Abstract

Improvement of double mediator system for BOD determination

Author(s): Hideaki Nakamura, Kyota Suzuki, Seisaku Okuma,Mitsutoshi Yataka,Yotaro Mogi, Isao Karube

Adouble-mediator (DM) system, which is coupled with ferricyanide and a lipophilicmediator,menadione, and the eukaryote Saccharomyces cerevisiae, for biochemical oxygen demand (BOD) estimation was improved. In this study, dimethyl sulfoxide was used as solvent of menadione, and optimum conditions for the BODDM determination were reexamined. Then, measuring time was shortened from15 to 10min, practical wide range with highly linearity of a calibration curve to glucose glutamic acid concentration was obtained between 5.5 to 220mgO2 L-1 (r=0.998, 6 points, n=3, average of relative standard deviation; R.S.D.av=3.62%), and detection limit was improved from 6.6 to 5.5mg O2 L-1. Under the conditions, stable responses were obtained at least for 10 days and real sample measurements using river water were performed.