Determination of naringin in grapefruit juice by cathodic stripping differential pulse voltammetry at the hanging mercury drop electrode

A highly sensitive cathodic stripping voltammetric method for the determination of naringin is presented. It is based on the formation and accumulation of two naringin-mercury complexes at the electrode surface, followed by reduction of the surface species during a differential pulse voltammetric scan. The cathodic stripping responses at -0.25 V and -0.42 V, are evaluated with respect to various experimental conditions, such as composition and pH of the supporting electrolyte, naringin concentration, accumulation potential and preconcentration time. The new method is suitable for the determination of naringin concentrations between 0.1 mg l(-1) (1.72x10(-7) mol l(-1)) and 40 mg l(-1) (6.88x10(-5) mol l(-1)). A 3 sigma limit of detection of 32 mu g l(-1) (55 nmol l(-1)) can be reached. The relative standard deviation (r.s.d.) is <1.5%. Recovery experiments yielded a mean recovery of 97% (r.s.d.=4.1%). The application of the procedure to the selective determination of naringin in grapefruit juice is demonstrated. (C) 1998 Elsevier Science B.V.