title: A miniaturized fiber-optic colorimetric sensor for nitrite determination by coupling with a microfluidic capillary waveguide.
abstract: A microfluidic-capillary-waveguide-coupled fiber-optic sensor was developed for colorimetric determination of hazardous nitrite based on the Griess-Ilosvay reaction. The sensor was modularly designed by use of a light-emitting diode as the light source, silica fiber as the light transmission element, and a capillary waveguide tube as the light reaction flow cell. With the light interacting with the azo dye generated by the Griess-Ilosvay reaction between nitrite and Griess reagents, nitrite could be determined by a colorimetric method according to Beer's law. By use of the inexpensive and micro-sized elements mentioned above, the sensor provided a new low-cost and portable method for in situ and online measurement of nitrite. The sensor had a wide linear range for nitrite from 0.02 to 1.8 mg L(-1) and a low detection limit of 7 μg L(-1) (3σ), with a relative standard deviation of 0.37% (n = 10). With a low reagent demand of 200 μL, a short response time of 6.24 s, and excellent selectivity, the sensor is environmentally friendly and has been applied to nitrite determination in different water samples. The results were compared with those obtained by conventional spectrophotometry and ion chromatography, indicating the sensor's potential for practical applications.
authors.affiliation: State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan, 610500, China.|Oil and Gas Field Applied Chemistry Key Laboratory of Sichuan Province, Southwest Petroleum University, Chengdu, Sichuan, 610500, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Xiong
authors.affiliation: State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan, 610500, China.
authors.forename: Cheng-Jie
authors.initials: CJ
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan, 610500, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Tao
authors.affiliation: State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan, 610500, China. swpua124@126.com.|Oil and Gas Field Applied Chemistry Key Laboratory of Sichuan Province, Southwest Petroleum University, Chengdu, Sichuan, 610500, China. swpua124@126.com.
authors.forename: Ming
authors.initials: M
authors.lastname: Duan
authors.affiliation: State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan, 610500, China.
authors.forename: Shen-Wen
authors.initials: SW
authors.lastname: Fang
authors.affiliation: State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan, 610500, China.
authors.forename: Min
authors.initials: M
authors.lastname: Zheng
keywords: Fiber-optic colorimetric sensor; Griess–Ilosvay reaction; Microfluidic capillary waveguide; Nitrite determination