Development of Flow Analysis Methods toward High Quality and Operability of Chemical Analysis

Abstract

Advancements in analytical quality and management have been achieved using flow chemical analysis (FCA) techniques such as FIA, SIA, computer-controlled FCA (CC-FCA) and other related techniques. Using FIA, sensitivity improvement has been achieved and lowering tedious, time-consuming and laborious tasks in analytical chemistry laboratories have been improved. In the approach with FIA using mainly absorptiometry and fluorometry, a number of new methods were proposed and applied to practical samples for the determination of trace amounts of boron, phosphorus, ionic surfactants, alcohol etc. based on newly developed coloration or fluorescence reactions. Further, on-line pretreatment/FIA methods were developed for highly sensitive and selective determination of trace analytes; for example, such devices as solvent extraction, gas-diffusion separation, chromatomembrane cell separation, membraneless separation and platinum-tubing reactor etc. were applied to real samples. To improve tedious, time-consuming and laborious manual-batch methods, automated methods for the separation/preconcentration procedures for metals were developed using a CC-FCA system, which consisted of glass-syringe pumps, port valves, switching valves, solenoid-type pumps and valves, and were controlled by lab-written programs (LabVIEW and Visual Basic). The controlling programs, LMpro version 1 – 6, were used for several kinds of CC-FCA systems, and are now operable with Windows 7-11. One of the most useful programs and CC-FCA systems is an auto-pretreatment system (Auto-Pret system) with a mini-column, which could be used for research on the collection/concentration behaviors of metal ions with newly synthesized chitosan-based chelating resins, followed by ICP-MS and -AES measurement. One of the interesting CC-FCA systems is SIEMA, which enables the measurement of one or more analytes using carrier(s) and reagent(s) streams in a similar manner to FIA techniques. Hyphenated systems of CC-FCAs and detectors could improve the sensitivity and automation in trace analyses; for example, the techniques of SIA/voltammetric analysis, Auto-Pret/ET-AAS, Auto-Pret/LEP etc. are very useful for sensitivity improvement. In absorptiometric measurements, multi-channel (3-, 4-, 5-) LED-light detectors were very useful for multi-analyte detection in CC-FCA techniques. In order to analyze flow signals, the analyzer, SpectroX Analyser, was prepared by the authors for analyzing flow signals obtained with multi-channel LED detectors.