• Clean Technology
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• v.28 no.1
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• pp.38-45
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• 2022

CuCl₂-loaded V₂O₅-WO₃/TiO₂ catalyst showed excellent activity in the catalytic oxidation of elemental mercury to oxidized mercury even under SCR condition in the presence of NH₃, which is well known to significantly inhibit the oxidation activity of elemental mercury by HCl. Moreover, it was confirmed that, when SO₂ was present in the reaction gas together with HCl, excellent elemental mercury oxidation activity was maintained even though CuCl₂ supported on the catalyst surface was converted to CuSO₄. This is thought to be because not only HCl but also the SO₄ component generated on the catalyst surface promotes the oxidation of elemental mercury. However, in the presence of SO₂, the total mercury balance before and after the catalytic reaction was not matched, especially as the concentration of SO₂ increased. In order to understand the cause of this, further studies are needed to investigate the effect of SO₂ in the SnCl₂ aqueous solution employed for mercury species analysis and the effect of sulfate ions generated on elemental mercury oxidation. It was confirmed that SO₂ also promotes NO_x removal activity, which is thought to be because the increase in acid sites by SO₄ generated on the catalyst surface by SO₂ facilitates NH₃ adsorption. The composition change and structure of the components present on the catalyst surface under various reaction conditions were measured by XRD and XRF. These measurement results were presented as a rational explanation for the results that SO₂ enhances the oxidation activity of elemental mercury and the NO_x removal activity in this catalyst system.

• Journal of Food Hygiene and Safety
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• v.37 no.2
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• pp.39-45
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• 2022

This study aimed to investigate the validation and modify the analytical method to determine quercetin-3-𝑜-gentiobioside and isoquercitrin in Abelmoschus esculentus L. Moench for the standardization of ingredients in development of functional health products. The analytical method was validated based on the ICH (International Conference for Harmonization) guidelines to verify the reliability and validity there of on the specificity, linearity, accuracy, precision, detection limit and quantification limit. For the HPLC analysis method, the peak retention time of the index component of the standard solution and the peak retention time of the index component of A. esculentus L. Moench powder sample were consistent with the spectra thereof, confirming the specificity. The calibration curves of quercetin-3-𝑜-gentiobioside and isoquercitrin showed a linearity with a near-one correlation coefficient (0.9999 and 0.9999), indicating the high suitability thereof for the analysis. A. esculentus L. Moench powder sample of a known concentration were prepared with low, medium, and high concentrations of standard substances and were calculated for the precision and accuracy. The precision of quercetin-3-𝑜-gentiobioside and isoquercitrin was confirmed for intra-day and daily. As a result, the intra-day precision was found to be 0.50-1.48% and 0.77-2.87%, and the daily precision to be 0.07-3.37% and 0.58-1.37%, implying an excellent precision at level below 5%. As a result of accuracy measurement, the intra-day accuracy of quercetin-3-𝑜-gentiobioside and isoquercitrin was found to be 104.87-109.64% and the daily accuracy thereof was found to be 106.85-109.06%, reflecting high level of accuracy. The detection limits of quercetin-3-𝑜-gentiobioside and isoquercitrin were 0.24 ㎍/mL and 0.16 ㎍/mL, respectively, whereas the quantitation limits were 0.71 ㎍/mL and 0.49 ㎍/mL, confirming that detection was valid at the low concentrations as well. From the analysis, the established analytical method was proven to be excellent with high level of results from the verification on the specificity, linearity, precision, accuracy, detection limit and quantitation limit thereof. In addition, as a result of analyzing the content of A. esculentus L. Moench powder samples using a validated analytical method, quercetin-3-𝑜-gentiobioside was analyzed to contain 1.49±0.01 mg/dry weight g, while isoquercitrin contained 1.39±0.01 mg/dry weight g. The study was conducted to verify that the simultaneous analysis on quercetin-3-𝑜-gentiobioside and isoquercitrin, the indicators of A. esculentus L. Moench, is a scientifically reliable and suitable analytical method.