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Ana Herrero - One of the best experts on this subject based on the ideXlab platform.
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ad hoc blocked design for the robustness study in the determination of dichlobenil and 2 6 dichlorobenzamide in onions by Programmed Temperature vaporization gas chromatography mass spectrometry
Journal of Chromatography A, 2014Co-Authors: Ana Herrero, C. Reguera, Cruz M Ortiz, L A Sarabia, Sagrario M SanchezAbstract:Abstract An ‘ad-hoc’ experimental design to handle the robustness study for the simultaneous determination of dichlobenil and its main metabolite (2,6-dichlorobenzamide) in onions by Programmed Temperature vaporization-gas chromatography-mass spectrometry (PTV-GC-MS) is performed. Eighteen experimental factors were considered; 7 related with the extraction and clean up step, 8 with the PTV injection step and 3 factors related with the derivatization step. Therefore, a high number of experiments must be carried out that cannot be conducted in one experimental session and, as a consequence, the experiments of the robustness study must be performed in several sessions or blocks. The procedure to obtain an experimental design suitable for this task works by simultaneously minimizing the joint confidence region for the coefficient estimates and the correlation among them and with the block. In this way, the effect of the factors is not aliased with the block avoiding possible misinterpretations of the effects of the experimental factors on the analytical responses. The developed experimental design is coupled to the PARAFAC2 method, which allows solving some specific problems in chromatography when working with complex matrix such as co-elution of interferents (including silylation artifacts from the derivatization step) and small shifts in the retention time and, besides, the unequivocal identification of the target compounds according to document SANCO/12571/2013.
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determination of dichlobenil and its major metabolite bam in onions by ptv gc ms using parafac2 and experimental design methodology
Chemometrics and Intelligent Laboratory Systems, 2014Co-Authors: Ana Herrero, C. Reguera, M.c. Ortiz, Luis A. SarabiaAbstract:Abstract The optimization of a GC–MS analytical procedure which includes derivatization, Quick Easy Cheap Effective Rugged and Safe (QuEChERS) and Programmed Temperature vaporization (PTV) using design of experiments is performed to determine 2,6-dichlorobenzonitrile (dichlobenil) and 2,6-dichlorobenzamide (BAM) in onions, using 3,5-dichlorobenzonitrile and 2,4-dichlorobenzamide as internal standards. The use of a central composite design and two D -optimal designs, together with the desirability function, makes it possible to significantly reduce the economic, time and environmental cost of the study. The usefulness of PARAFAC2 for solving problems as the interference of unexpected derivatization artifacts unavoidably linked to some derivatization agents, or the presence of coeluents from the complex matrix, which share m/z ratios with the target compounds, is shown. The limits of decision (CCα) of the optimized procedure, 5.00 μg kg − 1 for dichlobenil and 1.55 μg kg − 1 for BAM (α = 0.05), are below the maximum residue limit (MRL) established by the EU for dichlobenil (20 μg kg − 1 ) in this commodity.
