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Retention Indices (retention + index)
Selected AbstractsAre behavioral differences among wild chimpanzee communities genetic or cultural?AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2010An assessment using tool-use data, phylogenetic methods Abstract Over the last 30 years it has become increasingly apparent that there are many behavioral differences among wild communities of Pan troglodytes. Some researchers argue these differences are a consequence of the behaviors being socially learned, and thus may be considered cultural. Others contend that the available evidence is too weak to discount the alternative possibility that the behaviors are genetically determined. Previous phylogenetic analyses of chimpanzee behavior have not supported the predictions of the genetic hypothesis. However, the results of these studies are potentially problematic because the behavioral sample employed did not include communities from central Africa. Here, we present the results of a study designed to address this shortcoming. We carried out cladistic analyses of presence/absence data pertaining to 19 tool-use behaviors in 10 different P. troglodytes communities plus an outgroup (P. paniscus). Genetic data indicate that chimpanzee communities in West Africa are well differentiated from those in eastern and central Africa, while the latter are not reciprocally monophyletic. Thus, we predicted that if the genetic hypothesis is correct, the tool-use data should mirror the genetic data in terms of structure. The three measures of phylogenetic structure we employed (the Retention Index, the bootstrap, and the Permutation Tail Probability Test) did not support the genetic hypothesis. They were all lower when all 10 communities were included than when the three western African communities are excluded. Hence, our study refutes the genetic hypothesis and provides further evidence that patterns of behavior in chimpanzees are the product of social learning and therefore meet the main condition for culture. Am J Phys Anthropol, 2010. © 2010 Wiley-Liss, Inc. [source] Approaches to identifying and quantifying polycyclic aromatic hydrocarbons of molecular weight 302 in diesel particulatesJOURNAL OF SEPARATION SCIENCE, JSS, Issue 1-2 2004Jean-Jacques Sauvain Abstract Among the PAH class of compounds, high molecular weight PAH are now considered as relevant cancer inducers, but not all of them have the same biological activity. However, their analysis is difficult, mainly due to the presence of numerous isomers and due to their low volatility. Retention indices (Ri) for 13 dibenzopyrenes and homologues were determined by high-resolution capillary gas chromatography (GC) with four different stationary phases: a 5% phenyl-substituted methylpolysiloxane column (DB-5 ms), a 35% phenyl-substituted methylpolysiloxane column (BPX-35), a 50% phenyl-substituted methylpolysiloxane column (BPX-50), and a 35% trifluoropropylmethyl polysiloxane stationary phase (Rtx-200). Correlations for retention on each phase were investigated by using 8 independent molecular descriptors. Ri has been shown to be linearly correlated to PAH volume, polarisability ,, Hückel-, energy on the four examined columns. Ionisation potential Ip is a fourth variable which improves the regression model for DB-5ms, BPX-35, and BPX-50 column. Correlation coefficients ranging from r 2 = 0.935 to r 2 = 0.952 are then observed. Application of these indices to the identification and quantification of PAH with MW 302 in certified diesel particulate matter SRM 1650a is presented and discussed. [source] RECONSTRUCTING PLUMAGE EVOLUTION IN ORIOLES (ICTERUS): REPEATED CONVERGENCE AND REVERSAL IN PATTERNSEVOLUTION, Issue 6 2000Kevin E. Omland Abstract. Several empirical studies suggest that sexually selected characters, including bird plumage, may evolve rapidly and show high levels of convergence and other forms of homoplasy. However, the processes that might generate such convergence have not been explored theoretically. Furthermore, no studies have rigorously addressed this issue using a robust phylogeny and a large number of signal characters. We scored the appearance of 44 adult male plumage characters that varied across New World orioles (Icterus). We mapped the plumage characters onto a molecular phylogeny based on two mitochondrial genes. Reconstructing