title: Analysis of ochratoxin A in grapes, musts and wines by LC-MS/MS: first comparison of stable isotope dilution assay and diastereomeric dilution assay methods.
abstract: Ochratoxin A (OTA) exhibits potent nephrotoxic, carcinogenic and teratogenic effects and its maximum level in wines has been set to 2 μg L(-1) by regulation. Consequently, the analytical procedures for OTA determination in wines have to be both very sensitive and reliable. In this paper, we compared two quantification methods: the stable isotope dilution assay (SIDA) and the diastereomeric dilution assay (DIDA). For this purpose, non-natural analogues of OTA were synthesized: the labeled OTA (OTA-d4) as a diastereomeric mixture for the SIDA and one non-natural OTA's diastereomer (OTA-dia) for the DIDA. To quantify OTA in red grapes, musts or wines, the sample preparation was optimized using immunoaffinity column extraction and the analysis was performed by LC-MS/MS in Multiple Reaction Monitoring mode. A validation procedure in agreement with the International Organization of Vine and Wine recommendations was conducted. It appeared that SIDA quantification exhibited excellent sensitivity (LOD<1 ng L(-1)), accuracy (recovery=98%), repeatability (RSD<3%) and intermediate reproducibility (RSD<4%) compared to quantification by DIDA. Indeed, DIDA method did not provide satisfactory results demonstrating that immunoaffinity extraction is exclusively selective for the natural OTA and not for its diastereomer, which therefore cannot be considered as a good internal standard for this particular method.
authors.affiliation: Nyseos, 2 place Pierre Viala, Montpellier Cedex 1 34060, France. Electronic address: aurelie@nyseos.fr.
authors.forename: Aurélie
authors.initials: A
authors.lastname: Roland
authors.affiliation: Institut Français de la Vigne et du Vin, UMT Qualinnov, 2 place Pierre Viala, Montpellier Cedex 1 34060, France. Electronic address: pauline.bros@gmail.com.
authors.forename: Pauline
authors.initials: P
authors.lastname: Bros
authors.affiliation: Nyseos, 2 place Pierre Viala, Montpellier Cedex 1 34060, France; Institut des Biomolécules Max Mousseron, UMR-CNRS-5247, Universités Montpellier I and II, Place Eugène Bataillon, 34095 Montpellier, France. Electronic address: anais.bouisseau@gmail.com.
authors.forename: Anaïs
authors.initials: A
authors.lastname: Bouisseau
authors.affiliation: Institut des Biomolécules Max Mousseron, UMR-CNRS-5247, Universités Montpellier I and II, Place Eugène Bataillon, 34095 Montpellier, France. Electronic address: florine@univ-montp2.fr.
authors.forename: Florine
authors.initials: F
authors.lastname: Cavelier
authors.affiliation: Institut Français de la Vigne et du Vin, UMT Qualinnov, 2 place Pierre Viala, Montpellier Cedex 1 34060, France. Electronic address: remi.schneider@vignevin.com.
authors.forename: Rémi
authors.initials: R
authors.lastname: Schneider
mesh_terms: D002623:Chemistry Techniques, Analytical / Q000379:methods*; D002851:Chromatography, High Pressure Liquid; D005506:Food Contamination / Q000032:analysis*; D007553:Isotope Labeling; D009793:Ochratoxins / Q000032:analysis*; D013237:Stereoisomerism; D053719:Tandem Mass Spectrometry; D027843:Vitis / Q000737:chemistry*; D014920:Wine / Q000032:analysis*
chemical_list: D009793:Ochratoxins; C025589:ochratoxin A
keywords: Diastereomeric dilution assay; Must; Ochratoxin A; Stable isotope dilution assay; Validation; Wine