GAS LIQUID CHROMATOGRAPHY

Fatty acid composition of human milk (HM) is known to change considerably during lactation. However, we were unable to find data on changes of fatty acid composition of HM during the very early phase of lactation, i.e. in the first week of life. HM samples were obtained from 18 healthy lactating women every day during the first week and thereafter on the 14th and 28th days of lactation. Fatty acid composition of colostrum and mature HM samples was determined by high-resolution capillary gas-liquid chromatography. Values of the n-6 essential fatty acid, linoleic acid, in HM did not change significantly during the first month of lactation, whereas values of the n-3 essential fatty acid, alpha-linolenic acid, showed significant increases during the first 2 weeks of lactation (1st day: 0.49 [0.12], % weight/weight, median [ranges from the 1st to the 3rd quartile], 14th day: 0.69 [0.31], p < 0.05). In contrast, values of the n-6 long-chain metabolites, eicosadienoic-, dihomo-gamma-linolenic- and arachidonic acid, as well as the values of the n-3 long-chain metabolites, eicosatrienoic-, and eicosapentaenoic acid exhibited significant decreases during the entire period investigated. The principal n-3 long-chain metabolite, docosahexaenoic acid, showed a significant increase between the 3rd and 14th days, but a significant decrease between the 14th and 28th days (3rd day: 0.15 [0.13], 14th day: 0.28 [0.11], p < 0.05, 28th day: 0.19 [0.12], p < 0.01). There were statistically significant positive correlations between arachidonic and docosahexaenoic acid values on the 1st (r = 0.67, p < 0.01), 5th (r = 0.56, p < 0.05) and the 6th (r = 0.53, p < 0.05) days of lactation. Fatty acid composition of HM changes significantly even during the first week of lactation. The lack of positive correlation between essential fatty acids and their long-chain metabolites suggests that it is not only the availability of essential fatty acids that influences the fatty acid composition of human colostrum.

A yeast identification procedure was developed with the aid of statistical methods. In this process cellular fatty acids of ten yeast species grown on yeast nitrogen base medium were extracted from yeast cells by saponification and analyzed as methyl esters by gas-liquid chromatography. Each species produced a distinctive fatty acid 'fingerprint' characterized by certain fatty acid compositions. A statistical procedure was developed in order to transform the 'fingerprints' into a yeast profile which resulted in a marked reduction in variation between profiles of the same yeast species. With this identification method, it was possible to identify the ten species within 4 h after they were obtained from cultures of yeasts grown for 48 h on glucose yeast nitrogen base medium as compared with 7-10 days for the more conventional methods.

A time course study of the fate of glucose, sucrose, and arabitol added to surface soils collected from vegetated and bare sites near Casey Station, Wilkes Land, Antarctica, was performed using gasliquid chromatography. For both soils, hydrolysis of added sucrose was observed after 24 hours. Following 168 hours incubation at both 5~ and 15~ hydrolysis of sucrose to glucose and fructose was greater than 95%. Maximum rates of sugar uptake were observed in soils from the vegetated site incubated at 15~ After 168 hours 44%, 52% and 94% of the added arabitol, glucose and sucrose respectively had been consumed. There did not appear to be any cell-free extracellular enzymatic activity in the soils as levels of added sucrose, trehalose and maltose within soil water extracts showed no change after 168 hours incubation. The results are discussed in relation to earlier work on the microbial activity of Antarctic soils and the sources of carbohydrate input into this ecosystem.

Background Animal studies have demonstrated dramatic changes in the intestinal flora during total enteral (TEN) or parenteral (TPN) nutrition. Aim of the study To assess the impact of TEN and TPN on human intestinal microflora. Methods Eight patients on fiber-free TEN, five patients on TPN, and ten controls were studied. Fecal bacteria were identified and numbered (logCFU/g feces), and fecal shortchain fatty acids (SCFAs) were measured in stool samples, by gas-liquid chromatography. Results In TEN patients, compared to controls (P<0.01), aerobes were increased (8.46±0.24) while anaerobes were decreased (5.79±0.84). In TPN patients, both aerobes and anaerobes were decreased compared to controls (5.64±0.27 and 5.31±1.09 respectively, P<0.01). Total SCFAs were lower in TPN patients than in TEN patients (48.3±16.6 vs 118.6± 24.1 mmol/kg, P<0.05). Conclusions Both TPN and TEN induce modifications in the intestinal microflora. During TPN, a homogeneous decrease occurs in both aerobic and anaerobic bacteria. TEN decreases only anaerobic bacteria, while aerobic bacteria are increased. This imbalance may play a role in the pathophysiology of TEN-induced diarrhea.

mThe fatty acid compositions of the seed oils from ten pine species have been established by capillary gasliquid chromatography of the methyl esters. With regard to either normal fatty acids or D5-olefinic acids, the general pattern of fatty acids did not differ from that of other pine seed oils reported previously. The main fatty acid was linoleic (9,12±18:2) acid (44.4±57.1%), followed by either oleic (9±18:1) acid (13.4±24.5%) or pinolenic (5,9,12±18:3) acid (1.5±25.2%). When applying multivariate analyses to the chemometric data (13 variables) of 49 pine species (ca. 40% of the living pine species), it was possible to distinguish between several sections: Pinea, Longifolia, Halepensis, Ponderosa-Banksiana, Sylvestris, and Cembra. The latter section was clearly divided into two subgroups. A few species that presented a low overall content of D5olefinic acids, and that grow in warm-temperate regions, were isolated from the bulk of other pine species. It is hypothesized that D5-olefinic acids might be related to cold-acclimation.

