Sylvie Héron | PubMed Health

PubMed2005

A study of interlaboratory influence on column evaluation.

A liquid chromatography method for the characterization of base deactivated columns was investigated in a collaborative study involving six laboratories. This work was carried out on two chromatographic supports (Xterra RP 18 and Symmetry Shield). Different cooling systems, namely water bath and air oven, were tested and it was shown that column thermoregulation did not significantly influence chromatographic data. In order to control the mobile phase composition, the latter was prepared by weight rather than volume. Thanks to the injection of a set of selected neutral compounds, extra-column effects were evaluated in each of the participating laboratories. The results showed that chromatographic supports tested in different laboratories and following the same test protocol could be effectively compared.

Chromatography, High Pressure Liquid↗

PubMed2004

Post-column addition as a method of controlling triacylglycerol response coefficient of an evaporative light scattering detector in liquid chromatography-evaporative light-scattering detection.

The non-linear response is generally the main limitation to the general quantitative use of evaporative light-scattering detection (ELSD). In the particular case of triacylglycerol (TG) analysis, we present a preliminary paper dealing with the use of post-column additives as a means of monitoring the response of such a detector. As TG can form molecular association complexes (ligand-ligate associations) with either cholesterol, urea or silver nitrate, we report the influence of the concentration of each of these chemical compounds in the liquid phase directed towards the ELSD system. The results show that the response coefficient b of the calibration curve either decreases from 1.25-1.30 to 0.51 or increases from 1.25-1.30 to 1.78 according to the nature and concentration of post-column additive. The use of cholesterol as additive, at a discrete concentration, may lead to a linear response curve (b = 1), i.e. to the direct proportionality of ELSD response versus the TG concentration, making quantitative analysis of such solutes easier. On the other hand, to improve sensitivity, the addition of silver nitrate may be chosen for an increase in b value.

Cholesterol↗