Microarray-Based Nanoextraction Combined with Ambient Ionization Mass Spectrometry for Analysis of Drugs of Abuse in Wastewater.

There is a significant need to simplify the analytical workflow for complex sample analysis. In particular, those innovations that are high-throughput, miniaturized, reliable, and more-resource conscientious are especially important. Given these considerations, a nanoextraction microarray composed of sessile microdroplets is herein proposed; this nanoextraction is achieved using a long-chain organic acid, namely, myristic acid, as the extractant. Different drugs of abuse (i.e., cocaine, fentanyl, methamphetamine, and oxycodone) in wastewater were used as the analyte:sample model. Under the optimized conditions (i.e., pH = 10, 23 nL of myristic acid as the extractant, and 20 min as the extraction time), the method was applied to a complex matrix (i.e., wastewater) as a proof-of-principle, giving limits of detection and preconcentration factors in the ranges of 0.194-0.871 μg/L and 2.1-9.9, respectively. The chemically green(er) organic acid extractant, high preconcentration factors, and throughput are advantages of the proposed method.