Tuning polymeric ionic liquid sorbent coatings for thin film microextraction to selectively isolate pesticides from cannabis matrix components

Description:
Analysis of cannabis components is challenging due to the complexity of the plant matrix. Commonly regulated pesticides for cannabis testing are found in low abundance (ppb levels) and span a wide range of polarities. For these reasons, extraction methods tend to be non-selective for these analytes of interest or require expensive detectors for analysis. Additionally, methods for extracting pesticides from cannabis often require homogenizing the sample in water. Due to the strong hydrogen bonding network of water, polar pesticides tend to have low recoveries from aqueous matrices. In this work, robust polymeric ionic liquid (PIL) sorbent coatings, consisting of polymerizable IL monomers and crosslinkers, were designed for direct-immersion thin film microextraction (DI-TFME). The TF blade bear a thin film of sorbent with a high surface area-to-volume ratio, which allows for rapid mass transfer kinetics and a larger mass of analytes to be preconcentrated within shorter amounts of time. Analytes that have preferential interactions with the sorbent coating exhibit higher partition coefficients. By making structural modifications to the PIL sorbent coatings, interactions between the sorbent film and pesticides can be tuned. Polar substituents, including hydroxyl, ether, and/or sulfonate groups, were incorporated into the final PIL chemical structure to capture pesticides from cannabis matrix components. Extraction of polar pesticides and cannabinoids was carried out in parallel and monitored using high-performance liquid chromatography with ultraviolet detection to develop an analyte-selective methodology. Conditions including sample pH, salt content, percentage of organic solvent, extraction temperature, extraction time, desorption time, desorption volume, and desorption solvent were all optimized. By calculating and monitoring partition coefficients for each analyte, trends pertaining to analyte functional groups and the overall extraction mechanism will be discussed.

Speaker: Victoria Zeger - Iowa State University