Effects of the Cathode Current Density in the Karl Fischer Coulometric Titration Method

Katoh, Hiromasa; Fujimoto, Yuka; Kakuda, Masuko

doi:10.2116/analsci.8.575

Cited by 8 publications

(8 citation statements)

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“…At 30 mA/cm 2 , this figure dropped to about 75%. If the results reported by Katoh et al are extrapolated to low current densities, it can be concluded that only a very small fraction of the current leads to the formation of hydrogen. The analytical consequences of these findings were demonstrated by comparison of results obtained by pulse electrolysis (current larger than 1000 mA/cm 2 ) with those obtained with continuous electrolysis (i.e., current flowing in proportion to the polarizing voltage of the bipotentiometric indicating system).…”

mentioning

confidence: 97%

“…Katoh et al found that, for current densities above 1000 mA/cm 2 , this requirement is fulfilled 2 for a number of reagents containing 1 M sulfur dioxide and bases like diethanolamine, 1,3-di(4-pyridyl)propane, pyridine, and imidazole. According to this report, the most promising methanolic reagent was shown to be a mixture of 0.75 M diethanolamine and 0.75 M 1,3-di(4-pyridyl)propane. For such a reagent containing 1 M sulfur dioxide, the fraction of hydrogen generated at a current density of 100 mA/cm 2 (cathode surface 0.28 cm 2 ) was as high as 97%.…”

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confidence: 99%

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Diaphragm-Free Cell for Trace Determination of Water Based on the Karl Fischer Reaction Using Continuous Coulometric Titration

Cedergren

Jónsson

1997

Anal. Chem.

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A new type of diaphragm-free coulometric cell for continuous coulometric Karl Fischer titrations of water in the range 0.1-1000 μg is described. The relative standard deviation obtained for titrations of 1 μg amounts of water was typically 1%. The background due to diffusion of water from the air was normally in the range 0.3-0.9 μg of water min(-1) depending on environmental humidity. The variation in the background was normally ±0.01 μg min(-1). The construction makes it possible, at any time in a sequence of titrations, to renew the catholyte by means of a Teflon plunger inside the cathode compartment. In this way, the interference effects caused by oxidizable reduction products of methyl sulfite which are formed at the cathode can be controlled in a very simple way. These products are rapidly eliminated by means of a normal titration before a new titration starts. The need for this draining step differs depending on the type of reagent used. The coulometric titration system makes use of true potentiometric end-point detection, and this principle makes it possible to control the iodine level at the end-point at much lower levels as compared with commercial instrumentation. The analytical advantages gained by this option are demonstrated for the determination of water in ethylenediamine, a task which was found to be impossible when using end-point concentrations in the range (3-7) × 10(-5) M, which is typical for the bipotentiometric indicating system used in commercial instruments. Recovery rates in the range 100-102% were obtained and are shown to be dependent on the type of reagent used. The most accurate results were obtained for an imidazole-buffered methanolic reagent in which the concentration of sulfur dioxide was kept relatively low (0.10 M). The diaphragm-free cell described was shown to be compatible with all of the commercial reagents (designed for coulometry) investigated, including the well-known Hydranal products Coulomat A, AK, AG, AG-H, and AD.

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confidence: 97%

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confidence: 99%

Diaphragm-Free Cell for Trace Determination of Water Based on the Karl Fischer Reaction Using Continuous Coulometric Titration

Cedergren

Jónsson

1997

Anal. Chem.

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“…On the other hand, the amount of sulfur dioxide in reagents 2 and 3 (especially reagent 3) containing organic chlorine compounds slowly dropped. Based on this result, it was assumed that reactions (3) or (4) competed with the reducing reaction of sulfur dioxide and repressed it, and that the electrophoretic migration of sulfur dioxide to the anode was retarded due to the migration of the chloride ions produced in reactions (3) and (4).…”

Section: Resultsmentioning

confidence: 99%

Role of Carbon Tetrachloride in the Cathodic Reaction of Karl Fischer Coulometric Titration

Nakagawa¹,

Scholz²

1994

ANAL. SCI.

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“…Although KFCT is a direct method, the recovery of water is affected by the current density of electrolysis and any side reaction, such as the Bunsen reaction. 18,19 In the determination of water content of liquid and solid samples, the home-made water standard prepared by the gravimetry was used to calibrate KFCT to make the result traceable and accurate. 19,20 Up to now, there is no report on the calibration of KFCT for the determination of water content of a gas sample.…”

Section: Introductionmentioning

confidence: 99%

Determination of Water Content of Nitrogen Containing Hydrogen Sulfide by Karl Fischer Coulometric Titration

et al. 2019

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Measuring the water content in natural gas is important for safety; however, complex matrixes make the results inaccurate. Natural gas contains hydrogen sulfide (H2S), which react with iodine (I2), causing Karl Fischer coulometric titration (KFCT) to give higher results. The KFCT method for the determination of water content of nitrogen containing H2S was investigated. A chilled mirror hygrometer offered a reference water content to calibrate the KFCT. The interfering of H2S was reduced by subtracting I2 consumed by H2S according to the reaction mechanism of ISO 10101; however, the modified results remained higher. A possible reaction mechanism with a stoichiometry of H2S to I2 of 1:2.5 was proposed. The improved KFCT method had an error of water content no more than (3 + 2%•x) mg/kg (x, water content in mg/kg) and had the potential of online monitoring of natural gas.

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Effects of the Cathode Current Density in the Karl Fischer Coulometric Titration Method

Cited by 8 publications

References 1 publication

Diaphragm-Free Cell for Trace Determination of Water Based on the Karl Fischer Reaction Using Continuous Coulometric Titration

Diaphragm-Free Cell for Trace Determination of Water Based on the Karl Fischer Reaction Using Continuous Coulometric Titration

Role of Carbon Tetrachloride in the Cathodic Reaction of Karl Fischer Coulometric Titration

Determination of Water Content of Nitrogen Containing Hydrogen Sulfide by Karl Fischer Coulometric Titration

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