Emmanuelle Cognard

Comprehensive fast multiresidue screening of 150 veterinary drugs in milk by ultra-performance liquid chromatography coupled to time of flight mass spectrometry ☆

This paper shows the use of ultra-performance liquid chromatography (UPLC) coupled to orthogonal acceleration time of flight mass spectrometry (TOF MS) for the comprehensive screening of 150 veterinary drugs residues in raw milk. An easy sample preparation based on protein precipitation associated with ultrafiltration was hyphenated to fast chromatography. This method enabled the screening for more than 50 samples per day and searched for 150 drugs and metabolites including avermectines, benzimidazoles, beta-agonists, beta-lactams, corticoides, macrolides, nitroimidazoles, quinolones, sulfonamides, tetracyclines and some others. Identification of contaminants is based on accurate mass measurement. UPLC-TOF also showed very good performances for quantitation and allowed the determination of majority of compounds below MRL. An in-house validation procedure was conducted based on European directive 2002/657/EC with measurement of response function, accuracy, repeatability, limits of detection (LOD), decision limit (CCalpha) and detection capability (CCbeta).

Aminoglycoside analysis in food of animal origin with a zwitterionic stationary phase and liquid chromatography–tandem mass spectrometry

In this study, fourteen highly polar aminoglycoside (AGs) antibiotics were selected. Various stationary phases were tested, including Obelisc R, ZIC-HILIC, BEH amide and aminopropyl. The nature of the stationary phase, mobile phase (water or buffer solutions and acetonitrile), pH (percentage of formic acid), gradient conditions and injection solvents were systematically studied as relevant parameters for tuning retention selectivity and detectability of AGs in liquid chromatography electrospray tandem mass spectrometry (LC-(ESI)-MS/MS). Only the two zwitterionic phases (Obelisc R and ZIC-HILIC) achieved a proper chromatographic separation considering interferences due to the crosstalk effect in low resolution mass spectrometers. The water/acetonitrile mobile phase containing 1% formic acid used with Obelisc R provided more sensitivity than the highly concentrated buffered mobile phases required for ZIC-HILIC. A solid phase extraction (SPE) clean-up procedure with polymeric weak cation exchange (WCX) cartridges was optimized for honey, milk and liver samples. Different brands of cartridges and elution solvents were tested, and the Taurus WCX offered the best recovery rate with a buffer elution at pH 3. The final optimized method was validated in these matrices according to Decision 2002/657/EC. A monitoring campaign for sixty honey, milk and liver samples was carried out at the Food Authority Control in Geneva. The concentration of dihydrostreptomycin (DSTP) found in one ovine liver exceeded the established maximum residue levels (MRLs) within the European and Swiss legislations but it was compliant taking into account the validation data.

Analysis of dihydroartemisinin in plasma by liquid chromatography—Mass spectrometry

SummaryArtemisinin (ART), or qinghaosu, a sesquiterpene lactone containing an endoperoxide bridge, is an efficient drug against chloroquine-resistant strains ofPlasmodium falciparum in the treatment of cerebral malaria. ART and its derivatives are rapidly metabolized into dihydroartemisinin (DHA), which is responsible for the antimalarial activity. After a simple liquid-liquid extraction (LLE), determination of DHA in plasma was conducted by liquid chromatography-mass spectrometry (LC-MS) with an electrospray ionization (ESI) interface. Addition of dodecylamine to the mobile phase and analysis in selected-ion monitoring (SIM) mode resulted in enhanced sensitivity and selectivity. Use of a primary amine, e.g. propylamine, pentylamine, hexylamine or dodecylamine, in the mobile phase can inhibit the formation of multimer clusters and ion adducts by forming one dominating species (analyte-primary amine adduct). Dodecylamine (DDA) was selected after several assays as a competitive agent for adduct formation. The procedure was validated and precision and accuracy were found to be good for the matrix studied. The method was applied to samples provided by patients receiving artesunate (ARS) for antimalarial treatment.

Determination of Nicotine and Its Major Metabolite Cotinine in Plasma or Serum by Gas Chromatography-Mass Spectrometry Using Ion-Trap Detection

Abstract A specific method has been developed for the quantitative determination of nicotine and its major metabolite cotinine in plasma or serum of active and passive smokers. Deuterium-labelled nicotine and cotinine were used as internal standards. The amounts of nicotine and cotinine present in a sample of plasma or serum were extracted with a simple extraction procedure (liquid-liquid or solid-phase extraction). The extracts were analysed by gas chromatography coupled with mass spectrometry using ion-trap detection. The analysis was done in positive chemical ionisation with methanol as the liquid reagent. The method has been demonstrated to be linear up to 1000 μg/l. Limits of quantification for nicotine and cotinine are 10 and 5 μg/l, respectively with liquid-liquid extraction, and 1 μg/l for each of the compounds with solid-phase extraction. The present method has been applied to several real cases.

Comprehensive screening of veterinary drugs in honey by ultra-high-performance liquid chromatography coupled to mass spectrometry

In the context of multi-residue screening in honey, a complete methodology was developed for 200 veterinary drugs comprising a sample preparation step and an ultra-high-performance liquid chromatography (UHPLC) coupled to time-of-flight (TOF) mass spectrometry analysis. In addition, specific analytical strategies were developed for two compounds, streptomycin and chloramphenicol, using UHPLC and tandem mass spectrometry (MS/MS). Methodologies were then applied to real honey samples obtained from the Swiss market.

Control strategies against grey mould (Botrytis cinerea Pers.: Fr) and corresponding fungicide residues in grapes and wines

This study examines the most effective anti-Botrytis strategies leading to possible lower pesticides residues in wine. To provide wine growers with a number of high-quality solutions for protection against Botrytis for their vineyards while minimizing pesticide residues in the final product, various treatment approaches were tested. A total of 10 strategies with different specific fungicide treatments for controlling Botrytis cinerea were applied to grapes at different growing stages: flowering, bunch closure and colour change. The type of vine chosen was Gamay, as it is very sensitive to Botrytis cinerea. In each experimental plot, disease incidence and severity were assessed at harvest. In addition, pesticide residue analysis was carried out on grapes, musts and wines to monitor residue levels in each treatment and to follow changes at each stage of the wine-making process. A correlation was established between the efficiency of anti-Botrytis fungicide treatment and pesticide residues in wine. Several strategies using various fungicides showed good results in terms of treatment efficiency while minimizing pesticide residues in wine, thus providing interesting alternatives to limit the development of fungal resistance.