The Experts below are selected from a list of 225 Experts worldwide ranked by ideXlab platform
Josep Caixach - One of the best experts on this subject based on the ideXlab platform.
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Characterization of Toxaphene by High Resolution Gas Chromatography Combined with High Resolution Mass Spectrometry and Tandem Mass Spectrometry
Rapid Communications in Mass Spectrometry, 1997Co-Authors: Francisco Javier Santos, Josep Rivera, Josep Caixach, M.t. Galceran, X. HuguetAbstract:We examined the use of high resolution Gas Chromatography-electron ionization high resolution mass spectrometry (HRGC/EI-HRMS) in determining the toxaphene homologue distribution. Operating parameters such as electron energy, trap current and source temperature were optimized in order to obtain the maximum signal of the [M–C]+ and [M–HCl]+• fragment ions of each homologue group. Internal interferences due to the fragment ions from the homologues with one and two additional chlorine atoms were eliminated using EI-HRMS at a resolving power of 10 000 or higher. Tandem mass spectrometry (EI-MS/MS) was used in the fragmentation studies. HRGC/EI-HRMS-selected ion monitoring (SIM) at a resolving power of 10 000 was used to determine the homologue distribution of a commercial toxaphene mixture. This technique gave detection limits of ppb level. The performance of HRGC/EI-HRMS-SIM was compared to HRGC/ECNI-MS using isobutane as a moderating Gas. © 1997 John Wiley & Sons, Ltd.
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Determination of polychlorinated biphenyls in sewage sludges from Catalonia (N.E. Spain) by High-Resolution Gas Chromatography with electron-capture detection
Journal of Chromatography A, 1994Co-Authors: F. Paune, Josep Rivera, I. Espadaler, Josep CaixachAbstract:A study was carried out on the presence of polychlorinated biphenyls (PCBs) in sewage sludges from Catalonia (N.E. Spain) using High-Resolution Gas Chromatography with electron-capture detection. Aroclor 1254 and 1260 were characterized. The concentrations were between 2310 and 69 μg/kg (dry mass). High-Resolution Gas Chromatography coupled with low-resolution mass spectrometry was used for screening the samples. No reports of the presence of PCBs in Spanish sewage sludges have been published previously. These analyses were performed in order to establish the availability of these sludges for disposal in agricultural soils.
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Homologue distributions of polychlorinated terphenyls by High-Resolution Gas Chromatography and High-Resolution mass spectrometry
Journal of Chromatography A, 1994Co-Authors: Josep Caixach, Josep Rivera, M.t. Galceran, Francisco Javier SantosAbstract:The use of High-Resolution Gas Chromatography—High-Resolution mass spectrometry in the selected-ion monitoring mode (HRGC-HRMS-SIM) to study the distribution of polychlorinated terphenyls (PCTs) in commercial and environmental samples is proposed. Interferences in the detection and measurement of the M+. ions due to chromatographic co-elution of PCT congeners were observed. In this paper, the interfering contribution of the [M − 2Cl]+ fragment from the terphenyl homologues with an additional two chlorine atoms was eliminated using HRMS at a resolving power between 30 000 and 35 000. Homologue distributions of PCTs in commercial mixtures, Aroclor 5460 and Leromoll 141, and in samples of shellfish from the Ebro Delta (Catalonia, Spain) are proposed.
Million B. Woudneh - One of the best experts on this subject based on the ideXlab platform.
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Pyrethroids, pyrethrins, and piperonyl butoxide in sediments by High-Resolution Gas Chromatography/High-Resolution mass spectrometry.
