Gas Chromatography-infrared Spectroscopy Research Articles

Combined Gas Chromatography–Mass Spectrometry, Gas Chromatography–Infrared, and Computational Approach to Differentiate Constitutional Isomers of Methylpyridine Derivatives

Methylpyridine derivatives serve as crucial components and intermediates in agrochemical products, particularly synthetic auxin herbicides. Accurate structural elucidation of these compounds is required for regulatory compliance and successful product registration. While mass spectrometry (MS) techniques are commonly employed for structural analysis, their effectiveness decreases when dealing with isomeric compounds. In this study, we propose an integrated workflow that combines gas chromatography–infrared spectroscopy (GC-IR) and density functional theory (DFT) calculations to enable structural elucidation of methylpyridine derivatives. GC-IR provides temporally resolved infrared (IR) spectra, enabling qualitative and quantitative analysis without compound isolation. GC-IR can effectively distinguish isomeric compounds by comparing IR spectra of energy-minimized structures calculated using DFT, even when the spectral differences are subtle. Our comprehensive approach leverages GC-MS, GC-IR, and DFT calculations, facilitating robust structural characterization of methylpyridine derivatives utilized in the production of diverse agrochemical products.

Essential Components from Plant Source Oils: A Review on Extraction, Detection, Identification, and Quantification.

Oils derived from plant sources, mainly fixed oils from seeds and essential oil from other parts of the plant, are gaining interest as they are the rich source of beneficial compounds that possess potential applications in different industries due to their preventive and therapeutic actions. The essential oils are used in food, medicine, cosmetics, and agriculture industries as they possess antimicrobial, anticarcinogenic, anti-inflammatory and immunomodulatory properties. Plant based oils contain polyphenols, phytochemicals, and bioactive compounds which show high antioxidant activity. The extractions of these oils are a crucial step in terms of the yield and quality attributes of plant oils. This review paper outlines the different modern extraction techniques used for the extraction of different seed oils, including microwave-assisted extraction (MAE), pressurized liquid extraction (PLE), cold-pressed extraction (CPE), ultrasound-assisted extraction (UAE), supercritical-fluid extraction (SFE), enzyme-assisted extraction (EAE), and pulsed electric field-assisted extraction (PEF). For the identification and quantification of essential and bioactive compounds present in seed oils, different modern techniques-such as high-performance liquid chromatography (HPLC), gas chromatography-mass spectrometry (GC-MS), Fourier transform infrared spectroscopy (FTIR), gas chromatography-infrared spectroscopy (GC-IR), atomic fluorescence spectroscopy (AFS), and electron microscopy (EM)-are highlighted in this review along with the beneficial effects of these essential components in different in vivo and in vitro studies and in different applications. The primary goal of this research article is to pique the attention of researchers towards the different sources, potential uses and applications of oils in different industries.

GC-IR technique a rapid tool for detection of Tramadol in Forensic Confiscated Drugs and Biological Fluids

Tramadol is placed under Drug Controlled Substance Act, in India since 2018, owing to its extensive abuse as a narcotic substance recently. Subsequently, there is increased illegal trafficking across our nation for the drug tramadol. Forensic Science Laboratory, Delhi receives confiscated drugs and toxicological samples for chemical analysis to evaluate their precise composition enabling regulations from law enforcement agencies. Although considered a safe drug for its anti-inflammatory properties when used under medical guidance nevertheless, unintentional fatal tramadol intoxication due to its action on opioid receptors has been reported in several autopsy cases. Contraband tramadol is presently being examined using Gas Chromatography-Mass Spectrometer (GC-MS) and Fourier-transform infrared spectroscopy (FTIR) instrumental techniques in routine forensic examination. In the proposed study, an advanced sensitive technique Gas Chromatography Infrared spectroscopy (GC-IR) was explored as an alternative tool for rapid identification and confirmation. Standard Tramadol was used for method establishment and the method was subsequently applied to seized drug samples and Biological Fluids (blood, and urine samples). Findings of the study indicate that this method can be successfully applied to seized drugs and biological toxicological samples in the forensic examination for the drug Tramadol which was successfully detected by GC-IR. This new rapid analytical method will prove beneficial for the forensic community during routine examination of forensic samples with confirmation.

