Retention times, gas chromatographic

The purity of the product is greater than 99% as determined by gas chromatographic analysis using a 6-m. column of 30% Carbowax 20M on 60-80 Chromosorb W. The major impurity (<1%) was shown to be 3-heptanol by comparison of gas chromatographic retention times and mass spectral fragmentation patterns with those of an authentic sample. 

Measurements of gas chromatographic retention time are often used as a fast and easy method of estimating vapor pressure. These estimated pressures are related to the gas/substrate partition coefficient, which can be regarded as a ratio of solubility of the substance in the gas to that in the substrate, both solubilities being of the substance in the liquid state. As a result the estimated vapor pressures are of the liquid state. To obtain the solid vapor pressure requires multiplication by the fugacity ratio. It is important to establish if the estimated and reported property is of the vapor or liquid. 

Su,Y., Lei, D.L. Daly, G.,Wania, F. (2002) Determination of octanol-air partition coefficient (KqA) values for chlorobenzenes and polychlorinated naphthalenes from gas chromatographic retention times. J. Chem. Eng. Data, 47, 449 455. 

Wania, F., Lei, Y.D., Hamer, T. (2002) Estimating octanol-air partition coefficients of nonpolar semivolatile organic compounds form gas chromatographic retention times. Anal. Chem. 74, 3478-3483. 

Identification of compounds in volatiles collected from hunting M. cornigera revealed three common components of moth sex pheromone blends (Z)-9-tetradecenal, (Z)-9-tetradecenyl acetate, and (Z)-ll-hexade-cenal [while there was insufficient material for mass spectrometry, gas chromatographic retention time evidence suggests that (Z)-ll-hexadece-... 

Figure 2.2 shows the total ion current trace and a number of appropriate mass chromatograms obtained from the pyrolysis gas chromatography-mass spectrometry analysis of the polluted soil sample. The upper trace represents a part of the total ion current magnified eight times. The peak numbers correspond with the numbers mentioned in Table 2.1 and refer to the identified compounds. The identification was based on manual comparison of mass spectra and relative gas chromatographic retention times with literature data [34, 35] and with data of standards available. In some cases unknown compounds were tentatively identified on the basis of a priori interpretation of their mass spectra (labelled tentative in Table 2.1). 

Tributyltin carboxylates undergo rapid chemical exchange, as evidenced by NMR. As a consequence, even the interfacial reaction between tributyltin carboxylate and chloride is fast. IR, mass spectra, gas chromatographic retention time and chloride assay show that the product of the reaction is tributyltin chloride. 

Controlled release epoxy formulations in which tin is chemically anchored as tributyltin carboxylate to the polymer chain are discussed. NMR evidence is presented to establish that rapid exchange exists in tributyltin carboxylates. Consequently, even the interfacial reaction between tributyltin carboxylates and chloride is very fast equilibrium constants are reported for the reaction between tributyltin acrylate in hexane and sodium chloride in water. IR spectra, gas chromatographic retention time, chloride assay, and the complex intensity pattern of the molecular ion peaks in the mass spectrum show that the product of the reaction is tributyltin chloride, suggesting that it is the chemical species responsible for antifouling activity in marine environment. 

Lucic, B., Trinajstic, N., Sild, S., Karelson, M., Katritzky, A. R. J. Chem. Inf. Comput. Sci. 39, 1999, 610-621. A new efficient approach for variable selection based on multiregression Prediction of gas chromatographic retention times and response factors. 

Although the company officials and plant personnel cooperated fully in acquiring wastewater samples for analysis, they provided little information concerning identities of reactants of company products. Specific ring substitution patterns are not easily derived from mass spectrometrlc data and are included here only for cases where the literature specifies the Isomer or in cases where we have purchased standards and observed identical mass spectra and gas chromatographic retention times. 

Identification of compounds in the river water extracts was based on the coincidence of gas chromatographic retention times and on the equivalence of electron impact and chemical ionization mass spectra with those of authentic compounds. Quantitation was based on standard curves generated for selected compounds. 

