Alternative spectrophotometric method for standardization of chlorite aqueous solutions

Philippi, Marilia; Santos, Heldiane Souza dos; Martins, Aline O.; Azevedo, Carla M.N.; Pires, Marçal

doi:10.1016/j.aca.2006.12.053

Cited by 32 publications

(22 citation statements)

References 8 publications

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“…In Figure 8, the ferric resting enzyme is depicted in black, the first spectrum monitored 1 ms after mixing with chlorite (final concentrations either 200 or 1000 μM) is shown in cyan and the final spectrum, monitored after 20 or 60 s, in red. During very rapid degradation of 200 μM chlorite (ε 260nm = 155 M − 1 ·cm − 1 ) [49] at k obs of 8.7 s − 1 , wild-type NdCld loses Soret absorbance. This suggests haeme bleaching as reported previously (Figure 8) [25].…”

Section: Impact Of H-bond Disruption On Chlorite Degradation and Enzymentioning

confidence: 99%

From chlorite dismutase towards HemQ–the role of the proximal H-bonding network in haeme binding

et al. 2016

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SynopsisChlorite dismutase (Cld) and HemQ are structurally and phylogenetically closely related haeme enzymes differing fundamentally in their enzymatic properties. Clds are able to convert chlorite into chloride and dioxygen, whereas HemQ is proposed to be involved in the haeme b synthesis of Gram-positive bacteria. A striking difference between these protein families concerns the proximal haeme cavity architecture. The pronounced H-bonding network in Cld, which includes the proximal ligand histidine and fully conserved glutamate and lysine residues, is missing in HemQ. In order to understand the functional consequences of this clearly evident difference, specific hydrogen bonds in Cld from 'Candidatus Nitrospira defluvii' (NdCld) were disrupted by mutagenesis. The resulting variants (E210A and K141E) were analysed by a broad set of spectroscopic (UV-vis, EPR and resonance Raman), calorimetric and kinetic methods. It is demonstrated that the haeme cavity architecture in these protein families is very susceptible to modification at the proximal site. The observed consequences of such structural variations include a significant decrease in thermal stability and also affinity between haeme b and the protein, a partial collapse of the distal cavity accompanied by an increased percentage of low-spin state for the E210A variant, lowered enzymatic activity concomitant with higher susceptibility to self-inactivation. The high-spin (HS) ligand fluoride is shown to exhibit a stabilizing effect and partially restore wild-type Cld structure and function. The data are discussed with respect to known structure-function relationships of Clds and the proposed function of HemQ as a coprohaeme decarboxylase in the last step of haeme biosynthesis in Firmicutes and Actinobacteria.

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Section: Impact Of H-bond Disruption On Chlorite Degradation and Enzymentioning

confidence: 99%

From chlorite dismutase towards HemQ–the role of the proximal H-bonding network in haeme binding

et al. 2016

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“…It is currently believed that the most accurate and reliable method for measuring ClO 2 gas concentrations is to trap ClO 2 gas in KI solution and then to measure ClO 2 -ions using ion chromatography [27] . However, this method cannot be easily used to measure the gas concentrations of actual living rooms for longer periods of time.…”

Section: Discussionmentioning

confidence: 99%

“…Pharmacology 2017;99:114-120 DOI: 10.1159/000452339 117 and titrating it using Na 2 S 2 O 3 is a reliable method for measuring the amount of ClO 2 [27] . In fact, we collected almost 100% of the ClO 2 gas as ClO 2 -using the KI solution ( fig.…”

Section: Disinfection Of Room Air Using Clo 2 Gasmentioning

confidence: 99%

Generation and Measurement of Chlorine Dioxide Gas at Extremely Low Concentrations in a Living Room: Implications for Preventing Airborne Microbial Infectious Diseases

Ogata

Sogawa²,

Takigawa³

et al. 2016

Pharmacology

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Background/Aims: Preventing respiratory diseases caused by airborne microbes in enclosed spaces is still not satisfactorily controlled. At extremely low concentrations (about 30 parts per billion), chlorine dioxide (ClO₂) gas can inactivate airborne microbes and prevent respiratory disease. It has no toxic effect on animals at this level. However, controversies still remain regarding how to measure concentrations of ClO₂ gas at such low levels. It is therefore necessary to prove that measured gas concentrations are accurate and reproducible. Methods: ClO₂ gas was released from a gas generator and its concentration was measured by a novel highly sensitive gas analyzer. We compared its data with those from ion chromatography. Results: We demonstrate that the gas concentrations measured in a room using the gas analyzer are accurate and reproducible after comparing the results with those from ion chromatography. However, the temperature dependence of the gas analyzer was found. Therefore, data correction is required for each temperature at which gas concentration is measured. A theoretical analysis of the gas concentrations predicted by the rate of ClO₂ gas released from the ClO₂ generator was also performed. Conclusion: Our results advance progress toward using low concentration ClO₂ gas to prevent airborne infectious diseases such as influenza.

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“…Traditionally, chloride ions have been determined by argentometry, however this method suffers from long experimental times and poor selectivity. Other techniques have been developed for chloride quantification: chromatography [1,2], spectroscopy [3,4], voltammetry [5] and turbidimetry [6]. Even when these techniques are accurate and precise, their operation, maintenance and possible miniaturization are very expensive.…”

Section: Introductionmentioning

confidence: 99%

Development of a Chloride Ion‐Selective Solid State Sensor Based on Doped Polypyrrole‐Graphite‐Epoxy Composite

et al. 2010

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This paper reports the development and characterization of a solid state potentiometric sensor for chloride ions, based on doped polypyrrole-graphite-epoxy composite. The optimum mixture proportion found for polypyrrole:graphite was 60 : 40 meanwhile a 50 : 50 proportion was used for the polypyrrol þ graphite:epoxy mixture. The stabilization time was approximately 16 min, while the response times varied within 2 and 23 s. The sensor displayed a sensitivity of 58 mV/decade [Cl À ], and 3 Â 10 À6 M detection limit. The selectivity coefficients showed a greater selectivity to that reported for commercial-type sensors. The statistical analysis for chlorides determination in commercial saline serums did not show significant differences respect to data reported by the manufacturers.

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Alternative spectrophotometric method for standardization of chlorite aqueous solutions

Cited by 32 publications

References 8 publications

From chlorite dismutase towards HemQ–the role of the proximal H-bonding network in haeme binding

From chlorite dismutase towards HemQ–the role of the proximal H-bonding network in haeme binding

Generation and Measurement of Chlorine Dioxide Gas at Extremely Low Concentrations in a Living Room: Implications for Preventing Airborne Microbial Infectious Diseases

Development of a Chloride Ion‐Selective Solid State Sensor Based on Doped Polypyrrole‐Graphite‐Epoxy Composite

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