An interlaboratory study to evaluate the utility of gas chromatography-mass spectrometry and gas chromatography-infrared spectroscopy spectral libraries in the forensic analysis of fentanyl-related substances.

Synthetic opioids such as fentanyl account for over 71,000 of the approximately 107,000 overdose deaths reported in the United States in 2021. Fentanyl remains the fourth most identified drug by state and local forensic laboratories, and the second most identified drug by federal laboratories. The unambiguous identification of fentanyl-related substances (FRS) is challenging due to the absence or low abundance of a molecular ion in a typical gas chromatography-mass spectrometry (GC-MS) analysis and due to a low number of fragment ions that are similar among the many potential isomers of FRS. This study describes the utility of a previously reported gas chromatography-infrared (GC-IR) library for the identification of FRS within a blind, interlaboratory study (ILS) involving seven forensic laboratories. Twenty FRS reference materials, including those with isomer pairs in the library, were selected based on either their presence in the NIST library and/or some similarity of the mass spectra information produced. The ILS participants were requested to use the Florida International University (FIU) GC-MS and GC-IR libraries supplied by FIU to search for matches to their unknown spectra generated from in-house GC-MS and GC-IR analysis. The laboratories reported improvement in the positive identification of unknown FRS from ~75% using GC-MS alone to 100% correct identification using GC-IR analysis. One laboratory participant used solid phase IR analysis, which produced spectra incompatible with the vapor phase GC-IR library to generate a good comparison spectrum. However, this improved when searched against a solid phase IR library.

Utility of gas chromatography infrared spectroscopy (GC-IR) for the differentiation of positional isomers of fentanyl related substances

Forensic laboratories routinely use gas chromatography mass spectrometry (GC–MS) in the identification of controlled substances using both retention time and electron impact ionization (EI) mass spectra. Certain drugs such as positional isomers of some fentanyl related substances (FRS) can produce indistinguishable EI mass spectra but may be differentiated using retention time. The core structure of fentanyl consists of an amide group, a piperidine ring, an aniline ring, and an N-alkyl chain, each providing opportunities for points of substitution that create FRS and corresponding positional isomers. For this study, the analysis by GC coupled to a vapor-phase infrared spectroscopy detector (GC-IR) was used as a complementary technique to GC–MS for the identification of positional isomers of FRS. The result is a novel fentanyl library consisting of 212 different FRS reference compounds. A collaboration among three different laboratories yielded correct identifications of twenty blind samples when searched against the GC-IR FRS library created at Florida International University (FIU). The expected limits of detection for fentanyl using GC-IR range between 0.10 and 0.19 mg/mL, depending on the sample introduction (injector) method and other instrumental parameters. The newly created GC-IR library and its GC–MS counterpart of 212 FRS are shared in the supplementary materials for future use by researchers and practitioners.

Identification and Composition of Clasper Scent Gland Components of the Butterfly Heliconius erato and Its Relation to Mimicry.

The butterfly Heliconius erato occurs in various mimetic morphs. The male clasper scent gland releases an anti‐aphrodisiac pheromone and additionally contains a complex mixture of up to 350 components, varying between individuals. In 114 samples of five different mimicry groups and their hybrids 750 different compounds were detected by gas chromatography/mass spectrometry (GC/MS). Many unknown components occurred, which were identified using their mass spectra, gas chromatography/infrared spectroscopy (GC/IR)‐analyses, derivatization, and synthesis. Key compounds proved to be various esters of 3‐oxohexan‐1‐ol and (Z)‐3‐hexen‐1‐ol with (S)‐2,3‐dihydrofarnesoic acid, accompanied by a large variety of other esters with longer terpene acids, fatty acids, and various alcohols. In addition, linear terpenes with up to seven uniformly connected isoprene units occur, e. g. farnesylfarnesol. A large number of the compounds have not been reported before from nature. Discriminant analyses of principal components of the gland contents showed that the iridescent mimicry group differs strongly from the other, mostly also separated, mimicry groups. Comparison with data from other species indicated that Heliconius recruits different biosynthetic pathways in a species‐specific manner for semiochemical formation.