Journal of chromatography. A, 2006Co-Authors: Million B. Woudneh, Daniel Ray OrosAbstract:A new method for determination of pyrethroids, pyrethrins, and piperonyl butoxide (PBO) by High-Resolution Gas Chromatography/High-Resolution mass spectrometry (HRGC/HRMS) was developed for aquatic sediments. The method detection limits for pyrethroids (15 compounds), pyrethrins, and PBO ranged from 0.16 to 1.50 ng/g sediment, which was suitable for detecting these chemicals at environmentally relevant concentrations (low ng/L range) that are toxicologically significant to benthic organisms. Recovery of the analytes from a low level spiked sediment ranged from 89.7% to 135%. Resmethrin showed the lowest recovery at 23.5% and pyrethrins showed the highest recovery at 154%. To confirm the utility of this new method for environmental applications, sediment samples collected from five tributaries of the San Francisco Bay, California were analyzed. Individual pyrethroids were detected in concentrations of up to 17.6 ng/g, while PBO was detected in all sediment samples in concentrations of 0.010-0.215 ng/g. Pyrethrins were not found in the sediment samples.
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Quantitative Determination of Pyrethroids, Pyrethrins, and Piperonyl Butoxide in Surface Water by High-Resolution Gas Chromatography/High-Resolution Mass Spectrometry
Journal of agricultural and food chemistry, 2006Co-Authors: Million B. Woudneh, Daniel Ray OrosAbstract:A new method for determination of pyrethroids, pyrethrins, and piperonyl butoxide (PBO) by High-Resolution Gas Chromatography/High-Resolution mass spectrometry (HRGC/HRMS) was developed for surface water samples. The method is based on sampling 100 L of ambient surface water with a solid phase extraction (SPE) technique that uses both wound glass fiber filters for collecting the particulate-associated chemicals and XAD-2 resin for collecting the dissolved chemicals. The method detection limits of the analytes ranged from 0.58 to 8.16 ng/sample, which is equivalent to a detection limit range of 0.0058-0.082 ng/L for a 100 L water sample collected by the SPE technique. The SPE when coupled with HRGC/HRMS was a suitable match for detecting these chemicals at subnanogram per liter ranges that are toxicologically significant to aquatic organisms. To confirm the utility of this method for environmental applications, pyrethroids and PBO were found at subnanogram per liter concentrations in surface water samples collected from five tributaries (primarily urban creeks) of the San Francisco Bay, California.
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Isotope dilution High-Resolution Gas Chromatography/High-Resolution mass spectrometry method for analysis of selected acidic herbicides in surface water.
Journal of chromatography. A, 2006Co-Authors: Million B. Woudneh, Mark Sekela, Taina Tuominen, Melissa GledhillAbstract:In this work, an isotope dilution method for determination of selected acidic herbicides by High-Resolution Gas Chromatography/High-Resolution mass spectrometry (HRGC/HRMS) was developed for surface water samples. Average percent recoveries of native analytes were observed to be between 70.8 and 93.5% and average recoveries of labeled quantification standards [(13)C(6)]2,4-D and [(13)C(6)]2,4,5-T were 85.5 and 101%, respectively. Using this method, detection limits of 0.05 ng/L for dicamba, MCPA, MCPP, and triclopyr, and 0.5 ng/L for 2,4-D were routinely achieved. The method was applied to measuring the concentration of these analytes in surface water samples collected from five sampling locations in the Lower Fraser Valley region of British Columbia, Canada. All of the herbicides monitored were detected at varying levels in the surface water samples collected. The highest concentrations detected for each analyte were 345 ng/L for 2,4-D, 317 ng/L for MCPA, 271 ng/L for MCPP, 15.7 ng/L for dicamba, and 2.18 ng/L for triclopyr. Average detection frequencies of the herbicides were 95% for MCPA, 80% for MCPP, 70% for dicamba, 65% for 2,4-D, and 46% for triclopyr. Seasonal variations of herbicide levels are also discussed.
Josep Rivera - One of the best experts on this subject based on the ideXlab platform.
