Gas Chromatography-mass Spectrum Research Articles

Sinapate dehydrodimers and sinapate-ferulate heterodimers in cereal dietary fiber.

Two 8-8-coupled sinapic acid dehydrodimers and at least three sinapate-ferulate heterodimers have been identified as saponification products from different insoluble and soluble cereal grain dietary fibers. The two 8-8-disinapates were authenticated by comparison of their GC retention times and mass spectra with authentic dehydrodimers synthesized from methyl or ethyl sinapate using two different single-electron metal oxidant systems. The highest amounts (481 microg/g) were found in wild rice insoluble dietary fiber. Model reactions showed that it is unlikely that the dehydrodisinapates detected are artifacts formed from free sinapic acid during the saponification procedure. The dehydrodisinapates presumably derive from radical coupling of sinapate-polymer esters in the cell wall; the radical coupling origin is further confirmed by finding 8-8 and 8-5 (and possibly 8-O-4) sinapate-ferulate cross-products. Sinapates therefore appear to have an analogous role to ferulates in cross-linking polysaccharides in cereal grains and presumably grass cell walls in general.

Composition and Molluscicidal Properties of Essential Oils of Five Moroccan Pinaceae

Essential oils from Pinus halepensis, P. brutia, P. pinaster, P. pinea and Cedrus atlantica were chemically analyzed by gas chromatographic and gas chromatographic mass-spectra, and tested for molluscicidal activity against Bulinus truncatus. The oil from C. atlantica was found the most active (LC 50 = 0.47 ppm). Among their main constituents, a-pinene, ß-pinene and myrcene exhibited potent molluscicidal activity (LC 50 = 0.49; 0.54 and 0.56 ppm, respectively). These findings have important application of natural products in combating schistosomiasis.

Identification of methyl salicylate as the principal volatile component in the methanol extract of root bark of Securidaca longepedunculata Fers.

Securidaca longepedunculata Fers (Polygalaceae) is commonly used as a medicine in many parts of Africa and shows promise for protecting stored grain against insect pests. Analysis of a methanol extract of the root bark by gas chromatography linked to mass spectrometry (GC/MS) showed a major component accounting for over 90% of the volatile material. This was identified as methyl 2-hydroxybenzoate (methyl salicylate) by comparison of the GC retention times and mass spectrum with those of synthetic standards. This conflicts with an earlier report that the major component is methyl 4-hydroxybenzoate. Two minor components had mass spectra characteristic of 2-hydroxybenzoate esters and were identified as methyl 2-hydroxy-6-methoxybenzoate and its benzyl analogue, again conflicting with an earlier report.

An internal airlift loop bioreactor with Burkholderia pickttii immobilized onto ceramic honeycomb support for degradation of quinoline

A novel kind of bioreactor with a ceramic honeycomb support installed in a draught tube was developed and the ceramic honeycomb support could be used for immobilization of microbial cells. A strain of bacterium was isolated from activated sludge and identified as Burkholderia pickttii for degradation of quinoline and could grow on quinoline which served as a sole source of carbon, nitrogen and energy. Quinoline was degraded by the bioreactor in both batch and continuous flow operations when they were immobilized onto the ceramic honeycomb support. Experimental results indicated that quinoline could be degraded effectively by B. pickttii immobilized onto the ceramic support. Immobilized B. pickttii exhibited better stability in its metabolism and proliferation and degradation of quinoline in continuous flow operation conditions. More than 95% of quinoline could be removed for 4 h of hydraulic retention time (HRT). Quinoline was degraded through 2-hydroxy quinoline according to the analysis of gas chromatography–mass spectrum (GC–MS).

Induced volatiles in elicitor-treated and rice blast fungus-inoculated rice leaves.