The bphospholipid hypothesisQ attributes a pathophysiologic role to the polyunsaturated fatty acid (PUFA) composition of phospholipids in depression. The aim of the present study was to determine whether the hypothesis is relevant to social anxiety disorder (SAD). The study sample consisted of 27 untreated, nondepressed patients with SAD (DSM-IV) and 22 controls. Severity of SAD was assessed with the Liebowitz Social Anxiety Scale (LSAS). Erythrocyte PUFA concentrations were measured by gas-liquid chromatography. Concentrations of most n-3 PUFAs were lower in the patients: 18 : 3n-3 by 32% (p b 0.002), 20 : 3n-3 by 34%, 20 : 5n-3 by 36% (all p b 0.001) and 22 : 6n-3 by 18% (p = 0.002). No significant differences were observed in other fatty acids. Significant inverse correlations were obtained between levels of n-3 PUFAs and LSAS scores. In conclusion, the phospholipid hypothesis may apply to SAD, thereby opening new therapeutic options. The robust relationship between low erythrocyte n-3 PUFA concentrations and SAD justifies exploration of relevant neuropathophysiological mechanisms.

Densities, viscosities and refractive indices have been determined for mixtures of acetophenone with N,N-dimethylethanolamine or with N,N-diethylethanolamine over the entire composition range at temperatures of (303.15, 313.15 and 323.15) K. The viscosity values were fitted to the Krishnan-Laddha and McAllister models. The thermophysical properties under study were also fitted to the Jouyban-Acree model. The excess values were correlated using the Redlich-Kister polynomial equation. It was found that, in all cases, the obtained data were correlated very well by the corresponding models. The molecular interactions existing between the components are also discussed.

Isotope Ratio Mass Spectrometry (IRMS) is a specialized technique used to provide information about the geographic, chemical, and biological origins of substances. The ability to determine the source of an organic substance stems from the relative isotopic abundances of the elements which comprise the material. Because the isotope ratios of elements such as carbon, hydrogen, oxygen, sulfur, and nitrogen can become locally enriched or depleted through a variety of kinetic and thermodynamic factors, measurement of the isotope ratios can be used to differentiate between samples which otherwise share identical chemical compositions. Several sample introduction methods are now available for commercial isotope ratio mass spectrometers. Combustion is most commonly used for bulk isotopic analysis, whereas gas and liquid chromatography are predominately used for the real-time isotopic analysis of specific compounds within a mixture. Here, highlights of advances in instrumentation and applications within the last three years are provided to illustrate the impact of this rapidly growing area of research. Some prominent new applications include authenticating organic food produce, ascertaining whether or not African elephants are guilty of night-time raids on farmers' crops, and linking forensic drug and soil samples from a crime scene to a suspected point of origin. For the sake of brevity, we focus this Minireview on the isotope ratio measurements of lighter-elements common to organic sources; we do not cover the equally important field of inorganic isotope ratio mass spectrometry.

Biodiesel, as an alternative fuel, is gradually receiving more popularity for use in internal combustion engines. However questions continue to arise with regard to its compatibility with elastomeric materials. The present work aims to investigate the comparative degradation of physical properties for different elastomers [e.g. ethylene propylene diene monomer (EPDM), silicone rubber (SR), polychloroprene (CR), polytetrafluroethylene (PTFE) and nitrile rubber (NBR)] upon exposure to diesel and palm biodiesel. Static immersion tests in B0(diesel), B10 (10% biodiesel in diesel), B20, B50 and B100(biodiesel) were carried out at room temperature (25 °C) for 1000 h. Different physical properties like, changes in weight and volume, hardness and tensile strength were measured at every 250 h of immersion time. Compositional changes in biodiesel due to exposure of different elastomers were investigated by Gas chromatography mass spectroscopy (GCMS). The overall sequence of compatible elastomers in palm biodiesel is found to be PTFE > SR > NBR > EPDM > CR.

http://www.sciencedirect.com/science/article/pii/S0360544210007139

Phragmytes vallatoria belongs to the family poaceae. The complexity of leaf ethanolic extract can be simplified through column chromatography. Different solvent mixtures were used in elution systems i.e., hexane, ethyl acetate and methanol. The concentrated ethanolic leaf extract of 100 g was fractionated by column chromatography on silica gel (60-120 mesh). Major fractions were (hexane + ethyl acetate 9:1 and ethyl acetate + methanol 8.5: 1.5 fraction) and identified the major phytochemicals through NIST Electron Ionization Mass database. The identified compounds were 9, 12, 15-Octadecatrienoic acid, ethyl ester, (Z, Z, Z)-, Androstane-11, 17-dione, 3-hydroxy-, (3.alpha. 5. alpha)-, 9,12-Octadecadienoic acid ethyl ester and 9-12-15-Octadecatrienoic acid, ethyl ester, (Z,Z,Z)-. Only one peak was observed in ethyl acetate and methanol (8.5: 1.5) fraction and it was subjected to GC-MS and HPLC. The structures were (Benzenamine, 3-(methylthio)-, Morpholine, Phenanthrene and 3-Eicosene, (E).

