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Polyunsaturated fatty acids (PUFA) like arachidonic (C20:4) and docosahexaenoic (C22:6) acids are essential for harmonious fetal development. This study evaluates, at near term, the distributions of free fatty acids (FFA) and their fetal carrier protein, alpha-fetoprotein (AFP) in the maternal (M) and fetal circulation (umbilical arteries (A) and vein (V)), focusing on the feto-material interface where maternal intervillous blood (I) contacts the fetal trophoblast. FFA concentrations in intervillous and maternal blood were similar, while those in umbilical arteries and vein were 2- to 4-fold lower (P < 0.001). There were more saturated FFA in umbilical vein (41%) and arteries (44%) blood than in maternal (30%) and intervillous (32% blood (P < 0.001). Monounsaturated FFA predominated (P < 0.001) in maternal (43%) blood, but not in intervillous (35%), umbilical vein (33%) and arteries (31%) blood. Di-triunsaturated FFA were similar in intervillous and maternal (25%) blood and lower in umbilical vein and arteries (16%) (P < 0.001). PUFA were low in maternal (2.5%) blood and higher in intervillous and umbilical vein and arteries (9%, P < 0.001); consequently, C20:4 (40 microM) and C22:6 (16 microM) were the most abundant in the intervillous space. The AFP concentrations and AFP lectin-reactive isoforms were similar in intervillous and umbilical vein and arteries blood, but immuno-electrophoresis revealed a particular AFP conformation (less immuno-reactive, more anionic) in the intervillous space, suggesting that AFP is heavily loaded with PUFA at the feto-maternal interface. Prostacyclin derived from C20:4 was similar in all compartments but the thromboxane A2 concentration was 10-fold higher in intervillous blood than in maternal and umbilical vein and arteries blood. Thus the feto-maternal interface has a specific pattern of cell signalling molecules that might critically influence parturition.

The online combination of reversed-phase liquid chromatography and supercritical fluid chromatography (online RPLC × SFC) is an attractive technique for the characterization of complex samples containing neutral compounds as the two techniques are highly complementary, especially with a polar stationary phase in supercritical fluid chromatography (SFC). However, the setup is challenging due to the presence of hydro-organic solvents in RPLC, which become injection solvent in SFC. In this study, numerous key experimental parameters were identified and found to have a major effect on peak shape under RPLC × SFC conditions. These parameters included the organic modifier in reversed-phase liquid chromatography (RPLC), the co-solvent in SFC, the gradient conditions and the column ID in SFC, the configuration of the valve and finally, the injection volume in SFC that should be maximized. Acetonitrile (ACN) in RPLC, a mixture of ACN and methanol (MeOH) (50/50, v/v) in SFC, a minimum initial composition of 5% B in SFC, column IDs of 1.0 mm and 2.1 mm in RPLC and SFC respectively and flushing the interface loops with pure CO 2 while adding the co-solvent after the valve, are all conditions that have been identified as perfectly suitable for online RPLC × SFC. They were successfully applied to the online RPLC × SFC separations of microalgae bio-oil samples. Despite unusual injection conditions, the peaks were symmetrical over the entire chromatogram, leading to a high separation power., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Bio-oils obtained by thermochemical or biochemical conversion of biomass represent a promising source of energy to complement fossil fuels, in particular for maritime or air transport for which the use of hydrogen or electricity appears complicated. As these bio-oils are very rich in water and heteroatoms, additional treatments are necessary before they can be used as biofuel. In order to improve the efficiency of these treatments, it is important to have a thorough knowledge of the composition of the bio-oil. The characterization of bio-oils is difficult because they are very complex mixtures with thousands of compounds covering a very wide range of molecular weight and polarity. Due to the high degree of orthogonality between the two chromatographic dimensions, the on-line combination of reversed-phase liquid chromatography and supercritical fluid chromatography (on-line RPLC x SFC) can significantly improve the characterization of such complex matrices. The hyphenation was optimized by selecting, in SFC, the stationary phase, the co-solvent, the make-up solvent prior to high resolution mass spectrometry (HRMS) and the injection solvent. Additionally, a new interface configuration is described. Quality descriptors such as the occupation of the separation space, the peak shapes and the signal intensity were considered to determine the optimal conditions. The best results were obtained with bare silica, a co-solvent composed of acetonitrile and methanol (50/50, v/v), a make-up solvent composed of methanol (90%) and water (10%) with formic acid (0.1%), an addition of co-solvent through an additional pump for SFC separation in a 2.1 mm column, and an hydro-organic solvent as injection solvent. The optimized setup was used to analyze two microalgae bio-oils: the full bio-oil coming from hydrothermal liquefaction and Soxhlet extraction of microalgae, and the gasoline cut obtained after distillation of the full bio-oil. Results in on-line RPLC x SFC-qTOF were particularly interesting, with very good peak shapes and high reproducibility. Moreover, the high degree of orthogonality for microalgae bio-oils of RPLC and SFC was highlighted by the very large occupation of the separation space. Isomeric profiles of compound families could be obtained in RPLC x SFC-qTOF and many isomers not separated in SFC alone were separated in RPLC and vice versa, thus showing the complementarity of the two chromatographic techniques., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