The volatiles released from elicitor (copper chloride, jasmonic acid, UV, L-methionine and chitosan oligomer)-treated and rice blast fungus-inoculated rice leaves were collected by the solid-phase microextraction technique and analyzed by GC-MS. (Z)-3-Hexen-1-ol, monoterpenes, methyl salicylate, and sesquiterpenes were identified as elicitor-induced volatiles by a comparison of their GC retention times and mass spectra with those of authentic compounds. The different elicitors resulted in some qualitative and quantitative differences in the production of volatiles. Monoterpenes and sesquiterpenes were identified as the rice blast fungus-induced volatiles.

Pheromone components of the wheat stem sawfly: identification, electrophysiology, and field bioassay.

Volatiles collections and cuticular extracts of the wheat stem sawfly, Cephus cinctus Norton (Hymenoptera: Cephidae), were analyzed by coupled gas chromatographic-electroantennographic detection (GC-EAD) in order to detect possible pheromone components of this species. Volatiles collections from male and female sawflies contained the same 13 GC-EAD-active compounds that stimulated both male and female antennae. GC-EAD-active compounds were identified by mass spectrometry, and the identities were verified by acquiring or synthesizing authentic standards with identical GC retention times and mass spectra. 9-Acetyloxynonanal gave the strongest EAD response. Additional GC-EAD-active compounds included 13-acetyloxytridecanal, aldehydes with 9-16 carbon chain lengths, acids with 8-10 carbon chain lengths, and phenylacetic acid. The last was instantly detectable by human nose when several males were allowed to interact, but not from isolated insects. On a per-insect basis, grouped males overall released higher amounts of the GC-EAD-active compounds than grouped females. Notable quantitative differences between the sexes were relatively higher amounts of 9-acetyloxynonanal, phenylacetic acid, and tetradecanal from males and hexadecanal from females. In the absence of an absolute, qualitative difference between sexes, these relative differences might be important for sex recognition. Field bioassay demonstrated the attractiveness of 9-acetyloxynonanal for male and female C. cinctus. The major compounds of male and female cuticular extracts showed no GC-EAD activity, but ozonolysis of extracts gave dramatically increased amounts of GC-EAD-active material. Hence, double-bond-containing cuticular compounds are suggested as precursors of the aldehydic pheromone components.

Biotransformation of cyclizine in greyhounds. 2: N 1 -dealkylation and identification of some neutral and phenolic metabolites in canine urine by gas chromatography-mass spectrometry

1. The in vivo enzymatic Phase I biotransformation of cyclizine (Marezine ®) in the racing greyhound has been shown to proceed via several different pathways. Aromatic and heterocyclic oxidation and the N 4 -demethylation of cyclizine lead to the formation of unconjugated and conjugated (Phase II) basic metabolites excreted in canine urine. 2. Enzymatic N 1 -dealkylation of cyclizine and its basic metabolites leads to the formation of the neutral and phenolic Phase I metabolites containing the diphenylmethane/methylene substructures. Further, Phase I metabolism of the neutral metabolites could also lead to the formation of several secondary phenolic products. These neutral and phenolic compounds are then excreted as unconjugated and Phase II conjugates in greyhound urine. 3. Following enzymatic deconjugation of selected post-Marezine administration urine samples from two greyhounds, the total aglycones were extracted and separated into neutral/acidic and basic fractions using copolymeric mixed-mode solid-phase extraction cartridges. 4. The neutral/acid isolates were further separated into neutral and phenolic fractions by column chromatography on a lipophilic strong anion-exchanger gel, triethylaminohydroxypropyl Sephadex LH-20 in OH - form. 5. The individual neutral and phenolic fractions obtained from the acid/neutral isolate were derivatized as trimethylsilyl ethers and analysed by positive-ion electron ionization gas chromatography-mass spectrometry (EI + -GC-MS). 6. Three compounds, diphenylmethane (M1), benzophenone (or diphenyl ketone, M2) and benzhydrol (M3), were identified in the neutral isolates by comparison of their EI + mass spectra with authentic standards. At least seven secondary compounds containing the functionalized diphenylmethylene substructure were detected in the phenolic isolates. As no authentic compounds are available, the structures of these putative metabolites (M4 → M10) were elucidated from an interpretation of the EI + -GC-mass spectra of their TMS derivatives.

