HPLC-MS analysis of cypermethrin metabolites in fish bile as biomarker of exposure.

CARRIQUIRIBORDE, P; MARINO, D.; GIACHERO, G.; RONCO, A.E.

Montevideo, Uruguay,

Congreso; VIII Congreso SETAC Latinoamérica; 2007

SETAC Latinoamérica. Society of Environmental Toxicology and Chemistry Branch Latin-American

Cypermethrin is a pyrethroid insecticide broadly used in soybean crops of the pampas region. It is highly toxic to fish and aquatic organisms. Cypermethrin is mostly metabolized by the liver and excreted by the bile. In trout, metabolites could be 1000 fold bioconcentrated in the bile. Main metabolites found in exposed trout were 4’-hydroxy-cipermethrin-glucuronid (80%) and dichlorovinyldimethyl-cyclopropanecarboxylic-acid-glucuronid (7%). In those studies metabolites were determined by means of HPLC-UV and using radio-labeled standards. HPLC-MS is a powerful tool allowing separation and accurately identifying chemicals on the basis of their mass spectra, with potential applications for field samples. The present contribution is aiming to the assessment of HPLC-MS potentiality to detect cypermethrin metabolites in fish bile as a biormarker of exposure in feral organisms. A series of experiments were conducted using juveniles of pejerrey (Odontesthes bonariensis) as test organism. Fish (SL:69.02±1.60mm) were exposed to 0 (controls) or 5µg/L of technical grade cypermethrin during 24 h in La Plata tap water, dechlorinated and filtered through activated carbon. Bile samples were extracted in diethyl ether. HPLC was performed using a C18 column and acetonitrile-water (85:15). Mass analysis was performed using both APCI and API-ES ionization sources. Recovery in control bile spiked with cypermethrin was 93.9±2.3%. The best instrument detection limit for cypermethrin was 10µg/L with the API-ES in SIM positive mode (ion-432). Ions corresponding to single cipermethrine, 4’-hydroxy-cipermethrin or dichlorovinyldimethyl-cyclopropanecarboxylic-acid were not detectable. Further analyses are being conducted to identify the conjugated species. A discussion on the advantages of the method and potential uses is given at the stage of its present development.