Molecularly imprinted polymer with high-fidelity binding sites for the selective extraction of barbiturates from human urine

In this paper the authors describe the synthesis of a molecularly imprinted polymer (MIP) by pptn. polymn., with barbital as the template mol., and the application of the barbital MIP as a molecularly selective sorbent in the solid-phase extn. (SPE) of barbiturates from human urine samples. The MIP was synthesized by pptn. polymn. using 2,6-bis-acrylamidopyridine as the functional monomer and DVB-80 as the crosslinking agent. The spherical MIP particles produced were 4.2 μm in diam.; a non-imprinted control polymer (NIP) in bead form was 4.8 μm (mean ± std. deviation) in diam. The particles were packed into a solid-phase extn. cartridge and employed as a novel sorbent in a molecularly imprinted solid-phase extn. (MISPE) protocol. The MIP showed high selectivity for the template mol., barbital, a feature which can be ascribed to the high-fidelity binding sites present in the MIP which arose from the use of 2,6-bis-acrylamidopyridine as the functional monomer. However, the MIP also displayed useful cross-selectivity for other barbiturates besides barbital. For real samples, the MIP was applied for the extn. of four barbiturates from human urine. However, due to the high urea concn. in this sample which interfere the proper interaction of barbiturates onto the MIP, a tandem system using a com. available sorbent was developed.