Direct potentiometric determination of chloride ion in whole blood

Oka, Syotaro; Sibazaki, Yaichiro.; Tahara, Shu

doi:10.1021/ac00227a007

Cited by 82 publications

(44 citation statements)

References 44 publications

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“…There is experimental evidence from different papers that the addition of lipophilic ion of the same charge as the measuring ion to the sensing part of the electrode not only reduces the Ohmic resistance 23 and improves the response behavior and selectivity, 24 but also, in cases where the exchange capability of the ion-exchanger is poor, enhances the sensitivity of the electrode. 25 ISEs without ionic additives should be avoided, since otherwise inherent ionic impurities could have a decisive influence on the response characteristics.…”

Section: Optimizing the Lower Detection Limits Of The Electrodesmentioning

confidence: 99%

Modified Carbon Paste Sensor for Cetyltrimethylammonium Ion Based on Its Ion-associate with Tetrachloropalladate(II)

Ibrahim

Khorshid

2007

ANAL. SCI.

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Experimental ApparatusPotentiometric measurements in a batch mode were carried out at 25 ± 1˚C using a Jenway 3010 digital pH/mV meter with a surfactant-CMCPE sensor in conjunction with an Ag/AgCl reference electrode. A Techne circulator thermostat, Model C-100 (Cambridge, England), was used to control the temperature A comparative study was made between developed chemically modified carbon paste electrodes and PVC membrane electrodes for the cationic surfactant cetyltrimethylammonium bromide (CTAB). The carbon paste electrode modified with cetyltrimethylammonium-tetrachloropalladate(II) (CTA-TClP) provides a more sensitive and stable device than that shown by electrodes with an inner reference solution. The best performance was obtained by an electrode based on the paste containing 3.6 wt% CTA-TCIP, 1.8 wt% ethylhexadecyldimethylammonium bromide, 37.6 wt% graphite and 57 wt% tricresyl phosphate. The sensor exhibited a Nernstian response for CTAB over a wide concentration range of 3.5 × 10 -7 to 1.0 × 10 -3 M with a detection limit of 2.0 × 10 -7 M between pH 2.7 and 8.2 with a fast response time of ≤15 s. The electrode showed excellent selectivity for CTAB over a large number of ions. Interferences caused by common cationic surfactants have been investigated in simulated mixtures containing high concentration levels of interfering surfactants, and the sensor was found to be tolerant against these compounds.

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Section: Optimizing the Lower Detection Limits Of The Electrodesmentioning

confidence: 99%

Modified Carbon Paste Sensor for Cetyltrimethylammonium Ion Based on Its Ion-associate with Tetrachloropalladate(II)

Ibrahim

Khorshid

2007

ANAL. SCI.

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“…Chloride is generally accepted to be its physiological substrate because it is present at high concentrations in plasma (100-140 mM) [8,9]. In contrast, iodide ( 1 µM), bromide (20-100 µM) and thiocyanate (20-120 µM) are present in relatively low concentrations [10,11].…”

Section: Introductionmentioning

confidence: 99%

Thiocyanate and chloride as competing substrates for myeloperoxidase

Dalen

Whitehouse

Winterbourn

et al. 1997

Biochemical Journal

384

293

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The neutrophil enzyme myeloperoxidase uses H2O2 to oxidize chloride, bromide, iodide and thiocyanate to their respective hypohalous acids. Chloride is considered to be the physiological substrate. However, a detailed kinetic study of its substrate preference has not been undertaken. Our aim was to establish whether myeloperoxidase oxidizes thiocyanate in the presence of chloride at physiological concentrations of these substrates. We determined this by measuring the rate of H2O2 loss in reactions catalysed by the enzyme at various concentrations of each substrate. The relative specificity constants for chloride, bromide and thiocyanate were 1:60:730 respectively, indicating that thiocyanate is by far the most favoured substrate for myeloperoxidase. In the presence of 100 mM chloride, myeloperoxidase catalysed the production of hypothiocyanite at concentrations of thiocyanate as low as 25 μM. With 100 μM thiocyanate, about 50% of the H2O2 present was converted into hypothiocyanite, and the rate of hypohalous acid production equalled the sum of the individual rates obtained when each of these anions was present alone. The rate of H2O2 loss catalysed by myeloperoxidase in the presence of 100 mM chloride doubled when 100 μM thiocyanate was added, and was maximal with 1 mM thiocyanate. This indicates that at plasma concentrations of thiocyanate and chloride, myeloperoxidase is far from saturated. We conclude that thiocyanate is a major physiological substrate of myeloperoxidase, regardless of where the enzyme acts. As a consequence, more consideration should be given to the oxidation products of thiocyanate and to the role they play in host defence and inflammation.

