LIQUID CHROMATOGRAPHY ELECTROCHEMICAL DETECTION OF PHENOLS AT A POLY[NI-(PROTOPORPHYRIN IX)] CHEMICALLY-MODIFIED ELECTRODE/

Poly(Ni-(Protoporphyrin IX)) modified glassy carbon electrodes showed an enhanced response for the oxidation of different phenolic compounds (p-chlorophenol, p-nitrophenol and phenol). It can also suppress the oxidation of more polar substances such as ascorbic acid and potassium hexacyanoferrate(II). These substantial improvements in the sensitivi ty and selectivity of liquid chromatography with electrochemical detec tor (LCEC) for the determination of phenols can be obtained by using e lectrodes thus coated. The method gives a linear range up to 1.3 mu g ml(-1) and a detection limit of 13 ng ml(-1) for p-nitrophenol. The dy namic behaviour of the detector is evaluated with respect to the solut e concentration and flow rate. The surface coating is highly stable un der the hydrodynamic conditions prevailing in the flow cell.