Biosensor based on platinum nanoparticles dispersed in ionic liquid and laccase for determination of adrenaline

The platinum nanoparticles dispersed in ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (Pt-BMI.PF6) were used in the construction of a novel biosensor for the determination of adrenaline in pharmaceutical formulations by square-wave voltammetry. This biosensor was constructed based on laccase from Aspergillus oryzae and the responses under optimized conditions were obtained for a composition of 50:20:15:15% (w/w/w/w) graphite powder:laccase:Nujol:Pt-BMI.PF6, phosphate buffer solution (0.1 mol L−1, pH 6.5), with frequency, pulse amplitude, and scan increment at 20 Hz, 80 mV, and 5.0 mV, respectively. The analytical curve was linear for adrenaline concentrations from 9.99 × 10−7 to 2.13 × 10−4 mol L−1 (r = 0.9998) with a detection limit of 2.93 × 10−7 mol L−1. This biosensor demonstrated suitable stability (ca. 90 days; 300 determinations) and good repeatability and reproducibility, with a relative standard deviation of 3.7% and 4.8%, respectively. The recovery study of adrenaline in pharmaceutical samples gave values from 95.5% to 104.2% and the concentrations determined are in agreement with those using the standard method at the 95% confidence level.