New polar embedded aromatic stationary phases (mono- and trifunctional versions) that contain an amide-embedded group coupled with a tricyclic aromatic moiety were developed for chromatographic applications and described in the first paper of this series. These phases offered better separation performance for PAHs than for alkylbenzene homologues, and an enhanced ability to differentiate aromatic planarity to aromatic tridimensional conformation, especially for the trifunctional version and when using methanol instead of acetonitrile. In this second paper, a density functional theory study of the retention process is reported. In particular, it was shown that the selection of the suitable computational protocol allowed for describing rigorously the interactions that could take place, the solvent effects, and the structural changes for the monofunctional and the trifunctional versions. For the first time, the experimental data coupled with these DFT results provided a better understanding of the interaction mechanisms and highlighted the importance of the multimodal character of the designed stationary phases: alkyl spacers for interactions with hydrophobic solutes, amide embedded groups for dipole-dipole and hydrogen-bond interactions, and aromatic terminal groups for π-π interactions., (Copyright © 2017 Elsevier B.V. All rights reserved.)

New polar embedded aromatic stationary phases of different functionalities (mono- and trifunctional) and on different silica supports (Fully Porous Particle (FPP) and Superficially Porous Particle (SPP)) were synthesized to determine the impact of the functionality on the retention process and the selectivity towards aromatic compounds. A full experimental characterization was performed using a combination of techniques (elemental analysis, thermogravimetric measurements, infrared spectroscopy and solid-state NMR) to differentiate unambiguously the mono- and trifunctional Stationary Phases (SP). Commercially available columns with either an aromatic group or a polar embedded group were compared to the new stationary phases. The latter presented enhanced affinity for polycyclic aromatic hydrocarbons (PAH) structures compared to alkylbenzenes, especially when using methanol instead of acetonitrile as the organic modifier., (Copyright © 2017 Elsevier B.V. All rights reserved.)

This study reports the impact of thermal pretreatment between 400 and 1100°C on superficially porous silica particles (e.g. core-shell, fused-core; here abbreviated as SPP silica). The different thermally pretreated SPP silica (400°C, 900°C and 1100°C) were chemically bonded with an octadecyl chain under microwave irradiation. The bare SPP silica, thermally untreated and pretreated, as well as the chemically bonded phases (CBPs) were fully characterized by elemental analysis, diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), and solid state cross polarization magic angle spinning (CP-MAS) (29)Si NMR. The chromatographic properties of the overall set of C18-thermally pretreated SPP silica stationary phases were determined using the Tanaka test. Complementary, the simplified Veuthey test was used to deeply study the silanol activity, considering a set of 7 basic solutes with various physicochemical properties. Both tests were also performed on different commercial SPP silica columns and different types of bonding chemistry (C18, Phenyl-hexyl, RP-amide, C30, aQ). Multivariate data analyses (hierarchical cluster analysis and principal component analysis) were carried out to define groups of stationary phases with similar chromatographic properties and situate them in relation to those commercially available. These different C18-thermally pretreated SPP silicas represented a wide range of stationary phases as they were spread out along the score plot. Moreover, this study highlighted that the thermal pretreatment improved the chemical stability of the SPP silica compare to untreated SPP silica and untreated porous silica. Consequently, higher thermal pretreatment can be applied (up to 900°C) before functionalization without destruction of the silica matrix. Indeed, a significantly lower dissolution of the thermally pretreated SPP silica under aggressive conditions could allow the use of the corresponding functionalized stationary phases at high temperature (60°C) with good lifetime of the columns., (Copyright © 2015 Elsevier B.V. All rights reserved.)