Frying process has been considered to be a source of trans fatty acids. However, most truns fatty acids found in foods would come from the oil used and not from the process itself. To test this, the rruns fatty acid production was measured frying in extra virgin olive oil (EVOO), high oleic sunflower oil (HOSO) and sunflower oil (SO) various frozen foods 20 times with frequent replenishment (FR) or without replenishment @JR) of the used oil with fresh oil during the frying. Further, the fat extracted from potatoes fried in the EVOO, HOSO and SO from the frying 8 and 20 was also analyzed by gas liquid chromatography to compare it trans fatty acid profile with that of the corresponding fryer oil. Z'rans fatty acids appear in lower amounts than 5 mg/g oil or fat in both IX and NR. Elaidic acid was the most abundant tram fatty acid in EVOO or in the fat extracted from EVOO fried potatoes while tram linoleic isomers were more abundant in SO. HOSO was in between. Present data suggest that frequent addition of fresh oil through the frying process minimizes the fatty acid changes contributing to obtain fried foods with less amount of tram fatty acids. The consumption of a large standard ratio (-140 g) of these fried potatoes would implied the irrelevant amount of less than 0.13 g of tram fatty acids. 0 2000 Elsewa Saence Inc

A stability indicating high performance liquid chromatographic method has been developed for the determination of norfloxacin. Optimum separation was achieved in less than 10 minutes using Phenomenex ODS C 18 (250x 4.6mm packed with 5µ) column. The analyte was resolved by using a mobile phase 20 mmol L -1 ammonium formate and acetonitrile (70:30) pH adjusted to 4.0 with formic acid at flow rate 1 ml/min on a isocratic high performance liquid chromatographic system at a wavelength of 280 nm. The method was validated according to the ICH guidelines with respect to specificity, linearity, accuracy, precision, ruggedness and robustness and can be successfully applied for determination of this drug in commercial tablets. For stress studies the drug was subjected to acid, alkali and neutral hydrolysis, oxidation, dry heat and photolytic degradation. The degradation studies indicated the drug to be susceptible to acid, alkali hydrolysis and oxidative degradation. The analytical conditions and solvent developed provided good resolution within a short analysis time and economic advantages. The proposed method not required highly sophisticated and expensive instrumentation.

Our objective is to demonstrate the analytical capabilities of Advanced Surface Logging or Advanced Mud Logging (AML), the results borne from an extensive use of wellsite techniques and their use in time-critical situations. The work revolves around ascertaining and characterizing from the surface the nature of fluids found downhole using a number of integrated analytical techniques on oil samples and rock cuttings. We aim to evaluate the reservoir fluid properties flowing from the fractures and fluids which are suspected to be present within the pores of the reservoir matrix via cross-referencing multiple sample mediums.
The work studies data collected from a well in the Middle East; “Well-A”, which was drilled as a producer from the Upper-Middle Jurassic (UMJ) Formations and an appraisal from the porous interval of the Lower Jurassic formation (LJ). The primary target of the operating company was to determine the in-situ fluid characteristics of the UMJ Formations. The communication between these two intervals as well as the contact depth is unknown and crucial at the current stage of the field development.
Reservoir and hydrocarbon fluid characterization was investigated using cuttings samples taken from Well-A. All samples were analyzed in-lab, post-drilling using Advanced Mudlogging (AML) techniques such as Thermal Extraction Gas Chromatography (TEGC), Chemical Elemental Analysis and Mineralogical analysis (the latter two performed using X-Ray based techniques). Additional Mudlogging datasets gathered in real-time during drilling were integrated within the interpretation including Advanced Mud Gas (Methane to Toluene), together with the Computer Processed Image Logs and PVT test data provided by the operator. Finally, three dead oil samples from the tested intervals were analyzed in-lab with TEGC.
The chromatographic analysis of the commercially produced oil from the UJ showed a bimodal distribution which was interpreted as a mix of two different maturity fluids. We were able to trace the individual levels from which these two fluids were most probable to originate, by comparing the chromatographic characteristics of these oils across the TEGC results from the cuttings analysis. Furthermore, the in-lab geochemical analysis supported the understanding of the fluid mechanism within this reservoir interval. This interpretation resulted in potentially identifying a sub interval which could yield a higher gravity oil than initially tested and potentially transform this, now unproductive interval, into a prospect.
The innovative workflow, integrating all formation evaluation data collected from rock cuttings and mud gas data was applied for the first time at this level of complexity. Although prior studies investigated thepotential of integrating multiple datasets to determine reservoir fluid characteristics, never before, was such an integrated approach utilized based specifically on surface logging solutions. The case study demonstrated the value of supporting interpreters to bolster their interpretations thanks to data coming from separate independent sources.

"La chromatographie en phase gazeuse (CPG) est toujours un outil très utilisé dans le domaine de la chimie analytique et du contrôle, en particulier en chimie environnementale où les besoins deviennent de plus en plus nombreux et variés. Sa popularité s’étend même au grand public par l’intermédiaire des médias, où il n’est pas exceptionnel de voir des appareils de chromatographie en phase gazeuse dans des reportages télévisés sur des thèmes les plus divers (cosmétologie, dopage, archéologie, pétrochimie…).
Cet article fait suite à celui paru en 1998 (1) et il nous a paru intéressant de réactualiser les caractéristiques des appareils de CPG commercialisés en ce début de siècle et de millénaire. Si aucune grande nouveauté technologique n’est apparue dans ce domaine, la grande évolution sur les appareils disponibles se situe surtout au niveau du choix des injecteurs-vaporisateurs proposés par les fabricants. Dans le précédent article, nous avions décrit en détail le fonctionnement des différents détecteurs ; c’est pourquoi, nous allons décrire ici, celui des injecteurs-vaporisateurs classiques. Puis, des tableaux synoptiques des principaux appareils rencontrés sur le marché français seront donnés, en nous basant sur les informations fournies par les constructeurs.
Mots clés : chromatographie en phase gazeuse, appareillage, aspects techniques, injecteur."