the evolution of these characters revealed evidence of convergence or reversal in 42 of the 44 plumage characters. No plumage character states are restricted to any groups of species higher than superspecies in the oriole phylogeny. The high frequency of convergence and reversal is reflected in the low overall retention index (RI = 0.66) and the low overall consistency index (CI = 0.28). We found similar results when we mapped plumage changes onto a total evidence tree. Our findings reveal that plumage patterns and colors are highly labile between species of orioles, but highly conserved within the oriole genus. Furthermore, there are at least two overall plumage types that have convergently evolved repeatedly in the three oriole clades. This overall convergence leads to significant conflict between the molecular and plumage data. It is not clear what evolutionary processes lead to this homoplasy in individual characters or convergence in overall pattern. However, evolutionary constraints such as developmental limitations and genetic correlations between characters are likely to play a role. Our results are consistent with the belief that avian plumage and other sexually selected characters may evolve rapidly and may exhibit high homoplasy. The overall convergence in oriole plumage patterns is an interesting evolutionary phenomenon, but it cautions against heavy reliance on plumage characters for constructing phylogenies. [source] ALKALOID COMPOSITION OF LUPINUS CAMPESTRIS FROM MEXICOJOURNAL OF FOOD BIOCHEMISTRY, Issue 2 2001J. MARTÍNEZ-HERRERA ABSTRACT The content of quinolizidine alkaloids (QA) in Lupinus campestris, Fabaceae family, was analyzed by Gas Chromatography-Mass Spectrometry (GC-MS), Samples of various organs of Lupinus campestris collected at different monthly stages of the growing plant, were subjected to extraction in a Merck Extrelut column. The quinolizidine alkaloid patterns of stems, leaves, flowers, pods and seeds were assessed and then identified and quantified by GC. Alkaloid structures were identified according to their mass fragmentation patterns, in combination with their indicative Kovats retention index. Alkaloids found in several developmental stages of the plant were mainly: aphyllidine, 5, 6-dehydrolupanine, aphylline, dehydro-oxosparteine, lupanine, ,-isolupanine, hydroxyaphylline and hydroxyaphyllidine, plus two alkaloids that -were not identified. During the third month the relative abundance of total alkaloids were highest. The main alkaloids found in seeds were hydroxyaphylline and hydroxyaphyllidine. [source] Determination of radix ginseng volatile oils at different ages by comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometryJOURNAL OF SEPARATION SCIENCE, JSS, Issue 19 2008Yaqiong Qiu Abstract Comprehensive 2-D GC (GC×GC) coupled with TOF MS or flame ionization detector (FID) was employed to characterize and quantify the chemical composition of volatile oil in the radixes of Panax ginseng C. A. Mey. (ginseng) at different ages. Thirty-six terpenoids were tentatively identified based on the MS library search and retention index in a ginseng sample at the age of 3 years. An obvious group-type separation was obtained in the GC×GC-TOF MS chromatogram. The data collected by GC×GC-FID were processed using a principal component analysis (PCA) method to classify the samples at different ages. The compounds responsible for the significant differentiation among samples were defined. It was found that the relative abundances of ,-cadinol, ,-bisabolol, thujopsene, and n -hexadecanoic acid significantly rise with the increase in age. [source] The utility of quantitative calf muscle near-infrared spectroscopy in the follow-up of acute deep vein thrombosisJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 4 2006T. YAMAKI Summary.,Background:,To investigate patterns of venous insufficiency and changes in calf muscle deoxygenated hemoglobin (HHb) levels after an acute deep vein thrombosis (DVT). Methods:,A total of 78 limbs with an acute DVT involving 156 anatomic segments were evaluated with duplex scanning and near-infrared spectroscopy (NIRS) at 1, 3, 6 and 12 months. Venous segments were examined whether they were occluded, partially recanalized, and totally recanalized, and the development of venous reflux was noted. The NIRS was used to measure calf muscle HHb levels. Calf venous blood