The Experts below are selected from a list of 810 Experts worldwide ranked by ideXlab platform
F. Peterlongo - One of the best experts on this subject based on the ideXlab platform.
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Characterization of proanthocyanidins from grape seeds
Fitoterapia, 2000Co-Authors: Bruno Gabetta, A. Griffini, E. Lolla, Nicola Fuzzati, Roberto Pace, Tiziano Ruffilli, F. PeterlongoAbstract:Abstract Leucoselect™ (grape seed selected proanthocyanidins) was analyzed. HPLC Thermospray mass spectrometry (TSP-MS) allowed the detection of monomeric flavan-3-ols and dimeric proanthocyanidins. Fractionation over Sephadex® LH-20 resin and analysis of the isolated fractions by gel permeation chromatography (GPC) and electrospray mass spectrometry (ESI-MS) led to the complete characterization of the proanthocyanidin constituents of Leucoselect™. The analysis revealed the presence of approximately 15% of (+)-catechin (1) and (−)-epicatechin (2) , 80% of (−)-epicatechin 3- O -gallate (3) , dimers, trimers, tetramers and their gallates and 5% of pentamers, hexamers, heptamers and their gallates.
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Liquid chromatography-Thermospray mass spectrometry analysis of beta-escin
Fitoterapia, 1997Co-Authors: A. Griffini, E. Lolla, F. PeterlongoAbstract:A fingerprint of the β-escin composition has been obtained by liquid chromatography-mass spectrometry (LC-MS) using a Thermospray (TSP) interface.
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identification of soyasaponins by liquid chromatography Thermospray mass spectrometry
Journal of Chromatography A, 1997Co-Authors: Nicola Fuzzati, R Pace, Gianluca Papeo, F. PeterlongoAbstract:Abstract Saponins are important bioactive molecules widespread in the plant kingdom. Soyasaponins, isolated from Glicine max (Leguminosae), have been shown to exhibit various biological activities, e.g., an inhibitory effect on lipid-oxidation and liver-lesion generation and an improving effect on hyper-cholesteremia. Mass spectral investigation of these metabolites requires soft ionization techniques such as desorption chemical ionization, fast atom bombardment and Thermospray mass spectrometry. A high-performance liquid chromatographic method was developed for Thermospray mass spectrometric analysis of saponins contained in soybean flour extracts. The analyses were performed using a ternary eluent (water–acetonitrile–methanol) in gradient conditions with post-column addition of aqueous ammonium acetate. Six saponin components could be separated and identified. The mass spectra obtained provided information concerning both molecular masses and aglycone composition.
Marco Aurelio Zezzi Arruda - One of the best experts on this subject based on the ideXlab platform.
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Thermospray generation directly into a flame furnace an alternative to improve the detection power in atomic absorption spectrometry
Talanta, 2010Co-Authors: Marcos A Bezerra, Valfredo Azevedo Lemos, Jerusa S Garcia, Douglas Goncalves Da Silva, Andre S Araujo, Marco Aurelio Zezzi ArrudaAbstract:Recent developments and applications in the production of Thermosprays directly into flame furnaces to improve the analytical sensitivity in atomic absorption spectrometry are reviewed in this manuscript. Principles, characteristics, instrumentation, and applications of this analytical technique for trace elements determination in several matrices are discussed. The use of preconcentration procedures to allow low detection limits for ultra-trace levels using TS-FF-AAS is presented and current perspectives and future trends of this technique are also discussed.
