Air segmented amplitude modulated multiplexed flow analysis with software-based phase recognition: Determination of phosphate ion

Ogusu, Takeshi; Uchimoto, Katsuya; Takeuchi, Masaki; Tanaka, Hideji

doi:10.1016/j.talanta.2013.10.001

Cited by 8 publications

(6 citation statements)

References 32 publications

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“…Figure 2 shows the principle of software-based deaeration by using real data, where 0.05 mol dm -3 HCl was titrated with 0.1 mol dm -3 NaOH containing 0.047 mmol dm -3 Bromothymol Blue (BTB). In the previous study, 30 air and liquid phases were rather easily identified because air bubbles gave steep peak-shaped Vd. Two kinds of threshold values, the deviation (DVd) of acquired Vd from the latest liquid Vd (T1) and the slope (dVd/dt) of the acquired Vd from the latest raw Vd (T2) were sufficient for the phase recognition.…”

Section: Principlementioning

confidence: 93%

“…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%

“…Both liquid and air phases were led to a detector without physical phase separation. 30 Instead, air signals were removed by a signal processing. Air-segmentation with software-based deaeration was effective for limiting axial dispersion and for the improvement in sensitivity.…”

Section: Introductionmentioning

confidence: 99%

“…In the present study, the concept of air-segmentation with software-based deaeration 30 was introduced to a flow ratiometry. After analytical parameters were optimized, the method was applied to titrations of various acids and bases including nonaqueous titration of the 17 th Japanese Pharmacopoeia drug.…”

Section: Introductionmentioning

confidence: 99%

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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: Principlementioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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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Energy‐Dispersive X‐Ray Fluorescence Spectrometric Determination of Phosphate in Water Samples via a 12‐Molybdophosphate–Crystal Violet Complex

Pytlakowska

2015

CLEAN Soil Air Water

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A simple and eco-friendly procedure for determining total phosphate content in water has been developed by combining a miniaturized ion-associated complex-based preconcentration method with energy-dispersive X-ray fluorescence spectrometry (EDXRF). The method is based on indirect determination of phosphorus using molybdenum present in the ion-associated complex formed by 12-molybdophosphate and crystal violet. Since phosphorus is determined indirectly, via fluorescent radiation of molybdenum, the difficulties stemming from low fluorescence yield and low energy of phosphorus radiation can be successfully overcome. A good mole ratio of phosphorus to molybdenum (1:12) and a sensitive K a line of molybdenum make it possible to determine low phosphorus concentrations. Under optimized conditions, a good linearity (up to 2 mg mL À1 of phosphorus, r ¼ 0.9991), and a detection limit of 1.3 ng mL À1 were achieved. The total relative standard deviation (RSD) for EDXRF determination of phosphorus, following precipitation of the ion-associated complex and its dissolution in a microdrop of 1-hexanol was 2.6%. The enrichment factor was 167. The developed method was used to determine total phosphate content in surface waters. The reliability of the proposed methodology was tested with the use of samples spiked with a known concentration of the determined element and by comparative inductively coupled plasma-optical emission spectrometry. The recovery (in the range of 93.5-97%) was satisfactory and indicates usefulness of the developed procedure.

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Air segmented amplitude modulated multiplexed flow analysis with software-based phase recognition: Determination of phosphate ion

Cited by 8 publications

References 32 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

Energy‐Dispersive X‐Ray Fluorescence Spectrometric Determination of Phosphate in Water Samples via a 12‐Molybdophosphate–Crystal Violet Complex

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