filling index (HHbFI) was calculated on standing, then the calf venous ejection index (HHbEI), and the venous retention index (HHbRI) were obtained after exercise. Results:,The segments investigated were the common femoral vein (CFV; 38 segments), femoral vein (FV; 37), popliteal vein (POPV; 44), and calf veins (CV; 37). At 1 year, thrombi had fully resolved in 67% of the segments, 27% remained partially recanalized, 6% were occluded. The venous occlusion was predominant in the FV (24%) at 1 year. On the contrary, rapid recanalization was obtained in CV than proximal veins at each examination (P < 0.01). Venous reflux was predominant in POPV (55%), followed by FV (19%), and no reflux was found in CV. At 1 year, the HHbFI in POPV reflux patients was significantly higher than those with resolution (0.19 ± 0.14, 0.11 ± 0.05 ,m s, P = 0.009, respectively). Similarly, there was a significant difference in the HHbRI between the two groups (3.08 ± 1.91, 1.42 ± 1.56, P = 0.002, respectively). In patients with FV occlusion, the value of HHbRI was significantly higher than those with complete resolution (2.59 ± 1.50, 1.42 ± 1.56, P = 0.011, respectively). Conclusions:,The lower extremity venous segments show different proportions of occlusion, partial recanalization, and total recanalization. The CV shows more rapid recanalization than proximal veins. The NIRS-derived HHbFI and HHbRI could be promising parameters as the overall venous function in the follow-up of acute DVT. These findings might be very helpful for physician in detecting patients who require much longer follow-up studies. [source] Prediction of Volatile Components Retention Time in Blackstrap Molasses by Least-Squares Support Vector MachineMOLECULAR INFORMATICS, Issue 5 2008Yongna Yuan Abstract House flies are pestiferous insects that have the potential to spread many diseases to humans and livestock, so it is very significant for us to manage house fly populations. Many commercial types of bait are available to attract house flies, but most are designed for outdoor or limited indoor use, due to their malodorous components. This study sought to identify compounds present in blackstrap molasses that might be attractive to house flies. An effective Quantitative Structure-Property Relationship (QSPR) model between the Retention Time (RT) and five molecular descriptors of the volatile compounds in blackstrap molasses, was built using a modified algorithm of Least-Squares Support Vector Machine (LS-SVM). Descriptors calculated from the molecular structures alone were used to represent the characteristics of compounds. The five molecular descriptors selected by the Heuristic Method (HM) in CODESSA were used as inputs for LS-SVM. The results obtained by LS-SVM were compared with those obtained by the HM. The LS-SVM model gives better results with the predicted correlation coefficient () 0.919 and Root Mean-Square Errors (RMSE) 2.193 for the test set, as well as that 0.824 and 2.728 in the MLR model. The prediction results of log RT are in very good agreement with the experimental values. This paper provided a new and effective method for predicting the chromatography retention index. [source] Syntheses, Characterizations, and Biological Activities of Tetradeca-4,8-dien-1-yl Acetates as Sex Attractants of Leaf-Mining Moth of the Genus Phyllonorycter (Lepidoptera: Gracillariidae)CHEMISTRY & BIODIVERSITY, Issue 9 2009Ilme Liblikas Abstract The four possible isomers of tetradeca-4,8-dien-1-yl acetate and corresponding alcohols were synthesized stereoselectively by synthetic routes employing Wittig coupling reaction for the preparation of (Z,E)- and (Z,Z)-isomers, and alkylation of terminal alkynes for the preparation of (E,E)- and (E,Z)-isomers as the key steps. Synthetic products were characterized by 13C- and 1H-NMR spectroscopy as well as mass-spectrometric methods. All four isomers gave distinctive mass spectra where m/z 81 fragments clearly dominated. Elution order, followed by retention index presented in parenthesis, of tetradeca-4,8-dien-1-ols was determined as (Z,Z) (2082.1), (Z,E) (2082.8), (E,E) (2083.1), and (E,Z) (2083.2) from unpolar SPB-1 column, and as (E,E) (2210.2), (Z,E) (2222.1), (E,Z) (2223.4), and (Z,Z) (2224.7) from polar DB-WAX column. The isomers of tetradeca-4,8-dien-1-yl acetates eluted in the order of (Z,Z) (2176.1), (Z,E) (2178.4), (E,Z) (2185.9), and (E,E) (2186.4) from