Abstract
The process of the extraction and preconcentration of drugs is usually complicated, labour-intensive and time consuming. Therefore, the selection of an appropriate sample preparation procedure is a key factor in a successful sample analysis, while the whole analytical process can be wasted if an unsuitable sample preparation method is used. The aim of this work was to fabricate a material with the ability to preconcentrate drugs of abuse in biological fluids with a high extraction efficiency. This was achieved by the fabrication of a monolithic materials, followed by modification of the surface of the silica-based monolith with octyl groups, and then placing the octyl-hybrid silica monolithic disc inside a plastic syringe for the subsequent analysis. The fabricated materials were characterised using different techniques, such as SEM coupled with EDAX analysis and BET analysis. In this study, the isolation of non-steroidal anti-inflammatory drugs (NSAIDs), namely ketoprofen (KEP) and ibuprofen (IBP), was achieved using an octyl-hybrid silica monolith onto which the drugs were adsorbed on a solid support while any contaminants were removed by washing the monolithic materials; finally the purified drugs were eluted from the monolithic material. The results showed that the extraction efficiencies of the two NSAIDs were both more than 95%. Linearity (R-2, 0.9974-0.9978) was obtained in the range of 40-800 mu g mL(-1). The intra- and inter-monolithic columns indicated good monolith reproducibility, with relative standard deviations (RSDs) of less than 5.9% and 7.6%, respectively.