Development of compact photometric titrator and absorptiometric detector for flow-injection analysis using light-emitting diode as light source

Abstract

Two colorimetric instruments, a photometric titrator and an absorptiometric detector for flow-injection analysis, were developed for experiments in under-graduate course. They were based on the colorimeter using a light-emitting diode (LED) as a light source. The photometric titrator had a holder for a 2-cm cell and a magnetic stirrer. This titrator was applied to titration of Cu(II) and Ca(II) with EDTA. Cu-ammine complex was produced and its absorbance was measured with a red LED (630 nm). The titration curve obtained by this titrator was better than the one obtained by a conventional titrator. Moreover, the volume of the sample and reagents were greatly reduced due to the built-in stirrer. On the other hands, the detector for FIA had a circuit to output flow-signal to a recorder. This detector was applied to the FIA determination of iron in an aluminum sample with 1,10-phenanthroline. Dual-wavelength measurements were performed to reduce the noise caused by peristaltic pumps. From the absorbance at the wavelength absorbed by iron(II) chelate (530 nm), background signal measured at 630 nm was subtracted. The obtained results were good agreement with those by atomic absorption spectrometry. Both instruments had small dimensions (125 x 90 x 60 mm) and were low power consumption. © 2005 The Japan Society for Analytical Chemistry.