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Thermospray nebulization for flame furnace atomic absorption spectrometry correlations between spray formation and cadmium analytical sensitivity
Spectrochimica Acta Part B: Atomic Spectroscopy, 2009Co-Authors: Marcel Luis Brancalion, Edvaldo Sabadini, Marco Aurelio Zezzi ArrudaAbstract:Abstract Some parameters which influence Thermospray formation at low flow rate used in Thermospray flame furnace atomic absorption spectrometry were systematically evaluated using spray morphology (through high-speed images acquisition) and Cd determination (used as an analytical probe). A correlation was observed between Cd sensitivity and the Sauter mean diameter of droplets of the spray introduced into the furnace. The SMD was calculated according to the empiric equation proposed by Elkotb and some physical properties of the carriers were used. Among the parameters studied, the most important is the total area of the inlets of flame gases (bottom holes of the nickel atomizer tube), since Cd sensitivity was drastically reduced when this area was increased. Another important parameter is the chemical nature of the carrier solution, which affects the pulse rate of the Thermospray. The average rates measured for the different carriers were 320 ± 50, 290 ± 50 and 60 ± 20 pulses/s for water, 0.9 mmol L− 1 Triton® X-100 and 44% (w/w) acetonitrile, respectively. Cadmium determinations were performed in certified reference materials using different carrier solutions, and accurate determinations were attained with the use of four carrier liquids (water, 1.4 mol L− 1 nitric acid, 0.6 mol L− 1 hydrochloric acid, 8% (w/w) ethanol).
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description of the Thermospray formed at low flow rate in Thermospray flame furnace atomic absorption spectrometry based on high speed images
Analytical Chemistry, 2007Co-Authors: Marcel Luis Brancalion, Edvaldo Sabadini, Marco Aurelio Zezzi ArrudaAbstract:The mechanism of the Thermospray formed at low flow rates using a peristaltic pump in Thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) is described here for the first time. The study was based on magnified images of the Thermospray formed inside the hot tube furnace by using a high-speed CMOS camera. For this purpose different image acquisition speeds were used (from 1000 to 18000 frames/s), revealing that the Thermospray obtained under such conditions is quite different from those already reported. The frames of the Thermospray evolution indicate that the Leindenfrost effect plays an important role and allow us to propose a mechanism for its formation. The analysis of the images contributed to calculation of parameters related to Thermospray formation, such as pulse incidence average (110 ± 10, 320 ± 50, and 1200 ± 150 pulses per second) and pulse speed (6 ± 1, 10 ± 1, and 14 ± 2 m s-1) for 0.1, 0.4, and 1.0 mL min-1 flow rate, respectively, for both parameters. Additionally, the evap...
Kurt Hostettmann - One of the best experts on this subject based on the ideXlab platform.
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a liquid chromatography Thermospray ionisation mass spectrometry guided isolation of a new sesquiterpene aryl ester from armillaria novae zelandiae
Journal of The Chemical Society-perkin Transactions 1, 2000Co-Authors: Peadar Cremin, Jeanluc Wolfender, Kurt Hostettmann, Patrick J Guiry, Dervilla M X DonnellyAbstract:A liquid chromatography–Thermospray ionisation–mass spectrometry guided fractionation of the mycelial extract of Armillaria novae-zelandiae (strain CBS 432.72) led to the isolation of a new protoilludane sesquiterpene aryl ester, 6′-chloro-10α-hydroxymelleolide (9). The antibacterial and antifungal activity of 9 was determined.
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evaporative light scattering and Thermospray mass spectrometry two alternative methods for detection and quantitative liquid chromatographic determination of ginkgolides and bilobalide in ginkgo biloba leaf extracts and phytopharmaceuticals
Phytochemical Analysis, 1995Co-Authors: Fabrizio F Camponovo, Jeanluc Wolfender, Marc Maillard, Olivier Potterat, Kurt HostettmannAbstract:Evaporative light scattering and Thermospray mass spectrometry have been investigated as two alternative methods for the liquid chromatographic detection of ginkgolides and bilobalide. Both techniques were used to quantify these metabolites in leaf extracts and in some phytopharmaceuticals. Only a minimum of sample pre-purification was required. Results were compared with those obtained by gas chromatography (flame ionization detection), which is one of the most suitable methods for routine determinations of such compounds. The isolation of ginkgolides A, B, C, and J and bilobalide from leaves of Ginkgo biloba is also described.
