Development of a liquid injection system dedicated to on-line analysis by gas chromatography and its refining applications : study of the behavior and contribution of short monolithic columns in high pressure gas chromatography

En milieu industriel, si l'analyse en ligne d'effluents gazeux à l'aide de la chromatographie en phase gazeuse est actuellement réalisée sans difficultés majeure, l'analyse des liquides reste une des principales problématiques à résoudre. En effet, comparée à une analyse réalisée au laboratoire, l'analyse en ligne d'un échantillon liquide permettrait de s'affranchir de l'étape de prélèvement et de préparation avant injection ainsi que des problèmes de contamination et de représentativité de l'échantillon. Des systèmes d'injection de liquide en ligne sont actuellement disponibles, cependant, des difficultés d'injection liées à la discrimination des analytes sont rencontrées. C'est dans ce contexte qu'une vanne dédiée à l'injection des liquides en ligne a été développée, puis validée en laboratoire, et enfin mise en œuvre sur des applications industrielles pétrolières. Un tout autre enjeu, lié entre autres à la réduction des coûts de maintenance et d'installation, ainsi qu'à la compatibilité de systèmes analytiques destinés à l'industrie et aux micro-pilotes, a orienté des développements instrumentaux vers la miniaturisation des systèmes. Un assemblage de différentes briques technologiques a ensuite été réalisé afin d'évaluer la faisabilité d'un système miniaturisé incorporant la technologie d'injection des liquides en ligne. Finalement et toujours dans ce contexte de miniaturisation, des colonnes monolithiques courtes ont été mises en œuvre en chromatographie en phase gazeuse à haute pression, au laboratoire pour commencer, puis sur des effluents industriels gazeux. Elles ont permis de réaliser des analyses très rapides avec une grande efficacité par unité de longueur tout en pouvant agir sur la sélectivité des colonnes grâce à un contrôle de leurs propriétés de surfaceIn industry, although on-line analysis of gaseous effluents using gas chromatography is carried out without major difficulty, the analysis of liquids remains problematic and is one of the main issues to be solved. Indeed, compared to an analysis carried out in a laboratory, the on-line analysis of a liquid sample would bypass the steps of sampling and preparation prior to injection and would avoid problems of contamination and representativeness of the sample. Systems for injecting liquids on-line are currently available; however, difficulties are encountered, due to the discrimination of analytes. It is in this context that a valve dedicated to the on-line injection of liquids was developed, validated under laboratory conditions and finally implemented in the oil industry. Another issue, related, amongst other things, to the reduction of maintenance and installation costs, as well as to the compatibility of analytical systems for industry and for micro-pilots, steered instrumental developments towards the miniaturization of systems. Different technological bricks were therefore brought together to assess the feasibility of a miniaturized system involving the technology for on-line injection of liquid. Finally, and still in the context of miniaturization, short monolithic columns were implemented in gaseous phase chromatography at high pressure, first in the laboratory and then on industrial gas effluents. They allowed very fast analyses to be performed which had greater efficiency per unit of length while still being able to act on the selectivity of the columns thanks to the control of their surface propertie

Développement d’une vanne d’injection de liquide pour l’analyse en ligne par chromatographie en phase gazeuse et ses applications dans le domaine du raffinage : étude du comportement et apport des colonnes monolithiques courtes pour la chromatographie en phase gazeuse haute pression

In industry, although on-line analysis of gaseous effluents using gas chromatography is carried out without major difficulty, the analysis of liquids remains problematic and is one of the main issues to be solved. Indeed, compared to an analysis carried out in a laboratory, the on-line analysis of a liquid sample would bypass the steps of sampling and preparation prior to injection and would avoid problems of contamination and representativeness of the sample. Systems for injecting liquids on-line are currently available; however, difficulties are encountered, due to the discrimination of analytes. It is in this context that a valve dedicated to the on-line injection of liquids was developed, validated under laboratory conditions and finally implemented in the oil industry. Another issue, related, amongst other things, to the reduction of maintenance and installation costs, as well as to the compatibility of analytical systems for industry and for micro-pilots, steered instrumental developments towards the miniaturization of systems. Different technological bricks were therefore brought together to assess the feasibility of a miniaturized system involving the technology for on-line injection of liquid. Finally, and still in the context of miniaturization, short monolithic columns were implemented in gaseous phase chromatography at high pressure, first in the laboratory and then on industrial gas effluents. They allowed very fast analyses to be performed which had greater efficiency per unit of length while still being able to act on the selectivity of the columns thanks to the control of their surface propertiesEn milieu industriel, si l'analyse en ligne d'effluents gazeux à l'aide de la chromatographie en phase gazeuse est actuellement réalisée sans difficultés majeure, l'analyse des liquides reste une des principales problématiques à résoudre. En effet, comparée à une analyse réalisée au laboratoire, l'analyse en ligne d'un échantillon liquide permettrait de s'affranchir de l'étape de prélèvement et de préparation avant injection ainsi que des problèmes de contamination et de représentativité de l'échantillon. Des systèmes d'injection de liquide en ligne sont actuellement disponibles, cependant, des difficultés d'injection liées à la discrimination des analytes sont rencontrées. C'est dans ce contexte qu'une vanne dédiée à l'injection des liquides en ligne a été développée, puis validée en laboratoire, et enfin mise en œuvre sur des applications industrielles pétrolières. Un tout autre enjeu, lié entre autres à la réduction des coûts de maintenance et d'installation, ainsi qu'à la compatibilité de systèmes analytiques destinés à l'industrie et aux micro-pilotes, a orienté des développements instrumentaux vers la miniaturisation des systèmes. Un assemblage de différentes briques technologiques a ensuite été réalisé afin d'évaluer la faisabilité d'un système miniaturisé incorporant la technologie d'injection des liquides en ligne. Finalement et toujours dans ce contexte de miniaturisation, des colonnes monolithiques courtes ont été mises en œuvre en chromatographie en phase gazeuse à haute pression, au laboratoire pour commencer, puis sur des effluents industriels gazeux. Elles ont permis de réaliser des analyses très rapides avec une grande efficacité par unité de longueur tout en pouvant agir sur la sélectivité des colonnes grâce à un contrôle de leurs propriétés de surfac