SPB-1, and (Z,E) (2124.3), (E,E) (2157.7), (Z,Z) (2128.9), and (E,Z) (2135.9) from DB-WAX columns. Field-screening tests for attractiveness of tetradeca-4,8-dien-1-yl acetates revealed that (4Z,8E)-tetradeca-4,8-dien-1-yl acetate significantly attracted Phyllonorycter coryli and Chrysoesthia drurella males. (4E,8E)-Tetradeca-4,8-dien-1-yl acetate was the most efficient attractant for Ph. esperella and Ph. saportella males, and (4E,8Z)-tetradeca-4,8-dien-1-yl acetate was attractive to Ph. cerasicolella males. [source] A Cladistic Analysis of the New World Species of Lotus L. (Fabaceae, Loteae)CLADISTICS, Issue 3 2000Ana M. Arambarri The genus Lotus L. is a monophyletic group diagnosed by the possession of a standard claw with thickened infolded margin, stamens diadelphous, and the style hardened from the base. It comprises approximately 200 species distributed throughout the world. A cladistic analysis of the New World species was performed using 39 morphological and anatomical characters (29 from seed morphology and anatomy, 1 from plant habit, 1 from leaf morphology, 6 from flower morphology, and 2 from fruit morphology). Dorycnium, Edentolotus, Krokeria, and Pedrosia, of the Old World, and 28 species of the New World were considered terminal taxa. Tetragonolobus Scop. was chosen to root the cladograms and Dorycnium Mill. to reroot them. With Tetragonolobus the analysis yielded 15 equally parsimonious trees, each with a length of 74 steps, a consistency index of 0.62, and a retention index of 0.89. The 15 initial trees and the strict consensus tree defined 12 monophyletic groups. All terminal taxa form a monophyletic group diagnosed by the presence of a radicular lobe discernible to conspicuous (character 10); rim aril thick (character 13); stipules absent (character 31); and style simple and nondilated (character 36). The New World species form a monophyletic group on the basis of the seed relationship of length to width in hilar view 1.5:1 to 2:1 (character 5); micropyle linear-deltoid to bifurcate (character 19); and keel erostrate (character 33). Identical monophyletic groups were obtained when Dorycnium was used as root. These results are discussed in the context of data on cytology and morphology. [source] The Role of Functional Parameters for Topographical Characterization of Bone-Anchored ImplantsCLINICAL IMPLANT DENTISTRY AND RELATED RESEARCH, Issue 2 2006Anna Arvidsson MSc ABSTRACT Background, The surface topographical characterization of bone-anchored implants has been recommended to be based on amplitude, spatial, and hybrid parameters. There are also functional parameters that have the potential to describe characteristics important for a specific application. Purpose, The aim of the present study was to evaluate if parameters that have been described as functional in engineering applications are also relevant in the topographical characterization of bone-anchored implants. Materials and Methods, The surface topography of threaded titanium implants with different surface roughness (Sa, Sds, and Sdr) was analyzed with an optical interferometer, and five candidating functional parameters (Sbi, Sci, Svi, Sm, and Sc) were calculated. Examples of the same parameters for five commercially available dental implants were also calculated. Results, The highest core fluid retention index (Sci) was displayed by the turned implants, followed by fixtures blasted with 250- and 25-,m particles, respectively. Fixtures blasted with 75-,m Al2O3 particles displayed the lowest Sci value. This is the inverse order of the bone biological ranking based on earlier in vivo studies with the experimental surfaces included in the present study. Conclusion, A low core fluid retention index (Sci) seems favorable for bone-anchored implants. Therefore, it is suggested to include Sci to the set of topographical parameters for bone-anchored implants to possibly predict the biological outcome. [source] Clinical analysis of the soft tissue integration of non-submerged (ITI) and submerged (3i) implants: a prospective-controlled cohort studyCLINICAL ORAL IMPLANTS RESEARCH, Issue 10 2008Ricardo Vieira Garcia Abstract Aim: The aim of this study was to compare the soft tissue integration of submerged and non-submerged implants by means of periodontal parameter assessments and analysis. Material and methods: Thirty-one patients, who received 42 