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). Using this approach, molecular signature of human urine was obtained showing that metabonomics could be a complementary tool to discriminate different urinary profiles and to track down metabolic changes in humans.

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. The data obtained show that the limits of detection varied between 0.2 and 0.6 microg kg(-1) for the metabolites and between 1 and 2 microg kg(-1) for nitrofuran parent drugs. The method was applied to different flower honeys. The results showed that nitrofurans (used as antibiotics) are consistently present in this matrix, the predominant compound being furazolidone. Figure Working bees.

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. We initially performed liquid-liquid extraction to isolate the neem oil from other ingredients in the commercial mixture. This was followed by a purification using flash chromatography and semi-preparative chromatography, leading to (13)C NMR identification of structures such as azadirachtin-A, azadirachtin-B, and azadirachtin-H. The neem extract was also characterized by HPLC-MS using two ionization sources, APCI (atmospheric pressure chemical ionization) and ESI (electrospray ionization) in positive and negative ion modes of detection. This led to the identification of other compounds present in the extract-azadirachtin-D, azadirachtin-I, deacetylnimbin, deacetylsalannin, nimbin, and salannin. The comparative study of data gathered by use of the two ionization sources is discussed and shows that the ESI source enables the largest number of structures to be identified. In a second part, kinetic changes in the main product (AZ-A) were studied under precise conditions of pH (2, 4, 6, and 8), temperature (40 to 70 degrees C), and light (UV, dark room and in daylight). This enabled us to determine the degradation kinetics of the product (AZ-A) over time. The activation energy of the molecule (75+/-9 kJ mol(-1)) was determined by examining thermal stability in the range 40 to 70 degrees C. The degradation products of this compound were identified by use of HPLC-MS and HPLC-MS-MS. The results enabled proposal of a chemical degradation reaction route for AZ-A under different conditions of pH and temperature. The data show that at room temperature and pH between 4 and 5 the product degrades into two preferential forms that are hydrolyzed to a single product over time and as a function of pH change.

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. The development of this method enabled us to identify and quantify the pesticides of interest.

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. In the case of lemon essential oils, all twenty residues were separated by liquid/solid extraction on a mixed Florisil-C(18) cartridge. The method enabled the analysis of the twenty pesticide residues at levels of 2 to 30 ppm with limits of detection ranging between 0.02 to 0.50 mg L(-1).

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. The catalyst was titania Degussa P-25. The aim of this article was the identification of the intermediate products formed during the irradiation, to establish the degradation pathway of dicyclanil. The kinetics of the reactions were followed by liquid chromatography with a diode array detector (LC-DAD). Most of the organic compounds occurring during the photodegradation have been identified by means of liquid chromatography and mass spectrometry coupled techniques (HPLC-MS). Additional analyses were carried out to evaluate the mineralization rates into nitrate and ammonium ions.