Microbial degradation of quinoline by immobilized cells of Burkholderia pickettii

A quinoline-biodegrading microorganism was isolated from activated sludge of coke-oven wastewater treatment plant using quinoline as sole carbon and nitrogen source. It is a gram negative, rod-shaped and aerobic strain, which was identified as Burkholderia pickettii. The biodegradation of quinoline was carried out with this isolated strain. Analysis by high performance liquid chromatography and gas chromatography/mass spectrum (GC/MS) revealed that 2-hydroxyquinoline (2-OH-Q) was the first intermediate in the course of quinoline biodegradation. A novel immobilization carrier, that is, polyvinyl alcohol (PVA)-gauze hybrid carrier, was developed. The isolated strain was immobilized by two different immobilizing techniques and used for the quinoline degradation. It was found that biodegradation rate of quinoline by the microorganisms immobilized on PVA-gauze hybrid carrier was faster than that by the microorganisms immobilized in PVA gel beads. Kinetics of quinoline biodegradation by cells of Burkholderia pickettii immobilized on PVA-gauze hybrid carrier was investigated. The results demonstrate that quinoline degradation could be described by zero-order reaction rate equation when the initial quinoline concentration was in the range of 50–500 mg l −1.

Fluazifop-P Inhibits Terbacil Metabolism in Strawberry (Fragaria×ananassa)1

We examined the effect of a postemergence application of fluazifop-P on root uptake, translocation, and metabolism of 14C-terbacil in ‘Kent’ strawberry. Fluazifop-P had no effect on uptake of 14C-terbacil from a nutrient solution over 48 h, nor did it affect the proportional distribution of 14C-label in the plants. The 14C-label was readily translocated to the foliage where it tended to accumulate in vascular tissue. Fluazifop-P reduced the overall conversion of 14C-terbacil to metabolites by about 50%. Thin layer chromatography of methanol extracts of leaflets, petioles, crowns, and roots separated the 6-hydroxymethyl derivative, and several unidentified metabolites, including a major water-soluble metabolite at the origin. At least 50% of the latter could be converted to the 6-hydroxymethyl metabolite by β-glucosidase, but other metabolites could be separated in other solvent systems. The levels of metabolites were generally two- to threefold higher in plants treated with terbacil alone than in those pretreated with fluazifop-P. Therefore, we conclude that the interaction observed between these herbicides in the field results from fluazifop-P inhibiting detoxification of terbacil by strawberry.Nomenclature: Fluazifop-P; terbacil; strawberry, Fragaria × ananassa Duchensne ‘Kent’.Additional index words: Herbicide interaction, synergism, root uptake.Abbreviations: GC-ECD, gas chromatography electron capture detection; GC-MSD, gas chromatography mass spectrum detection; HPLC, high-performance liquid chromatography; LSS, liquid scintillation spectrometry; PPFD, photosynthetic photon flux density; SEM, standard error of the mean; TLC, thin layer chromatography.

Determination of vanillin in orange, grapefruit, tangerine, lemon, and lime juices using GC-olfactometry and GC-MS/MS.

The presence of vanillin in orange, tangerine, lemon, lime, and grapefruit juices has been identified and confirmed using high-resolution GC retention index values, mass spectra, and aroma quality. The impact of vanillin on the flavor score for grapefruit juice is discussed and reported to be minimal. Vanillin concentrations are determined to be in the low parts-per-million range for the various citrus juices. The calculated concentrations in the orange, tangerine, lemon, lime, and grapefruit juices are 0.20, 0.35, 0.41, 0.35, and 0.60 ppm, respectively. Pasteurization produced an average 15% increase in the concentration of vanillin in grapefruit juices. Vanillin did not correlate well with the overall flavor score despite a rather intense signal using OSME gas chromatography-olfactometry software.

Oxidative metabolites of the mammalian lignans enterodiol and enterolactone in rat bile and urine.