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“…14) However, Cl Ϫ has been assumed to be the physiological substrate for myeloperoxidase, since plasma concentrations of Cl Ϫ are high (100-140 mM), 15) in contrast to 39- 19) reported that 8-nitro-2Ј-deoxyguanosine was generated by the reaction of dG with the myeloperoxidase-H 2 O 2 -Cl Ϫ system in the presence of NO 2 Ϫ at plasma concentrations of Cl . Similarly, Henderson et al 20) reported the formation of 5-bromo-2Ј-deoxycytidine in the reaction of 2Ј-deoxycytidine (dC) with the myeloperoxidase-H 2 O 2 -Cl Ϫ system in the presence of Br .…”

mentioning

confidence: 99%

Modification by Fluoride, Bromide, Iodide, Thiocyanate and Nitrite Anions of Reaction of a Myeloperoxidase-H2O2-Cl- System with Nucleosides.

Suzuki

Ohshima

2003

CHEMICAL & PHARMACEUTICAL BULLETIN

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Hypochlorous acid (HOCl) is generated as an endogenous product of the respiratory burst in mammalian neutrophils by myeloperoxidase from hydrogen peroxide (H 2 O 2 ) and chloride (Cl Ϫ ).1) HOCl generated by myeloperoxidase is of central importance in immune surveillance and host defense mechanisms. However, it also has potential to harm normal tissue and contribute to inflammatory injury. Indeed, reagent HOCl and/or the myeloperoxidase-H 2 O 2 -Cl Ϫ system have been reported to react with nucleic acid bases to form various compounds. [2][3][4][5][6][7][8] We have examined the reaction of 2Ј-deoxyguanosine (dG) with reagent HOCl and/or the myeloperoxidase-H 2 O 2 -Cl Ϫ system and found that a diimino-imidazole nucleoside, an amino-imidazolone nucleoside, a spiroiminodihydantoin nucleoside and 8-chloro-2Ј-deoxyguanosine were generated. reported that 8-nitro-2Ј-deoxyguanosine was generated by the reaction of dG with the myeloperoxidase-H 2 O 2 -Cl Ϫ system in the presence of NO 2 Ϫ at plasma concentrations of Cl . These papers showed that NO 2 Ϫ and Br Ϫ were significant regents with respect to nucleoside damage caused by the myeloperoxidase-H 2 O 2 -Cl Ϫ system. However, in these studies and others of damage caused by myeloperoxidase, specific products and their yields were determined, but data for the whole reaction, i.e., for consumption of the target nucleosides, were extremely limited.In the present study, we investigated the reaction of a nucleoside mixture with the myeloperoxidase-H 2 O 2 -Cl Ϫ system in the presence of various anions including F , and the consumption of each nucleoside was determined by HPLC. Results and Discussion pH-Dependence of the Reaction of the Nucleoside Mixture with the Myeloperoxidase-H 2 O 2 -Cl؊ System A nucleoside mixture (dG, dC, 2Ј-deoxythymidine (dT) and 2Ј-deoxyadenosine (dA); 100 mM each) was incubated with 50 nM myeloperoxidase in 100 mM sodium phosphate buffers of different pH with 200 mM H 2 O 2 and 100 mM NaCl at 37°C for 30 min. The reaction was terminated by addition of Nacetylcysteine. The reaction mixture was analyzed by reversed-phase HPLC to determine the remaining concentration of each nucleoside. Figure 1 shows a plot of the concentrations of nucleosides versus pH. Consumption of nucleosides was observed under mildly acidic conditions. The myeloperoxidase-H 2 O 2 -Cl Ϫ system consumed nucleosides in the following order: dGϾdCϾ ϾdTϾdAÅ0. The optimal pH for consumption of nucleosides was 4.7. At pH 4.7, total consumption was 67.3 mM corresponding to 33.7% relative to H 2 O 2 added.It has been reported that dC reacts with a myeloperoxi-

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Direct potentiometric determination of chloride ion in whole blood

Cited by 82 publications

References 44 publications

Modified Carbon Paste Sensor for Cetyltrimethylammonium Ion Based on Its Ion-associate with Tetrachloropalladate(II)

Modified Carbon Paste Sensor for Cetyltrimethylammonium Ion Based on Its Ion-associate with Tetrachloropalladate(II)

Thiocyanate and chloride as competing substrates for myeloperoxidase

Modification by Fluoride, Bromide, Iodide, Thiocyanate and Nitrite Anions of Reaction of a Myeloperoxidase-H2O2-Cl- System with Nucleosides.

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