Toxicological investigations in a death involving 2-MAPB

New psychoactive substances are becoming increasingly popular. However, there is a lack of mass spectral information on parent substances and their corresponding metabolites as well as fatal concentrations in body liquids and tissues. Only very few clinical reports and user reports exist. This is also the case for methylaminopropylbenzofuran (MAPB) isomers.Urine from a decedent was screened using different immuno assays, gas chromatography-mass spectrometry (GC-MS), and liquid chromatography-high resolution mass spectrometry (LC-HRMS/MS). Additionally, respective targets were quantitated in all analyzed specimens by LC-MS/MS. Gas chromatography-infrared spectroscopy (GC-IR) was applied to confirm the identity of the intoxication.GC-MS and the amphetamine immuno assay were useful to track the putative intoxication. However, the chemical structure of 2-MAPB was only elucidated by means of LC-HRMS/MS and GC-IR. 2-MAPB was highest in urine (167µg/mL), followed by gastric content (98.9µg/mL), bile fluid (30.8µg/mL), liver (22.2µg/g), heart blood (16.7µg/mL), and lowest in femoral blood (7.3µg/mL). Besides the parent substance, we detected N-demethyl-2-MAPB and hydroxy-2-MAPB in the urine sample.This case report presents an intoxication caused by 2-MAPB. The 2-MAPB concentration found in femoral blood exceeded those reviewed for 5/6-MAPB. The concentrations of the other specimens cannot be evaluated because there exist no comparative data. The values presented can be applied to assess 2-MAPB intoxications in the future.

Kinetic Studies on the Photo-oxidation Reactions of Methyl-2-methyl Butanoate and Methyl-3-methyl Butanoate with OH Radicals

Kinetics for the reactions of methyl-2-methyl butanoate (M2MB) and methyl-3-methyl butanoate (M3MB) with OH radicals were carried out using the relative rate technique with gas chromatography-flame ionization detection (RR-GC-FID) in the temperature range of 268-363 K and at 760 Torr of N2. The temperature-dependent rate coefficients (k in cm3 molecule-1 s-1) for the reaction of M2MB with OH radicals from 268 to 363 K were measured to be k268KM2MB+OH = (4.62 ± 1.50) × 10-12, k283KM2MB+OH = (4.46 ± 1.41) × 10-12, k298KM2MB+OH = (4.27 ± 1.20) × 10-12, k313KM2MB+OH = (3.99 ± 1.06) × 10-12, k343KM2MB+OH = (3.65 ± 0.94) × 10-12, and k363KM2MB+OH = (3.53 ± 0.80) × 10-12, respectively. Similarly, the temperature-dependent kinetics for the reaction of M3MB with OH radicals were measured to be k268KM3MB+OH = (4.49 ± 1.46) × 10-12, k283KM3MB+OH = (4.40 ± 1.36) × 10-12 , k298KM3MB+OH = (4.14 ± 1.18) × 10-12 , k313KM3MB+OH = (3.90 ± 1.06) × 10-12 , k343KM3MB+OH = (3.52 ± 0.85) × 10-12, and k363KM3MB+OH = (3.42 ± 0.81) × 10-12 respectively. Furthermore, computational calculations were carried out for the title reactions using the CVT/SCT/ISPE method. In addition to this, the product analyses for the studied reactions were elucidated using gas chromatography-mass spectrometry (GC-MS) and gas chromatography-infrared spectroscopy (GC-IR) as analytical tools. Based on the identified products, the possible degradation mechanisms were proposed. Atmospheric lifetimes, radiative forcings (RFs), global warming potentials (GWPs), and photochemical ozone creation potentials (POCPs) were also estimated.

Determining the Regiochemistry and Relative Stereochemistry of Small and Druglike Molecules Using an Alignment Algorithm for Infrared Spectra.