Recent studies have shown that the mammalian lignans enterodiol (END) and enterolactone (ENL) are biotransformed in vitro by hepatic microsomes from rats and humans to various metabolites carrying one additional hydroxy group either at the aromatic or at the aliphatic moiety. To clarify whether these metabolites are also formed in vivo, each lignan was administered intraduodenally at a dose of 10 mg/kg of bw to bile duct-catheterized female Wistar rats and the 6 h bile analyzed by HPLC and GC-MS. With END-dosed rats, three products of aromatic and two of aliphatic monohydroxylation were found, whereas six aromatic and five aliphatic monohydroxylated biliary metabolites were detected after administration of ENL. The metabolites hydroxylated at the aromatic rings were unequivocally identified by comparison with synthetic reference compounds. The structures of the in vivo metabolites arising from aliphatic hydroxylation could not be completely elucidated; they were identical with some of the formerly reported microsomal products according to GC retention times and mass spectra. Significant amounts of most of the metabolites of the mammalian lignans identified in bile were also found in the urine of female rats after oral administration of 10 mg/kg of bw END or ENL and in the urine of female and male Wistar rats after they had been fed a diet containing 5% flaxseed. Thus, the mammalian lignans END and ENL give rise to several hydroxylated metabolites in vivo, which may contribute to the biological effects of these important food constituents.

Lead Zirconate Titanate Stable Stock Solution: Characterization and Applications

Lead zirconate titanate (PZT) thin films were prepared by the sol-gel process using acetic acid and 1,2-propanediol as solvents. Acetone was used as final solvent and in this way a stable stock sol (for more than 12 months) was obtained. The PZT sols prepared were reproducible and suitable for the preparation of PZT thin films. To study the sol structure evolution gas chromatography mass spectrum (GC-MS) and Fourier-transform-infrared (FT-IR) spectra were recorded and analyzed on each step of the synthesis. The rheological behavior and the stability of the stock sol were checked using a rheometer. It is observed that the addition of acetone leads to a very stable stock sol. The preliminary investigation of the electric properties of the obtained PZT thin films showed that the crystallized films deposited from a fresh prepared sol and a 12 months aged sol exhibit similar ferroelectric properties and comparable to those reported in the literature.

Reidentification of the female sex pheromone of the Indian meal moth, Plodia interpunctella: evidence for a four‐component pheromone blend

AbstractPheromone gland extracts from calling female Plodia interpunctella contained at least seven compounds that consistently elicited electroantennographic responses from male antennae upon gas chromatographic analysis. Three of these compounds were found to be the previously identified gland constituents, i.e., (Z,E)‐9,12‐tetradecadienyl acetate (Z9,E12‐14:OAc), (Z,E)‐9,12‐tetradecadienal (Z9,E12‐14:Ald) and (Z,E)‐9,12‐tetradecadienol (Z9,E12‐14:OH). A fourth EAD‐active compound was identified as (Z)‐9‐tetradecenyl acetate (Z9‐14:OAc). The homologue (Z)‐11‐hexadecenyl acetate (Z11‐16:OAc) was also identified in the extracts, but showed no EAD activity. The identity of all five compounds was confirmed by comparison of GC retention times and mass spectra with those of synthetic standards. In flight tunnel tests there were no significant differences in response of male P. interpunctella to the bait containing all four EAD‐active compounds and the responses to female gland extacts. A behavioural assay of different two‐compound blends in the flight tunnel showed that only addition of the corresponding aldehyde to the major pheromone component Z9,E12‐14:OAc raised the male response. A subtractive assay, however, revealed that the exclusion of any of the compounds from the complete four‐compound blend reduced its activity significantly. We thus conclude that the female‐produced sex pheromone of P. interpunctella consists of at least four components, i.e., Z9,E12‐14:OAc, Z9,E12‐14:Ald, Z9,E12‐14:OH and Z9‐14:OAc.In a field trapping test performed in a storage facility, the four‐component blend attracted significantly more males of P. interpunctella than traps baited with Z9,E12‐14:OAc alone. In contrast, the highest number of Ephestia kuehniella males was found in the traps baited with this major component, suggesting that the secondary pheromone components contribute to the species specificity of the blend.

