Detection of Phosphatidylcholine Content in Crude Oil with Bio-Enzyme Screen-Printed Electrode

A low-cost bio-enzyme screen-printed electrode (SPE) was produced by immobilizing choline oxidase (ChOx) and horseradish peroxidase (HRP) on an SPE with MWCNTs/SnO2/CS as modified material. The conditions of ChOx were as follows: concentration of 3 U, HRP concentration of 4 U, and pH 7.5. The bio-enzyme SPE had a significant electrochemical response to phosphatidylcholine (PC); the linear relationship between the peak current and PC content ranged from 30 to 270 mg/L, and the detection limit was 3 mg/L (S/N = 3). Bio-enzyme SPE was used to detect the content of PC in soybean crude oil. The spiked recovery of the samples ranged from 96.68 to 106.21%. The detection results obtained using high-performance liquid chromatography (HPLC) confirmed the results of the bio-enzyme SPE with a high correlation (r2 = 0.9978). After 45 days of storage of the bio-enzyme SPE, the current value remained 90% of initial current. The reproducibility and stability of the PC content detected by the bio-enzyme SPE in soybean crude oil exhibited a high performance.