Development of biosensor based on ionic liquid and corn peroxidase immobilized on chemically crosslinked chitin

Biosensors based on the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BMIPF6) were constructed in order to determine adrenaline in pharmaceuticals by square-wave voltammetry. In these biosensors Nujol was used as the binder and a corn (Zea Mays L.) homogenate as a source of peroxidase, which was immobilized in chitin chemically crosslinked with carbodiimide and glyoxal. In the presence of hydrogen peroxide, the peroxidase catalyzes the oxidation of adrenaline to the corresponding o-quinone, which is electrochemically reduced at a potential of −0.23 V vs. Ag/AgCl. The best analytical responses were obtained employing peroxidase (7.5 units mg−1 of carbon paste), BMIPF6:Nujol (50:50%, w/w) and 0.1 mol L−1 phosphate buffer solution (pH 7.0). The analytical curves were linear for adrenaline concentrations of 9.89 × 10−7 to 1.22 × 10−4 mol L−1. These biosensors demonstrated long-term stability and reproducibility with a relative standard deviation of 2.0%. The recovery of adrenaline in pharmaceutical samples ranged from 97.8 to 100.8% and the results obtained using the proposed biosensors are in agreement with those using the standard method.