Sex Pheromone of Ascogaster quadridentata, a Parasitoid of Cydia pomonella

Porapak Q volatile extracts of female Ascogaster quadridentata, an egg-larval endoparasitoid of codling moth, Cydia pomonella, bioassayed in Y-tube olfactometers attracted male, but not female, A. quadridentata. Coupled gas chromatographic–electroantennographic detection (GC-EAD) analysis of bioactive extracts revealed three compounds that elicited responses by male A. quadridentata antennae. GC-mass spectra (MS) indicated, and comparative analyses of authentic standards confirmed, that these compounds were (Z,Z)-9,12-octadecadienal, (Z)-9-hexadecenal, and 3,7,11-trimethyl-6E,10-dodecadienal. (Z,Z)-9,12-Octadecadienal alone attracted laboratory-reared male A. quadridentata in Y-tube olfactometer and field-cage bioassays, and attracted feral A. quadridentata in a field experiment. This sex pheromone could be used to help detect populations of A. quadridentata, delineate their distributions, and determine potential sources of parasitoids for capture and release in integrated programs for control of C. pomonella.

Identification and field evaluation of components of female sex pheromone of millet stem borer, coniesta ignefusalis

Five active compounds were detected during analyses of ovipositor washings and effluvia from virgin female Coniesta ignefusalis moths by gas chromatography (GC) linked to electroantennographic (EAG) recording from a male moth. These were identified as (Z)-7-dodecen-1-ol (Z7–12:OH), (Z)-5-decen-1-ol (Z5–10:OH), (Z)-7-dodecenal (Z7–12:Ald), (Z)-7-dodecenyl acetate (Z7–12:Ac), and (Z)-9-tetradecen-1-ol (Z9–14:OH) by comparison of their GC retention times, mass spectra, and EAG activities with those of synthetic standards. Laboratory tests of dispensers for these compounds showed that release rates from polyethylene vials increased to relatively uniform values after three to four days, but release from septa was very rapid and nonuniform and decreased to low levels after two to three days. Trapping tests in Niger showed that the major component, Z7–12:OH, and two of the minor components, Z5–10:OH and Z7–12:Ald, were essential for attraction of male C. ignefusalis moths. The most attractive blend contained these three components in a 100:5:3.3 ratio in a polyethylene vial, which emitted the components in similar proportions to those produced by the female C. ignefusalis moth. Water traps baited with this blend containing 1 mg of Z7–12:OH caught more male C. ignefusalis moths than traps baited with newly emerged female moths. Addition of up to 10% of the corresponding E isomers of the pheromone components had no effect on catches, but addition of the other two minor components detected, Z7–12:Ac and/or Z9–14:OH, to the attractive blend at naturally occurring levels caused significant reductions in trap catch.

Fatal opiates overdose. Toxicological identification of various metabolites in a blood sample by GC–MS after silylation

A fatal opiates overdose, where ethylmorphine, hydrocodone, dihydrocodeine and codeine were consumed concomitantly, is reported. This case report may contribute to data on fatal blood concentrations of drugs with rare incidence. The relative retention times in capillary gas chromatography and full mass spectra of various opiates in their silylated forms, detected together in one sample, may serve as a helpful analytical reference for clinical and forensic toxicologists.

