Determination of bilirubin by adsorptive stripping voltammetry

Abstract A stripping method for the determination of bilirubin at the submicromolar and nanomolar concentration levels is described. The method is based on controlled adsorptive accumulation of bilirubin at the static mercury drop electrode followed by differential pulse measurement of the surface species. After 15 min preconcentration, a detection limit near 5 × 10 −10 M bilirubin is obtained. The adsorptive stripping response is evaluated with respect to concentration dependence, preconcentration time and potential, pH, ionic strength, the presence of surfactants and other variables. Best results are obtained using sodium acetate (pH 8.2) solution. A signal enhancement factor of 11 is observed using 5 min preconcentration (compared to the response of solution-phase voltammetry). The relative standard deviation at the 2 × 10 −7 M level is 2.7%.