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optimization of a gc ms procedure that uses parallel factor analysis for the determination of bisphenols and their diglycidyl ethers after migration from polycarbonate tableware
Talanta, 2013Co-Authors: M L Oca, Ana Herrero, M.c. Ortiz, L A SarabiaAbstract:Abstract Bisphenol A (BPA), bisphenol F (BPF) and their corresponding diglycidyl ethers (BADGE and BFDGE) are simultaneously determined using a Programmed-Temperature vaporizer-gas chromatography/mass spectrometry (PTV-GC/MS) system. BPA is used in the production of polycarbonate (PC), whereas BADGE and BFDGE are for manufacturing epoxy resins. Several food alerts caused by the migration of this kind of substances from contact food materials have led to the harmonization of the European legislation in Commission Regulation (EU) No. 10/2011, in force from 14 January 2011. In consequence, the use of BPA has been prohibited in the manufacture of plastic infant feeding bottles from 1 May 2011 and from 1 June 2011 regarding the placing on the market and importation into the European Union. Recently, the French Parliament has decreed that the presence of BPA in any food containers will be banned. Similarly, the use and/or presence of BFDGE are not allowed. In this work, a GC/MS method has been developed for the simultaneous determination of BPF, BPA, BFDGE and BADGE. For each one of the I samples that are analyzed, the abundance of J characteristic m/z ratios is recorded at K times around the retention time of each peak, so a data tensor of dimension I × J × K is obtained for every analyte. The decomposition of this tensor by means of parallel factor analysis (PARAFAC) enables to: (a) identify unequivocally each analyte according to the maximum permitted tolerances for relative ion intensities, and (b) quantify each analyte, even in the presence of coeluents. This identification, based on the mass spectrum and the retention time, guarantees the specificity of the analysis. This specificity could fail if the total ion chromatogram (TIC) is considered when there is poor resolution between some peaks or whether interferents coelute. With the aim of studying the effect of shortening the time of the analysis on the quality of the determinations while maintaining the specificity of the identifications, two of the heating ramps in the oven Temperature program are changed according to a two-level factorial design. Each analyte is identified by means of a PARAFAC decomposition of a data tensor obtained from several concentration levels, in such a way that five figures of merit are calculated for each experiment of the design. The analysis of these figures of merit for the 16 objects (4 compounds×4 heating ramps) using principal component analysis (PCA) shows that the shortest Temperature program should be considered, since this is the one the best figures of merit for BPA and BFDGE (both banned) are achieved with. At these conditions and with probabilities of false positive and false negative fixed at 0.05, values of detection capability (CCβ) between 2.65 and 4.71 μg L −1 when acetonitrile is the injection solvent, and between 1.97 and 5.53 μg L −1 when acetone, are obtained. This GC/MS method has been applied to the simultaneous determination of BPF, BPA, BFDGE and BADGE in food simulant D1 (ethanol–H 2 O, 1:1 v/v), which had been previously in contact with PC tableware for 24 h at 70 °C and then pretreated by a solid-phase extraction (SPE) step. The migration of BPA from the new PC containers analyzed is confirmed, and values between 104.67 and 181.46 μg L −1 (0.73 and 1.27 μg L −1 after correction) of BPA have been estimated. None of the results obtained exceeds the specific migration limit of 600 μg L −1 established by law for BPA in plastic food materials different from PC infant feeding bottles. Severe problems of coelution of interferents have been overcome using PARAFAC decompositions in the analysis of these food simulant samples.
H J Schenk - One of the best experts on this subject based on the ideXlab platform.
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kinetics of petroleum generation and cracking by Programmed Temperature closed system pyrolysis of toarcian shales
Fuel, 1998Co-Authors: V Dieckmann, H J Schenk, Brian Horsfield, D H WelteAbstract:Abstract Primary kerogen-to-petroleum and secondary oil-to-gas conversion processes in marine source rocks have been studied contemporaneously by Programmed-Temperature closed-system (MSSV) pyrolysis of Toarcian Shale concentrates at heating rates of 0.1, 0.7 and 5.0K min −1 in the Temperature range of 300–610°C. All pyrolysates were analysed by single-step on-line gas chromatography. The cumulative evolution profiles of liquid and gaseous compounds were deconvoluted into generation curves for oil (C 6+ ), primary gas and secondary gas using complementary open-system experiments and simple stoichiometric relationships. The subsequent kinetic analysis resulted in potential versus activation energy distributions which turned out to be comparatively broad for oil and primary gas and rather narrow for secondary gas, indicating that the formerer are generated from more inhomogeneous precursor materials than the latter. The dominant activation energies were found to increase from 52 (217.9) (oil) to 53 (222) (primary gas) and 55 (230.5) kcal mol −1 (kJ mol −1 ) (secondary gas); the best-fit frequency factors were calculated around 1015 min −1 . By extrapolation to a geological heating rate of 5.3K my −1 (10 −11 K min −1 ) the onset of oil generation is predicted to occur at 90°C, the maximum oil formation rate at 140°C and the onset (peak generation) of primary and secondary gas at 110°C (165°C) and 150°C (180°C), respectively.