Chromosorb P. In chromatograms obtained from this column at 100°, the retention times of 4-penten-2-one and 3-penten-2-one are 2.6 and 3.9 minutes, respectively. The crude product contains several additional low-boiling components with gas chromatographic retention times in the range 1.6-2.8 minutes. Any 4-penten-2-one present as an impurity exhibits infrared absorption (carbon tetrachloride solution) at 1720 cm.-1 (nonconjugated C=0). 

Stromberg, L. Minor components of Cannabis resin V. Mass spectrometric data and gas chromatographic retention times of cannabinoid components with retention times shorter than that of cannabidiol. J Chromatogr 1974 96 179. 

Decomposition of a 0.07M solution of 2-butene-3-hydroperoxide in benzene at 100°C. had a half-life of 23 hours. The final products were 37% methyl vinyl ketone, 37% methyl vinyl carbinol, and 26% acetone. Attempts to substantiate the identity of the acetone were unsuccessful, but it was the only anticipated product with the correct gas chromatographic retention time on four different absorbents. 

Finkle et al. (46) have established a GC/MS reference data system for the identification of drugs of abuse. The data include phenethylamine derivatives, opiate and synthetic narcotics, barbiturates, and urinary metabolites. These data have been established for use with the gas chromatographic retention time index previously developed. 

Tse et al. (1992) have reported a gas chromatographic retention time method which is simple and rapid for estimating of Henry s law constants. 

For positive identifications by GC/MS, the full mass spectrum of a tentatively identified component was compared to the mass spectrum of an authentic sample. If the spectra were identical, within experimental error, and if the gas chromatographic retention times of standard and unknown components on a 30-meter SE-54 fused silica capillary column agreed within two seconds, the identification was considered positive. When the amount of material present was insufficient for detection using full scan GC/MS techniques, the more sensitive single and multiple ion monitoring techniques were employed. Confirmation in these cases consisted of coincidences of retention times of mass chromatograms of the unknown and of the authentic sample. For chlorinated materials, the molecular ions contained additional information about the chlorine isotope distribution. Confirmation in those cases included the correct isotope... 

The reactions of tetralin in the presence of coal were investigated to determine the extent of conversion along various pathways in the absence of further added catalysts. As may be seen from Figure 1, the yield of products generated under typical liquefaction conditions (450°C, 30 minutes) increases with the amount of coal added. Three products arise from tetralin naphthalene, n-butylbenzene, and 1-methylindan. Positive identification of the latter isomer was made by comparison of gas chromatographic retention times with those of authentic samples of 1- and 2-methylindan prepared by independent synthesis. 

Yang and Yang reported the formation of 12 % 1-methyl cyclobutanol in cyclohexane at room temperature. The identification was made by the gas chromatographic retention time and the infrared spectrum. 

Some difficulties were encountered in the absolute confirmation of configurational and structural isomers where mass spectral peak intensities and mass values of characteristic fragment ions were too similar under the conditions of the analysis. In those instances, however, identification was readily made on the basis of gas chromatographic retention time data. The estimated lower limit of detectability of organochlorine pesticide residues by this analytical scheme and instrument configuration was determined to be approximately 0.05 to 0.1 ppm. 

Acuna-Cueva, R. Hueso-Urena, F. Caheza, N.A.J. Jimenez-Pulido, S.B. Moreno-Carretero, M.N. Martos, J.M.M. Quantitative stmcture-capillary column gas chromatographic retention time relationships for natural sterols (trime-thylsilyl esters) from olive oil. J. Am. Chem. Soc. 2000, 77, 627-630. 

Katritzky, A.R., Ignatchenko, E.S., Barcock, R.A., Lobanov, V.S. and Karelson, M. (1994). Prediction of Gas Chromatographic Retention Times and Response Factors Using a General Quantitative Structure-Property Relationship Treatment. Anal.Chem.,66,1799-1807. 

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