GC Retention Indices Research Articles

Volatile Components of a Chicken Feather Hydrolysate that is Highly Attractive to the West Indian and Mexican Fruit Fly (Diptera: Tephritidae)2

A chicken feather hydrolysate prepared by heating feathers with 6N hydrochloric acid was highly attractive to the West Indian fruit fly, Anastrepha obliqua (Macquart), and the Mexican fruit fly, Anastrepha ludens (Loew). In cage-top laboratory tests to determine the influence of pH on attraction, chicken feather hydrolysate, adjusted to pH 8.0, elicited the greatest response from adult A. obliqua; the attraction response was more than twice that observed for a 10% NuLure® (Miller Chemical and Fertilizer Corp., Hanover, PA) standard. Neutral or slightly acidic preparations of chicken feather hydrolysate were less effective. While A. ludens was less attractive in the laboratory tests to a 25% chicken feather hydrolysate than a 10% NuLure standard, A. obliqua appeared slightly more attracted to the hydrolysate than NuLure, but not significantly. In a 5-day field test using sterile released A. ludens, 4.5% chicken feather hydrolysate, adjusted to pH 8.0, caught almost 2.5 times more flies than 10% NuLure. Twenty-three volatile compounds that emanated from chicken feather hydrolysate were identified by headspace analysis using GC-MS and GC retention index comparison techniques. Among the volatiles were 7 ketones, 6 alcohols, 2 aldehydes, 2 chlorocarbons and 2 furans. At pH 8.0, the five most abundant compounds in decreasing order were 4-methyl-2-pentanone (76.3%), 4-methyl-2-pentanol (16.5%), 1-hexanol (3.1%), 1-heptanol (0.81%) and 2-butoxyethanol (0.64%).

Leaf Oils of Two Myrcianthes Species from Argentina: M. pungens (Berg.) Legrand and M. cisplatensis (Camb.) Berg.

The essential oils isolated by hydrodistillation from the leaves of Myrcianthes cisplatensis (Camb.) Berg, and M. pungens (Berg.) Legrand were analyzed using GC (retention indices) and GC/MS. The major components of the oils of M. cisplatensis and M. pungens were 1,8-cineole (40.7–45.8%) and limonene (17.3–22.1%).

Calibration of a Commercial Solid-Phase Microextraction Device for Measuring Headspace Concentrations of Organic Volatiles

Solid-phase microextraction (SPME) is a versatile new technique for collecting headspace volatiles prior to GC analysis. The commercial availability of uniform SPME fibers makes routine, practical quantitation of headspace concentrations possible, but straightforward information for relating GC peak areas from SPME analyses to headspace concentrations has not been available. The calibration factors (amount absorbed by the fiber divided by headspace concentration) were determined for 71 compounds using SPME fibers with a 100 μm poly(dimethylsiloxane) coating. The compounds ranged from 1 to 16 carbons in size and included a variety of functional groups. Calibration factors varied widely, being 7000 times higher for tetradecane than for acetaldehyde. Most compounds with a Kovats retention index of <1300 on a nonpolar GC column (DB-1) equilibrated with the fiber in 30 min or less. A regression model is presented for predicting the calibration factor from GC retention index, temperature, and analyte functional class. The calibration factor increased with retention index but decreased with increasing sampling temperature. For a given retention index, polar compounds such as amines and alcohols were absorbed by the fibers in greater amounts than were hydrocarbons. Henry's law constants determined using SPME were in general agreement with literature values, which supported the accuracy of the measured calibration factors. An unexpected concentration dependence of calibration factors was noted, especially for nitrogen-containing and hydroxy compounds; calibration factors were relatively higher (the SPME fiber was more sensitive) at the lower analyte concentrations.

An Environmentally Significant Experiment Using GC/MS and GC Retention Indices in an Undergraduate Analytical Laboratory

An undergraduate laboratory experiment has been developed in which the students extract and analyze the additives from plastic food wrap, Tygon tubing and plastic soda bottles that have been crushed in a bottle return machine. The modifiers are extracted from the plastics using methylene chloride and/or methanol as solvents and the extracts are analyzed by GC/MS. Identifications are carried out by a combination of automated computer and manual library searches and chromatographic retention indices.

Essential Oil of the Wood ofThuja occidentalisL.