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Characterization of Toxaphene by High Resolution Gas Chromatography Combined with High Resolution Mass Spectrometry and Tandem Mass Spectrometry
Rapid Communications in Mass Spectrometry, 1997Co-Authors: Francisco Javier Santos, Josep Rivera, Josep Caixach, M.t. Galceran, X. HuguetAbstract:We examined the use of high resolution Gas Chromatography-electron ionization high resolution mass spectrometry (HRGC/EI-HRMS) in determining the toxaphene homologue distribution. Operating parameters such as electron energy, trap current and source temperature were optimized in order to obtain the maximum signal of the [M–C]+ and [M–HCl]+• fragment ions of each homologue group. Internal interferences due to the fragment ions from the homologues with one and two additional chlorine atoms were eliminated using EI-HRMS at a resolving power of 10 000 or higher. Tandem mass spectrometry (EI-MS/MS) was used in the fragmentation studies. HRGC/EI-HRMS-selected ion monitoring (SIM) at a resolving power of 10 000 was used to determine the homologue distribution of a commercial toxaphene mixture. This technique gave detection limits of ppb level. The performance of HRGC/EI-HRMS-SIM was compared to HRGC/ECNI-MS using isobutane as a moderating Gas. © 1997 John Wiley & Sons, Ltd.
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Determination of polychlorinated biphenyls in sewage sludges from Catalonia (N.E. Spain) by High-Resolution Gas Chromatography with electron-capture detection
Journal of Chromatography A, 1994Co-Authors: F. Paune, Josep Rivera, I. Espadaler, Josep CaixachAbstract:A study was carried out on the presence of polychlorinated biphenyls (PCBs) in sewage sludges from Catalonia (N.E. Spain) using High-Resolution Gas Chromatography with electron-capture detection. Aroclor 1254 and 1260 were characterized. The concentrations were between 2310 and 69 μg/kg (dry mass). High-Resolution Gas Chromatography coupled with low-resolution mass spectrometry was used for screening the samples. No reports of the presence of PCBs in Spanish sewage sludges have been published previously. These analyses were performed in order to establish the availability of these sludges for disposal in agricultural soils.
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Homologue distributions of polychlorinated terphenyls by High-Resolution Gas Chromatography and High-Resolution mass spectrometry
Journal of Chromatography A, 1994Co-Authors: Josep Caixach, Josep Rivera, M.t. Galceran, Francisco Javier SantosAbstract:The use of High-Resolution Gas Chromatography—High-Resolution mass spectrometry in the selected-ion monitoring mode (HRGC-HRMS-SIM) to study the distribution of polychlorinated terphenyls (PCTs) in commercial and environmental samples is proposed. Interferences in the detection and measurement of the M+. ions due to chromatographic co-elution of PCT congeners were observed. In this paper, the interfering contribution of the [M − 2Cl]+ fragment from the terphenyl homologues with an additional two chlorine atoms was eliminated using HRMS at a resolving power between 30 000 and 35 000. Homologue distributions of PCTs in commercial mixtures, Aroclor 5460 and Leromoll 141, and in samples of shellfish from the Ebro Delta (Catalonia, Spain) are proposed.
Daniel Ray Oros - One of the best experts on this subject based on the ideXlab platform.
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Pyrethroids, pyrethrins, and piperonyl butoxide in sediments by High-Resolution Gas Chromatography/High-Resolution mass spectrometry.
Journal of chromatography. A, 2006Co-Authors: Million B. Woudneh, Daniel Ray OrosAbstract:A new method for determination of pyrethroids, pyrethrins, and piperonyl butoxide (PBO) by High-Resolution Gas Chromatography/High-Resolution mass spectrometry (HRGC/HRMS) was developed for aquatic sediments. The method detection limits for pyrethroids (15 compounds), pyrethrins, and PBO ranged from 0.16 to 1.50 ng/g sediment, which was suitable for detecting these chemicals at environmentally relevant concentrations (low ng/L range) that are toxicologically significant to benthic organisms. Recovery of the analytes from a low level spiked sediment ranged from 89.7% to 135%. Resmethrin showed the lowest recovery at 23.5% and pyrethrins showed the highest recovery at 154%. To confirm the utility of this new method for environmental applications, sediment samples collected from five tributaries of the San Francisco Bay, California were analyzed. Individual pyrethroids were detected in concentrations of up to 17.6 ng/g, while PBO was detected in all sediment samples in concentrations of 0.010-0.215 ng/g. Pyrethrins were not found in the sediment samples.
