Urinary signature of anabolic steroids and glucocorticoids in humans by LC-MS.

A metabonomic strategy based on LC-MS was employed to investigate the metabolic profile of urine samples from 20 athletes who had been tested positive for corticoids and anabolic steroids and 29 controls. In this aim, different sample preparations and chromatographic conditions were compared. The acquired LC-MS data of doped athletes and controls were subjected to analysis of variance (ANOVA) and principal component analysis (PCA).

Comparison of the analysis of beta-blockers by different techniques.

In this work we have compared three analytical techniques (ELISA, GC-MS, and LC-MS) for the analysis of 16 beta-blockers: acebutolol, alprenolol, atenolol, betaxolol, bisoprolol, carteolol, labetalol, metipranolol, metoprolol, nadolol, oxprenolol, pindolol, propranolol, sotalol, timolol, and bupranolol. Several sample-preparation methods were optimized for each technique and enabled compounds of interest to be extracted from small urine samples (1-2.5 mL).

Photochemical transformation of azoxystrobin in aqueous solutions.

The photochemical behaviour of azoxystrobin fungicide (AZX) in water was studied under laboratory conditions. Photodegradation was initiated using a solar simulator (xenon arc lamp) or a jacketed Pyrex reaction cell equipped with a 125 W, high-pressure mercury lamp. HPLC/MS analysis (APCI and ESI in positive and negative modes) was used to identify AZX photoproducts.

Advantages of LC-MS-MS compared to LC-MS for the determination of nitrofuran residues in honey.

In the framework of developing analyses for exogenous contaminants in food matrices such as honey, we have compared data obtained by high-performance liquid chromatography coupled with mass spectrometry (LC-MS) to those provided by high-performance liquid chromatography and tandem mass spectrometry (LC-MS-MS). Initial results obtained with LC-MS showed that the technique lacked selectivity, which is why the method was validated by LC-MS-MS. This method involves a solid-phase extraction (SPE) of nitrofuran metabolites and nitrofuran parent drugs, a derivatization by 2-nitrobenzaldehyde for 17 h, and finally a clean-up by SPE.

Comparison of the analysis of corticosteroids using different techniques.

In this work we have optimized the analysis of 18 human corticosteroids, some endogenous (tetrahydrocortisol, tetrahydrocortisone, cortisol, and cortisone) and others synthetic (betamethasone, budesonide, cortisone acetate, desonide, dexamethasone, dexamethasone acetate, flunisolide, fluocinolone acetonide, halcinonide, methylprednisolone, prednisolone, prednisone, triamcinolone, and triamcinolone acetonide). Three analytical techniques were developed: ELISA, gas chromatography coupled with mass spectrometry (GC-MS), and liquid chromatography coupled with mass spectrometry (LC-MS). Several sample-preparation methods were optimized for each technique and enabled compounds of interest to be extracted from small urine samples (several mL).

Analysis of neem oils by LC-MS and degradation kinetics of azadirachtin-A in a controlled environment. Characterization of degradation products by HPLC-MS-MS.

Since it was first isolated, the oil extracted from seeds of neem (Azadirachtin indica A juss) has been extensively studied in terms of its efficacy as an insecticide. Several industrial formulations are produced as emulsifiable solutions containing a stated titer of the active ingredient azadirachtin-A (AZ-A). The work reported here is the characterization of a formulation of this insecticide marketed under the name of Neem-azal T/S and kinetic studies of the major active ingredient of this formulation.

Determination of residual pesticides in olive oil by GC-MS and HPLC-MS after extraction by size-exclusion chromatography.

This work describes the development of a method for analyzing pesticide residues in olive oil by GC-MS and HPLC-MS. Pesticides were separated from the oily matrix by size-exclusion chromatography. After extraction, 20 pesticides were separated and analyzed by GC-MS and 11 others HPLC-MS in electrospray mode.

Analysis of pesticide residues in essential oils of citrus fruit by GC-MS and HPLC-MS after solid-phase extraction.

A robust reliable method for the analysis of residues of pesticides in citrus groves was developed. Residues of twelve pesticides were extracted from citrus essential oils by SPE, separated by liquid chromatography and analyzed by GC-MS. In addition, ten pesticides were extracted by SPE, separated and analyzed by electrospray HPLC-MS.

Degradation pathway of dicyclanil in water in the presence of titanium dioxide. Comparison with photolysis.

The solar photolytic behavior of the pesticide 4,6-diamino-2-cyclopropyl-pyrimidine-5-carbonitrile, currently known as dicyclanil, has been mimicked in a photoreactor operating with an artificial light flux. The rate and pathway of degradation were performed. An additional study, using TiO(2) photocatalysis, has been achieved in order to determine the efficiency of photocatalysis to degrade the molecule.

Analysis of aromatic sulfur compounds in gas oils using GC with sulfur chemiluminescence detection and high-resolution MS.

The analysis of alkylbenzothiophenes (alkyl-BT) and alkyl-dibenzothiophenes (alkyl-DBT) in light cycle oil (LCO) and straight run (SR) gas oils is described. A detailed identification and quantitative analysis of alkyl-BT and alkyl-DBT present in LCO gas oils was carried out using GC-SCD. For the SR gas oils, the simultaneous presence of thiophenic and nonthiophenic compounds does not allow for a selective analysis of thiophenic compounds by GC-SCD.

Simulated sunlight-induced photodegradations of triasulfuron and cinosulfuron in aqueous solutions.

To elucidate the photochemical behavior of two sulfonylureas (cinosulfuron and triasulfuron) for which the chemical formulas are relatively close, their photodegradation was studied in water. All experiments were carried out under laboratory conditions using a xenon arc lamp as the source of radiation to simulate environmental conditions. Polychromatic quantum efficiencies were calculated to determine the photochemical pesticide lifetimes at pH 7, and a comparison with hydrolysis lifetimes has been performed.

Detection of new propofol metabolites in human urine using gas chromatography/mass spectrometry and liquid chromatography/mass spectrometry techniques.

Using hyphenated analytical techniques, gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS), a study on minor propofol metabolites in human urine was conducted. These techniques allowed identification of two new phase I metabolites (2-(omega-propanol)-6-isopropylphenol and 2-(omega-propanol)-6-isopropyl-1,4-quinol). In addition, their four corresponding conjugates (three glucuronides and one sulphate) were detected.

Approach to the analysis of diuretics and masking agents by high-performance liquid chromatography-mass spectrometry in doping control.

The application of thermospray and plasmaspray high-performance liquid chromatography-mass spectrometry to the analysis of diuretics and probenecid has been investigated. The latter method gave better ionization efficiency than the former, and its response was optimized by altering the solvent composition: best results were obtained with water-methanol-acetonitrile-trifluoroacetic acid. Using different proportions of these solvents, three isocratic systems were developed to separate the compounds under study.