Development of miniature key devices for flow analysis and their applications

Abstract

Micro or miniature devices have been developed for flow analysis to obtain excellent performance. Some kinds of devices that we have developed are discussed in this paper. One of the advantages of miniaturization is a small reagent consumption and a field affordable size for "environmentally- friendly environmental analysis". The miniature device is better for not only the operational usefulness, but also for the performance of the instrument. For example, a perfect collection efficiency is obtained in an electrochemical detection system microfabricated in a thin-layered wall-jet cell, and incubation is not needed in an enzyme-immobilized capillary cell. A small heat capacity is necessary for thermal detection, and a high-performance thermal sensor for flow enthalpimetry has been developed using a small stainless steel capillary. A gas diffusion scrubber has also been miniaturized so as to be placed into a flow system. The small diffusion scrubber has a large surface-to-volume ratio so that the sample gas is highly accumulated into the absorbing solution. The solution volume of the diffusion scrubber is same as that of the sample loop of FIA-sample-injector, and the scrubber is suited for being combined with the conventional flow injection system. Near real-time measurements of atmospheric gases have been conducted with miniature gas diffusion scrubbers and flow injection systems. In addition, novel collection/detection cells were developed for measuring atmospheric gases in-situ in a cell using the stopped-flow method.