A  simple,  robust,  precise  HPLC  method  was  developed  and  the
method  has  been  validated  for  the  estimation  of  valsartan  and
nebivolol  simultaneously  in  its  combined  dosage  forms  as  well  as
individual formulations. Both the compounds are well resolved in a
isocratic  method  by  using  the  mobile  phase  composition  of
acetonitrile: methanol: pH4.0 0.02M Potassium hydrogen phosphate
buffer in the ratio of 50:20:30 v/v at a flow rate of 1.0mL/min using a
C-18 column. The detection was carried out at 210nm.. The retention
time  of  Nebivolol  and  Valsartan  were  2.5  min  and  4.3  min
respectively.  The  developed  method  was  validated  for  specificity,
linearity,  precision,  accuracy,  limit  of  detection  (LOD),  limit  of
quantification (LOQ) and robustness as per ICH guidelines. Linearity
for Nebivolol and Valsartan were found in the range of 48-112 µg/ml
and  3.0-7.0  µg/ml,  respectively.  The  percentage  recoveries  for
Nebivolol  and  Valsartan  ranged  from  98.9-100.8  %  and  98.9-101.1
%,  respectively.  The  proposed  method  could  be  used  for  routine
analysis of Nebivolol and Valsartan in their combined dosage forms

This review focuses on the recent developments in the area of FOS research-its microbial production, functional properties and applications and an overview of the different analytical methods for the determination of the FTase. Different microbial sources of FTase reported in literature to produce FOS with different linkages to form 1-kestose, 6-kestose and neokestose in varying yields based on initial sucrose concentration is discussed. Different fermentative methods have been used for production of FOS. SSF has been used for the production of a value added product FOS utilizing various agroindustrial byproducts. The nutritional and culture parameters when optimized, the FOS yields and productivity could be improved. The use of immobilized enzymes and cells has led to the development of effective and economic methods for large-scale production of FOS. Forced flow Membrane reactor systems, biocatalyst system with a bioreactor equipped with a microfiltration systems, have been used for production of high content FOS by removing the released glucose and unreacted sucrose from the reaction mixture resulting in up to 98% FOS. The use of mixed enzyme system of Fructosyl Transferase and glucose oxidase or glucose dehydrogenase, could produce highly concentrated FOS up to 90-98%. Nano-filtration for removing glucose resulted in FOS of 90% concentration. The purified enzyme was found to produce kestose and nystose unlike the crude enzyme which produced GF 5 and GF 6 oligosaccharides Kinetic parameters (V m , K m , and K i ) of the enzyme were determined from experimental data on the transfructosylation rate at various substrate concentrations with and without addition of glucose Techniques like HPLC, using polar-bonded phase and resin-based HPLC columns are commonly used for separation of oligosaccharides with refractive Index Detector or pulsed amperometric detector and annular size exclusion chromatography for large scale and continuous fractionation. Other techniques like gas liquid chromatography, thin layer chromatography, NMR and Mass Spectrometry have been used for structure analyses. The functional properties like use as prebiotics, dietary fiber, role in absorption and defense/Immunity, lipid metabolism control of diabetics have been discussed. A variety of applications in food formulations are also discussed.

The new definition of total fat in FDA regulations implementing the Nutrition Labeling and Education Act of 1990 necessitates the quantitation of all lipid fatty acids and the summation of their triglyceride equivalents. A gas-liquid chromatographic (GLC) method using a packed column has been developed for quantitative measurement of total fat and saturated fat in foods. Fatty acids are released from food matrices by acid hydrolysis, and then extracted, esterified to their methyl esters and determined by GLC. Total fat and saturated fat are calculated in accordance with the new definitions of these components. Fat content determined by the acid hydrolysis--GLC methodology was compared with fat content determined by a direct AOAC gravimetric method for 23 food products containing between about 1 and 75% fat by weight. For all food products studied, the relationship between the results obtained by the two methods was best described by a straight line that had a correlation coefficient of 0.94. Results of repeated extractions and analysis of a milk-based infant formula (SRM 1846) suggest that this material may be useful as a quality control standard.

Previous research found that docosahexaenoic acid (C22:6n-3) was a component of fish oil that promotes trans-C18:1 accumulation in ruminal cultures when incubated with linoleic acid. The objective of this study was to determine if eicosatrienoic acid (C20:3n-3) and docosatrienoic acid (C22:3n-3), n-3 fatty acids in fish oil, promote accumulation of trans-C18:1, vaccenic acid (VA) in particular, using cultures of mixed ruminal microorganisms. Treatments consisted of control, control plus 5 mg of C20:3n-3 (ETA), control plus 5 mg of C22:3n-3 (DTA), control plus 15 mg of linoleic acid (LA), control plus 5 mg of C20:3n-3 and 15 mg of linoleic acid (ETALA), and control plus 5 mg of C22:3n-3 and 15 mg of linoleic acid (DTALA). Treatments were incubated in triplicate in 125-mL flasks, and 5 mL of culture contents was taken at 0 and 24 h for fatty acid analysis by gas-liquid chromatography. After 24 h of incubation, the concentrations of trans-C18:1 (0.87, 0.88, and 0.99 mg/culture), and VA (0.52, 0.56, and 0.62 mg/culture) were similar for the control, ETA, and DTA cultures, respectively. The concentrations of trans-C18:1 (5.51, 5.41, and 5.36 mg/culture), and VA (4.78, 4.62, and 4.59 mg/culture) were also similar between LA, ETALA, and DTALA cultures, respectively. These data suggest that C20:3n-3 and C22:3n-3 are not the active components in fish oil that promote VA accumulation when incubated with linoleic acid.