On line liquid valve coupled to GCxGC technique

International audienc

Molecular characterization of petroleum mixtures using multiple ionization modes and GC×GC-HRTOFMS

Introduction: Comprehensive two-dimensional gas chromatography (GC×GC) has become a method of choice for complex mixture characterization, especially in the petroleum industry. Indeed, the high resolving power of the 2D separations offers structured separation allowing pattern recognition and group type classification of sample composition. For years, the technique was relying on electron ionization (EI) fragmentogram and chromatographic-based identification due to practical limitations on the detector side, mainly the high acquisition frequency required. The development of high-speed high-resolution time-of-flight mass spectrometers (TOFMS) offers opportunities to go deeper in the sample characterization. To obtain the most of the HRMS dimension, there is a growing interest to combine EI with softer ionization techniques, which preserve the molecular ion. Method: In this study, different base oil samples and standard mixtures were analyzed by GC×GC-HRTOMS. Three different soft-ionization techniques including photo ionization (PI), chemical ionization (CI), and field ionization (FI) were compared against EI to elucidate their relative capabilities to reveal different base oil hydrocarbon classes. Deeper investigations were also conducted on the PI fragmentation process for different chemical families. All the experiments were performed on a single system, a JEOL AccuTOF GCv 4G with modular ionization technologies. A low-polar (ZB-XLB-HT Inferno, 15.0 m, 0.25 mm ID, 0.1 μm, Phenomenex ) and polar (ZB-50HT, 2.0 m, 0.1 mm ID, 0.1 μm, Phenomenex) columns were used for base oil analysis for first and second dimension separation respectively. Preliminary Data: Compared to EI (70 eV), capabilities and limitations of PI were tested using an authentic mixture of compounds of several chemical classes. Ionization energy exhibited by PI, equivalent to 10.8 eV, resulted in significant retention of molecular ion information; [M]+• for alkanes, ketones, FAMEs, aromatics, [M−H]+• for chloroalkanes, and [M−H2O]+• for alcohols. In addition, considering the potential of PI for hydrocarbons, base oils, complex mixtures of saturated and unsaturated hydrocarbons blended for finished lubricant formulations, were extensively evaluated. PI retained significant molecular ion (M+‧) information for a large number of isomeric species including branched-alkanes and saturated mono-cyclic hydrocarbons along with unique fragmentation patterns. However, for bi-/poly cyclic naphthenic and aromatic compounds, EI played upper hand by retaining molecular as well as fragment ions to identify the species, whereas PI exhibited mainly molecular ion signals. CI revealed selectivity towards different base oil groups, particularly for steranes, sulfur-containing thiophenes, and esters; yielding protonated molecular ions (M+H) + for unsaturated and hydride abstracted ions (M-H+) for saturated hydrocarbons. FI, as expected, generated intact molecular ions (M+‧) irrespective to the base oil chemical classes. It allowed elemental composition by TOFMS with a mass resolving power up to 8,000 (FWHM) and a mass accuracy of 1 mDa, leading to the calculation of heteroatomic content, and carbon number of the compounds. The qualitative and quantitative results presented herein offer a unique perspective into the detailed comparison of different ionization techniques corresponding to several chemical classes. Novel aspect: The GC×GC field is ongoing a paradigm shift in which the MS dimension is even further contributing than before

Behavior of macroporous vinyl silica and silica monolithic columns in high pressure gas chromatography

International audienc

Behavior of short silica monolithic columns in high pressure gas chromatography.