ABSTRACT Composition of the heartwood oil of Thuja occidentalis L. was investigated by a combination of capillary GC (retention indices) and GC/MS. The oil was obtained by steam distillation of various lots of waste residues from cedar shingle industries. Twelve out of 20 observed compounds were identified. Monooxygenated sesquiterpene compounds are the most important components (80% of the total). Occidentalol is the main component: its relative concentration varies between 20% and 50%, depending on the isolation parameters. This concentration decreased as the isolation proceeded, typically from 40–50% to 10–20% between 1 and 5 hours of distillation. Three occidol isomers, occidenol, and α-, β- and gamma;-eudesmols were also observed in relative concentrations of 4% to 12%. The monoterpene family is represented by terpinen-4-ol, and carvacrol. α-Thujaplicin, a tropolone derivative, is also among the products. The relative concentration of thujaplicin decreased from 5% to 0% between 1 and 5 hours of disti...

Prediction of Temperature-Programmed Retention Indexes for Polynuclear Aromatic Hydrocarbons in Gas Chromatography

The objective of this study was to relate temperatureprogrammed GC retention indexes of nonsubstituted PAHs with calculated molecular properties. Prediction of retention was made by use of a partial least squares regression equation using the descriptors, i.e., first-order valence molecular connectivity, ionization potential, length, height, and quadrupole moment. Retention index predictabitity was studied with respect to individual molecular weight ranges. Pericondensed PAHs were more accurately predicted (RMS=1.6 index units (iu) or coefficient of variation of 0.31%) than catacondensed PAHs (RMS=5.8 iu or coefficient of variation of 1.1%) with the descriptor set employed

Pyrolysis—gas chromatography—mass spectrometry of poly(dialkylsilylenes)

A series of silylene copolymers with di- n-alkyl substituent groups varying from dimethyl to di- n-hexyl were pyrolysed in an analytical pyrolyser coupled to a capillary GC—MS system. The thermal decomposition of the silylene copolymers begins at about 200°C and proceeds via cyclic oligomer formation. The pyrolysis at 300°C of those copolymers which contain dimethylsilylene units lead to tetracycles and pentacycles, but those which have ethyl or longer alkyl substituents decompose exclusively to tetracycles. The copolymer composition and structure were evaluated from the pyrolysis product distribution data. Mass spectra and GC retention indices were obtained on several di- n-alkylsilylene cyclotetramers and cyclopentamers.

Analysis of amines in petroleum

AbstractAn analytical method for differentiation of primary, secondary, and tertiary amines using exhaustive trifluoroacetylation prior to GC/MS has been developed. Using the conditions described in the report, most primary amines add two and secondary amines add one trifluoroacetyl group. In general, tertiary amines do not react. GC retention indices and relative GC/MS total ion current response factors for 102 trifluoroacetyl derivatives are reported. Examples of the application of the method to petroleum and coal liquid products are provided. Because of the limited thermal stability of the derivatives of primary amines, the method is applicable only to distillates boiling below 370 °C (700 °F).

The Essential Oil of the Flowers of Heracleum antasiaticum Manden. Grown in Russia

ABSTRACT The essential oil of the flowers of Hogweed (Heracleum antasiaticum) cultivated in St. Petersburg region, was collected by water distillation. It was analyzed by GC (retention indices) and GC/MS. Thirteen components were identified and the major constituent was found to be octyl 4-methylvalerate (86%).

Compositional studies of high-temperature coal tar by GC/FTIR analysis of light oil fractions

A method for determination of the composition of the light oil fractions in high-temperature coal tar by means of distillation, followed by gas chromatography on a crosslinked fused-silica, capillary column coated with optimum amount of stationary phase and identification by capillary gas chromatography/Fourier transform infrared spectrometry combined with GC retention indices (GC/FTIR-RI) is described. This method was effectively used to identify complex mixture such as coal tar without any standard samples, especially, adapted for isomeric compounds. More than 60 and 50 compounds were also separated and identified respectively in light oil fractions. This shows the capability of the capillary GC/FTIR combined with GC retention indices to identify isomers not accomplished by GC/MS.

Speciation and GC retention indices of some organotin compounds in water

AbstractAnalytical methods have been developed for the quantitative determination of Bu4Sn, Bu3Sn+, Bu2Sn2+, BuSn3+, Me3BuSn, Me2Bu2Sn, MeBu3Sn, MeBuSn2+, Me2BuSn+ and MeBu2Sn+ in water. Organotin compounds are extracted from water with tropolone at 0.1 % in n‐pentane, derivatized with n‐pentylmagnesium bromide and determined by gas chromatography with flame photometric detection or flame ionization detection. Absolute detection limits are 0.05‐0.12 ng and 1.2‐13 ng as tin, respectively. The method was applied to the analysis of spiked tap‐water containing 0.3‐1000 ng cm−3 of each of the organotin compounds.

