Midio A.F., Moreau R.L.M., Nakaharada N.M.

Toxicology-College of Pharmaceutical Sciences, University of S.Paulo, Av. Lineu Prestes, 580 - 05508-900, S.P. S.Paulo, Brazil

A sensitive and specific method for the quantification of sodium fluroacetate (SFA), also known as Compound 1080, present in biological samples (blood, gastric contents, food etc.) was developed using ion-exchange chromatographic technique for its isolation. SFA is a potent rodenticide, extremely toxic to all vertebrates including man. Human and vetrinary accidental poisonings as well as suicide attempts have been registered all over Brazil where formulations of the pesticide have been illegally commercialized.
The biological samples were homogenized with deionized water, filtered and transferred to a 185x5 mm glass column filled (6 cm) with a previously treated weakly basic ion-exchanger (Amberlite IR-4B-BDH). Fluoracetate was eluted with a saturated sodium chloride solution with a flow rate of 1 ml/min. An aliquot of the eluate was injected into a HPLC system using a 25 cm x 4.6 mm, 5 µm particle size reverse phase column (Supelcosil LC-NH₂). The remaining eluate was evaporated to dryness and 1 ml of 1.5% thiosalyicilic acid and two drops of 50% sodium hydroxide were added to the residue. The mixture was concentrated to a small volume and dried completely in an oven at 130° C overnight. The residue was first dissolved with 3 ml of deionized water and 1 ml of 2% ferricyanide solution was added. The appearance of a red color is indicative of the presence of fluoroacetate. This thioindigo dye formed was extracted with 10 ml of chloroform and read at 450 nm in a spectrophotometer for the quantitative measurement. The isolation of Compound 1080 from biological samples by ion-exchange has proved to provide good recoveries (>80%). In addition, the thioindigo reaction is specific for mono halogen acetic acids and is sensitive for 500 µg of fluoracetate in the sample.