L'analyse environnementale des Hépatotoxines : La spectrométrie de masse en temps de vol couplée à la chromatographie liquide

Environmental analysis of hepatotoxins: time of flight mass spectrometry coupled with liquid chromatography

Anjou Recherche - Veolia Water, 1 Place de Turenne, 94417 Saint Maurice cedex, France

Résumé

Cette étude concerne l'analyse des hépatotoxines par chromatographie liquide couplée au spectromètre de masse en temps de vol. Le spectromètre de masse offre la spécificité nécessaire pour l'identification et la quantification des analytes grâce à des ions caractéristiques différents.

Une comparaison de la méthode développée avec les résultats obtenus grâce au test PP2A démontre également la complémentarité des 2 techniques.

Abstract

Blooms of algae are commonly observed in freshwater in several areas of the world. This is a serious water quality problem because many of the species as cyanobacteria are able to produce potent toxins.

The development of the Blue-green algae in eutrophic water wherever proper conditions for their growth are found (temperature, pH and mineral nutriments) open up the possibility of recreational areas or drinking water reservoirs contamination.

The most frequently reported toxins are hepatotoxins, classified as microcystins and nodularins. In 2001, French decree (n° 2001-1220) fixe at 1 µg/L the limit of drinking water quality for LR Microcystin, the most toxic substance.

The method commonly used to detect cyanobacterial hepatotoxins in water samples is Liquid Chromatography method coupled with Diode Array Detector. But confirmation by UV detection is always problematic in complex environmental matrix.

In our study we evaluated electrospray ionization coupled with a Time Of Flight analyzer (TOF) to determine their suitability for hepatotoxins group of algae toxins determination. The method involves SPE extraction of the analytes by C18 cartridges followed by separation and identification by LC with UV/TOF.

Coupled with LC Mass Spectrometry detection provides the necessary specificity for identification and quantification of compounds provided each has different characteristic ions with the same limit of quantification (0,1 µg/L) as UV detection. With time of flight mass spectrometer, it's able to provide extensive structural information which might allow the identification of unknown analytes at trace levels or interferences.

The comparison of this developed method with results obtained thank to PP-2A test show the complementarity of the 2 techniques. In fact, the comparison of the values obtained for some real samples can reveal an excessive quantification by PP-2A test.

So it become necessary to confirm positive results with the chromatographic method coupled with mass spectrometer.