Abstract − Analytical Sciences, 28(5), 523 (2012).
Simultaneous Determination of Nitrite and Nitrate Ions by Air-Segmented Amplitude-Modulated Multiplexed Flow Analysis
Haruka YOSHIDA,* Koji INUI,* Masaki TAKEUCHI,** and Hideji TANAKA**
*Faculty 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
**Institute of Health Biosciences, Tokushima University, 1-78-1 Shomachi, Tokushima 770-8505, Japan
The concept of amplitude-modulated multiplexed flow analysis has been extended to the simultaneous determination of multiple analytes in a sample. A sample solution containing nitrite and nitrate ions is delivered from two channels, but the flow rates are varied at different frequencies. One of the channels has a reduction column for converting nitrate ions to nitrite ions. Downstream, the absorbance of the diazo-coupling product is monitored after the merging of both solutions with a Griess reagent. The signal is analyzed by a fast Fourier transform (FFT) in real time. From the thus-obtained amplitude, a μmol dm−3 level of the ions can be determined. The introduction of air bubbles is effective to reduce any axial dispersion, and hence to improve the sensitivity.
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