Analytical Sciences

Carbon Felt-based Bioelectrocatalytic Flow Detectors: Highly Sensitive Amperometric Determination of Hydrogen Peroxide Using Adsorbed Peroxidase and Thionine

Yasushi HASEBE, Ryosuke IMAI, Masaki HIRONO, and Shunichi UCHIYAMA

Department of Applied Chemistry, Faculty of Engineering, Saitama Institute of Technology, 1690 Fusaiji, Fukaya, Saitama 369-0293, Japan

Horseradish peroxidase (HRP) and thionine (TN) were co-adsorbed onto a porous carbon felt (CF), and the resulting HRP and TN-adsorbed CF (HRP-TN-CF) was successfully used as a working electrode unit of a novel bioelectrocatalytic flow detector for a highly sensitive amperometric determination of hydrogen peroxide (H₂O₂). Co-adsorbed TN was essential to enhance the cathodic peak current of H₂O₂, and the current responses of the HRP-TN-CF-based detector were much larger than those of the HRP-CF-based detector (without TN). When air-saturated 0.1 M phosphate buffer (pH 7.0) was used as a carrier at a flow rate of 3.9 ml/min, cathodic peak currents of H₂O₂ (sample injection volume, 200 µl) obtained at an applied potential of 0 V (vs. Ag/AgCl) increased linearly up to 50 µM with a detection limit of 0.1 µM. Repetitive 100 sample injection of 100 µM H₂O₂ induced no serious current decrease, and RSD was 0.41 to 1.21% (n = 100). The HRP-TN-CF retained 42% of its original activity after 8 days of storage in 0.1 M phosphate buffer at 4°C.

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