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the conversion of oil into gas in petroleum reservoirs part 1 comparative kinetic investigation of gas generation from crude oils of lacustrine marine and fluviodeltaic origin by Programmed Temperature closed system pyrolysis
Organic Geochemistry, 1997Co-Authors: H J Schenk, R Di Primio, Brian HorsfieldAbstract:The thermal alteration of reservoired petroleum upon burial was simulated comparatively by closed-system Programmed-Temperature pyrolysis of produced crude oils of lacustrine, fluviodeltaic, marine clastic and marine carbonate origin using the microscale sealed vessel (MSSV) technique. Bulk kinetics of oil-to-gas cracking and accompanying compositional changes were studied at heating rates of 0.1, 0.7 and 5.0 K/min. The oil type related variations of experimental cracking Temperatures were small compared to those related to heating rate, but the high-Temperature shift of gas evolution curves with increasing rate of heating turned out to be more pronounced for the marine than for the non-marine oils. Accordingly the kinetic frequency factors were derived to be higher for gas generation from the lacustrine and fluviodeltaic oils (A ≈ 4·1019 min−1) than from the marine oils (A ≈ 2·1018 min−1) and the gas potential vs. activation energy distributions were calculated to be centered around 71–72 kcal/mol for the former and around 67 kcal/mol for the latter. These kinetic parameters and compositional observations give some evidence that gas generation is accompanied by the formation of aromatic compounds in the case of the marine oils whereas alkene intermediates seem to be involved in the case of the non-marine high was oils. Under geological heating conditions (e.g. 5 K/My), the onset of gas generation and peak gas generation are extrapolated to occur at about 180°C and 225°C for the high wax oils. The marine oils turn out to be slightly less stable with peak gas generation at 215°C and the onset of decomposition reactions predicted at about 170°C. In the absence of reservoir bitumen and minerals severe oil-to-gas cracking is very unlikely to take place at Temperatures less than 160°C, whatever the crude oil type or the geological heating rate.
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an investigation of the in reservoir conversion of oil to gas compositional and kinetic findings from closed system Programmed Temperature pyrolysis
Organic Geochemistry, 1992Co-Authors: B Horsfield, H J Schenk, N Mills, Dietrich H WelteAbstract:The thermal alteration of reservoired petroleum upon burial was simulated by closed-system non-isothermal pyrolysis. Samples of a medium gravity oil from the Norwegian North Sea Central Graben were pyrolysed in microscale sealed glass or quartz vessels at heating rates of 0.1, 0.7 and 5.0 K · min−1 up to Temperatures varying from 300 to 650°C. The composition of the oil and gas in each vessel was determined by a single-step on-line gas chromatographic analysis. With increasing rate of heating the onset of all oil degradation reactions was shifted to higher Temperatures. The same successive compositional changes occurred in each case: increase in the total yield of GC-detectable compounds, significant gas (C1C4), generation accompanied by a decrease in yield of heavy components, aromatisation and attainment of maximum gas yield and finally a cracking of the C2+ gas components. The stable final mixture consisted of methane, aromatic hydrocarbons, pyrobitumen and possibly hydrogen. Kinetic modelling of the oil to gas conversion resulted in a narrow gas potential vs activation energy distribution between 66 and 70 kcal/mol assigning 35% of the total gas potential (460 mg per g of oil) to an energy of 66 kcal/mol and 29% to 67 kcal/mol (pre-exponential factor 1.1 × 1016 s−1). By extrapolation to natural maturation conditions the onset of gas generation is predicted to occur between 160 and 190°C for geological heating rates between 0.53 and 5.3 K·Ma−1. Predictions from the model are in accordance with the observed preservation of liquid hydrocarbons in a deep, hot (165°C) petroleum reservoir from the Saga 2/4–14 well, Norwegian Continental Shelf.
Brian Horsfield - One of the best experts on this subject based on the ideXlab platform.
