A sensitive and selective imprinted solid phase extraction coupled to HPLC for simultaneous detection of trace quinoxaline-2-carboxylic acid and methyl-3-quinoxaline-2-carboxylic acid in animal muscles.

A new molecularly imprinted polymer (MIP), selective for major metabolites of quinoxaline-1,4-dioxides, was prepared through bulk polymerisation using quinoxaline-2-carboxylic acid (QCA) as template, diethylaminoethylmethacrylate as functional monomer and ethylene glycol dimethacrylate as cross-linker in tetrahydrofuran. The synthesised MIP was characterised by Fourier transform infrared and adsorption experiments. MIP exhibited high affinity, fast kinetics for QCA and good selectivity for QCA and methyl-3-quinoxaline-2-carboxylic acid (MQCA). MIP obtained was used as a selective sorbent for molecularly imprinted solid phase extraction (MISPE) coupled with HPLC to detect QCA and MQCA. Under the optimal conditions, the limits of detection (S/N=3) of porcine, chicken and fish muscles were 0.1, 0.3, 0.1 μg/kg for QCA and 0.2, 0.3, 0.1 μg/kg for MQCA, respectively and good recoveries were obtained in the range from 60.0 to 119.4%. These results indicated the MISPE-HPLC procedure could be successfully used for the determination QCA and MQCA in animal muscles.