Monitoring of the prohibited 2-phenethylamine in dietary supplements using a t-Butyl calix[8]arene/Ag/CuO composite-based potentiometric sensor

Abstract

2-phenethylamine (PEA) is a prohibited trace amine, that possesses amphetamine-like effect and toxicity. However, it is still present in many weight loss dietary supplements on which the quantities of PEA are not always listed. Therefore, monitoring of this toxic compound in these hypothetically safe products is essential. Herein, PEA was assayed using ion-selective potentiometric membrane sensors. A novel combination of silver doped copper oxide (Ag/CuO) nanoparticles with 4-tert-butylcalix[8]arene (BCX8) was investigated as a new ion-to-electron transducer layer used with solid contact glassy carbon electrodes. To study the effect of this novel combination, three sensors were proposed based on the incorporation of plain sodium tetraphenylborate (TPB) ion exchanger (sensor 1), TPB with BCX8 only (sensor 2) and TPB with Ag/CuO nanoparticles and BCX8 (sensor 3). The doped metal oxide nanoparticles were prepared using a simple wet co-precipitation synthesis procedure and were characterized for particle shape and size, elemental composition, and optical band gap energy. Near Nernstian responses were achieved with slope values of 52.28 ± 0.45, 54.64 ± 0.98 and 55.34 ± 0.35 mV/concentration decade and LOD of 9.88 × 10⁻⁵, 7.18 × 10⁻⁵, and 9.77 × 10⁻⁶ M for sensors 1, 2 and 3; respectively. Sensor 3 showed linearity range 1 × 10⁻⁵ to 1 × 10⁻² M and response time of 10 s. The Ag/CuO nanoparticles incorporated within BCX8 network provided improved electron transfer kinetics, and was found to provide the best sensitivity, widest linearity range and the most stable and fastest response among the compared sensors. The proposed sensors showed excellent percent recoveries when applied for the analysis of PEA in its multi-ingredient formulation and showed no statistical difference with the reported method.