International audienceIn order to analyze light hydrocarbons mixtures with silica monolithic columns, a conventional gas chromatograph was modified to work with carrier gas pressure as high as 60bar. To understand hydrodynamic flow and retention with short columns (less than 30cm), special attention was required due to the temperature difference between the oven area and the FID detector which contain a significant length of the column. Efficiency and selectivity using various carrier gases (helium, nitrogen and carbon dioxide) at different inlet pressure for different oven temperature were studied. Carrier gas nature was a very significant parameter: on one side, linked to adsorption mechanism for gases like nitrogen and carbon dioxide onto the stationary phase modifying retention and selectivity, on the other side in relation to the minimum theoretical plate height which was as low as 15μm (66 000 platem(-1)) using carbon dioxide as carrier gas. The chromatographic system was then used to separate methane, ethane, ethylene, acetylene, propane, cyclopropane, and butane in less than 30s

Advanced mono‐ and multi‐dimensional gas chromatography–mass spectrometry techniques for oxygen‐containing compound characterization in biomass and biofuel samples

A wide variety of biomass, from triglycerides to lignocellulosic‐based feedstock, are among promising candidates to possibly fulfill requirements as a substitute for crude oils as primary sources of chemical energy feedstock. During the feedstock processing carried out to increase the H:C ratio of the products, heteroatom‐containing compounds can promote corrosions, thus limiting and/or deactivating catalytic processes needed to transform the biomass into fuel. The use of advanced gas chromatography techniques, in particular multi‐dimensional gas chromatography, both heart‐cutting and comprehensive coupled to mass spectrometry, has been widely exploited in the field of petroleomics over the past 30 years and has also been successfully applied to the characterization of volatile and semi‐volatile compounds during the processing of biomass feedstock. This review intends to describe advanced gas chromatography–mass spectrometry‐based techniques, mainly focusing in the period 2011–early 2020. Particular emphasis has been devoted to the multi‐dimensional gas chromatography–mass spectrometry techniques, for the isolation and characterization of the oxygen‐containing compounds in biomass feedstock. Within this context, the most recent advances to sample preparation, derivatization, as well as gas chromatography instrumentation, mass spectrometry ionization, identification, and data handling in the biomass industry, are described

Advanced mono- and multi-dimensional gas chromatography–mass spectrometry techniques for oxygen-containing compound characterization in biomass and biofuel samples

A wide variety of biomass, from triglycerides to lignocellulosic-based feedstock, are among promising candidates to possibly fulfill requirements as a substitute for crude oils as primary sources of chemical energy feedstock. During the feedstock processing carried out to increase the H:C ratio of the products, heteroatom-containing compounds can promote corrosion, thus limiting and/or deactivating catalytic processes needed to transform the biomass into fuel. The use of advanced gas chromatography techniques, in particular multidimensional gas chromatography, both heart-cutting and comprehensive coupled to mass spectrometry, has been widely exploited in the field of petroleomics over the past 30 years and has also been successfully applied to the characterization of volatile and semi-volatile compounds during the processing of biomass feedstock. This review intends to describe advanced gas chromatography– mass spectrometry-based techniques, mainly focusing in the period 2011–early 2020. Particular emphasis has been devoted to the multi-dimensional gas chromatography–mass spectrometry techniques, for the isolation and characterization of the oxygen-containing compounds in biomass feedstock. Within this context, the most recent advances to sample preparation, derivatization, as well as gas chromatography instrumentation, mass spectrometry ionization, identification, and data handling in the biomass industry, are described

Analysis of mixed plastic pyrolysis oil by comprehensive two-dimensional gas chromatography coupled with low- and high-resolution time-of-flight mass spectrometry with the support of soft ionization.

peer reviewedAccording to the annual production of plastics worldwide, in 2020 about 370 million tons of plastic were produced in the world. Chemical recycling, particularly pyrolysis of plastic wastes, could be a valuable solution to resolve these problems and provide an alternative pathway to produce "recycled" chemical products for the petrochemical industry. Nevertheless, the pyrolysis oils need a detailed characterization before the upgrading test to re-use them to generate new recycled products. Multidimensional gas chromatography coupled with both low- and high-resolution time-of-flight mass spectrometers was employed for a detailed investigation among and within different chemical classes present in bio-plastic oil. The presence of several isomeric species as well as homologs series did not allow a reliable molecular identification, except for a few compounds that showed both MS similarity >800/1000 and retention index within ±20. Indeed, the identification of several isomeric species was assessed by high-resolution mass spectrometry equipped with photoionization interface. This soft ionization mode was an additional filter in the identification step allowing unambiguous identification of analytes not identified by the standard electron ionization mode at 70 eV. The injection method was also optimized using a central composite design to successfully introduce a wide range of carbon number compounds without discrimination of low/high boiling points

In-depth characterization of complex molecules using GC×GC-TOFMS

peer reviewe