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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 25, Number 6
BKCSDE 25(6)
June 20, 2004 
 
Title
 Amperometric Detection of Hydroquinone and Homogentisic Acid with Laccase Immobilized Platinum Electrode
Author
 De Quan*, Woonsup Shin*
Keywords
 Laccase, Amperometric biosensor, Hydroquinone, Homogentisic acid, Substrate recycling
Abstract
 DeniLiteTM laccase immobilized platinum electrode was used for amperometric detection of hydroquinone (HQ) and homogentisic acid (HGA) by means of substrate recycling. In case of HQ, the obtained sensitivity is 280 nA/ μM with linear range of 0.2-35 μM (r2 = 0.998) and detection limit (S/N = 3) of 50 nM. This high sensitivity can be attributed to chemical amplification due to the cycling of the substrate caused by enzymatic oxidation and following electrochemical regeneration. In case of HGA, the obtained sensitivity is 53 nA/ μM with linear range of 1-50 μM (r2 = 0.999) and detection limit of 0.3 μM. The response times (t90%) are about 2 seconds for the two substrates and the long-term stability is 60 days for HQ and around 40-50 days for HGA with retaining 80% of initial activities. The very fast response and the durable long-term stability are the principal advantages of this sensor. pH studies show that optimal pH of the sensor for HQ is 6.0 and that for HGA is 4.5-5.0. This shift of optimal pH towards acidic range for HGA can be attributed to the balance between enzyme activity and accessibility of the substrate to the active site of the enzyme.
Page
 833 - 837
Full Text
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