The relative stereochemistry and isomeric substitution pattern of organic molecules is typically determined using nuclear magnetic resonance spectroscopy (NMR). However, NMR spectra are sometimes nonconclusive, e.g., if spectra are extremely crowded, coupling patterns are not resolved, or if symmetry reasons preclude interpretation. Infrared spectroscopy (IR) can provide additional information in such cases, because IR represents a molecule comprehensively by depiction of the complete set of its normal vibrations. The challenge is thereby that diastereomers and substitution isomers often give rise to highly similar IR spectra, and visual distinction is insufficient and may be biased. Here we show the adaptation of an alignment algorithm, originally developed for vibrational circular dichroism (VCD) spectroscopy, to automatically match IR spectra and provide a quantitative measure of the goodness of fit, which can be used to distinguish isomers. The performance of the approach is demonstrated for different use cases: diastereomers of flexible druglike molecules, E/Z-isomers, and substitution isomers of pyrazine and naphthalene. It can be applied to IR spectra measured both in the gas phase (gas chromatography IR) and in solution.

Cl Atom-Initiated Photo-Oxidation Reactions of Vinyl Trifluoroacetate and Allyl Trifluoroacetate in Tropospheric Conditions.

Relative rate (RR) technique coupled with gas chromatography (GC) was used to investigate the kinetics of the reactions of two hydrofluoroesters (allyl trifluoroacetate (CF3C(O)OCH2CH═CH2, ATFA) and vinyl trifluoroacetate (CF3C(O)OCH═CH2, VTFA)) with Cl atoms between 268 and 363 K and at 760 Torr of N2 (or air). The temperature-dependent Arrhenius expressions for the title reactions were obtained to be k268-363KVTFA+Cl = [(7.83 ± 2.26) × 10-12 exp((974 ± 89)/T)] cm3 molecule-1 s-1 and k268-363KATFA+Cl = [(9.03 ± 1.92) × 10-12 exp((883 ± 65)/T)] cm3 molecule-1 s-1, respectively. A negative temperature dependency was observed for both the reactions. In addition to this, the kinetics of the studied reactions was evaluated computationally at the CCSD(T)/cc-pVTZ//MP2/6-311++G(d,p) level of theory in the temperature range of 200-400 K using canonical variational transition (CVT) state theory in conjunction with small curvature tunneling (SCT) corrections and interpolated single point energy (ISPE) methods. The product analysis of the reactions of VTFA and ATFA with Cl atoms in the presence of O2 was also investigated using gas chromatography-mass spectrometry (GC-MS) and gas chromatography-infrared spectroscopy (GC-IR). The plausible oxidation mechanism of the title reactions was proposed based on the product analyses. Further, to comprehend the impact of these molecules on the troposphere, atmospheric lifetimes, lifetime-corrected radiative forcing (RF), and global warming potential (GWP) were estimated and are presented in this manuscript.

Kinetics and Mechanistic Study for Gas Phase Tropospheric Photo-oxidation Reactions of 2,2,2-Trifluoroethyl Methacrylate with OH Radicals and Cl Atoms: An Experimental and Computational Approach.

The photo-oxidation reactions of 2,2,2-trifluoroethyl methacrylate (TFEMA) initiated by OH radicals and Cl atoms were investigated via experimental as well as computational methodologies. The rate coefficients for these reactions were investigated using the relative rate technique (RR) at temperatures between 268 and 363 K. The rate coefficients for the reaction of OH radicals with TFEMA were measured with reference to diethyl ether and propylene. Propane and propylene were used in the kinetic measurements as reference compounds. At 298 K, experimentally obtained rate coefficients for the reaction of TFEMA with OH radicals and Cl atoms are kTFEMA+OHexp-298K = (2.81 ± 0.54) × 10-11 and kTFEMA+Clexp-298K = (1.91 ± 0.44) × 10-10 cm3 molecule-1 s-1, respectively. The Arrhenius expression obtained for the respective reactions are kTFEMA+OHexp-(268-363K) = (7.32 ± 0.62) × 10-12 exp[(400 ± 53) and kTFEMA+Clexp-(268-363K) = (4.10 ± 0.78) × 10-12 exp[(1228 ± 115)/T]. To further complement our experimental findings, rate coefficients were also calculated computationally for the reactions of OH radicals and Cl atoms with TFEMA at CCSD(T)/cc-pVDZ//M062X/6-31+G(d,p) and CCSD(T)/cc-pVDZ//MP2/6-31+G(d,p) levels of theory using canonical variational transition state theory (CVT) with small curvature tunneling (SCT) over the temperature range 200-400 K. Moreover, to analyze the end products formed during the title reactions, qualitative analyses were performed using gas chromatography-mass spectrometry (GC-MS) and gas chromatography-infrared spectroscopy (GC-IR) as analytical tools and degradation mechanisms were proposed for the title reactions. Branching ratios, thermochemical parameters of these reactions, and their impact on the troposphere were discussed.

