【Introduction】Liquid-liquid extraction techniques are widely used for concentration and separation in various fields, ranging from organic synthesis to biotechnology and nuclear energy. However, at the laboratory scale, glass-ware such as separatory funnels and centrifuge tubes are still commonly employed. We have focused on a method that simultaneously generates ionic liquids (ILs) in aqueous solutions while extracting chemicals1), and through this approach, we have identified the potential to develop a new device for concentration and separation that does not require shaking. We have attempted to design a disk using CAD and fabricate it using a 3D printer. The ILs generated have the advantage of not damaging resin-based extraction devices. In this study, we aimed to create a disk-shaped extraction device capable of processing multiple samples simultaneously.
【Experiments】We selected two combinations of cations and anions and compared the IL co-extraction method with the water-IL two-phase extraction method for the extraction of pigments in aqueous solutions, or bioactive substances such as cannabis metabolites and complexes, and investigated the extraction behavior of several substances. Next, using a disk created with a 3D printer, we mixed solutions from the cation solution reservoir and the sample solution reservoir within a centrifuge, then introduced a solution from the anion reservoir. We confirmed that IL was generated beyond the solubility product and retained in the IL reservoir due to centrifugal force. Brilliant green dye and cannabis metabolites were used as samples.
【Results and Discussion】
Using this method, it was confirmed that the sample was concentrated in the IL reservoir farthest from the center of the disk. Additionally, fractionation and quantification were possible during this process. One of the objectives is to impart the function of a spectrophotometric cell to the IL reservoir, enabling the measurement of chemicals before the disk stops rotating. Currently, a device with an extraction unit featuring 8 or 16 ports is under development.
To date, solvent extraction has been considered a labor-intensive and complicated process that requires shaking, making automation difficult. As a result, solid-phase extraction has become the primary method for bioanalysis requiring the processing of multiple samples (especially DNA extraction). However, since co-extraction does not require shaking, it is expected to mark a turning point in reevaluating the advantages of liquid-liquid extraction. Currently, this method has been successfully applied to metal complex extraction, forensic analysis of cannabis metabolites in human urine, phosphate ions in seawater, and DNA extraction.