Detection of Pesticides in Complex Matrices Using QCM-Based Piezoelectric Immunosensors

Pesticide exposure through food and water is a significant concern in Mexico, where lax regulations have allowed the ongoing use of highly hazardous compounds such as carbaryl. Recognized by the EPA as a probable human carcinogen, carbaryl has been linked to neurological, liver, and reproductive harm. This study evaluates the performance of piezoelectric immunosensors based on quartz crystal microbalances (QCMs) for detecting carbaryl in real samples, including drinking water, fruit juice, and honey. A competitive immunoassay was conducted after immobilizing a BSA–carbaryl conjugate onto a self-assembled monolayer (SAM) activated with EDC/NHS and blocked with ethanolamine on the QCM gold surface. Measurements utilized a microfluidic system connected to a frequency QCM monitor (Q-1 device) from OpenQCM. For each sample type, optimal dilution factors were determined to minimize matrix interference while preserving sensitivity: 1:4 for water, 1:20 for juice, and 1:100 for honey. Results indicated frequency shifts similar to those observed in buffer, confirming the potential of QCM sensors as a quick and user-friendly tool for pesticide detection in food samples.