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A SIMPLE HPLC METHOD FOR DETECTING CARBARYL AND 1-NAPHTHOL IN BIOLOGICAL TISSUES.
Citation:
GRAFF, J., C. SPIVEY, AND D. W. HERR. A SIMPLE HPLC METHOD FOR DETECTING CARBARYL AND 1-NAPHTHOL IN BIOLOGICAL TISSUES. Presented at Society of Toxicology, San Diego, CA, March 05 - 09, 2006.
Description:
Carbamates are a class of pesticide used in both agricultural and residential applications. A simple HPLC method for detecting Carb and its metabolite 1-naphthol (Naph) in tissues was developed to try to correlate tissue levels of carbaryl (Carb) (a prototypical carbamate) with cholinesterase inhibition and physiological effects. Rat brain and plasma, spiked with chlorpyrifos-methyl as an internal standard (CPF-CH3), were extracted using ethyl acetate, dried under N2, and reconstituted in 52.5/47.5 acetonitrile (ACN)/phosphate buffer. HPLC detection, using a photodiode array, was at 211 (Naph) and 221 (Carb) nm. Compounds were separated using a Nova-pak C18 60 4 m 3.9X150 mm column and guard column, and a mobile phase gradient from 95% pH 3 phosphate buffer/5%ACN to 100% ACN. Quantification was based on peak height ratio, with Carb, Naph and CPF-CH3 identified by both retention time and spectra. Recovery efficiencies in plasma averaged: Carb: 98.83%; Naph: 137.35%, and CPF-CH3: 103.68%. Recovery efficiencies in brain averaged: Carb: 95.54%, Naph: 118.09%, and CPF-CH3: 98.53%. The limits of detection (LODs) and limits of quantification (LOQs) were determined in tissue matrices, using 50 l HPLC injection volumes. The LODs were established using 3X signal-to-noise criteria. The LOQs were determined as the minimum concentrations back calculated from standard curves to within 10% the nominal value, with 10% variance after multiple injections. The LODs for both compounds were 0.02 ng/ l in plasma, and 0.01 ng/ l for in brain. The LOQs were 0.25 ng/ l for both compounds in plasma, and 0.20 ng/ l for Carb and 0.10 ng/ l for Naph in brain. Applying the method to samples from animals given different doses of carbaryl detected dose-related concentrations of compounds in brain and plasma. Use of the method on samples from animals dosed with carbaryl but sacrificed at different times detected time-related levels of compounds. This information will be useful in understanding the biological effects of carbamate pesticides. This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.