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Quantitative Determination of Pyrethroids, Pyrethrins, and Piperonyl Butoxide in Surface Water by High-Resolution Gas Chromatography/High-Resolution Mass Spectrometry
Journal of agricultural and food chemistry, 2006Co-Authors: Million B. Woudneh, Daniel Ray OrosAbstract:A new method for determination of pyrethroids, pyrethrins, and piperonyl butoxide (PBO) by High-Resolution Gas Chromatography/High-Resolution mass spectrometry (HRGC/HRMS) was developed for surface water samples. The method is based on sampling 100 L of ambient surface water with a solid phase extraction (SPE) technique that uses both wound glass fiber filters for collecting the particulate-associated chemicals and XAD-2 resin for collecting the dissolved chemicals. The method detection limits of the analytes ranged from 0.58 to 8.16 ng/sample, which is equivalent to a detection limit range of 0.0058-0.082 ng/L for a 100 L water sample collected by the SPE technique. The SPE when coupled with HRGC/HRMS was a suitable match for detecting these chemicals at subnanogram per liter ranges that are toxicologically significant to aquatic organisms. To confirm the utility of this method for environmental applications, pyrethroids and PBO were found at subnanogram per liter concentrations in surface water samples collected from five tributaries (primarily urban creeks) of the San Francisco Bay, California.
Francisco Radler De Aquino Neto - One of the best experts on this subject based on the ideXlab platform.
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analysis and quantitation of rotenoids and flavonoids in derris lonchocarpus urucu by high temperature high resolution Gas Chromatography
Journal of Chromatographic Science, 2000Co-Authors: Alberto Dos Santos Pereira, Angelo C. Pinto, Francisco Radler De Aquino Neto, Maria Angelis Afonso Serrano, Dulcineia Furtado Texeira, Benjamin GilbertAbstract:: A glass capillary column coated with PS-086 (15% phenyl-80% methylpolysiloxane, 15 m x 0.30-mm i.d., 0.1-microm film thickness) is used to analyze extracts from Lonchocarpus urucu (Derris urucu). Several secondary metabolites (8 flavonoids, 10 rotenoids) are characterized without derivatization, and the rotenoids are quantitated by high-temperature High-Resolution Gas Chromatography (HTHRGC) and HTHRGC coupled with mass spectrometry (HTHRGC-MS). The limit of detection in flame ionization detection of rotenone is approximately 0.5 microg/mL, and the limit of quantitation was 2 microg/mL. Derris urucu bark is an excellent source of rotenone isomers (80 mg/g), deguelin (30 mg/g), and rotenolone (26 mg/g). Single solvent extractions (hexane, methylene dichloride, acetone, or methanol) are not able to fully extract the flavonoids and rotenoids. Complete extraction is achieved using a mixture of methanol-methylene dichloride (1:1), indicating a complex association of these compounds with the plant tissue. HTHRGC and HTHRGC-MS are shown to be quick and informative tools for the rapid analysis of crude extracts without the need for prior derivatization and fractionation.
