Rapid Detection of Total Phytosterol Content in Cereals, Oils, and Foodstuff by Electrochemical Analysis

Abstract:

The electrochemical reaction process of plant sterols in a bare glassy carbon electrode was investigated to develop a new differential-pulse voltammetric method for rapid detection of phytosterols in cereals, oils, and other foodstuff. Cyclic voltammogram of phytosterols showed that the oxidation peak appeared at 1.72 V and no reduction peak was observed, which indicated that the electrode reaction process was irreversible. The electrochemical conditions were optimized for the detection of phytosterols. The results showed that the optimal conditions were: acetonitrile and 2-propanol (9:1,V/V) as organic solvent, 50 mmol/L LiClO4 as supporting electrolyte, pulse amplitude of 50 mV, potential increment of 3 mV, pulse width of 0.05 s, and pulse interval of 0.3 s. Under these optimized conditions, the calibration curves for determination of phytosterol demonstrated an excellent linear response within the range 160 to 800 μg/mL (r = 0.998), with the detection limit at 8.8 μg/mL (S/N = 3). The proposed method was successfully applied to the determination of phytosterol in corn germ oil deodorizer distillate and the recovery rate was 97.0% to 101.3%. The results indicate that the electrochemical analysis method is feasible for the detection of phytosterols in non-aqueous solvents, easy to perform, and does not require complicated pretreatment of samples.