Amonabactin: a family of novel siderophores from a pathogenic bacterium

Four peptide-based bis-catecholate siderophores, collectively known as the amonabactins, have been isolated from Aeromonas hydrophila. They have been fully characterized: tandem mass spectroscopy established the sequence of the amino acid components, chiral gas chromatographic mass spectra established the amino acid chirality, and two-dimensional NMR techniques determined the full connectivity and structure. Each of the amonabactins was synthesized and the synthetic material was compared to the natural product as a final proof of structure. These siderophores are bis-catecholates with the backbone composed of either tri- or tetrapeptides in the sequence (gly)-(L)-lys-(L)-lys-(D)-aro, where glycine is the optional amino acid attached to the Ne of the N terminus lysine and aro is either tryptophan or phenylalanine. The ligand units, 2,3-dihydroxybenzamide groups, are attached to the Ne amine of the C terminus lysine and either to glycine, if present, or to Ne amines of the N terminus lysine. Each of the amonabactins supports growth of the organism under low-iron conditions in vitro and in serum. The architecture of these siderophores includes an inverted aromatic amino acid and unusual linkages which should prevent enzymatic hydrolysis of the peptide backbones. This, along with their ability to successfully compete for iron in serum, suggests a role in the pathogenicity of the organism.

Identification of YH439 and its metabolites in rat urine by gas chromatography–mass spectrometry and liquid chromatography–mass spectrometry

YH439 is a potential drug candidate for the treatment of various hepatic disorders. YH439 and its three metabolites have been identified in rat urine by liquid chromatography–mass spectrometry (LC–MS) and by gas chromatography (GC)–MS. Identification of YH439 and its metabolites was established by comparing their GC retention times and mass spectra with those of the synthesized authentic standards. Both electron impact- and positive chemical ionization MS have been evaluated. The metabolism study was performed in the rat using oral administration of the drug. A major metabolite (YH438) was identified as the N-dealkylation product of YH439. Other identified metabolites were caused by the loss of the methyl thiazolyl amine group (metabolite II) from YH439, the isopropyl hydrogen malonate group (metabolite IV) and the decarboxylated product (metabolite III) of metabolite II.

Identification and biosynthesis of (E,E)-10,12-tetradecadienyl acetate in Spodoptera littoralis female sex pheromone gland

A minor component of the sex pheromone gland of the Egyptian cotton leafworm. Spodoptera littoralis, has been identified as ( E, E)-10,12-tetradecadienyl acetate. Structural elucidation has been carried out by isobutane-chemical ionization mass spectrometry of the fatty acyl biosynthetic precursor-derived methyl ester. To assign the stereochemistry of the double bonds, the four isomers of both 10,12-tetradecadienyl acetates and methyl 10,12-tetradecadienoates have been synthesized and their gas chromatography retention times and mass spectra have been compared to those of the corresponding natural compounds. Mass-labeling experiments showed that the ( E, E)-10,12-tetradecadienoyl moiety is biosynthetically derived from (Z)-11-tetradecenoic acid in the insect pheromone gland.

MICROBIAL SUSCEPTIBILITY AND BIODEGRADABILITY TO TAXODIUM DISTICHUM SEED OIL

Isolates of two fungal species from rotted orange fruits as well as standard bacterial cultures were screened for their susceptibility and ability to metabolise Taxodium Distichum ( bald cypress) seed oil over a twelve- day period by adding the oil to fungal spore or bacterial culture suspension. Under these conditions, all tested strains metabolized the oil in variable rates ranged from 8 to 100% . The proportions of the oil component degraded differed widely with the microorganism. The highest degradation was observed with Aspergillus and Penicillium species (100%), certain other standard cultures, notably of Pseudomonas aeruginosa ; Klebsiella pneumoniae and Bacillus subtilis metabolized, about 15-30%, of the oil. The in vitro antimicrobial activity of the oil revealed higher efficacy against Candida albicans but limited towards Gram - positive bacteria (Staphylococcus aureus and B. subtilis). No significiant activity was noted against Gram - negative bacteria and true fungi. Microbial degradability of T. distichum oil is found to be inversely proportional with the oil bio-activity complete resistance followed by complete degradation exhibited by true fungi to bald cypress oil. By the end of the biodegradation period, antimicrobial activity of the resulted products exhibited no significant difference than that of the substrate. Thus , cultures that were established within 12 days failed to yield significant oil biodegraders. The estimation of the oil was carried out by Gas chromatography (GC) and GC mass spectrum (GC-MS)