Abstract
Penicillin G (PG) in milk is unsafe for human and is a big problem for the foods industry. Hence, the better analytical and eliminative techniques are demanded. We investigated a PG molecular imprinted polymer (MIP), which can sensitively detect and extract the PG from milk and other samples. The MIP synthesis involved a β-lactam antibiotics PG, methacrylic acid (MAA) and dimethyl formamide (DMF). Its properties were analyzed with Scatchard plot, which showed that there were two affinity sites of the PG polymer. The first equilibrium dissociation constant of the high-affinity binding sites Kd1 was 1.14 × 10−4 mol/L and the binding capacity Qmax1 was 46.01 µmol/g; the second equilibrium dissociation constant of the low-affinity binding sites Kd2 was 1.35 × 10−3 mol/L and the binding capacity Qmax2 was 72.55 µmol/g. Furthermore, two PG determination methods using the polymer were developed. The first was carried out quantitatively with a spectrophotometer and the detection limit was 1 ppm. The other one was the combination of the MIP particles with milk fermentation for PG analysis and the sensitivity was 10 ppb.
Acknowledgments
Authors would like to thanks the Ministry of Education, the Tianjin Municipal Science and Technology Commission (07ZHXHNC04500) and the Tianjin University of Science and Technology to support the work.
Notes
†co-second author.