ELSEVIER Analytica Chimica Acta 329 (1996) 127-l 34 ANALYTICA CHIMICA ACTA Highly sensitive chemiluminescence flow injection analysis system using microbial peroxidase and a photodiode detector Kenji Hayashi”, Satoshi Sasakib, Kazunori Ikebukurob, Isao Karubeb** zyxwvutsrqponm aNichirei Corporation, 6-19-20 Tsukiji, Chuo-ku, Tokyo 104, Japan bResearch Center for Advanced Science and Technology, University of Tokyo, 4-6-l Komaba, Megutv-ku, Tokyo 153, Japan Received 2 October 1995; revised 23 February 1996; accepted 26 February 1996 zyxwvutsrqponmlkjihgfedcbaZY Abstract A highly sensitive chemiluminescence flow injection analysis system (CL-FIA) was developed using an Si-photodiode as a detector. The CL-FIA system with peroxidase from Artheromyces rmnosus (ARP) showed a higher chemiluminescence intensity than that with the enhanced chemiluminescence of horse radish peroxidase (HRP) and p-iodophenol. The optimum conditions for chemiluminescence using ARP were a carbonate buffer (pH 10.1) containing 17.5 PM luminol in the flow cell. The photocurrent of the photodiode was linearly related to the hydrogen peroxide concentration in a log-log plot from 3 nM to 10 FM under these optimum conditions. The RSD was estimated to be 3.2% for 1 pM of hydrogen peroxide, and the time for one analysis was less than 20 s. A CL-FTA system for hypoxanthine (Hx) measurement was also constructed with this CL-FIA system by addition of a bioreactor column of xanthine oxidase. With its compactness, ease of use, and sensitivity comparable with CL-FIA using a photomultiplier tube, this system has potential applicability for daily measurements in the industrial field. Keywortls: Photodiode; Chemiluminescence; Arthemmyces ramosus peroxidase; Flow injection; Hypoxanthine 1. Introduction Flow injection analysis (FIA) using the chemilu- minescence of luminol has been widely accepted as a sensitive method for determination of various biocomponents as well as H202 [l-3]. The chemilu- minescence (CL) reaction of luminol is Luminol + Hz02 Catalyst + Aminophthalate +Nz+HzO+hv. * Corresponding author. Tel.: 81-3-3481-4470; fax: 81-3-3481- 4581. Electrodes made of metals or carbons [4,5] also have been used as detectors in FIA systems for sensitive measurements of biocomponents. However, a CL-FIA system using luminol has some great advantages in its application to medical and food analyses, compared to such electrodes. One is selectivity, and another is sensitivity. For example, uric acid or ascorbic acid is usually studied as an interference compound in the measurement of bio- components using such electrodes as detectors. On the contrary, such compounds at low concentrations have no serious influence on the CL-FIA system using luminol [l]. 0003-2670/96/$15.00 Q 1996 Published by Elsevier Science B.V. All rights reserved J’II SOOO3-2670(96)00125-O