The determination of plant growth regulators is of great importance for the quality monitoring of crops. In this work, 4-bromophenoxyacetic acid (4-BPA), one of the phenoxyacetic acids, was detected via the electrochemical method for the first time. A CeO2-decorated electrochemical exfoliated graphene (eGr) composite (CeO2/eGr) was constructed as the sensor for sensitive detection of 4-BPA due to the synergistic effect of the excellent catalytic active sites of CeO2 and good electron transference of the eGr. The developed CeO2/eGr sensor displayed a good linearity in a wide range from 0.3 to 150 μmol/L and the lowest detection limit of 0.06 μmol/L for 4-BPA detection. Electrochemical oxidation of 4-BPA follows a mix-controlled process on the CeO2/eGr electrode, which involves 2e in the transference process. This developed CeO2/eGr sensor has excellent repeatability with a relative standard deviation (RSD) of 2.35% in 10 continuous measurements. Moreover, the practical application of the sensor for 4-BPA detection in apple juice has recoveries in the range of 90-108%. This proposed CeO2/eGr sensor has great potential for detecting plant growth regulators in the agricultural industry.
Keywords: 4-bromophenoxyacetic acid; CeO2/eGr composite; electrochemical determination; lowest detection limit; plant growth regulators.