Gas-diffusion flow injection assay for the selective determination of chlorine dioxide based on the fluorescence quenching of chromotropic acid |
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Authors: | Demetrius G Themelis Fotini S Kika |
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Institution: | Laboratory of Analytical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece |
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Abstract: | The present work reports the first spectrofluorimetric gas-diffusion flow injection (GD-FI) assay for the determination of chlorine dioxide in water samples (tap, mineral and soda water). The method is based on the fluorescence quenching of chromotropic acid (CA) (λex. = 347 nm, λem. = 371 nm) caused by the analyte. The chemical and instrumental variables of the system were studied in terms of maximum sensitivity. The gas-diffusion cell was thermostated at 40 °C to enhance the vaporization of chlorine dioxide and thus the sensitivity of the method. The quenching effect of chlorine dioxide on CA was linear in the range 0.09-3.41 mg l− 1, while the precisions either close to the quantitation limit or near to the middle of the linear section of the calibration graph were satisfactory in both cases (sr = 2.6% and 1.5% (n = 10) at 0.17 and 1.71 mg l− 1 level, respectively). The developed method proved to be adequately selective and sensitive with 3σ limit of detection equal to cL = 0.03 mg l− 1. The application of the assay to spiked tap, mineral and soda water samples yielded accurate results with recovery values in the range 94.1-105.9%. |
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Keywords: | Gas-diffusion Flow injection Chlorine dioxide Fluorimetry Chromotropic acid Water |
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