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analysis of flavonol glycosides of thirteen epilobium species onagraceae by lc uv and Thermospray lc ms
Phytochemistry, 1995Co-Authors: B Ducrey, Andrew Marston, Jeanluc Wolfender, Kurt HostettmannAbstract:Abstract Analysis of the flavonol glycoside patterns of 13 Epilobium species was carried out by Thermospray liquid chromatography-mass spectrometry (TSP/LC-MS) and high performance liquid chromatography coupled with a photodiode array detector (LC-UV). Mass-data and UV spectra recorded online, before and after post-column addition of shift reagents, provided useful structural information on the different compounds present in crude extracts. Nineteen flavonol glycosides were identified by this means. In order to confirm the on-line assignments, 13 of the compounds were isolated and their structures were elucidated. They were all 3- O -glycosides of kaempferol, quercetin and myricetin.
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Thermospray liquid chromatography mass spectrometry in phytochemical analysis
Phytochemical Analysis, 1994Co-Authors: Jeanluc Wolfender, Marc Maillard, Kurt HostettmannAbstract:Liquid chromatography-mass spectrometry (LC-MS) has become a successful analytical tool and is no longer regarded as a pure research instrument without any routine practical applications. The development of the Thermospray interface (TSP) has been of great help in this respect, allowing the direct use of standard HPLC conditions (1 mL/min, aqueous solvents) for the LC-MS coupling. TSP LC-MS has been used in phytochemical analysis as a powerful detection technique for on-line identification and for quantification of plant constituents, even in trace amounts. Applications of this technique to different classes of plant metabolites such as polyphenols, terpenes, sugars, glucosinolates, alkaloids and glycosides are described. The potential of TSP LC-MS in the analysis of crude plant extracts is discussed.
Damià Barceló - One of the best experts on this subject based on the ideXlab platform.
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resolution and quantitative determination of coeluted pesticide mixtures in liquid chromatography Thermospray mass spectrometry by multivariate curve resolution
Journal of Chromatography A, 1998Co-Authors: J S Salau, M Honing, Roma Tauler, Damià BarcelóAbstract:Abstract Resolution and quantitative determination of a mixture of coeluted pesticides (carbofuran, propoxur and pirimicarb) in liquid chromatography–Thermospray mass spectrometry by multivariate curve resolution is shown. Carbofuran and pirimicarb both exhibit an ion with m / z 239 in their Thermospray mass spectrum. For the first compound this ion is attributed to the ammonium adduct [M+NH 4 ] + ion, whereas the corresponding ion of pirimicarb is the protonated molecule, [M+H] + . A third carbamate, propoxur, was added because this compound partly coelutes with carbofuran under normal experimental conditions during multiresidue analysis of carbamates with C 1 8 packed analytical columns. With this additional compound, the so-called suppression effects on the ion formation of these compounds in Thermospray mass spectrometry and their quantitative resolution using chemometric methods were studied.
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applications of lc ms in environmental chemistry
1996Co-Authors: Damià BarcelóAbstract:Part 1 Fundamental aspects and instrumentation: Developments in interface technology for combined liquid chromatography, capillary electrophoresis and supercritical fluid chromatography-mass spectrometry, W.M.A. Niessen Ionisation methods in LC-MS and LC-MS-MS (TSP, APCI, ESP and CF-FAB), B.L.M. van Baar Optimization of instrumental parameters for flow-injection analysis, Thermospray tandem mass spectrometry, R.B. Geerdink. Part 2 Environmental applications: LC-MS techniques for the analysis of dyes, J. Yinon et al LC-MS: a new window for trace-level monitoring of pesticides and their transformation products in environmental water samples, D. Barcelo et al Separation, identification and quantification of surfactants and their metabolites in waste water, surface water and drinking water by LC-TSP-MS, FIA-TSP-MS and MS-MS, H.F. Schroder Particle beam mass spectrometry for the identification of environmental contaminants and agrochemicals, M.J.I. Mattina Particle beam mass spectrometry for the analysis of aqueous and hazardous waste leachates, J. Hsu Liquid chromatography-mass spectrometry of organotic compounds, L.D. Betowski, T.L. Jones Liquid chromatography-mass spectrometry of seafood toxins, M.A. Quilliam. Part 3 Complementary techniques: On-line post column liquid-solid and liquid-liquid extractions in environmental liquid chromatography-Thermospray-mass spectrometry, R.J. Vreeken Capillary electrophoresis/mass spectrometry applied to environmental analysis, W.C. Brumley and W. Winnink.