A new rapid, precise and sensitive reverse phase high performance
liquid chromatographic (RP-HPLC) method has been developed and
validated  for  the  estimation  of  Perindopril  and  Amlodipine
simultaneously  in  combined  dosage  form.  The  two  components
Perindopril  and  Amlodipine  were  well  resolved  on  an  isocratic
method,  C18  column,  utilizing  a  mobile  phase  composition  of
acetonitrile:  methanol:  a  mixed  buffer  of  0.02M  Potassium
dihydrogen  phosphate  buffer  and  0.02M  Sodium  dihydrogen
Phosphate buffer with 1mL Tri ethyl amine (40:20:40), v/v, pH 5.0)
at  a  flow  rate  of  1.0  mL/min  with  UV  detection  at  226  nm.  The
retention time of Perindopril and Amlodipine were 2.9 min and 4.9
min  respectively.  The  developed  method  was  validated  for
specificity,  linearity,  precision,  accuracy,  limit  of  detection  (LOD),
limit of quantification (LOQ) and robustness as per ICH guidelines.
Linearity for Perindopril and Amlodipine were found in the range of
48-112 µg/ml and 60.0-140.0 µg/ml, respectively. The percentage
recoveries for Perindopril and Amlodipine ranged from 98.9-100.4 %
and 98.9-100.7 %, respectively. The proposed method could be used
for routine analysis of Perindopril and Amlodipine in their combined
dosage forms.

Metabolite profiling has been used to assess the potential for unintended composition changes in potato (Solanum tuberosum L. cv. Desirée) tubers, which have been genetically modified (GM) to reduce glycoalkaloid content, via the independent down-regulation of three genes SGT1, SGT2 and SGT3 known to be involved in glycoalkaloid biosynthesis. Differences between the three groups of antisense lines and control lines were assessed using liquid chromatography-mass spectrometry (LC-MS) and gas chromatography (GC)-MS, and data analysed using principal component analysis and analysis of variance. Compared with the wild-type (WT) control, LC-MS revealed not only the expected changes in specific glycoalkaloid levels in the GM lines, but also significant changes in several other metabolites, some of which were explicable in terms of known pathways. Analysis of polar and non-polar metabolites by GC-MS revealed other significant (unintended) differences between SGT lines and the WT, but also between the WT control and other control lines used.

Previous studies found that feeding dairy cows a blend of fish and soybean oils enhanced milk vaccenic acid (VA) and conjugated linoleic acid (CLA) concentrations more than when the oils were fed separately. In these studies, the authors concluded that a component in fish oil was stimulating ruminal VA production from other sources of unsaturated fatty acids; however, that component was not identified. The objective of this study was to determine whether docosahexaenoic acid (DHA), an omega-3 fatty acid (FA) in fish oil, is the active component that promotes trans-C18:1 FA, VA in particular, accumulation using cultures of mixed ruminal microorganisms. Treatments consisted of control, control plus 5 mg of DHA (DH), control plus 30 mg of soybean oil (SBO), and control plus 5 mg of DHA and 30 mg of SBO (DHSBO). Treatments were incubated in triplicate in 125-mL flasks, and 5 mL of culture contents was taken at 0 and 24 h for fatty acid analysis by gasliquid chromatography. After 24 h of incubation, the level of trans-C18:1 FA (14.1 and 11.7 mg/culture) and VA (13.0 and 10.2 mg/culture) increased more with added DHA than with added SBO, respectively. Combining DHA and SBO yielded higher quantities of trans-C18:1 FA (21.3 mg/culture) and VA (19.8 mg/culture) in the cultures than either fat source alone. These data suggest that DHA is the component in fish oil that promotes VA accumulation when incubated with linoleic acid. (Key words: docosahexaenoic acid, soybean oil, vaccenic acid)

Cachaç a, the most popular alcoholic beverage in Brazil, is a sugar cane spirit similar to rum. Its production is around 2 billion liters per year, of which <1% is exported. Although rum is similar to cachaç a its flavor difference is easily recognizable. Using gas chromatography-olfactometry (GCO) to separate and characterize the odorants present in cachaç a and rum, these two sugar cane products were compared and standards identified to use in a descriptive sensory analysis (DSA). In the DSA cachaç a was more intense in the grassy, spicy, sulfury, and vinegar descriptors, whereas apple and caramel were the same in both rum and cachaç a. The GCO data for the apple-smelling compounds -damascenone along with ethyl butyrate, isobutyrate, and 2-methylbutyrate were at the same potency in both cachaç a and rum, whereas the spicy-smelling eugenol, 4-ethylguaiacol, and 2,4-nonadienal were much more potent in cachaç a.

The kinetics of the polymerization of styrene in bulk and in dilute systems in the presence of p-acetyi benzylidene triphenylarsonium ylide (p-ABTAY) as radical initiator has been examined at 60+0.1°C for 20 h under N2. The values of the initiator exponent and the monomer exponent showed that the system follows ideal radical kinetics with bimolecular termination. The overall activation energy and average value of k~/k t are 64.6 kJ moi -1 and 0.10 × 10-21 mol -1 s -1, respectively. The ylide dissociates to produce phenyl radical, which brings about polymerization.

