381 x MTI). The obtained equation represents a new and simple tool for the prediction of gas chromatographic (retention indices) data for esters of straight long-chain fatty alcohols and branched short aliphatic acids.

scholarly journals Congener-specific partition properties of chlorinated paraffins evaluated with COSMOtherm and gas chromatographic retention indices

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jort Hammer ◽  
Hidenori Matsukami ◽  
Satoshi Endo
Keyword(s):  
Chemical Properties ◽  
High Volume ◽  
Retention Indices ◽  
Chromatographic Retention ◽  
Linear Free Energy Relationship ◽  
Linear Free Energy ◽  
Chlorinated Paraffins ◽  
Gas Chromatographic Retention Indices ◽  
High Volume Production ◽  
Volume Production

AbstractChlorinated Paraffins (CPs) are high volume production chemicals and have been found in various organisms including humans and in environmental samples from remote regions. It is thus of great importance to understand the physical–chemical properties of CPs. In this study, gas chromatographic (GC) retention indexes (RIs) of 25 CP congeners were measured on various polar and nonpolar columns to investigate the relationships between the molecular structure and the partition properties. Retention measurements show that analytical standards of individual CPs often contain several stereoisomers. RI values show that chlorination pattern have a large influence on the polarity of CPs. Single Cl substitutions (–CHCl–, –CH2Cl) generally increase polarity of CPs. However, many consecutive –CHCl– units (e.g., 1,2,3,4,5,6-C11Cl6) increase polarity less than expected from the total number of –CHCl– units. Polyparameter linear free energy relationship descriptors show that polarity difference between CP congeners can be explained by the H-bond donating properties of CPs. RI values of CP congeners were predicted using the quantum chemically based prediction tool COSMOthermX. Predicted RI values correlate well with the experimental data (R2, 0.975–0.995), indicating that COSMOthermX can be used to accurately predict the retention of CP congeners on GC columns.

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