Liquid Chromatography Column Screening for the Analysis of Corrosion Inhibitor Molecules Using Derringer Desirability Functions.

Corrosion inhibitors (CIs) are extensively employed in the oil and gas industry, yet their analysis remains a challenge. To develop a suitable liquid chromatography method for a wide array of CIs, a column screening was conducted. Nine different chromatographic conditions were tested across eight RPLC and mixed-mode columns (Accucore C18, CORTECS Shield RP18, Acquity HSS T3, Acquity Premier HSS T3, Accucore 150-C4, Accucore PFP, Synergi Polar RP, and Acclaim WCX-1).

State-of-the-art and challenges in the analysis of renewable gases.

The development of renewable and low-carbon gases for injection into the gas grid obtained by different processes such as anaerobic digestion, pyrogasification, hydrothermal gasification, and methanation, followed by upgrading steps, increases the demand for analysis and characterization in order to fully manage their integration into the gas value chain. If the analysis of the main compounds (methane, carbon dioxide, hydrogen, and carbon monoxide) is well described, the analysis of impurities in renewable gases remains more challenging due to their various natures and quantities. After a brief description of renewable and low-carbon methane production processes, the review focuses on the methods used for the analysis of the different compounds in renewable gases, from the main ones to impurities at ppb levels.

Characterization of Flavor Compounds in Distilled Spirits: Developing a Versatile Analytical Method Suitable for Micro-Distilleries.

Over the last few years, the development of micro-distilleries producing diverse spirits with various flavors has been observed. Versatile analytical techniques for the characterization of aroma compounds in such alcoholic beverages are therefore required. A model mixture embodying a theoretical distilled spirit was made according to the data found in literature to compare usual extraction techniques.

Gas Digital Microfluidic Platform: Application to Highly Volatile Compound Preconcentration.

Digital microfluidics platforms (DMFPs) have shown their efficiency in sample handling, using elementary operations that may be combined to perform complex applications. In this article, we present a new platform for gaseous samples handling involving a two-step digital preconcentration using the miniaturized preconcentrators of the DMFP. Choosing -pentane at very low concentrations as a model for highly volatile compounds, poorly retained on the sorbent, the DMFP allowed bypassing the limit set by the breakthrough volume by repeating an elementary operation.

Oxidation of ethidium-based probes by biological radicals: mechanism, kinetics and implications for the detection of superoxide.

Hydroethidine (HE) and hydropropidine ([Formula: see text]) are fluorogenic probes used for the detection of the intra- and extracellular superoxide radical anion ([Formula: see text]). In this study, we provide evidence that HE and [Formula: see text] react rapidly with the biologically relevant radicals, including the hydroxyl radical, peroxyl radicals, the trioxidocarbonate radical anion, nitrogen dioxide, and the glutathionyl radical, via one-electron oxidation, forming the corresponding radical cations. At physiological pH, the radical cations of the probes react rapidly with [Formula: see text], leading to the specific 2-hydroxylated cationic products.

Corona charged aerosol detector non-uniform response factors of purified alcohol ethoxylated homologues using liquid chromatography.

Surfactants are used in various applications: cosmetics, pharmaceuticals, petrochemicals, environmental, etc. Many of these compounds are polydisperse, and because of this intrinsic polydispersity, it is essential to have a universal detector with a uniform response to quantify them in a simple way. Indeed, Charged Aerosol Detector (CAD) was presented as a universal detector with a uniform response.

A microfluidic device for digital manipulation of gaseous samples.

Digital microfluidics is known for fine manipulation of sub-millimeter samples, with applications from biological sample preparation to diagnostic testing. Unfortunately, until now, it has been only limited to liquid phases. In this paper, we present a new system based on a digital microfluidic platform (DMFP), which is able to digitally manipulate gaseous samples, such as alkanes from n-hexane to n-nonane.

Analysis of multiclass organic pollutant in municipal landfill leachate by dispersive liquid-liquid microextraction and comprehensive two-dimensional gas chromatography coupled with mass spectrometry.

