十字型マイクロ流体デバイスを用いたマイクロ滴定法によるタハロア砂鉄の全鉄定量

抄録

A microfluidic titration method using a cross-type microchannel device was developed for to the determination of total iron in steel samples. The redox titration reaction proceeded within the microchannel, and the titration endpoint was determined based on the differential value of grayscale intensity derived from blue-channel image analysis. The reaction behavior was visualized in real time, enabling quantitative evaluation of concentration-dependent color changes. Optimization of the flow rate and observation point revealed that a flow rate of 0.05 mL min⁻¹ and a detection position 1.5 cm downstream from the junction yielded the highest sensitivity. The obtained calibration plot exhibited a semi-logarithmic relationship with iron concentration. When applied to the certified reference material JSS 831-2 Taharoa iron sand, the total iron concentration determined by the microfluidic method (46.9 ± 1.9 mM) was statistically indistinguishable from that obtained by the conventional volumetric analysis based on JIS M 8212 (45.49 ± 0.18 mM), as confirmed by a t-test. These results demonstrate that the proposed system achieves analytical accuracy comparable to traditional wet chemical methods, while eliminating subjective endpoint determination, reducing sample and reagent consumption, and enabling automated and reproducible operation. The results demonstrate the feasibility of integrating redox titration within a microchannel as a new approach to miniaturized, automated wet analysis. The microfluidic titration platform offers a promising approach for miniaturized, automated wet analysis and has potential for extension to other volumetric techniques such as chelatometric and acid–base titrations.