An electronic nose in conjunction with an electrochemical molecularly imprinted polymer sensor for triclosan sensing in wastewater samples

In recent years, wastewater treatment plants (WWTPs) have been identified as important emitters of microparticles into aquatic systems. These include preservatives from cosmetic products, such as Triclosan (TCS). It is therefore desirable to develop simple and portable tools for wastewater analysis. In this context, this paper highlights TCS analysis in wastewater samples, using an electronic nose (e-nose) and a molecularly imprinted polymer (MIP) sensor. The wastewater samples are collected at the Kasba site (Meknes, Morocco). First, qualitative analysis was performed using the e-nose based on an array of 6 semi-conductors gas sensors. Wastewater samples spiked with TCS at different concentrations (0.1-1000 pg/mL) were exposed to the e-nose. As result, the conductances increase with increasing TCS concentrations. Thus, the e-nose could classify wastewater samples depending on their TCS concentrations. Furthermore, using radar plots, a clear variation between these samples spiked with different TCS concentrations was remarked. Second, an electrochemical sensor based on MIP was developed for the quantitative detection of TCS in order to validate the outcomes from e-nose. The electrochemical MIP sensor was fabricated by polymerizing polyacrylamide onto a screen-printed gold electrode (Au-SPE). Under optimal conditions, the MIP sensor exhibits proportional responses to TCS concentrations in the same range as the e-nose of 0.1-1000 pg/mL with a detection limit of 0.23 pg/mL. The MIP sensor was applied for TCS detection in the same wastewater samples as e-nose with the recovery rates in the range of 99-121 % demonstrating the excellent trueness and reliability of the developed sensor device. In the aim of correlating results from the e-nose and the MIP sensor, a partial least squares (PLS) prediction model was established with a regression correlation coefficient R = 0.98. Correspondingly, both electro-analytical devices could be viable tools for monitoring cosmetic product residues in wastewater matrices.