Anodic adsorptive stripping voltammetric determination of the anesthetic drug: methohexital sodium

Methohexital (MS) determination is based on the formation of insoluble merc ury salt on a hanging mercury drop electrode after preaccumulation by adsor ption. This property was exploited in developing a highly sensitive strippi ng voltammetric procedure for the determination of the drug. The anodic cur rent of adsorbed compound is measured by linear sweep anodic stripping volt ammetry (LSASV), preceded by a period of preconcentration. The effect of va rious parameters such as supporting electrolyte composition, pH, initial po tential, scan rate, accumulation time and ionic strength are discussed to c haracterize the interfacial and redox behavior. The detection limit was fou nd to be 2 x 10(-7) M (56.8 ppb) with 180-s accumulation time. The interfer ence of some amino acids, ascorbic acid and some metal ions was investigate d. The application of this method was tested in the determination of methoh exital in spiked urine samples. The precision of the method is satisfactory with a relative standard deviation of 2.5%. (C) 1999 Elsevier Science B.V. All rights reserved.