Gas Phase Kinetics and Mechanistic Insights for the Reactions of Cl atoms with Isopropyl Formate and Isobutyl Formate.

Rate coefficients for the reactions of Cl atoms with isopropyl formate (IPF) and isobutyl formate (IBF) were measured experimentally over the temperature range of 268-363 K and at 760 Torr of nitrogen using relative rate method. Ethyl acetate and ethyl formate were used as reference compounds for the measurement of rate coefficients for the reaction of IPF with Cl atoms. Ethane and ethylene were used as reference compounds for the measurement of rate coefficients for the reaction of IBF with Cl atoms. The obtained rate coefficients for the reactions of IPF and IBF with Cl atoms at 298 K are (1.56 ± 0.47) × 10-11 and (7.60 ± 1.10) × 10-11 cm3 molecule-1 s-1 respectively. The derived temperature dependent Arrhenius expression for the reactions of IPF and IBF with Cl atoms are kR1(268-363K)Experimental = (3.87 ± 0.88) × 10-12 exp [(418 ± 70)/T] and kR2(268-363K)Experimental = (1.83 ± 0.45) × 10-11 exp [(421 ± 70)/T] cm3 molecule-1 s-1 respectively. A qualitative analysis of the products formed during the reactions of Cl atoms with IPF and IBF were carried out using gas chromatography-mass spectrometry (GC-MS) and gas chromatography-infrared spectroscopy (GC-IR) as analytical tools, and the degradation mechanisms were proposed on the basis of end products. To rationalize our experimentally obtained results, computational calculations were performed to calculate the temperature dependent rate coefficients for these reactions over the temperature range of 200-400 K at CCSD(T)/cc-pVDZ//MP2/6-31+G(d, p) level of theory using canonical variational transition state theory (CVT) with small curvature tunneling (SCT). Detailed discussions on the thermochemistry of the reactions, branching ratios, and atmospheric implications are discussed in the manuscript.

Cl Atom Initiated Photo-oxidation of Mono-chlorinated Propanes To Form Carbonyl Compounds: A Kinetic and Mechanistic Approach.

Cl atom initiated photo-oxidation of monochlorinated propanes to form the carbonyl compounds was investigated. Propionaldehyde and acetone were identified to be major products in the oxidation of 1-chloropropane and 2-chloropropane, respectively. The complete product analyses were carried out using gas chromatography-mass spectrometry (GC-MS) and gas chromatography-infrared spectroscopy (GC-IR) as analytical tools, and an appropriate oxidation mechanism was proposed on the basis of the product analyses. The temperature dependent rate coefficients for the reactions of Cl atoms with 1-chloropropane (1-CP) and 2-chloropropane (2-CP) were measured experimentally in the gas phase, using the relative rate method in the temperature range 268-363 K and at 1 atm pressure. Ethane, ethylene, and ethyl acetate were used as reference compounds. The obtained rate coefficients for the reactions of Cl atoms with 1-CP and 2-CP at room temperature (298 K) and at 1 atm pressure were (4.64 ± 0.70) × 10-11 and (2.57 ± 0.44) × 10-11 cm3 molecule-1 s-1, respectively. Furthermore, to complement our experimentally obtained results, computational calculations were performed for these reactions using canonical variational transition state theory (CVT) with small curvature tunneling (SCT) in combination with the CCSD/cc-pVDZ//MP2/6-31+G(d,p) level of theory. Detailed discussion on feasibility of the reactions, branching ratios, degradation mechanism, and atmospheric implications are discussed in this manuscript.

