Analytical Sciences

Air-Segmented Amplitude-Modulated Multiplexed Flow Analysis

Koji INUI,* Takeshi UEMURA,** Takeshi OGUSU,* Masaki TAKEUCHI,*** and Hideji TANAKA***

*Faculty of Pharmaceutical Sciences, Tokushima University, 1-78-1 Shomachi, Tokushima 770-8505, Japan
**Graduate School of Pharmaceutical Sciences, Tokushima University, 1-78-1 Shomachi, Tokushima 770-8505, Japan
***Institute of Health Biosciences, Tokushima University, 1-78-1 Shomachi, Tokushima 770-8505, Japan

Air-segmentation is applied to amplitude-modulated multiplexed flow analysis, which we proposed recently. Sample solutions, the flow rates of which are varied periodically, are merged with reagent and/or diluent solution. The merged stream is segmented by air-bubbles and, downstream, its absorbance is measured after deaeration. The analytes in the samples are quantified from the amplitudes of the respective wave components in the absorbance. The proposed method is applied to the determinations of a food dye, phosphate ions and nitrite ions. The air-segmentation is effective for limiting amplitude damping through the axial dispersion, resulting in an improvement in sensitivity. This effect is more pronounced at shorter control periods and longer flow path lengths.

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