パージ＆トラップ法におけるＧＣ保持指標及び定量値の再現性について

パージ＆トラップ法におけるＧＣ保持指標及び定量値の再現性について

Relationship between gas chromatographic retention indexes and computer-calculated physical properties of four compound classes

The Austin Model (AM1) hamiltonian in MOPAC, a semi-empirical molecular orbital program, was used to calculate molecular polarizabilites, ionization potentials, and dipole moments for polycyclic aromatic hydrocarbons, polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins, and dibenzofurans. The relationship between these three physical properties and gas chromatographic retention behavior was inverstigated. Linear predictive equations were developped for four classes of compounds, using the physical properties as independent variables and GC retention indexes as dependent variables.

Analytical Chemistry of Airborne Nitrofluorenes

Abstract Analytical techniques for the analysis of 1-, 2-, 3- and 4-nitrofluorene were developed to enable these species to be determined in the gas and particle phases of the atmosphere. The nitrofluorene isomers were synthesized by electrophilic and gas-phase OH radical-initiated nitration of fluorene and identified by their 1H-NMR and mass spectra. For quantitative analysis deuterated 2- and 4-nitrofluorene were also synthesized for use as internal standard compounds. The GC retention indices of all six compounds were determined on DB-5, DB-1701 and SB-Smectic columns.

A New Identification Method for Aliphatic Compounds Using Linear Equations of the GC Retention Index Value

A New Identification Method for Aliphatic Compounds Using Linear Equations of the GC Retention Index Value

A new identification method for aliphatic compounds using linear equations of the GC Retention Index value.

The Retention Index (I) value and the different I values from two columns, carbowax 20M (20M) and OV101 (ΔI:I20M-IOV101) of aliphatic compounds were calculated by several kinds of linear equations under programmed linear temperature conditions. The equations could be used to predict appropriate compounds as well as a database of I and ΔI values.

Use of the 'ortho effect' for chlorinated biphenyl and brominated biphenyl isomer identification.

The 'ortho effect', observed for chlorinated biphenyls (PCBs) and brominated biphenyls (PBBs) having the 2,2', 2,2',6 or 2,2',6,6' halogens, can be combined with GC retention index for isomer specific identifications by gas chromatography/mass spectrometry (GC/MS). This technique reliably allows accurate structure assignments for environmental monitoring without the use of multiple GC determinations that employ different chromatographic phases. Validation of the ortho effect for 129 PCBs and PBBs is reported, including a survey of all PCB mass spectra in the EPA/NIH mass spectral database. Presence or absence of ortho effect and reduction in magnitude for 2,2', 6,6' substitution may be related to the formation of a planar, bridged halonium ion intermediate upon electron ionization in the mass spectrometer.

Electrophilic bromination of dibenzo- [formula omitted]-dioxin

Dibenzo- p -dioxin has been brominated under standard electrophilic conditions to yield mono- through octabromodibenzodioxin. The GC retention indices (RI) for thirteen products have been measured and correlated with the retention indices calculated for the corresponding chlorodibenzodioxins. Mass spectra for the eight major congeners are reported. Brominated dibenzodioxins (PBDDs) may be widely dispersed in the environment, arising from oxidative ring closure of fire retardant brominated diphenyl ethers, combustion of other bromine containing materials, from the use of brominated phenols as synthetic intermediates, and other routes analogous to the formation of the polychlorinated dibenzodioxins (PCDDs). In order to monitor possible environmental contamination by highly toxic PBDDs, authentic analytical chemical standards of these compounds must be available. We wish to report the synthesis of certain congeners of mono-through octa-PBDDs, mass spectral characteristics and retention indices for these compounds. The retention indices for these compounds were found to correlate well with the calculated and observed values of the PCDDs. We have recently developed a model which correlates retention index with structure and provides a simple method to calculate the RI for the PCDDs. This correlation was used to assist in assigning structures while minimizing potential human exposure to these materials.

Electrophilic bromination of dibenzofuran

Dibenzofuran has been brominated under standard electrophilic conditions to yield mono- through octabromodibenzofuran. The GC retention indices for ten products have been measured and correlated with the retention indices for the corresponding chloro dibenzofurans. Mass spectra for the eight major products are reported.

Utilization of the Sadtler standard RI system in micropollution analyses

AbstractDuring the development of a GC retention index library very rigorous standard parameters were used in the SADTLER laboratories. Because most chromatographers presumably have their “favourite” and well‐proven columns a study has been carried out on how to make use of them for standard index generation. Variables such as column geometry, split ratio, and film thickness were examined and the calculated indices were compared to some “basic” values. Splitless and cool on‐column injection techniques were also investigated and comparable temperature programming indices have been obtained. Finally, standard index values of 53 volatile halogenated hydrocarbons measured on very thick‐film bonded fused silica capillary columns are tabulated.