Fatal poisoning involving cyclopropylfentanyl — Investigation of time-dependent postmortem redistribution

A growing number of fatal overdoses involving opioid drugs, in particular involving fentanyl and its analogues, pose an immense threat to public health. Postmortem casework of forensic toxicologists in such cases is challenging, as data on pharmacodynamic and pharmacokinetic properties as well as reference values for acute toxicities and data on potential postmortem redistribution (PMR) mechanisms often do not exist. A fatal case involving cyclopropylfentanyl was investigated at the Zurich Institute of Forensic Medicine and the Zurich Forensic Science Institute; an unknown powder found at the scene was reliably identified as cyclopropylfentanyl by gas chromatography-infrared spectroscopy (GC-IR). Femoral blood samples were collected at two time points after death; 11h postmortem (t1) and during the medico-legal autopsy 29h after death (t2). At the autopsy, additional samples from the heart blood, urine and gastric content were collected. Cyclopropylfentanyl was quantified using a validated liquid chromatography-tandem mass spectrometric (LC–MS/MS) method. Femoral blood concentration of cyclopropylfentanyl at autopsy was 19.8ng/mL (t1=15.7ng/mL; heart blood concentration at autopsy=52.4ng/mL). In the light of the current literature and under the exclusion that no other morphological findings could explain the cause of death, contribution of cyclopropylfentanyl to death was proposed (polydrug use). Significant postmortem concentration increases of cyclopropylfentanyl in femoral blood during 18h after the first sampling were observed, thus indicating a relevant potential to undergo PMR. A central-to-peripheral blood concentration ratio of 2.6 supports this. Consequently, the current case suggests that postmortem cyclopropylfentanyl concentration should always be interpreted with care.

Disubstituted piperazine analogues of trifluoromethylphenylpiperazine and methylenedioxybenzylpiperazine: analytical differentiation and serotonin receptor binding studies

ABSTRACTA series of N,N-disubstituted piperazines were synthesized containing the structural elements of both methylenedioxybenzylpiperazine (MDBP) and trifluoromethylphenylpiperazine (TFMPP) in a single molecule. These six potential designer drug molecules having a regioisomeric relationship were compared in gas chromatography-mass spectrometry (GC–MS), gas chromatography-infrared spectroscopy and serotonin receptor affinity studies. These compounds were separated by capillary gas chromatography on an Rxi®-17Sil MS stationary phase film and the elution order appears to be determined by the position of aromatic ring substitution.The majority of electron ionization mass spectral fragment ions occur via processes initiated by one of the two nitrogen atoms of the piperazine ring. The major electron ionization mass spectrometry (EI-MS) fragment ions observed in all six of these regioisomeric substances occur at m/z = 364, 229, 163 and 135. The relative intensity of the various fragment ions is also equivalent in each of the six EI-MS spectra. The vapour phase infrared spectra provide a number of absorption bands to differentiate among the six individual compounds on this regioisomeric set. Thus, the mass spectra place these compounds into a single group and the vapour phase infrared spectra differentiate among the six regioisomeric possibilities.All of the TFMPP–MDBP regioisomers displayed significant binding to 5-HT2B receptors and in contrast to 3-TFMPP, most of these TFMPP–MDBP isomers did not show significant binding at 5-HT1 receptor subtypes. Only the 3-TFMPP-3,4-MDBP (Compound 5) isomer displayed affinity comparable to 3-TFMPP at 5-HT1A receptors (Ki = 188 nmol/L).

Differentiation of the six dimethoxypyrovalerone regioisomers: GC-MS, GC-MS/MS and GC-IR

Multiple and complementary analytical methods are often necessary for the identification of a specific compound from a series of closely related structural isomers. Gas chromatography-mass spectrometry (GC-MS), gas chromatography-product ion mass spectrometry (GC-MS/MS) and gas chromatography-infrared spectroscopy (GC-IR) were used to differentiate between the six dimethoxypyrrovalerone (DMPV) regioisomers. The six regioisomeric aminoketones were separated on a 50% phenyl stationary phase and the elution order is related to the positioning of substituents on the aromatic ring. These six DMPV regioisomers yield essentially identical mass spectral data in both chemical ionization (CI-MS) and electron ionization (EI-MS) spectra as well as identical product ion MS/MS spectra of the iminium cation base peak (m/z 126). These various mass spectral techniques provide data to identify all major structural features of these molecules except the dimethoxy substitution pattern of the aromatic ring. The region of the vapor phase infrared spectra between 1600cm−1 and 1000cm−1 provides a significant number of unique absorption bands characteristic of each individual DMPV regioisomer.

