Determination of a Small Amount of Biological Constituent by Use of Chemiluminescence. III. The Flow-injection Analysis of Protein by Direct Injection

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Abstract
A flow-injection analysis method of protein by direct injection has been established by use of the luminol-hydrogen peroxide luminescence system. The determination of protein is based on the measurement of the decreasing catalytic activity of copper(II) for the chemiluminescent reaction between luminol and hydrogen peroxide. The present flow-injection analysis in which a protein solution is directly injected is quite different from the previous one in which a protein solution is injected after having been previously allowed to react with copper(II) outside the flow-through system. The optimum conditions for the determination of protein were determined with regard to reagent concentration, flow rate, reaction time, and reaction temperature. The present method is simple, rapid, and applicable to the determination of 2×10−4–1×10−1 g dm−3 of protein with 40 ng of detection limit at a rate of about 30 samples per hour. The present method was also applied to the determination of the ratio of albumin to globulin in a sample. The present flow-injection system is expected to be a sensitive detector for the determination of small amounts of protein.