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kinetics of petroleum generation and cracking by Programmed Temperature closed system pyrolysis of toarcian shales
Fuel, 1998Co-Authors: V Dieckmann, H J Schenk, Brian Horsfield, D H WelteAbstract:Abstract Primary kerogen-to-petroleum and secondary oil-to-gas conversion processes in marine source rocks have been studied contemporaneously by Programmed-Temperature closed-system (MSSV) pyrolysis of Toarcian Shale concentrates at heating rates of 0.1, 0.7 and 5.0K min −1 in the Temperature range of 300–610°C. All pyrolysates were analysed by single-step on-line gas chromatography. The cumulative evolution profiles of liquid and gaseous compounds were deconvoluted into generation curves for oil (C 6+ ), primary gas and secondary gas using complementary open-system experiments and simple stoichiometric relationships. The subsequent kinetic analysis resulted in potential versus activation energy distributions which turned out to be comparatively broad for oil and primary gas and rather narrow for secondary gas, indicating that the formerer are generated from more inhomogeneous precursor materials than the latter. The dominant activation energies were found to increase from 52 (217.9) (oil) to 53 (222) (primary gas) and 55 (230.5) kcal mol −1 (kJ mol −1 ) (secondary gas); the best-fit frequency factors were calculated around 1015 min −1 . By extrapolation to a geological heating rate of 5.3K my −1 (10 −11 K min −1 ) the onset of oil generation is predicted to occur at 90°C, the maximum oil formation rate at 140°C and the onset (peak generation) of primary and secondary gas at 110°C (165°C) and 150°C (180°C), respectively.
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the conversion of oil into gas in petroleum reservoirs part 1 comparative kinetic investigation of gas generation from crude oils of lacustrine marine and fluviodeltaic origin by Programmed Temperature closed system pyrolysis
Organic Geochemistry, 1997Co-Authors: H J Schenk, R Di Primio, Brian HorsfieldAbstract:The thermal alteration of reservoired petroleum upon burial was simulated comparatively by closed-system Programmed-Temperature pyrolysis of produced crude oils of lacustrine, fluviodeltaic, marine clastic and marine carbonate origin using the microscale sealed vessel (MSSV) technique. Bulk kinetics of oil-to-gas cracking and accompanying compositional changes were studied at heating rates of 0.1, 0.7 and 5.0 K/min. The oil type related variations of experimental cracking Temperatures were small compared to those related to heating rate, but the high-Temperature shift of gas evolution curves with increasing rate of heating turned out to be more pronounced for the marine than for the non-marine oils. Accordingly the kinetic frequency factors were derived to be higher for gas generation from the lacustrine and fluviodeltaic oils (A ≈ 4·1019 min−1) than from the marine oils (A ≈ 2·1018 min−1) and the gas potential vs. activation energy distributions were calculated to be centered around 71–72 kcal/mol for the former and around 67 kcal/mol for the latter. These kinetic parameters and compositional observations give some evidence that gas generation is accompanied by the formation of aromatic compounds in the case of the marine oils whereas alkene intermediates seem to be involved in the case of the non-marine high was oils. Under geological heating conditions (e.g. 5 K/My), the onset of gas generation and peak gas generation are extrapolated to occur at about 180°C and 225°C for the high wax oils. The marine oils turn out to be slightly less stable with peak gas generation at 215°C and the onset of decomposition reactions predicted at about 170°C. In the absence of reservoir bitumen and minerals severe oil-to-gas cracking is very unlikely to take place at Temperatures less than 160°C, whatever the crude oil type or the geological heating rate.
D H Welte - One of the best experts on this subject based on the ideXlab platform.
