| Summary: | 碩士 === 國立交通大學 === 應用化學系所 === 96 === Flow injection analysis (FIA) is an automatic analysis technology. The recorded signals of FIA often appear in asymmetric tailing peaks. A hypothesis of temporal effect is proposed to explain the tailing phenomenon recently. Because the spatial distribution of the sample in the flow channel changes with time, the recorded signal from a traditional single-channel detector is actually taking the accumulation result of the spatial profile variation of the sample in the channel. Accordingly, the recorded signal as a function of time is different from the true spatial distribution of the sample in the flow channel .
The spatial profiles of the sample in the flow channel are recorded as a function of time using a multi-channel detection system. Under two tube diameters (500μm and 750μm) and various linear flow rates (1.83~18.3 cm/s), apparent differences are observed by comparing peak shapes between the spatial and temporal profiles. Thus the temporal effect is confirmed. This effect is found to increase as the inner diameters of the tube and flow speed become larger. The sample zone expands more pronounced in the earlier stage after sample injection. Thus, tailing peaks are obtained due to the greater temporal effect. When the sample flows in the channel for a longer time; however, the expansion of the sample zone becomes steady. Gaussian peak profiles are thus recorded due to the negligible temporal effect.
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