title: A four-wavelength channel absorbance detector with a light emitting diode-fiber optics assembly for simplifying the flow-injection analysis system.
abstract: A four-channel absorbance detector was developed for simplifying the flow-injection analysis (FIA). This detector used four light-emitting-diodes (LEDs) as light sources; their wavelengths were 470, 495, 590 and 635 nm, respectively. Their amplitudes were modulated electronically with different frequencies. The light emissions from them were merged by plastic-core fiber optics, and were detected by a photo-diode (PD). The mixed signal was then sent to and discriminated by a four-channel lock-in amplifier corresponding to each modulation frequency. Neither a monochromator nor an optical filter was used. This detector was conveniently applied to the determination of iron in river water by FIA using 1,10-phenanthroline. Though a noisy peristaltic pump was used to propel the solutions, practical precision and accuracy were obtained by means of on-line dual-wavelength measurements and off-line moving average calculations.
authors.affiliation: Department of Applied Chemistry and Biotechnology, Faculty of Engineering, University of Yamanashi, 4-3-11, Takeda, Kofu, Yamanashi 400-8511, Japan. yamatori@ab11.yamanashi.ac.jp
authors.forename: Yasutada
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Hori
authors.forename: Masaaki
authors.initials: M
authors.lastname: Iwatsuki
authors.forename: Takeshi
authors.initials: T
authors.lastname: Yamane