An evaluation of the MicroSeq 500 microbial identification system by nucleic acid sequencing and the Mayo Clinic experience with its integration into a routine clinical laboratory setting are described. Evaluation of the MicroSeq 500 microbial identification system was accomplished with 59 American Type Culture Collection (ATCC) strains and 328 clinical isolates of mycobacteria identified by conventional and 16S ribosomal DNA sequencing by using the MicroSeq 500 microbial identification system. Nucleic acid sequencing identified 58 of 59 (98.3%) ATCC strains to the species level or to the correct group or complex level. The identification results for 219 of 243 clinical isolates (90.1%) with a distance score of <1% were concordant with the identifications made by phenotypic methods. The remaining 85 isolates had distance scores of >1%; 35 (41.1%) were identified to the appropriate species level or group or complex level; 13 (15.3%) were identified to the species level. All 85 isolates were determined to be mycobacterial species, either novel species or species that exhibited significant genotypic divergence from an organism in the database with the closest match. Integration of nucleic acid sequencing into the routine mycobacteriology laboratory and use of the MicroSeq 500 microbial identification system and Mayo Clinic databases containing additional genotypes of common species and added species significantly reduced the number of organisms that could not be identified by phenotypic methods. The turnaround time was shortened to 24 h, and results were reported much earlier. A limited number of species could not be differentiated from one another by 16S ribosomal DNA sequencing; however, the method provides for the identification of unusual species and more accurate identifications and offers the promise of being the most accurate method available.

Detection of foreign fat in milk fat can be performed by analyzing triacylglycerols (TAGs) by gas-liquid chromatography (GLC) using the standardized methodology. The standard methodology recommends the use of a packed column, which allows the separation of milk TAGs according to their chain length (total carbon number). This procedure is not widely applied because these columns are not commercially available. This study describes a fast methodology by using a short apolar open-tubular capillary column. The developed experimental conditions can be used to obtain the chromatographic resolution required in the standardized procedure, and the separation of milk fat TAGs (C24 to C54) is achieved in less than 4 min. As indicated by the standardized method, the quantification was performed by calibration using the certified reference material CRM-519 butterfat as standard substance. The methodology was fully validated and relative repeatability values were compared with the values provided...

Wine extracts obtained by a dynamic headspace sampling technique were studied by quantitative gas chromatography-olfactometry (GC-O) to determine the aroma profiles of six young monovarietal Spanish white wines. A partial least-square regression study was carried out to look for models relating wine aroma properties with GC-O scores. Models were validated by sensory analysis. Four out of the five most important sensory descriptors were satisfactorily described by a model, and sensory tests confirmed most of the predictions. The main aroma differences between these wines are due to the ratio linalool/3-mercaptohexyl acetate. Floral, sweet, and muscat are positively related to the concentration of linalool and negatively to that of 3-mercaptohexyl acetate. Tropical fruit is related to the wine content in this last odorant. 2-Phenyl acetate, reinforced by other acetates, can also contribute to floral and sweet notes. Alkyl-methoxypyrazines lessen the tropical fruit note, and acetic acid lessens the muscat nuance.

Incubation of RAW 264.7 murine macrophages with 9,15-dihydroxy-11-oxo-, (5Z,9a,13E,15(S))-Prosta-5,13-dien-1-oic acid [prostaglandin D 2 (PGD 2 )] induced formation of considerable peroxisome proliferator-activated receptor-g (PPARg) activity [Nature 391 (1998) 79]. Because PGD 2 itself is a poor PPARg ligand, we incubated RAW 264.7 macrophage cultures with prostaglandin D 2 for 24 h and studied the ability of the metabolites formed to activate PPARg. PGD 2 products were extracted and fractionated by reverse phase highperformance liquid chromatography. Chemical identification was achieved by UV spectroscopy, gas -liquid chromatography/mass spectrometry and chemical syntheses of reference compounds. PGD 2 was converted to eight products, six of which were identified. Ligandinduced interaction of PPARg with steroid receptor coactivator-1 was determined by glutathione-S-transferase pull-down assays and PPARg activation was investigated by transient transfection of RAW 264.7 macrophages. In addition to the previously known ligand 11-oxo-(5Z,9,12E,14Z)-Prosta-5,9,12,14-tetraen-1-oic acid (15-deoxy-D 12,14 -PGJ 2 ), a novel PPARg ligand and activator viz. 9-hydroxy-11-oxo-, (5Z,9a,12E,14Z)-Prosta-5,12,14-trien-1-oic acid (15-deoxy-D 12,14 -PGD 2 ) was identified. The biological significance of these results is currently under investigation. D

Mosquitoes are important vectors of diseases to humans and domestic animals. Chemical control of vectors remains a main resource for the prevention and control of vector-borne diseases. Due to the development of insecticide resistance and risks to human health and the environment of synthetic compounds, the search for alternative pesticides is encouraged. This work assessed the insecticidal activity of essential oils (EOs) from Lippia turbinata and L. polystachya from Argentina on Culex quinquefasciatus mosquitoes. EOs were extracted by hydro-distillation and analyzed with gas-liquid chromatography and mass spectrometry. The insecticidal activity against mosquito larvae, pupae, and adults were evaluated according to World Health Organization protocols. Concentrations ranking from 10 to 160 ppm were assessed at 1, 2, 3, and 24 h posttreatment. The composition of the EO of L. polystachya and L. turbinata were qualitatively similar, with α-thujone and carvone as main constituent; differences were mostly due to the proportion of each component. βcaryophyllene was also an important constituent of the EO of L. turbinata. Both EO were larvicidal at concentrations of 80 ppm or higher, but only L. turbinata was adulticidal.

Residues of ethion were estimated in cucumber by gas liquid chromatography following three applications of the insecticide at 375 and 750 g a.i ha−1. The average initial deposits of ethion on cucumber fruits were found to be 2.40 and 4.97 mg kg−1 at single and double dosages, respectively. Residues of ethion dissipated below the maximum residue limit (MRL) of 0.5 mg kg−1 in 7 days. Half-life (T1/2) for degradation of ethion on cucumber was observed to be 2.92 days at recommended dosage. A waiting period of 7 days is suggested for safe consumption of cucumber.

