Biomedical subjects

Eric Lesellier

Publications and source records attributed to Eric Lesellier.

4 recordsLinked to original sources

PubMed2005

A simple subcritical chromatographic test for an extended ODS high performance liquid chromatography column classification.

This paper describes a new test designed in subcritical fluid chromatography (SFC) to compare the commercial C18 stationary phase properties. This test provides, from a single analysis of carotenoid pigments, the absolute hydrophobicity, the silanol activity and the steric separation factor of the ODS stationary phases. Both the choice of the analytical conditions and the validation of the information obtained from the chromatographic measurements are detailed. Correlations of the carotenoid test results with results obtained from other tests (Tanaka, Engelhard, Sander and Wise) performed both in SFC and HPLC are discussed. Two separation factors, calculated from the retention of carotenoid pigments used as probe, allowed to draw a first classification diagram. Columns, which present identical chromatographic behaviors are located in the same area on this diagram. This location can be related to the stationary phase properties: endcapping treatments, bonding density, linkage functionality, specific area or silica pore diameter. From the first classification, eight groups of columns are distinguished. One group of polymer coated silica, three groups of polymeric octadecyl phases, depending on the pore size and the endcapping treatment, and four groups of monomeric stationary phases. An additional classification of the four monomeric groups allows the comparison of these stationary phases inside each group by using the total hydrophobicity. One hundred and twenty-nine columns were analysed by this simple and rapid test, which allows a comparison of columns with the aim of helping along their choice in HPLC.

Chromatography, High Pressure Liquid↗

PubMed2004

Glycolipid class profiling by packed-column subcritical fluid chromatography.

The potential of packed-column subcritical fluid chromatography (SubFC) for the separation of lipid classes has been assessed in this study. Three polar stationary phases were checked: silica, diol, and poly(vinyl alcohol). Carbon dioxide (CO2) with methanol as modifier was used as mobile phase and detection performed by evaporative light scattering detection. The influence of methanol content, temperature, and pressure on the chromatographic behavior of sphingolipids and glycolipids were investigated. A complete separation of lipid classes from a crude wheat lipid extract was achieved using a modifier gradient from 10 to 40% methanol in carbon dioxide. Solute selectivity was improved using coupled silica and diol columns in series. Because the variation of eluotropic strength depending on the fluid density changes, a normalized separation factor product (NSP) was used to select the nature, the number and the order of the columns to reach the optimum glycolipid separation.

Chromatography, Liquid↗

PubMed2003

Optimization of headspace solid phase microextraction for gas chromatography/mass spectrometry analysis of widely different volatility and polarity terpenoids in olibanum.

The aim of this study was the optimization of headspace SPME conditions for trapping diterpenes present in frankincense (olibanum). Diterpenes like cembrenes or incensole and its derivatives are characteristic of olibanum. So in order to detect by SPME the occurrence of olibanum in archeological objects, it appears essential to have the best extraction conditions for these diterpenes that will be in very small quantities. Both sampling time and extraction temperature were studied and five fiber coatings were tested: polydimethylsiloxane (PDMS), polydimethylsiloxane/divinylbenzene (PDMS/DVB), carboxen/polydimethylsiloxane (CAR/PDMS), divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) and carbowax/divinylbenzene (CW/DVB). The PDMS/DVB fiber was found to be the most efficient for trapping olibanum characteristic diterpenes, with a sampling time of 1 h and a sampling temperature of 80 degrees C.

Boswellia↗

PubMed2003

Isolation of ceramide fractions from skin sample by subcritical chromatography with packed silica and evaporative light scattering detection.

Separative method of lipid classes from the stratum corneum was developed with packed silica and supercritical CO2 containing 10% of methanol at 15 degrees C, 15 MPa and 3 ml min(-1). The elution order of lipid classes was first esterified cholesterol, triglycerides, squalene co-eluted in a single peak, then free fatty acids, free cholesterol, ceramides and finally glycosylceramides. The ceramides were eluted in several fractions which depended on the number of hydroxyl groups in the molecule, i.e. more hydroxyl groups were contained in ceramides, more important was the retention. Moreover, the retention was not altered by the presence of carbon double bond and variation of the alkyl chain length. The ceramide response with the evaporative light scattering detector was improved by turning the influence of the solvent nature on the response to advantage. Therefore, addition of various solvents with or without triethylamine and formic acid were tested in post-column due to the incompatibility of such modifiers with silica stationary phase. Thereby the solvent conditions for the separation and the detection can be adjusted almost independently. The response was greatly increased by post-column addition of 1% (v/v) triethylamine and its equivalent amount of formic acid in dichloromethane introduced at 0.1 ml min(-1) into the mobile phase. This device had allowed the detection of 400 ng of ceramide with a S/N = 21, whereas no peak was observed in absence of the post-column addition. Finally, the method was applied to the treatment of skin sample which led to highly enriched ceramide fraction.

Ceramides↗