non-submerged implants (ITI) and 48 submerged implants (3i), participated in the study. There was no significant difference (P>0.05) between both groups considering gender; educational level; handedness; toothbrushing frequency; the number of auxiliary devices used; and smoking habits. The parameters assessed were gingival index (GI), plaque index (PII), retention index (RI), pocket probing depth (PPD) and keratinized mucosa index. Results: At evaluation, 66.67% of all sites showed a GI of 0; 72.22% a PI of 0, and 93.33% the absence of calculus. The average PPD was 2.56 mm in the non-submerged and 2.70 mm in the submerged group. With regard to the width of keratinized mucosa, 100% of the ITI implants showed a band of keratinized gingiva around the implant, whereas 14.58% in the 3i group showed a complete absence of keratinized mucosa. The intra-examiner reproducibility was 90.96% for all parameters and the Kendall tau-b analysis showed a powerless correlation between the chosen parameters for both studied groups. Conclusions: The study material showed no major differences between submerged and non-submerged dental implants regarding GI, PII, RI and PPD, except the width of keratinized mucosa. Regarding the presence of keratinized mucosa, there is a need for further longitudinal studies to elucidate a possible benefit of one implant system over the other. [source] Synthesis and GC,MS analysis of angelates and tiglates as an aid to identification of these components in essential oilsFLAVOUR AND FRAGRANCE JOURNAL, Issue 2 2010Robert P. Adams Abstract One-hundred-and-forty-one angelates and tiglates were synthesized and their Kováts retention indices and mass spectra are presented. It is anticipated that the publication of these data will aid in the identification of angelates and tiglates from natural sources. Copyright © 2009 John Wiley & Sons, Ltd. [source] Aroma-impact compounds in Lysimachia foenum-graecum extractsFLAVOUR AND FRAGRANCE JOURNAL, Issue 1 2009Na Shu Abstract Two different extraction methods were used to obtain representative extracts from stems and leaves of Lysimachia foenum-graecum, a Chinese plant with a smoky, spicy, green, woody and caramel aroma. An extract was obtained by steam distillation followed by pentane back-extraction. Plants were also extracted with dichloromethane, and the non-volatile compounds were separated from volatiles by high-vacuum distillation (SAFE). Compared to the steam distillate extract, the SAFE-distilled extract was judged to be more similar to the aroma of the starting materials. The aroma-impact compounds of the SAFE extract were then determined using multidimensional GC. From the detection frequencies and the intensities of the peaks, 47 peaks with odour-activity were determined, using an adaptation of the GC,SNIFF method, to have an impact on the overall aroma of the extract. Fifty-four compounds responsible for the peaks presenting odour-activity were identified from mass spectral data, retention indices, olfactory character and co-injection of authentic standards. Copyright © 2008 John Wiley & Sons, Ltd. [source] Linear retention indices in gas chromatographic analysis: a reviewFLAVOUR AND FRAGRANCE JOURNAL, Issue 5 2008Barbara d'Acampora Zellner Abstract The main purpose of any chromatographic analysis is to resolve mixtures of compounds into less complex mixtures or ultimately into pure components. In addition to this function, the chromatographic system can provide retention data which serve as complementary information for the positive identification of resolved components. The need to express gas chromatographic retention data in a standardized system has long been recognized and retention index values presented to be a valuable parameter. Those values are mainly calculated by applying the equations proposed by Kováts, for isothermal analysis, and van den Dool and Kratz, for programmed gas chromatographic runs. In general, these indices denote the retention behaviour of the compounds of interest according to a uniform scale determined by a series of closely related standard substances. The use of retention indices in the flavour and fragrance field is well-documented, and they are widely applied for the comparison of results between laboratories, as well as to characterize stationary phases. Copyright © 2008 John Wiley & Sons, Ltd. [source] Chemical composition and antibacterial