Liquid-Phase Microextraction with a Silica Monolith

Researchers from Huazhong University of Science and Technology (Wuhan, China) and the National University of Singapore (Singapore) developed a liquid-phase microextraction method based on solvent-bar microextraction. They used a silica monolith as the extractant solvent holder and used polycyclic aromatic hydrocarbons as model analytes. In this system the silica monolith containing the extractant solvent was exposed to the sample, and analytes diffused directly into the extractant solvent. The researchers examined the effects of agitation speed, extraction time, monolith length, and salt concentration on the extraction. They applied the method to a spiked river water sample and obtained recoveries of 87.1–100.7%. When compared with polymeric hollow-fiber-based solvent-bar microextraction and hollow-fiber-protected liquid-phase microextraction, the silica monolith method reportedly provided better results. The researchers noted that the monolith can be used at high temperature and pH and is compatible with various organic solvents.