19 January 1989 A Fiber Optic Colorimeter For Liquid Phase Chromatography Of Aminoacids
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Liquid phase chromatography is a well known technique routinely used in analytical chemistry for assays and measurements of aminoacids 1,2. Basically, the solution is pumped at high pressure in a long capillary tube (the chromatographic column) to fraction out the constituents, is mixed to a suitable reactant (usually ninhydrine) so as to develop a spectral absorbance, and is finally analyzed in a flow cell by a colorimeter. With ninhydrine, the reaction product is DIDA (diketo-hydrindilidene-diketolhydrin diamine) which exhibits absorbance peaks at 440 nm (blue) and 570 nm (yellow) in a proportion dependent on the specific aminoacid (Fig. 1), while the amplitude of peaks is proportional to the aminoacid concentration in view of Lambert-Beer law. Besides the two measurement channels of absorbance, either of which or the sum of which is taken as the output signal, a third channel at the wavelength 690 nm at which DIDA is transparent (Ar = 0), is used internally as the reference to the first two. Thus, the colorimeter is actually a spectrophotometer with two fixed-wavelength channels, each referenced in wavelength. In this paper, we report on the design and engineering of a colorimeter aimed to medium/high performances, high reliability and low cost. Use of fiber optics as the beamsplitter of the optical channels is shown to give substantial advantages.
© (1989) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
S. Donati, S. Donati, T. Tambosso, T. Tambosso, } "A Fiber Optic Colorimeter For Liquid Phase Chromatography Of Aminoacids", Proc. SPIE 0990, Chemical, Biochemical, and Environmental Applications of Fibers, (19 January 1989); doi: 10.1117/12.959975; https://doi.org/10.1117/12.959975

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