activity of the essential oil of Michelia foveolata Merryll ex Dandy from VietnamFLAVOUR AND FRAGRANCE JOURNAL, Issue 4 2007Dominique Lesueur Abstract The chemical composition of the volatile oil extracted from aerial parts (twigs, leaves and flowers) of Michelia foveolata growing wild in Vietnam was investigated by combination of column chromatography, GC (retention indices), GC,MS and 13C-NMR spectroscopy. Fifty-eight components were identified, with sabinene (32.4%) and terpinen-4-ol (13.7%) as the main constituents. The essential oil was tested against 11 bacteria using the agar disc diffusion method, and exhibited a significant antibacterial activity against Salmonella enterica, Staphylococcus epidermidis, Staphylococcus aureus and Bacillus cereus (MICs = 2,4 µl/ml). Copyright © 2007 John Wiley & Sons, Ltd. [source] A comparative study of the essential oils of the genus Plumeria Linn. from MalaysiaFLAVOUR AND FRAGRANCE JOURNAL, Issue 6 2006Norsita Tohar Abstract The chemical composition of the flower oils of three Malaysian Plumeria Linn. species, P. acuminata Ait. (white flower), P. rubra Linn. (reddish-orange flower) and P. rubra Linn. (red flower), were determined by gas chromatography on two columns of different polarity, GC,MS and Kováts retention indices. The oil of P. acuminata Ait. (white flower) was made up predominantly of benzyl salicylate (39.0%), benzyl benzoate (17.2%), trans -nerolidol (10.6%), neryl phenylacetate (10.5%) and linalool (8.9%). Phenylethyl benzoate at 12.3% was the most abundant compound in the oil of P. rubra Linn. (reddish-orange flower), followed by dodecanoic acid at 11.8% concentration. Hexadecanoic acid constituted 9.3% and 27.2% of the oils of P. rubra Linn. (reddish-orange flower) and P. rubra Linn. (red flower), respectively. Copyright © 2006 John Wiley & Sons, Ltd. [source] Composition of the essential oil of flowers of Chloranthus spicatus (Thunb.) MakinoFLAVOUR AND FRAGRANCE JOURNAL, Issue 4 2006Hailemichael Tesso Abstract The composition of the essential oil of the flowers of Chloranthus spicatus (Thunb.) Makino (Chloranthaceae) was investigated using capillary GC-GC/MS, preparative GC and NMR techniques. Forty-seven compounds were identified either by comparing their retention indices and mass spectra with a library of authentic samples established under identical experimental conditions or, by isolating the compounds and deriving their structures by one- and two-dimensional NMR investigations. Thus, four minor components, viz. chloranthalactone A (0.5%), isogermafurenolide (0.7%), eudesma-4(15),7(11),9-trien-12-olide (0.5%), and 7, -hydroxyeudesm-4-en-6-one (3.3%), were isolated for the first time as constituents of the essential oil of the flowers of C. spicatus and their structures established. The major components of the oil include (Z)- , -ocimene (6.3%), allo-aromadendrene (6.2%), sarisane (2-allyl-4,5-methylenedioxyanisol, 4.2%) and selina-4(15),7(11)-diene (6.4%). Copyright © 2006 John Wiley & Sons, Ltd. [source] Chemical composition and antimicrobial activity of essential oils from Tunisian Pituranthos tortuosus (Coss.) MaireFLAVOUR AND FRAGRANCE JOURNAL, Issue 1 2006A. Abdelwahed Abstract The aerial parts of Pituranthos tortuosus, collected during November and April, were analysed by GC and GC,MS. In total, 56 compounds were identified by their retention indices. Antimicrobial assays showed that the November essential oil is more effective than that of April against the Gram-positive bacteria Enterococcus faecalis and Staphylococcus aureus. The April essential oil displayed the highest activity against Staphylococcus aureus. Copyright © 2005 John Wiley & Sons, Ltd. [source] Advanced and innovative chromatographic techniques for the study of citrus essential oilsFLAVOUR AND FRAGRANCE JOURNAL, Issue 3 2005Giovanni Dugo Abstract A brief description is given of advanced chromatographic techniques currently employed in citrus essential oil analysis (the interactive use of linear retention indices and MS spectra probability matching in GC,MS; on-line ,heart cutting' multidimensional chromatographic techniques, comprehensive GC and LC; fast GC and GC,MS; fast HPLC; HPLC,MS). A series of applications are reported, demonstrating both the valid and the potential of these methods. Copyright © 2005 John Wiley & Sons, Ltd. [source] The essential oils of Boesenbergia stenophylla R. M. Sm. as