Microextraction Tech

  A decade ago, our research group introduced the concept of effervescence-assisted microextraction. The first approach of this alternative consisted of a micrometric sorbent (OASIS-HLB) compressed in a tablet along with a carbon dioxide source (sodium carbonate) and a proton donor (sodium dihydrogen phosphate) [1] . The tablet is then placed on a syringe, and an aqueous sample is drawn. Once the sample enters in contact with the tablet, an effervescent reaction occurs, and the sorbent is efficiently dispersed by the CO 2 bubbles formed. Later, the technique was challenged with a difficult-to-disperse nanometric sorbent, unmodified multi-walled carbon nanotubes (MWCNTs) [2] . In this second adaptation, the nanotubes are compressed along with the effervescence precursors in a tablet format, and as occurs with many pharmaceutical applications, dropped in a glass containing a large aqueous sample volume (100 mL) and effervescent reaction takes place. The in-situ generated gas can dispers

  In our latest research, wooden toothpicks (WTs) coated with a commercial polyamide such as nylon-6 (N6) were used in a solid phase microextraction (SPME) procedure for the determination of methadone, cocaine, and methamphetamine in saliva. Bare WTs present weak hydrophilic and hydrophobic forces provided by cellulose and lignocellulose, respectively. Consequently, the N6 polymeric coating was used to reinforce the hydrogen bonds and hydrophobic forces with the target analytes. The synthesis of N6-WTs is based on the dip coating technique, where the superficial -OH groups provided by the (ligno)cellulosic components of wood allow the coating of the WTs. This simple dipping-and-drying process consists of the immersion of the WTs in a N6 precursor solution (3 % (w/v) in formic acid), followed by the evaporation of the solvent to anchor the thin polymeric phase to the surface of the WTs. The synthesized sorbents were characterized by attenuated total reflection infrared spectroscopy (A