Acta Scientiarum Naturalium Universitatis Pekinensis

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On-line Monitoring of Dissolved Oxygen in Water by a Fiber-optic Chemical Sensor Based on Fluorescence Quenching

LI Wei,CHEN Xi,ZHUANG Zhixia,SUN Dahai,WANG Xiaoru   

  1. The Key Laboratory of Analytical Sciences of MOE and Department of Chemistry, Xiamen University, Xiamen, 361005
  • Received:2000-07-13 Online:2001-03-20 Published:2001-03-20



  1. 厦门大学化学化工学院现代分析科学教育部重点实验室,厦门,361005

Abstract: A novel circulatory system for on-line monitoring of dissolved oxygen that makes use of a fiber-optic chemical sensor is presented. An oxygen sensitive optode was combined with a membrane onto which was immobilized pyrenebutyric acid as a fluoroprobe, the membrane was composed of cellulose triacetate as a polymer and di-(2-ethyl hexyl)-o-phthalate as a plasticizer. The dissolved oxygen in water was determined via quenching of the fluorescence of pyrenebutyric acid. The optode shows a satisfactory linear response for the dissolved oxygen in water(r=0.9956, n=6). The relative standard deviations were 2.4%~6.1%. The detection limit was 0.03μg/mL(S/N=3). The exposure time and recovery time of the optode membrane are 5s and 25s respectively. The reversibility of the fluorescence signal was evaluated by alternate measurements in air saturated water and nitrogen-purged water. The relative standard deviation(n=6)were found to be 0.7%. The fluorescence intensity of the membrane in contact with flowing water was recorded over a period of 96h. From fluorescence intensity values taken every 4h(n=24)a RSD of 8% was obtained. After 3 month, the fluorescence signal of the membrane had decreased by 14%. The decrease may be due to washing out of fluoroprobe, but this was not an obstacle to its further use; the quantitative information(F0/F)did not change significantly, where F0 and F are the fluorescence intensities in the absence and in the presence of oxygen, respectively. The sensor has good reproducibility and long-term stability. The interference was investigated and the selectivity of method in seawater was affirmed by a conventional method.

Key words: fiber optic, chemical sensors, oxygen sensor, dissolved oxygen

摘要: 利用氧分子对芘丁酸的荧光具有猝灭作用的特性,构造出基于荧光猝灭原理的光纤氧化学传感器。就用于水中溶解氧在线监测的光纤光谱仪的搭建、传感探头的设计及传感膜的制作进行了探索,并对传感器的响应性能进行了考察。结果表明以三醋酸纤维素为固相支持剂、邻苯二甲酸二辛酯为增塑稳定剂、芘丁酸为分析物识别器制备的传感膜对溶解氧的响应具有良好的可逆性,稳定性,较快的响应时间和较长的使用寿命。与标准法相对照,用本仪器系统测定了不同盐度的人工海水中的溶解氧浓度,两种方法在不同浓度水平下的溶解氧测定值均无显著性差异。本法的日内和日间RSD在2.4%~6.1%之间。

关键词: 光导纤维, 化学传感器, 氧传感器, 溶解氧

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