The chemical composition and nutritional value of five wild edible mushroom species (Agaricus arvensis, Lactarius deliciosus, Leucopaxillus giganteus, Sarcodon imbricatus, Tricholoma portentosum) commonly consumed in the Trás-os-Montes region of Northeast Portugal was determined. Chemical composition evaluation included moisture, total oil content, crude protein, ash, carbohydrates, and nutritional value determination. The macronutrient profile in general revealed that the wild mushrooms were rich sources of protein and carbohydrates, and had low amounts of fat. On the basis of the proximate analysis, it can be calculated that an edible portion of 100 g of these mushrooms provides, on average, 28 kcal (118 kJ). The analysis of fatty acid composition, performed by gas-liquid chromatography coupled to a flame ionization detector, allowed the quantification of fifteen fatty acids. Unsaturated fatty acids and, in particular, oleic and linoleic acids, were predominant. The composition in individual sugars was also determined by high performance liquid chromatography coupled to a refraction index detector, mannitol and trehalose being the most abundant sugars.

In this study, a novel continuous reactor has been developed to produce high quality methyl esters (biodiesel) from palm oil. A microporous TiO2/Al2O3 membrane was packed with potassium hydroxide catalyst supported on palm shell activated carbon. The central composite design (CCD) of response surface methodology (RSM) was employed to investigate the effects of reaction temperature, catalyst amount and cross flow circulation velocity on the production of biodiesel in the packed bed membrane reactor. The highest conversion of palm oil to biodiesel in the reactor was obtained at 70°C employing 157.04g catalyst per unit volume of the reactor and 0.21cm/s cross flow circulation velocity. The physical and chemical properties of the produced biodiesel were determined and compared with the standard specifications. High quality palm oil biodiesel was produced by combination of heterogeneous alkali transesterification and separation processes in the packed bed membrane reactor. © 2010 Elsevier Ltd.

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In 1998, one of the largest determinations of organochlorine pesticides in a representative sample of a Spanish population (682 serum samples from the Canary Islands) was made in the context of the bCanary Islands Nutrition SurveyQ (ENCA). In the Canary Islands, extensive farming areas have been developed in these last decades, with greenhouses dedicated to intensive cultivation using DDT in huge amounts. In Spain, similarly to other European countries, DDT was banned in the late 1970s. The pesticide residues in human serum are indicative of past and present exposure to them. Our objective is to point out the differences of pesticide contamination between islands; and together with this, if a connection could be established with gender, age, or habitat of subjects. Concentration of selected persistent organochlorine pollutants ( p, pV-DDT, o, pV-DDT, p, pV-DDE, o, pV-DDE, p, pV-DDD, and o, pV-DDD) was measured with gas chromatography-electron capture detector. Almost all of the samples (99.3%) presented detectable levels of some DDT-derivatives, being p,pV-DDE the most frequently detected organochlorine. The median concentration of total DDT body burden, expressed in ng/g fat, present in the Canary Islands (370 ng/g fat) was similar to that found in other European countries, although it was noteworthy that a fourth of the population showed a total DDT body burden higher than 715 ng/g. Interestingly, statistical significant differences were found in serum levels of organochlorine pesticides between islands, being these levels higher in people from Tenerife and Gran Canaria (415 and 612 ng/g fat, respectively), the islands that present both highest population and highest surface devoted to intensive agriculture. As expected, serum levels of both total DDT body burden and p, pV-DDE increased with age. Statistically significant differences were also found in relation to gender, women showing higher levels of these organochlorine pesticides 0048-9697/$ -see front matter D Science of the Total Environment 339 www.elsevier.com/locate/scitotenv than men. One of the most relevant findings of this work is the presence of a very high DDT/DDE ratio in people from the Canary Islands, thus indicating a chronic exposure to DDT that persists nowadays. DDT and its derivatives are considered as xenoestrogens, and they have been linked to breast cancer. Having into account that the Canary Islands present high incidence and mortality for breast cancer, our results point to the possibility that these environmental contaminants may be playing a determining role that must be investigated in detail. The high levels of DDT and its derivatives in serum from people living in this Archipelago should be considered a matter of public health concern. D

Synthetic solutions containing amino acids, sugar, water, and yeast nutrients have been fermented by Saccharomyces cerevisiae, and the volatile composition of the fermented media has been analyzed by GC. Eleven amino acid compositions imitating the characteristic amino acid profile of 11 different grape varieties were tested. Significant differences in the levels of some important volatile compounds (ethanol, ethyl acetate, acetic acid, higher alcohols and some of their acetates, methionol, isobutyric acid, ethyl butyrate, and hexanoic and octanoic acids) were found. The levels of some of the volatile compounds are well correlated with the aromatic composition of wines made with grapes of the same varieties. A multiple linear regression study produced good models for most of the odorants for which the level was related to the must amino acid composition. Partial least-squares regression models confirm that amino acid composition explains a high proportion of the variance in the volatile composition and show that the relationship between both sets of variables is highly multivariate. According to the different models, the levels of some byproducts of fatty acid synthesis are related to threonine and serine, the level of -phenyletanol is closely related to the level of phenylalanine, and methionol is stongly correlated to the must methionine contents. The addition of selected amino acids to different musts confirms the previous observations.