natural sources of methyl (E)-cinnamateFLAVOUR AND FRAGRANCE JOURNAL, Issue 6 2003Fasihuddin bin Ahmad Abstract The rhizome and leaf oils of Boesenbergia stenophylla R. M. Sm. were analysed by gas chromatography on two columns of different polarity, retention indices and GC,MS. The oils were found to possess compositional similarities but quantitative differences in the concentration of each component. The oils are natural sources of methyl (E)-cinnamate, constituting 49.9,53.4% of the oils. They are also rich in sesquiterpenoids (39.8 and 40.3%, respectively) with , -elemene, , -elemene, , -santalene, , -humulene, , -muurolene, spathulenol, caryophyllene alcohol and kaur-16-ene as the main representatives. Copyright © 2003 John Wiley & Sons, Ltd. [source] Essential oil composition and antimicrobial activity of tuberous roots of Pimpinella tirupatiensis Bal.FLAVOUR AND FRAGRANCE JOURNAL, Issue 6 2002& Subr., India, an endemic taxon from eastern ghats Abstract The tuberous roots of Pimpinella tirupatiensis (Apiaceae) were subjected to sequential extraction with different polar solvents and the extracts were tested against eight bacterial and three fungal pathogenic strains for antimicrobial activity. The minimum inhibitory concentration of active extracts against six bacterial and two fungal strains were determined. The hexane and ethyl acetate fractions exhibited a broad spectrum of antimicrobial activity and were analysed for different phytochemicals. The active extracts contained significant amounts of alkaloids, flavonols, flavones and volatile oils. The hexane extract yielded an essential oil when subjected to GC with FID. The compounds were identified based on their retention indices and yielded 24 known compounds and one unknown compound. The major compounds are ,-bisabolene (9.2%), ,-3-carene (8.9%), cis -carveol (6.7%), elemol (5.8%), ,-cadinol (4.4%), methyl geranate (4.3%) and ,-nonalactone (3.4%). Copyright © 2002 John Wiley & Sons, Ltd. [source] Analysis of the essential oil of Lippia graveolens HBK from El Salvador,FLAVOUR AND FRAGRANCE JOURNAL, Issue 3 2001Gaston Vernin Abstract Essential oils from two samples of Lippia graveolens HBK (South American or Mexican oregano, common in El Salvador), were obtained by hydrodistillation and studied by GC and GC,MS. Forty-five compounds, constituting 92,93% of the oil, were identified. The two major components in both samples were carvacrol (71% and 34.6%, respectively) and thymol (5,7%, respectively). In addition, two unusual isomers, 2-isopropyl-4-methylphenol and 4-isopropyl-2-methylphenol, were found and identified by comparison with mass spectral data and retention indices and tentatively synthesized. Copyright © 2001 John Wiley & Sons, Ltd. [source] Modeling the semi-empirical electrotopological index in QSPR studies for aldehydes and ketonesJOURNAL OF CHEMOMETRICS, Issue 5 2009Érica Silva Souza Abstract The semi-empirical electrotopological index, ISET, used for quantitative structure,retention relationship (QSRR) models firstly developed for alkanes and alkenes, was remodeled for organic functions such as ketones and aldehydes. The ISET values for hydrocarbons are calculated through the atomic charge values obtained from a Mulliken population analysis using the semi-empirical AM1 method and their correlation with the SETi values attributed to the different types of carbon atoms according to experimental data. For ketones and aldehydes the interactions between the molecules and the stationary phase are slowly increased relative to the hydrocarbons, due to the charge redistribution that occurs in the presence of heteroatoms. For these polar molecules the increase in the interactions was included in the calculation of the ISET values through the dipole moment of the whole molecule and also through an equivalent local dipole moment related to the net charges of the atoms of the CO and HCO functional groups. Our findings show that the best definition of an equivalent local dipole moment is clearly dependent on the specific features of the charge distribution in the polar region of the molecules (e.g. ketones and aldehydes), which allows them to be distinguished. Thus, the QSRR models for 15 aldehydes and 42 ketones obtained using the remodeled ISET were of good quality as shown by the statistical parameters. The ability of this remodeled index to include charge distribution