Deep eutectic solvents incorporated in a polymeric film for organophosphorus pesticide microextraction from water samples

Background: Organophosphorus pesticides (OPPs) were extensively used in agriculture. Due to their adverse effect, there is a need for sensitive and reliable methods to determine these agrochemicals. Microextraction techniques (ME) afford the opportunity to substantially reduce the amount of organic solvent used in classical extraction methods for pesticide analysis. Moreover, deep eutectic solvents (DES) made of components of natural origin, have been applied in microextraction techniques as a green alternative to organic solvents. The combination of thin film microextraction and DES can be seen as an alternative for thin film microextraction of OPPs from water samples. Results: We describe a thin film microextraction-GC-MS method for the determination of OPPs from water samples. The thin film was prepared by solvent casting using cellulose triacetate (CTA) as the polymer and a deep eutectic solvent as the extracting phase. Lidocaine, menthol, dodecanoic acid, and camphor were tested as the components for DES-based film. With a film containing 70 % (w) of CTA and 30 % of the DES dodecanoic acid: lidocaine, quantitative results for the extraction of an OPPs mix were achieved. Then, the elution was performed with 2 mL of ethyl acetate. The validation of the TFME method was performed with a piece of the film suspended in 20 mL of sample solution with a contact time of 1 h. Limits of detection in the low mu g L-1 range were obtained using a single quadrupole mass analyser. The thin film with pipette tip configuration was tested and preliminary results for chlorpyrifos were satisfactory. Significance: This represents the first approach to use polymeric films made of CTA and DES for TFME of OPPs, in two configuration the suspended film and pipette tip.