Louise Urruty

Bio: Louise Urruty is an academic researcher from University of Bordeaux. The author has contributed to research in topics: Solid-phase microextraction & Solid phase extraction. The author has an hindex of 8, co-authored 10 publications receiving 337 citations.

Focused Microwave Assistance for Extracting Some Pesticide Residues from Strawberries into Water before Their Determination by SPME/HPLC/DAD

Abstract: A novel and simple method for the determination of some pesticide residues in strawberries using both focused microwave-assisted extraction (FMAE) and solid-phase micro extraction (SPME), coupled with high-performance liquid chromatography (HPLC), has been developed. The pesticides were first extracted from strawberries with water and the assistance of focused microwaves at 30 W for 7 min. Then, an aliquot of the resulting aqueous extract was subjected to SPME with a 60-μm thick poly(dimethylsiloxane)/divinylbenzene (PDMS/DVB) fiber for 45 min at room temperature, with the solution being stirred at 1000 rpm. The extracted pesticides on the SPME fiber were desorbed into the SPME/HPLC interface for quantitative analysis with a diode array detector (DAD). The whole sample pretreatment procedure before chromatographic analysis did not use any organic solvents or involve any blending or centrifugation steps. The five compounds (carbendazim, diethofencarb, azoxystrobine, napropamide, and bupirimate) were chosen...

Influence of ethanol on pesticide extraction in aqueous solutions by solid-phase microextraction.

Abstract: The new extraction method, so-called solid-phase microextraction (SPME), coupled with gas chromatography-mass spectroscopy (GC-MS), was examined for the determination of residues of insecticides and fungicides commonly used for vineyard protection Aqueous solutions containing between 0 and 15% ethanol were spiked with 12 selected compounds and diphenylamine at the level of 20 ppb (v/w), extracted onto a silica fiber coated with a 100-μm thickness of poly(dimethylsiloxane), and desorbed in the chromatograph injector The influence of ethanol on the partition equilibrium between the adsorbant and the liquid was studied for each product In several cases, equilibria were obtained, and the extracted amounts of pesticides were shown to be dependent on the nature of the molecule and on the ethanolic content of the solution In contrast, the time necessary to reach these equilibria was the same in the presence and absence of ethanol Additional experiments on natural wines spiked at the same level of concentrat

Solid phase microextraction of pesticide residues from strawberries.

Abstract: A new solid phase microextraction method for the determination of pesticide residues in strawberries for 16 commonly used compounds was described. The strawberries were crushed and centrifuged. An aliquot of the well agitated aqueous supernatant (4ml) was extracted with a fibre coated with polydimethylsiloxane (PDMS, 100 μm) for 45min at room temperature. Identification and quantification were achieved using a gas chromatography-mass spectrometry (GC-MS) system and selective ion monitoring (SIM). The method was tested for the following pesticides: carbofuran, diethofencarb, penconazole, hexaconazole, metalaxyl, folpet, bromopropylate, dichlofluanid, α-endosulfan, β-endosulfan, parathion ethyl, procymidone, iprodione, vinclozolin, myclobutanil and chlorothalonil. Limits of detection, repeatability and linearity for standard calibration in strawberries were obtained. Positive and negative effects of the matrix between the extracting solution of strawberries and water were observed. Stabilities of these comp...

Assessment of strawberry aroma through SPME/GC and ANN methods. Classification and discrimination of varieties.

