0000000000134871
AUTHOR
Valerio Leoni
Separation of pesticides, related compounds, polychlorobiphenyls and other pollutants into four groups by silica‐gel microcolumn chromatography (application to surface water analysis)
Multi‐residue analyses of pesticides and related compounds generally require clean‐up procedures for the elimination of interfering substances. An analytical procedure for use in the recovery and determination of pesticides and other pollutants in water samples is described, in which the purification of the extracts is improved by the separation of pesticides into four groups. The separation of pesticides by silica‐gel microcolumn chromatography is explained in detail. Copyright © 1991 John Wiley & Sons, Ltd
International descriptive and interventional survey for oxycholesterol determination by gas- and liquid-chromatographic methods
International audience; Increasing numbers of laboratories develop new methods based on gas-liquid and high-performance liquid chromatography to determine serum concentrations of oxygenated cholesterol metabolites such as 7alpha-, 24(S)-, and 27-hydroxycholesterol. We initiated a first international descriptive oxycholesterol (OCS) survey in 2013 and a second interventional survey 2014 in order to compare levels of OCS reported by different laboratories and to define possible sources of analytical errors. In 2013 a set of two lyophilized serum pools (A and B) was sent to nine laboratories in different countries for OCS measurement utilizing their own standard stock solutions. In 2014 eleven…
First international descriptive and interventional survey for cholesterol and non-cholesterol sterol determination by gas- and liquid-chromatography–Urgent need for harmonisation of analytical methods
International audience; Serum concentrations of lathosterol, the plant sterols campesterol and sitosterol and the cholesterol metabolite 5alpha-cholestanol are widely used as surrogate markers of cholesterol synthesis and absorption, respectively. Increasing numbers of laboratories utilize a broad spectrum of well-established and recently developed methods for the determination of cholesterol and non-cholesterol sterols (NCS). In order to evaluate the quality of these measurements and to identify possible sources of analytical errors our group initiated the first international survey for cholesterol and NCS. The cholesterol and NCS survey was structured as a two-part survey which took place…
Inverse correlation between plasma oxysterol and LDL-cholesterol levels in hepatitis C virus-infected patients
Background: Hepatitis C virus infection is characterised by enhanced oxidative stress, which can be measured quantitatively by plasma oxysterol concentration. These molecules may affect lipid metabolism through the activation of Liver X Receptors. Hepatitis C virus exploits host lipid metabolism to facilitate its replication and diffusion. In our study we aimed to evaluate and highlight the potential pathogenetic role of oxysterols, 7-ketocholesterol and 7-β-hydroxycholesterol, in hepatitis C virus-related lipid dysmetabolism. Methods: The study was performed in 42 patients with chronic hepatitis C (93% genotype 1b) and 38 non-alcoholic fatty liver disease patients. Plasma oxysterols 7-keto…