We propose a simple, fast, and inexpensive method for the analyses of 72 organic compounds in municipal landfill leachate, based on dispersive liquid-liquid microextraction and comprehensive two-dimensional gas chromatography coupled with mass spectrometry. Forty-one organic compounds belonging to several classes including hydrocarbons, mono- and polyaromatic hydrocarbons, carbonyl compounds, terpenes, terpenoids, phenols, amines, and phthalates, covering a wide range of physicochemical properties and linked to municipal landfill leachate, were quantitatively determined. Another 31 organic compounds such as indoles, pyrroles, glycols, organophosphate flame retardants, aromatic amines and amides, pharmaceuticals, and bisphenol A have been identified based on their mass spectra.

A promising "metastable" liquid crystal stationary phase for gas chromatography.

The liquid crystal state is an ordered physical state between a solid and a liquid. Previous research, in gas chromatography, proved that it provides a geometric selectivity, which allows the separation of geometric position isomers and cis-trans isomers that are difficult to separate on conventional gas chromatography stationary phases (polydimethyl siloxane derived and polyethylene glycol stationary phases). However, their use was generally very limited by the rather high temperature at which they must be operated, normally above the solid-liquid crystal transition temperature.

Chromatographic behavior and characterization of polydisperse surfactants using Ultra-High-Performance Liquid Chromatography hyphenated to High-Resolution Mass Spectrometry.

Surfactants are widely used in various petrochemical applications. Thus, it is essential to have highly efficient analytical tools to monitor the different classes of surfactants commonly used. Three among the four known classes of surfactants were studied in the present work: anionic (i.

Miniaturization of breath sampling with silicon chip: application to volatile tobacco markers tracking.

This work presents the performances of silicon micro-preconcentrators chips for breath sampling. The silicon chips were coupled to a handheld battery powered system for breath sampling and direct injection in a laboratory gas chromatography mass spectrometry system through thermal desorption (TD). Performances of micro-preconcentrators were first compared to commercial TD for benzene trapping.

Human odor and forensics: Towards Bayesian suspect identification using GC × GC-MS characterization of hand odor.

A new method for identifying people by their odor is proposed. In this approach, subjects are characterized by a GC × GC-MS chromatogram of a sample of their hand odor. The method is based on the definition of a distance between odor chromatograms and the application of Bayesian hypothesis testing.

Detection of mitochondria-generated reactive oxygen species in cells using multiple probes and methods: Potentials, pitfalls, and the future.

Reactive oxygen and nitrogen species (ROS/RNS) such as superoxide (O), hydrogen peroxide, lipid hydroperoxides, peroxynitrite, and hypochlorous and hypobromous acids play a key role in many pathophysiological processes. Recent studies have focused on mitochondrial ROS as redox signaling species responsible for promoting cell division, modulating and regulating kinases and phosphatases, and activating transcription factors. Many ROS also stimulate cell death and senescence.

Comprehensive two-dimensional gas chromatography for biogas and biomethane analysis.

The gas industry is going to be revolutionized by being able to generate bioenergy from biomass. The production of biomethane - a green substitute of natural gas - is growing in Europe and the United-States of America. Biomethane can be injected into the gas grid or used as fuel for vehicles after compression.

Active modulation in neat carbon dioxide packed column comprehensive two-dimensional supercritical fluid chromatography.

After demonstrating in a first paper the feasibility of SFCxSFC without decompression of the mobile phase, a modified interface has been developed in order to perform active modulation between the two SFC dimensions. In this paper, it is shown that the new interface enabled independent control of modulation parameters in SFCxSFC and performed a band compression effect of solutes between the two SFC dimensions. The effectiveness of this new modulation process was studied using a Design of Experiments.

Human odor and forensics. Optimization of a comprehensive two-dimensional gas chromatography method based on orthogonality: How not to choose between criteria.

The use of comprehensive two-dimensional gas chromatography coupled with mass spectrometry would be a real asset for the forensic profiling of human hand odor. This paper focuses on the optimization of a comprehensive gas chromatography method using a synthetic mixture of 80 compounds representative of human hand odor composition. In order to rank the candidate column sets, instead of using a unique criterion, we used a chemometric tool called desirability which is based on Derringer functions and enables to consider several criteria simultaneously and hence to get the best compromise.