and structural details opens a new way to study the correlations between the molecular structure and retention indices in gas chromatography. Copyright © 2009 John Wiley & Sons, Ltd. [source] Characterization of Fish Sauce Aroma-Impact Compounds Using GC-MS, SPME-Osme-GCO, and Stevens' Power Law ExponentsJOURNAL OF FOOD SCIENCE, Issue 4 2008A.J. Pham ABSTRACT:, The objectives of this study were to characterize volatile compounds and to determine the characteristic aromas associated with impact compounds in 4 fish sauces using solid-phase micro-extraction, gas chromatography-mass spectrometry, Osme, and gas chromatography olfactometry (SPME-Osme-GCO) coupled with Stevens' Power Law. Compounds were separated using GCMS and GCO and were identified with the mass spectral database, aroma perceived at the sniffing port, retention indices, and verification of compounds by authentic standards in the GCMS and GCO. Aromas that were isolated and present in all 4 fish sauce samples at all concentrations included fishy (trimethylamine), pungent and dirty socks (combination of butanoic, pentanoic, hexanoic, and heptanoic acids), cooked rice and buttery popcorn (2,6-dimethyl pyrazine), and sweet and cotton candy (benzaldehyde). All fish sauces contained the same aromas as determined by GCO and GCMS (verified using authentic standard compounds), but the odor intensity associated with each compound or group of compounds was variable for different fish sauce samples. Stevens' Power Law exponents were also determined using this analytical technique, but exponents were not consistent for the same compounds that were found in all fish sauces. Stevens' Power Law exponents ranged from 0.14 to 0.37, 0.24 to 0.34, 0.09 to 0.21, and 0.10 to 0.35 for dirty socks, fishy, buttery popcorn, and sweet aromas, respectively. This demonstrates that there is variability in Stevens' Power Law exponents for odorants within fish sauce samples. [source] Quantitative Structure-retention Relationship for Gas Chromatography of Polychlorinated Naphthalenes by Ab initio Quantummechanical Calculations and a Cl Substitution Position MethodMOLECULAR INFORMATICS, Issue 1 2006Zhi-Cai Zhai Abstract Three quantitative structure-retention relationship (QSRR) models have been developed for gas chromatographic relative retention indices (RIs) of polychlorinated naphthalene (PCN) congeners. With computation at HF/6-31G* and B3LYP/6-31G* levels in Gaussian98 program, the structural parameters of PCNs were obtained and used as chemical descriptors to correlate with their gas chromatographic RIs by multiple linear regression analysis, resulting in model,1 and model,2. The squared correlation coefficients (r2) of the first two models are 0.9814 and 0.9957, and the cross-validation correlation coefficients (q2) are 0.9771 and 0.9948, respectively. On the other hand, the third model, model,3, was developed using the relative position of chlorine substitution as molecular descriptor, and its multiple squared correlation coefficient is r2,=,0.9967 and q2,=,0.9959, suggesting model,3 is practical and especially has a optimum predictive power. [source] Microsynthesis and mass spectral study of Chemical Weapons Convention related 2-alkyl-1,3,6,2-dioxathiaphosphocane-2-oxidesRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 12 2008Meehir Palit Chemical Weapons Convention (CWC)-related compounds where the phosphorus atom is part of a ring have very limited representation in mass spectral libraries and the open literature. Here we report electron ionization (EI), chemical ionization (CI) and electrospray ionization tandem mass spectrometry (ESI-MSn) spectra and retention indices for 2-alkyl-1,3,6,2-dioxathiaphosphocane-2-oxides (alkyl C1 to C3) which are new cyclic chemicals covered under the CWC. The EI mass spectra show a pattern of ion fragmentation that is similar to that of other cyclic phosphonates in that loss of the alkylphosphonic acid as a neutral loss is more important than the presence of the protonated alkylphosphonic acid. In contrast to other cyclic phosphonates, the 2-alkyl-1,3,6,2-dioxathiaphosphocane-2-oxides show almost no protonated alkylphosphonic acid and as a result the spectra do not carry the same distinctive signature of the phosphorus,carbon bond that is required for the chemical to be covered under the CWC. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||||||||