Assay of the anti-psychotic drug haloperidol in bulk form, pharmaceutical formulation and biological fluids using square-wave adsorptive stripping voltammetry at a mercury electrode.

The cyclic voltammetric behavior of haloperidol at a hanging mercury drop electrode was studied in Britton-Robinson buffer series of pH 2.5-11 containing 40% (v/v) ethanol. A single two-electron irreversible cathodic peak was obtained which attributed to reduction of the CO double bond. In addition, a small enhanced adsorptive pre-wave was observed at less negative potentials over the pH range 3.5-11. Controlled adsorptive accumulation of haloperidol onto the hanging mercury drop electrode provided the basis for its direct trace assay in bulk form, pharmaceutical formulation and human biological fluids using square-wave adsorptive cathodic stripping voltammetry. Following preconcentration of bulk haloperidol onto the HMDE a well-developed square-wave cathodic peak was generated in Britton-Robinson buffer especially at pH values 9-10; its peak current showed a linear dependence on the concentration of haloperidol over the range 1 x 10(-9)M to 1.5 x 10(-6)M depending on the preconcentration duration. The procedural parameters for assay of haloperidol were studied. The achieved limits of detection (LOD) and quantitation (LOQ) were 3.83 x 10(-10)M and 1.28 x 10(-9)M bulk haloperidol, respectively. The procedure was successfully applied to assay haloperidol in tablets (Safinace) and in spiked human serum and urine. LOD of 3.3 x 10(-9)M and 5.46 x 10(-9)M, and LOQ of 1.10 x 10(-8) and 1.82 x 10(-8)M haloperidol were achieved in spiked human serum and urine samples, respectively.