Composition and Electrophysiological Activity of Constituents Identified in Male Wing Gland Secretion of the Bumblebee Parasite Aphomia sociella

Male wing gland secretion and volatiles emanating from calling males were investigated in the bumble bee wax moth, Aphomia. sociella, using comprehensive two-dimensional gas chromatography-mass spectrometry (GCxGC-TOF-MS), gas chromatography-infrared spectroscopy (GC-FTIR), enantioselective gas chromatography, electroantennography (EAG), gas chromatography with electroantennographic detection (GC-EAD), and NMR. GC-EAD analysis of the male wing gland secretion revealed seven active areas, corresponding to 1-hexanol (1), 2-phenylethanol (2), [(R),(Z)]-nona-2,6-dien-4-olide (3), [(S),(Z)]-nona-6-en-4-olide (4), mellein (5), phytone (6), and a mixture of C(18) fatty acids (7). Solid-phase microextraction (SPME) confirmed the presence of 2-phenylethanol, nona-2,6-dien-4-olide, nona-6-en-4-olide, mellein, and phytone in volatiles emanating from a calling male. Though the abundance of these compounds slightly differed in SPME and gland secretion analysis, nona-2,6-dien-4-olide and mellein dominated in both samples, followed by 2-phenylethanol, nona-6-en-4-olide, and phytone. The strong antennal responses elicited by components of the secretion suggest that one or more of these compounds constitute the sex pheromone. Both sexes perceived male wing gland secretion, with females being significantly more sensitive compared to males.

Mammalian exocrine secretions. XVIII: Chemical characterization of interdigital secretion of red hartebeest, Alcelaphus buselaphus caama.

Gas chromatography, coupled gas chromatography-mass spectrometry (electron impact mode and chemical ionization with methane as reactant gas), gas chromatography-infrared spectroscopy, and derivatization techniques were used to identity 53 compounds in the interdigital secretion of the red hartebeest, Alcelaphus buselaphus caama. These compounds included alkanes, isoalkanes, alcohols, ketones, carboxylic acids, oxiranes, furanoid linalool oxides, and a large number of branched and unbranched saturated and unsaturated aldehydes. The secretion probably plays a role in demarcation of territories by dominant bulls.

Application of gas chromatography-infrared spectroscopy to the confirmation of the double bond configuration of conjugated linoleic acid isomers

Application of gas chromatography-infrared spectroscopy to the confirmation of the double bond configuration of conjugated linoleic acid isomers

Identification of drinking water contaminants in the course of a childhood cancer investigation in Toms River, New Jersey.

Using a combination of gas chromatography/mass spectrometry (GC/MS) and gas chromatography/infrared spectroscopy (GC/IR) spectroscopic techniques, chemical contaminants and their hydrolysis products were identified in well water sampled in connection with a suspected childhood cancer cluster located in Dover Township, Ocean County, New Jersey. The drinking water contamination resulted from the leaching of industrial waste chemicals from drums that were disposed of at the site known as Reich Farm. Contaminants identified include dinitrile-tetralin compounds, known as 'trimers,' that are by-products of a polymerization process widely used by several polymer manufactures during the 1970s and 1980s (and still used today). Also identified were 'trimer' hydrolysis products, formed by the hydrolysis of their nitrile groups to amides. These industrial contaminants were not present in any of the mass or IR spectral library databases, and their identification required unconventional spectroscopic methods (including high resolution mass spectrometry, chemical ionization mass spectrometry, and IR spectroscopy), along with scientific reasoning and interpretation. It is currently not known whether these chemical contaminants are responsible for the childhood cancers observed in this area.