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determination of quaternary amine pesticides by Thermospray mass spectrometry
Journal of Chromatography A, 1993Co-Authors: Damià Barceló, G Durand, Rob J. VreekenAbstract:Abstract Positive-ion (PI) Thermospray mass spectrometry (TSP-MS) with methanol—water (50:50) + 0.05 M ammonium formate as eluent was used for the characterization of the quaternary amine pesticides paraquat, difenzoquat, diquat, mepiquat and chlormequat and gave as base peaks [Cat + H]+•, [Cat − CH3 + H]+•, [Cat]+•, [Cat]+• and [Cat]+•, respectively. A postcolumn ion-pair extraction system was developed for the determination of difenzoquat from water samples whereas the other quaternary amine pesticides were not extracted. An aqueous mobile phase with various sulphonate counter ions such as dodecanesulphonic acid, methyl orange, Blue Acid 113, Mordant Red 9 and sodium picrate was tested in combination with an extraction solvent containing cyclohexane—dichloromethane—n-butanol (45:45:10) with UV diode-array spectra and PI TSP-MS detection. Applications are reported for the TSP-MS determination of 500 μg/l of difenzoquat in spiked water samples using the postcolumn extraction system. Diquat and paraquat were determined at levels of 0.10–0.17 μg/g in soil samples from the Ebro delta (Tarragona, Spain) using a reversed-phase eluent containing 0.05 M ammonium formate.
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analysis of chlorotriazines and their degradation products in environmental samples by selecting various operating modes in Thermospray hplc ms ms
Journal of Agricultural and Food Chemistry, 1993Co-Authors: Joaquin Abian, G Durand, Damià BarcelóAbstract:Positive ion (PI) and negative ion (NI) modes in Thermospray HPLC/MS as well as the daughter ion and neutral loss modes in Thermospray HPLC/MS/MS were applied for the characterization of atrazine, simazine, cyanazine, deethylatrazine, deisopropylatrazine, hydroxyatrazine, and chlorodiamino-s-triazine. PI mode gave always the [M+H] + ion as base peak. Filament-on NI mode, which was 2-3 orders of magnitude less sensitive, gave [M+2H] .− ions except for cyanazine and hydroxyatrazine, which showed the [M-H] − ion. In the filament-off NI mode only cyanazine and hydroxyatrazine could be detected, both giving the [M-H] − signal (.)
