Simultaneous Determination of Nitrite and Nitrate Ions by Air-Segmented Amplitude-Modulated Multiplexed Flow Analysis

Yoshida, Haruka; Inui, Koji; Takeuchi, Masaki; Tanaka, Hideji

doi:10.2116/analsci.28.523

Cited by 8 publications

(3 citation statements)

References 12 publications

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“…To reduce axial dispersion in the conduit is also effective to acquire reliable results. In the previous studies, [28][29][30] we introduced air-segmentation approach 31,32 to amplitude modulated multiplexed flow analysis, 33 our original concept of flow analysis. Axial dispersion was limited within each liquid segment separated by air bubbles.…”

Section: Introductionmentioning

confidence: 99%

Introduction of Air-Segmentation Approach to Flow Titration by Feedback-based and Subsequent Fixed Triangular Wave-controlled Flow Ratiometry

et al. 2019

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Air-segmentation approach has been introduced to a feedback-based and subsequent fixed triangular wave-controlled flow ratiometry to suppress axial dispersion in flow titration. Flow rate of a base solution containing an indicator is linearly varied with a control signal Vc supplied from a computer. The solution is merged with an acid solution under constant total flow rate. Air is introduced to the merged solution in order to segment the solution with air bubbles. Both phases are led to a UV/Vis detector without phase separation. Air signals are removed by a signal processing. The effect of lag time between the merging of solutions upstream and the sensing of corresponding signal downstream is offset by feedback-based upward and downward Vc scans, and thus the Vc that gives the equivalence composition is determined. Subsequently, fixed triangular wave control is applied to narrower Vc range with higher scan rate to enhance the throughput rate (maximally 11.8 titrations/min). Air-segmentation has found to be effective to reduce axial dispersion and to preserve the titrand/titrant composition on their just being merged. Consequently, applicable range extended especially to lower titrand concentration. The proposed method has successfully been applied to various acid-base titrations including nonaqueous titration of the Japanese Pharmacopoeia drug.

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Section: Introductionmentioning

confidence: 99%

Introduction of Air-Segmentation Approach to Flow Titration by Feedback-based and Subsequent Fixed Triangular Wave-controlled Flow Ratiometry

et al. 2019

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“…The concentrations of analytes in the samples are simultaneously determined from the amplitudes of corresponding wave components. We have applied the concept to the determinations of food dyes, 1 ferrous ion, 1 chloride ion, 2 nitrite ion, 3 phosphate ion 3,4 and ammonium ion 5 in multiple samples, and to the simultaneous determinations of nitrite and nitrate ions 6 in a sample. AMMFA is less susceptible to baseline drift because the quantification is not based on the values of analytical signals, but on the amplitudes of analytical signals.…”

Section: Introductionmentioning

confidence: 99%

Internal Standard-Amplitude Modulated Multiplexed Flow Analysis

et al. 2017

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A new concept of flow analysis, internal standard-amplitude modulated multiplexed flow analysis, is proposed. A proof of concept was verified by applying it to the determination of ferrous ion (Fe 2+ ) by 1,10-phenanthroline (o-Phen) spectrophotometry. The flow rates of sample solutions containing Methylene Blue (MB) as an internal standard substance were sinusoidally varied at different frequencies. The solutions were merged with a color reagent (o-Phen) solution, while the total flow rate was held constant. Downstream, analytical signals were monitored at the maximum absorption wavelengths of Fe 2+ -o-Phen complex and of MB (510 and 644 nm, respectively). The signals were respectively analyzed by fast Fourier transform. The concentrations of the analytes in respective samples were simultaneously determined from the amplitudes of the corresponding wave components. The precision, linearity of the calibration curve, limit of detection and robustness against deliberate fluctuation in flow rate were greatly improved by introducing the internal standard method. Good recoveries of around 100% were obtained for Fe 2+ spiked into real water samples.

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“…The same holds true for analytical chemistry. While water has been used as one of the most important solvents, in which a number of analytical reactions occur, 3,4 positive uses of ice for analytical purpose have been few.…”

Section: Introductionmentioning

confidence: 99%

Design of Analytical Systems Based on Functionality of Doped Ice

Okada

2014

ANAL. SCI.

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43 IntroductionWater has received special attention from researchers in fundamental and practical sciences because it has various unique physicochemical properties, and is indispensable for sustaining terrestrial life.1,2 Although ice is also a material of scientific interest, much less attention has been paid to this solid material than to its liquid counterpart. The same holds true for analytical chemistry. While water has been used as one of the most important solvents, in which a number of analytical reactions occur, 3,4 positive uses of ice for analytical purpose have been few.It has been known that ice is involved in a number of environmental reactions and plays important roles e.g. in the circulation of some molecules of atmospheric importance, such as NO, NO2, and HONO. 5 Ice also adsorbs compounds, such as HCl, and facilitates their reactions on its surface. 6 These roles of ice in the global environment have led to ideas that novel analytical systems can be designed utilizing the chemical properties and functionality of ice. We first developed ice chromatography, in which ice is used as a chromatographic stationary phase.7-10 Various compounds can be separated by this method though there is a limitation in its separation capability. The optical properties of ice are also remarkable; it is transparent over a wide wavelength range, from UV to visible region, and is a rare solid material that has a lower refractive index than do usual liquids. We utilized this useful optical property of ice to fabricate a liquid-core ice-cladding optical waveguide. 11Not only pure ice but also ice involving some impurity is of analytical use. Salt is a common impurity found in natural ice. Such salt-doped ice can be prepared in the laboratory in such a simple way that an aqueous salt solution is frozen. The liquid water phase coexists with ice (WPI) at the temperature higher than the eutectic point of the system. Figure 1 shows a fluorescence micrograph of KCl-doped ice containing fluorescein to visualize the WPI. Interestingly, fluorescent spots are discretely distributed in the ice matrix, suggesting that liquid inclusions are isolated rather than interconnected. We have found that the number density of the liquid inclusions is constant and independent of the type of salt incorporated in ice and its concentration. Ice plays an important role for the circulations of some compounds in the global environment. Both the ice surface and the liquid phase developed in a frozen solution are involved in such reactions of the molecules of environmental importance. This leads to the idea that ice can be used to design novel analytical reaction systems. We devised ice chromatography, in which ice particles are used as the liquid chromatographic stationary phase, and have subsequently developed various analytical systems utilizing the functionality of ice. This review focuses our attention on the analytical facets of ice containing impurities such as salts; hereinafter, we call this "doped ice". The design of novel separation systems...

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Simultaneous Determination of Nitrite and Nitrate Ions by Air-Segmented Amplitude-Modulated Multiplexed Flow Analysis

Cited by 8 publications

References 12 publications

Introduction of Air-Segmentation Approach to Flow Titration by Feedback-based and Subsequent Fixed Triangular Wave-controlled Flow Ratiometry

Introduction of Air-Segmentation Approach to Flow Titration by Feedback-based and Subsequent Fixed Triangular Wave-controlled Flow Ratiometry

Internal Standard-Amplitude Modulated Multiplexed Flow Analysis

Design of Analytical Systems Based on Functionality of Doped Ice

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