The synthesis process of the sensor of WO3/Graphene sensor is as below: First, 20 mg of graphene oxide, which is typically synthesized, was added to a pre-prepared mixed solution of sodium tungstate in 50 mL of deionized water. Then 5mL HNO3 was added with stirring, and then sonicated for 15min. The suspension was sonicated at 50kHz in a 100W ultrasonic bath for 2 hours. Finally, WO3/Graphene nanocomposites were obtained by filtering and drying at 80°C for 12 hours. About 3 µL of WO3/Graphene nanomaterial dispersion solution (3mg/mL; ethanol/water; 50/50%) was dropped (3 times) on the pre-cleaned electrode surface. Finally, the WO3/Graphene modified electrode was dried at room temperature. In addition, the same products are used to manufacture control electrodes. Then, the modified electrode was applied to the electrochemical determination of PGT.Finally, the nanomaterial was characterized through the appropriate spectrophotometric techniques such as FESEM, HRTEM, XRD, XPS, EIS and electrochemical method.