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evaluation of eluents in Thermospray liquid chromatography mass spectrometry for identification and determination of pesticides in environmental samples
Journal of Chromatography A, 1991Co-Authors: Damià Barceló, Rob J. Vreeken, G Durand, G J De Jong, H Lingeman, U Th A BrinkmanAbstract:Abstract The influence of different eluents in positive and negative ion mode Thermospray liquid chromatography-mass spectrometry was studied with several groups of pesticides, including carbamates, chlorotriazines, phenylureas, phenoxy acids and organophosphorus and quaternary ammonium compounds, and the corresponding degradation products. Using the positive ion mode in combination with reversed-phase eluents the base peaks generally corresponded either to [M + H] + for the chlorotriazines and their hydroxy metabolites or to [M + NH 4 ] + for the carbamates, the phenylureas, the organophosphorus pesticides and their oxygen analogues. In the negative ion mode different processes such as (dissociative) electron-capture and anion attachment mechanisms occurred. Fragment ions such as [M — CONHCH 3 ] − for the carbamates, [M − H] − for the chlorotriazines, phenylureas and chlorinated phenoxy acids and [M] . − , [M − R] − (R being a methyl or ethyl group) for organophosphorus pesticides were usually formed. Depending on the eluent additive used (ammonium acetate, ammonium formate and/or chloroacetonitrile), three different adduct ions were formed: [M + CH 3 COO] − , [M + HCOO] − and [M + Cl] − . Normal-phase eluents with cyclohexane, n -hexane and/or dichloromethane provided more structural information and enhanced the response of several compounds. The positive ion mode was useful for the detection of chlorinated phenoxy acids and chlorophenols which could not be detected in the positive ion mode using reversed-phase systems. The base peaks generally corresponded to [M] . + , [M + H] + or [M − Cl] + . For the characterization of difenzoquat, a quaternary ammonium pesticide of which trace level analysis is troublesome, a post-column ion-pair extraction system was used. An aqueous mobile phase with a sulphonate-type counter ion was applied and an extraction solvent containing cyclohexane-dichloromethane- n -butanol (45:45:10) was used in Thermospray liquid chromatography-mass spectrometry. Illustrative examples of the determination of residue levels of pesticides in soil matrices are shown.
Seppo Auriola - One of the best experts on this subject based on the ideXlab platform.
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atmospheric pressure Thermospray ionization using a heated microchip nebulizer
Rapid Communications in Mass Spectrometry, 2009Co-Authors: Pekka Keskirahkonen, Markus Haapala, Ville Saarela, Sami Franssila, Tapio Kotiaho, Risto Kostiainen, Seppo AuriolaAbstract:When a standard atmospheric pressure chemical ionization (APCI) or atmospheric pressure photoionization (APPI) ion source is used without applying the corona discharge or photoirradiation, atmospheric pressure Thermospray ionization (APTSI) of various compounds can be achieved. Although largely ignored, this phenomenon has recently gained interest as an alternative ionization technique. In this study, this technique is performed for the first time on a miniaturized scale using a microchip nebulizer. Sample ionization with the presented microchip-APTSI (µAPTSI) is achieved by applying only heat and gas flow to a nebulizer chip, without any other methods to promote gas-phase ionization. To evaluate the performance of the described µAPTSI setup, ionization efficiency for a set of test compounds was monitored as the microchip positioning, temperature, nebulizer gas flow rate, sample solution composition, and solvent flow rate were varied. The µAPTSI mass spectra of the test compounds were also compared to those obtained with ESI and APCI. The µAPTSI produces ESI-like spectra with low background noise, favoring the formation of protonated or deprotonated molecules of compounds that are ionizable in solution. Multiple charging of peptides without in-source fragmentation was also observed. Unlike ESI, however, the µAPTSI source can tolerate the presence of mobile phase additives like trifluoroacetic acid (TFA) without significant ion suppression. The µAPTSI source can be used with standard mass spectrometer ion source hardware, being a unique alternative to the present interfacing techniques. Copyright © 2009 John Wiley & Sons, Ltd.
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determination of taxol by high performance liquid chromatography Thermospray mass spectrometry
Journal of Chromatography A, 1992Co-Authors: Seppo Auriola, Annamaija Lepisto, Toivo Naaranlahti, Seppo LapinjokiAbstract:Abstract A high-performance liquid chromatography-Thermospray mass spectrometry method has been developed for the determination of taxol, found in the Taxus species. The compound is chromatographed by isocratic elution in 14 min and is quantitated by selected-ion recording of the protonated molecule. The method is linear over the range 1–1000 ng (1.2 pmol-1.2 nmol) of taxol per injection. The standard deviation of replicate bark samples ( n = 6) was 12.8%.