Coriander (Coriandrum sativum L.) seeds were extracted with chloroform/methanol (2:1, v/v) and the amount of total lipid was 28.4% of seed weight. The major fatty acid was petroselinic acid (65.7% of the total fatty acid methyl esters) followed by linoleic acid. Chromatography on a silica column with solvent of increasing polarity yielded 93.0% neutral lipids, 4.14% glycolipids, and 1.57% phospholipids. Thin-layer chromatography on silica gel was used to obtain major neutral lipid subclasses. Fatty acid profile of neutral lipid subclasses, triacylglycerols, and sterol content were determined using gas-liquid chromatography. Six triacylglycerol molecular species were detected but one component (C54:3) corresponding to tripetroselinin, and/or dipetroselinoyl oleoyl glycerol comprised more than 50% of the total triacylglycerols. Sterol content was estimated to be at a high level (5186 µg g -1 oil). Stigmasterol, β-sitosterol, ∆5-avenasterol, and campesterol were found to be the sterol markers. Phospholipid subclasses were separated by high-performance liquid chromatography on a silica column by gradient elution from isooctane/2-propanol (6:8, v/v) to isooctane/2-propanol/water (6:8:0.6, v/v/v) with detection at 205 nm. The major individual phospholipid subclasses were phosphatidylcholine followed by phosphatidylethanolamine, phosphatidylinositol, and phosphatidylserine.

This study aimed to quantify concentrations of fatty acids in the hump and abdomen fats of three different age groups of camel. Hump and abdomen fats were extracted from eight each of one-humped camels (Camelus dromedarius) of three age groups: group 1 (< 1 year old), group 2 (1-3 years old) and group 3 ( > 3 years old). The fatty acid methyl ester concentrations of these fats were determined by gas-liquid chromatography (GLC). The percentage of fat in the hump (H) and abdomen (A) fats was significantly (P < 0.05) lower for group 1 (H 92.0% and A 94.3%) than for group 2 (H 97.4% and A 97.2%) and group 3 (H 97.6% and A 97.5%), on a dry matter basis. Hump and abdomen fats from the three different groups had similar fatty acid patterns with more saturated than unsaturated fatty acids. The saturated fatty acids in the hump fats accounted for 58.3, 67.6, and 63.0% of the total fatty acids for groups 1, 2 and 3, respectively; group 1 had significantly (P<0.05) lower saturated and higher unsaturated fatty acid concentrations than group 2. The iodine numbers were significantly (P< 0.05) higher in group 1 than either group 2 or 3. Palmitic acid (C16:0) was the major fatty acid in hump fat with 32.06, 32.90 and 34.37%, followed by oleic acid (C18:1) 33.65, 21.66 and 28.91.0% and stearic acid (C18:0) 18.85, 24.13 and 20.74% for groups 1, 2 and 3, respectively. Group 1 had significantly higher (P <0.05) oleic acid and lower stearic acid concentrations than group 2. The melting point of both hump and abdomen fats varied between the age groups. This study indicated that age has an effect on the fatty acid composition and the melting point of hump and abdomen fats in one-humped Arabian camels. #

The RapiD Ana and the API 20A systems for identification of anaerobic bacteria were compared for accuracy on 108 recent isolates of gram-negative and gram-positive anaerobic bacteria. No additional tests or gas-liquid chromatography were used. RapiD Ana identified 91.7 % of the isolated strains to species level and 6.5 % to genus level but failed to identify 1.8 % of the total strains. API 20A identified 85.2 % of strains to species level, 3.7 % to genus level but failed to identify 11.1% of the total strains. Although the difference between the identification rates of the two systems was not significant, it was concluded that Rapid Ana was easier to perform and interpret.

In-depth evaluation of an analytical method to detect and quantify long chain fatty acids (C 8 -C 16 ) at trace level concentrations (25-1000 g/l) is presented. The method requires derivatization of the acids with methanolic boron trifluoride, separation, and detection by gas chromatography-mass spectrometry. The calibration experiments passed all the tested performance criteria such as linearity, homoscedasticity, and ruggedness. The detection limits and related quantities were computed by applying the method detection limit, and the calibration line approximation. The values obtained by applying the latter approach were more reliable and consistent with the actual statistical theory of detection decisions and yielded the following concentrations: C 8 ,

Inverse gas chromatography is used in the characterization of aliphaticaromatic and aromatic ketones, their oximes, and ketone-oxime or oxime-oxime mixtures. All these organic materials are used as liquid stationary phases in gas chromatographic columns. A series of polarity and Flory-Huggins interaction parameters are determined and used to describe the physicochemical properties of examined materials, metal extractants, and products of their degradation. Principal component analysis (PCA) is performed on a data matrix consisting of polarity and interaction parameters for ketones, their oximes, and mixtures. The calculations are carried out on the correlation matrix. It is found that seven principal components account for more than 95% of the total variance in the data, indicating that the polarity (interaction) parameters are not correlating well. Physical meanings are attributed to the principal components, the most influential ones being that the first and the second principal components account for several Flory-Huggins interaction parameters, whereas the fifth is correlated with criterion "A". The plots of component loadings show characteristic groupings of polarity indicators, whereas that of component scores show several groupings of stationary phases. Cluster analysis provides mainly the same groupings. PCA allows for the grouping of polarity and solubility parameters based on the information carried within those parameters. There is no need to use more than one parameter from each cluster. McReynolds polarity and the partial molar excess Gibbs free energy of solution per methylene group carry the same information. The groups of ketones, oximes, and their mixtures can be distinguished with the use of PCA on the basis of the measured polarity, solubility parameters, or both.

Objectives and methods: The curing of several commercial powder/liquid mixtures of acrylic denture base materials was carried out at different temperatures and curing times. The levels of residual mononer, tensile strength, percentage elongation before break and water absorption were measured.