Abstract: To provide an efficient and running analytical tool to strawberry plant breeders who have to characterize and compare the aromatic properties of new cultivars to those already known, a HS-SPME/GC-MS analysis method has been coupled with a statistical treatment method issued from the current development of artificial neuron networks (ANN), and more specifically, the unsupervised learning systems called Kohonen self-organizing maps (SOMs). So, 70 strawberry samples harvested at CIREF from 17 known varieties have been extracted by using a DVB/Carboxen/PDMS SPME fiber according to the headspace procedure, and then chromatographed. A panel of 23 characteristic aromatic constituents has been selected according to published results relative to strawberry aroma. The complex resulting matrix, collecting the relative abundance of the 23 selected constituents for each sample, has been input into the SOM software adapted and optimized from the Kohonen approach described by one of the authors. After a period of training, the self-organized system affords a map of virtual strawberries to which real samples are compared and plotted in the best matching unit (BMU) of the map. The efficiency for discriminating the real samples according to their variety is dependent on the number of units selected to define the map. In this case, a 24-unit map allowed the complete discrimination of the 17 selected varieties. Moreover, to test the validity of this approach, two additional samples were blind-analyzed and the results were computed according to the same procedure. At the end of this treatment, both samples were plotted into the same unit as those of the same variety used for training the map.

Stable isotope dilution analysis of wine fermentation products by HS-SPME-GC-MS.

Abstract: The aim of this study was to quantify, in a single analysis, 31 volatile fermentation-derived products that contribute to the aroma of red and white wine. We developed a multi-component method based on headspace solid-phase microextraction coupled with gas chromatography mass spectrometry (HS-SPME-GC-MS). The 31 volatile compounds analysed include ethyl esters, acetates, acids and alcohols. Although these compounds have a range of functional groups, chemical properties, volatilities, affinities for the SPME fibre, and are found in wine at various concentrations, the accuracy of the analysis was achieved with the use of polydeuterated internal standards for stable isotope dilution analyses (SIDA). Nine of the labelled standards were commercially available, while 22 were synthesised. The method was validated by a series of duplicate spiked standard additions to model, white and red wine matrices over the concentration range relevant for each compound in wine. This demonstrated that the appropriate use of SIDA helped to account for matrix effects, for instance potential sources of variation such as the relative response to the MS detector, ionic strength, ethanol content and pH of different wine matrices. The resultant calibration functions had correlation coefficients (R2) ranging from 0.995 to 1.000. Each compound could be quantified at levels below its aroma threshold in wine. Relative standard deviations were all <5%. The method was optimised for the best compromise (over the 31 compounds) of wine dilution factor, level of sodium chloride addition, SPME fibre, SPME temperature, SPME time, GC column and MS conditions. Confirmation of identity was achieved by retention time and peak shape, and measurement of at least three ions for each analyte and internal standard with the MS operating in selected ion monitoring mode to facilitate more precise quantitation with a high sampling rate. The method is a valuable research tool with many relevant applications. A novel method for the combined chiral separation and SIDA quantification of 2- and 3-methylbutanoic acid is also demonstrated.

A review of theoretical and practical aspects of solid‐phase microextraction in food analysis

Abstract: Summary Solid-phase microextraction (SPME) is a modern, solvent-free sample preparation technique, commonly used in trace analysis. This technique has been developed to combine sampling and sample preparation in one step. This paper reviews selected theoretical and practical aspects of the SPME method used for the isolation and preconcentration of impurities, food constituents, additives and flavour compounds in food samples. The main parameters affecting the extraction effectiveness are discussed and exemplified by selected chromatograms. The review is intended for readers who are either new to the field of SPME or its use in food analysis and many examples of its application for different food matrices are listed.

Methods of sample preparation for determination of pesticide residues in food matrices by chromatography-mass spectrometry-based techniques: a review.

Abstract: Much progress has been made in pesticide analysis over the past decade, during which time hyphenated techniques involving highly efficient separation and sensitive detection have become the techniques of choice. Among these, methods based on chromatographic separation with mass spectrometric detection have resulted in greater likelihood of identification and are acknowledged to be extremely useful and authoritative methods for determination of pesticide residues. Even with such powerful instrumental techniques, however, the risk of interference increases with the complexity of the matrix studied, so sample preparation before instrumental analysis is still mandatory in many applications, for example food analysis. This article summarizes the analytical characteristics of the different methods of sample-preparation for determination of pesticide residues in a variety of food matrices, and surveys their recent applications in combination with chromatographic mass spectrometric analysis. We discuss the advantages and the disadvantages of the different methods, address instrumental aspects, and summarize conclusions and perspectives for the future.