Voltammetric behavior of strychnine, and its determination in Strychno nux-vomica seeds extract

The voltammetric behavior of strychnine has been studied with a pyrolytic graphite (PG) electrode. The redox process taking place at the PG electrode is discussed. The cyclic voltammetric response has also been evaluated with respect to various experimental conditions, such as scan rate, pH of the supporting electrolyte, strychnine concentrations and accumulation time. A highly sensitive voltammetric method for the determination of strychnine is consequently developed. The linear calibration is in the range of 1 x 10(-6) M - 1.1 x 10(-4) M, with the limit of detection (LOD) being 1 x 10(-8) M. The precision is excellent with a relative standard deviation (RSD) of 2.3%. The proposed cyclic voltammetric methodology has been applied to the determination of strychnine in the extract of Strychno nux-vomica seeds using the standard addition method. Consistent results have been obtained from both the electrochemical approach described here and the previously reported HPLC method.