Supercritical Fluid Chromatography of Drugs: Parallel Factor Analysis for Column Testing in a Wide Range of Operational Conditions.

Retention mechanisms involved in supercritical fluid chromatography (SFC) are influenced by interdependent parameters (temperature, pressure, chemistry of the mobile phase, and nature of the stationary phase), a complexity which makes the selection of a proper stationary phase for a given separation a challenging step. For the first time in SFC studies, Parallel Factor Analysis (PARAFAC) was employed to evaluate the chromatographic behavior of eight different stationary phases in a wide range of chromatographic conditions (temperature, pressure, and gradient elution composition). Design of Experiment was used to optimize experiments involving 14 pharmaceutical compounds present in biological and/or environmental samples and with dissimilar physicochemical properties.

Sampling method development and optimization in view of human hand odor analysis by thermal desorption coupled with gas chromatography and mass spectrometry.

Forensic profiling of human odor is challenging and would be useful to support information provided by dogs in courts of justice. Analyses of volatile compounds constitutive of human odor are commonly performed with gas chromatography coupled with mass spectrometry. All developed methods and sampling prototypes have to be easy to use in the field by crime scene investigators.

Synergetic Use of Principal Component Analysis Applied to Normed Physicochemical Measurements and GC × GC-MS to Reveal the Stabilization Effect of Selected Essential Oils on Heated Rapeseed Oil.

Lipid oxidation leads to the formation of volatile compounds and very often to off-flavors. In the case of the heating of rapeseed oil, unpleasant odors, characterized as a fishy odor, are emitted. In this study, 2 different essential oils (coriander and nutmeg essential oils) were added to refined rapeseed oil as odor masking agents.

Combination of partial least squares regression and design of experiments to model the retention of pharmaceutical compounds in supercritical fluid chromatography.

This work presents a first attempt to establish a model of the retention behaviour for pharmaceutical compounds in gradient mode SFC. For this purpose, multivariate statistics were applied on the basis of data gathered with the Design of Experiment (DoE) methodology. It permitted to build optimally the experiments needed, and served as a basis for providing relevant physicochemical interpretation of the effects observed.

Origin, Analytical Characterization, and Use of Human Odor in Forensics.

Developing a strategy to characterize the odor prints of individuals should be relevant to support identification obtained using dogs in courts of justice. This article proposes an overview of the techniques used for the forensic profiling of human odor. After reviewing the origin of human odor-both genetic and physiological-the different analytical steps from sample collection to statistical data processing are presented.

Alternative solvents for improving the greenness of normal phase liquid chromatography of lipid classes.

An evaluation of solvents alternative to n-heptane (d-limonene and hexamethyldisiloxane) and chloroform (cyclopentyl methyl ether, 2-methyltetrahydrofuran and isopentyl acetate) was developed for lipid classes separation of non-polar cholesteryl ester to highly polar phospholipids by high-performance liquid chromatography on bare silica stationary phase and evaporative light-scattering detection. Screening of alternative solvents was used to estimate their compatibility with liquid chromatography and evaporative light-scattering detection and to evaluate their chromatographic selectivity. This work shows that n-heptane can be advantageously replaced by hexamethyldisiloxane.

Validation of a headspace trap gas chromatography and mass spectrometry method for the quantitative analysis of volatile compounds from degraded rapeseed oil.

Due to lipid oxidation, off-flavors, characterized by a fishy odor, are emitted during the heating of rapeseed oil in a fryer and affect the flavor of rapeseed oil even at low concentrations. Thus, there is a need for analytical methods to identify and quantify these products. To study the headspace composition of degraded rapeseed oil, and more specifically the compounds responsible for the fishy odor, a headspace trap gas chromatography with mass spectrometry method was developed and validated.

Feasibility of the preparation of silica monoliths for gas chromatography: fast separation of light hydrocarbons.

The preparation conditions of silica monoliths for gas chromatography were investigated. Silica-based monolithic capillary columns based on sol-gel process were tested in the course of high-speed gas chromatographic separations of light hydrocarbons mixture (C1-C4). The impact of modifying the amount of porogen and/or catalyst on the monolith properties were studied.