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Determination of β2-Agonists in Bovine Urine: Comparison of Two Extraction/Clean-Up Procedures for High-Resolution Gas Chromatography-Mass Spectrometry Analysis
Journal of analytical toxicology, 2000Co-Authors: Bernardete Ferraz Spisso, Claudio C. Lopes, Marlice Aparecida Sipoli Marques, Francisco Radler De Aquino NetoAbstract:Two extraction/clean-up analytical procedures were investigated and compared regarding their recovery and matrix-purification efficiency for screening beta2-agonist residues in fortified bovine urine by High-Resolution Gas Chromatography-mass spectrometry (GC-MS). The first procedure, based on an analytical method originally developed for detecting anabolic steroids, consists of the employment of the nonionic resin, Amberlite XAD-2, a styrene-divinylbenzene copolymer for solid-phase extraction (SPE), followed by liquid-liquid extraction with diethyl ether. The second focuses on the use of a mixed SPE cartridge (reversed-phase and ion-exchange sorbent, Bond Elut Certify). In both cases, the trimethylsilylated derivatives were analyzed by GC-MS with an ion-trap detector. Clenbuterol, salbutamol, and terbutaline were used to spike urine samples during the comparison experimental phase. Afterwards, tulobuterol, mabuterol, mapenterol, cimbuterol, and brombuterol were included in the evaluation of the second procedure (the Bond Elut Certify procedure). At this stage, the detection was accomplished by GC-MS (quadrupole mass analyzer) with selective ion monitoring acquisition. The isotopic dilution method with the hexadeuterated analogues of clenbuterol and salbutamol was applied to prepare calibration curves and calculate recovery percentages. With XAD-2 resin, terbutaline and salbutamol (resorcinol and phenol-type beta2-agonists, respectively) could not be detected at 20 ng/mL or at 40 ng/mL. In spite of clenbuterol having been detected at 20 ng/mL, the results obtained were not reproducible. The use of the reversed-phase and ion-exchange sorbent Bond Elut Certify allowed multiresidue detection and showed several advantages for the screening of clenbuterol such as higher recoveries, cleaner final extracts, reduced sample preparation time, less labor intensive, and easier solvent consumption and disposal. Recoveries over 88% (concentrations ranging from 0.5 to 10 ppb) and limits of detection equal to 0.5 ppb were met for all the beta2-agonists studied with the last method.
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High-temperature High-Resolution Gas Chromatography: breaching the barrier to the analysis of polar and high molecular weight compounds
TrAC Trends in Analytical Chemistry, 1999Co-Authors: Alberto Dos Santos Pereira, Francisco Radler De Aquino NetoAbstract:Developments in stationary phase synthesis and capillary column technology have opened new perspectives in the analysis of high molecular weight compounds (≥600 Da) and thermolabile organic compounds by high-temperature High-Resolution Gas Chromatography (HT-HRGC). Apolar and medium polarity gum phases can now be operated at temperatures up to 400–480°C, and are being used for the analysis of compounds including n-alkanes up to C100, lipids, oligosaccharides, industrial resins, polyglycerols, cyclodextrins, and porphyrins.
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Analysis of Rotenoids by High Temperature High Resolution Gas Chromatography-Mass Spectrometry
Journal of High Resolution Chromatography, 1998Co-Authors: Alberto Dos Santos Pereira, João B. Fernandes, Paulo C. Vieira, Angelo C. Pinto, Jari N. Cardoso, Francisco Radler De Aquino Neto, M. Fátima Das G. F. Da Silva, Cesar Cornelio AndreiAbstract:A short glass capillary column coated with PS-090 (20% phenyl–80% methylpolysiloxane, of 10 m × 0.30 mm i.d.; with 0.1 μm film thickness) was used to analyze samples from Tephrosia candida; eighteen rotenoids were separated and identified without derivatization by HT-HRGC and HT-HRGC-MS. The mass spectra show the typical fragmentation pattern for rotenoids, with the base peaks either at M+, or originating from RDA (Retro Diels-Alder) rearrangements. HT-HRGC and HT-HRGC-MS were shown to be extremely valuable and neglected techniques for structural studies as well as the routine analysis of rotenoids in crude extracts. Possible applications to other classes of aromatic natural products, e.g. flavonoids, are envisaged.