Polydimethylsiloxane Rods for the Passive Sampling of Pesticides in Surface Waters

Abstract

In this work, the low cost synthesis of polydimethylsiloxane (PDMS) rods is described, and the performances of this new passive sampling device (in laboratory and in situ) are compared to the passive stir bar sorptive extraction (SBSE) for the monitoring of pesticides from different classes (herbicides, insecticides and fungicides) in surface waters. The influence of synthesis parameters of PDMS rods (i.e., heating temperature, heating time and relative amount of curing agent) were assessed regarding their efficiency for the extraction of the target pesticides through a Hadamard's experimental design. This allowed the determination of the effect of the three parameters on the sorption of pesticides within four experiments. Thus, specific conditions were selected for the synthesis of the PDMS rods (heating at 80 °C for 2 h with 10% of curing agent). Laboratory experiments led to similar to lower extraction recovery in the PDMS rods in comparison with passive SBSE, depending on the pesticide. The in situ application demonstrated the efficiency of the PDMS rods for the passive sampling of the target pesticides in river water, although lower amounts of pesticides were recovered in comparison with passive SBSE. So, these very low cost PDMS rods could be used as an alternative to passive SBSE for large-scale monitoring campaigns.