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kinetics of petroleum generation and cracking by Programmed Temperature closed system pyrolysis of toarcian shales
Fuel, 1998Co-Authors: V Dieckmann, H J Schenk, Brian Horsfield, D H WelteAbstract:Abstract Primary kerogen-to-petroleum and secondary oil-to-gas conversion processes in marine source rocks have been studied contemporaneously by Programmed-Temperature closed-system (MSSV) pyrolysis of Toarcian Shale concentrates at heating rates of 0.1, 0.7 and 5.0K min −1 in the Temperature range of 300–610°C. All pyrolysates were analysed by single-step on-line gas chromatography. The cumulative evolution profiles of liquid and gaseous compounds were deconvoluted into generation curves for oil (C 6+ ), primary gas and secondary gas using complementary open-system experiments and simple stoichiometric relationships. The subsequent kinetic analysis resulted in potential versus activation energy distributions which turned out to be comparatively broad for oil and primary gas and rather narrow for secondary gas, indicating that the formerer are generated from more inhomogeneous precursor materials than the latter. The dominant activation energies were found to increase from 52 (217.9) (oil) to 53 (222) (primary gas) and 55 (230.5) kcal mol −1 (kJ mol −1 ) (secondary gas); the best-fit frequency factors were calculated around 1015 min −1 . By extrapolation to a geological heating rate of 5.3K my −1 (10 −11 K min −1 ) the onset of oil generation is predicted to occur at 90°C, the maximum oil formation rate at 140°C and the onset (peak generation) of primary and secondary gas at 110°C (165°C) and 150°C (180°C), respectively.
C. Reguera - One of the best experts on this subject based on the ideXlab platform.
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ad hoc blocked design for the robustness study in the determination of dichlobenil and 2 6 dichlorobenzamide in onions by Programmed Temperature vaporization gas chromatography mass spectrometry
Journal of Chromatography A, 2014Co-Authors: Ana Herrero, C. Reguera, Cruz M Ortiz, L A Sarabia, Sagrario M SanchezAbstract:Abstract An ‘ad-hoc’ experimental design to handle the robustness study for the simultaneous determination of dichlobenil and its main metabolite (2,6-dichlorobenzamide) in onions by Programmed Temperature vaporization-gas chromatography-mass spectrometry (PTV-GC-MS) is performed. Eighteen experimental factors were considered; 7 related with the extraction and clean up step, 8 with the PTV injection step and 3 factors related with the derivatization step. Therefore, a high number of experiments must be carried out that cannot be conducted in one experimental session and, as a consequence, the experiments of the robustness study must be performed in several sessions or blocks. The procedure to obtain an experimental design suitable for this task works by simultaneously minimizing the joint confidence region for the coefficient estimates and the correlation among them and with the block. In this way, the effect of the factors is not aliased with the block avoiding possible misinterpretations of the effects of the experimental factors on the analytical responses. The developed experimental design is coupled to the PARAFAC2 method, which allows solving some specific problems in chromatography when working with complex matrix such as co-elution of interferents (including silylation artifacts from the derivatization step) and small shifts in the retention time and, besides, the unequivocal identification of the target compounds according to document SANCO/12571/2013.
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determination of dichlobenil and its major metabolite bam in onions by ptv gc ms using parafac2 and experimental design methodology
Chemometrics and Intelligent Laboratory Systems, 2014Co-Authors: Ana Herrero, C. Reguera, M.c. Ortiz, Luis A. SarabiaAbstract:Abstract The optimization of a GC–MS analytical procedure which includes derivatization, Quick Easy Cheap Effective Rugged and Safe (QuEChERS) and Programmed Temperature vaporization (PTV) using design of experiments is performed to determine 2,6-dichlorobenzonitrile (dichlobenil) and 2,6-dichlorobenzamide (BAM) in onions, using 3,5-dichlorobenzonitrile and 2,4-dichlorobenzamide as internal standards. The use of a central composite design and two D -optimal designs, together with the desirability function, makes it possible to significantly reduce the economic, time and environmental cost of the study. The usefulness of PARAFAC2 for solving problems as the interference of unexpected derivatization artifacts unavoidably linked to some derivatization agents, or the presence of coeluents from the complex matrix, which share m/z ratios with the target compounds, is shown. The limits of decision (CCα) of the optimized procedure, 5.00 μg kg − 1 for dichlobenil and 1.55 μg kg − 1 for BAM (α = 0.05), are below the maximum residue limit (MRL) established by the EU for dichlobenil (20 μg kg − 1 ) in this commodity.
