Abstract
The objectives of this study were to develop and validate a method for the simultaneous HPLC-UV determination of obidoxime (OBI), scopolamine (SCA), Atropine (ATR) and imipramine (I) in an aqueous antidote solution. An ion-pair mechanism with DAD (diode array detector) detection was used to quantitatively determine the four drugs. The proposed HPLC method uses a Kromasil 100-5C8 (250×4.6mm) column, gradient elution, at 25°C column temperature. The mobile phase consisted of 25% acetonitrile and 75% aqueous phase (5mM sodium 1-heptanesulfonate monohydrate, pH=3.5). The analyte detection was an UV detection at λ=230±4 nm, with reference λ=360± 8 nm. The calibration curve was linear between 1.3-152.5 μg/mL (r=0.9959, n=6) for OBI, between 0.13–13.75 μg/mL (r=0.9951, n=6) for SCA, between 0.25–25.5 μg/mL (r=0.9999, n=6) for ATR and between 0.58–50.80 μg/mL (r=0.9996, n=6) for I. In conclusion, this chromatographic assay fulfilled all the requirements for being a reliable and feasible method, including linearity accuracy, precision and stability. Keywords: HPLC-UV; organophosphate compounds; antidote.