Final report on the key comparison CCQM-K48: Assay of potassium chloride

Liandi, Ma; Máriássy, Michal; Pratt, Kenneth W.

doi:10.1088/0026-1394/47/1a/08009

Cited by 4 publications

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“…The bromide assay was 0.00039 mol kg -1 ± 1.3% with coverage factor (k = 2), for a confidence level of 95%. 2 Then, the KCl purity after bromide correction (determined by Inmetro in this exercise) was 99.9787%, which is equivalent to an amount content of 13.41077 ± 0.0029 mol kg -1 , (k = 2) for a confidence level of 95%.…”

Section: International Comparison Ccqm-k48mentioning

confidence: 79%

“…2 The authors believe that even though the results were considered satisfactory by the organizers, they might be a little biased. The main source of bias is believed to be the presence of different chemical species of bromide in the salt.…”

Section: International Comparison Ccqm-k48mentioning

confidence: 95%

“…Another problem could be the co-precipitation/adsorption of the chloride ion on AgCl precipitated. 2 In order to avoid this problem, the dissolved KCl in water should be added gradually into the cell, instead of adding solid KCl sample at once into the coulometric cell. Table 6 shows the results of the candidate CRM that was assayed by coulometric titration, considering the bromide ion as the main impurity determined by ion chromatography.…”

Section: International Comparison Ccqm-k48mentioning

confidence: 99%

“…The mass fraction of the bromide ion in the KCl sample was 182.47 mg kg -1 with expanded Comparison results of the purity of KCl for CCQM-K48 with bromide correction. 2 The error bar means 2×u c (u c is the combined uncertainty). Vol.…”

Section: International Comparison Ccqm-k48mentioning

confidence: 99%

“…In addition, it is research foundation for pH, electrolytic conductivity and mono-element standard solutions. 2 Metrology in chemistry has been currently acknowledged as a relevant area in researches of analytical and measuring chemistry. Its importance comes from the need to produce reliable and uniform measurements in science, technology and international trade.…”

Section: Introductionmentioning

confidence: 99%

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Constant-current coulometry and ion chromatography bromide determination to characterize the purity of the potassium chloride

Borges

Sobral

Silva³

et al. 2011

J. Braz. Chem. Soc.

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A coulometria é considerada o método de maior qualidade metrológica para medição de quantidade de substância de padrões primários. Entretanto, a contaminação de sais de elevada pureza está presente em níveis traços sendo necessária a sua identificação e quantificação. Este trabalho apresenta os estudos desenvolvidos pelo Inmetro (Instituto Nacional de Metrologia, Normalização e Qualidade Industrial, Brasil) para determinar a pureza do cloreto de potássio (KCl) por titulação coulométrica a corrente constante, além da determinação do brometo como seu principal contaminante por cromatografia iônica (IC). Esses estudos foram necessários para desenvolver material de referência certificado (MRC) de KCl para garantir a qualidade dos resultados das medições químicas principalmente as de titulometria. A caracterização do candidato a MRC de KCl apresentou pureza de 99,9662%, a qual foi obtida após a correção do brometo, em fração mássica, obtido por IC, de 182,47 ± 3,03 mg kg -1 (incerteza expandida, k = 2, para um nível de confiança de aproximadamente de 95%).Coulometry is considered the highest metrological method for measuring the amount of substance of high-purity compounds. However, the contamination of the high purity salts is present in trace levels and its identification and quantification are necessary. This work aims to present the studies performed by Inmetro (National Institute of Metrology, Standardization and Industrial Quality, Brazil) to determine the purity of potassium chloride (KCl) by constant-current coulometric titration, as well as the determination of bromide as the main impurity in the KCl through ion chromatography (IC). These studies were needed to develop certified reference material (CRM) of KCl to guarantee the quality of the chemical measurements, mainly those performed by titrimetric analysis. The characterization of the candidate CRM of KCl by coulometric titration presented the purity of 99.9662%. This value was obtained after bromide correction of 182.47 ± 3.03 mg kg -1 (expanded uncertainty for k = 2, for a confidence level of approximately 95%) for the mass fraction bromide assayed by IC.

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Section: International Comparison Ccqm-k48mentioning

confidence: 79%

Section: International Comparison Ccqm-k48mentioning

confidence: 95%

Section: International Comparison Ccqm-k48mentioning

confidence: 99%

Section: International Comparison Ccqm-k48mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Constant-current coulometry and ion chromatography bromide determination to characterize the purity of the potassium chloride

Borges

Sobral

Silva³

et al. 2011

J. Braz. Chem. Soc.

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Metrological evaluation of the certification of primary reference materials characterized by high-precision constant-current coulometry for the reliability of the titration analyses

Borges

Silva

2014

J Appl Electrochem

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The use of pure materials in chemical analysis is currently in high demand due to the need to provide reliable measurement results. In the Electrochemistry Laboratory of the National Institute of Metrology from Brazil (Inmetro) is located the primary system of coulometry, which is considered the standard of the measurement for the amount of substance. The main function of this primary system is to certify primary reference materials to ensure reliability and metrological traceability for titration analyses. Some important certified reference materials (CRMs), homogeneous, stable, and characterized with an accurate property value have been developed. This work aims to present the stages for certifying the primary reference materials in a metrological approach: potassium hydrogen phthalate for acid-base titration, potassium chloride for precipitation titration, and potassium dichromate for redox titration. In addition, the key comparisons that were necessary to demonstrate the national traceability structure's equivalence for these CRMs' international recognition will be shown.

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Candidate primary reference measurement procedure for the amount-of-substance content of a complexing agent expressed as EDTA based on the coulometric titration with electrogenerated Hg ions

Hwang²

2022

Metrologia

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The primary reference measurement procedure is a method to realize the definition of the quantity without relation to a reference standard of the same quantity. This paper presents a candidate primary reference measurement procedure for the measurement of the amount-of-substance of a complexing agent expressed as ethylenediaminetetraacetic acid (EDTA) based on coulometric titration. Herein, mercury (Hg) was used as the anode because it does not undergo spontaneous oxidation. Furthermore, a 1:1 complex is formed between the electrogenerated Hg2+ ions and EDTA (in the form of Y4−). Although the electrochemical oxidation of Hg may generate Hg2 2+ ion, Hg2 2+ undergoes disproportionation in the presence of EDTA, thereby forming the desired Hg2+ species. The equivalence point occurs at the maximum of the derivative of the theoretical titration curve. As such, the measurement results were obtained by assuming that the maximum of the derivative of the experimental titration curve was the end point. The developed procedure was employed for the measurement of the amount-of-substance content of the complexing agent in EDTA reference material certified at the Slovak Institute of Metrology. The experimental measurements agreed well with the certified value for the reference material within the measurement uncertainty. The candidate procedure will be useful in certifying EDTA reference material and establishing international equivalence of amount content of the complexing agent.

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Final report on the key comparison CCQM-K48: Assay of potassium chloride

Cited by 4 publications

References 0 publications

Constant-current coulometry and ion chromatography bromide determination to characterize the purity of the potassium chloride

Constant-current coulometry and ion chromatography bromide determination to characterize the purity of the potassium chloride

Metrological evaluation of the certification of primary reference materials characterized by high-precision constant-current coulometry for the reliability of the titration analyses

Candidate primary reference measurement procedure for the amount-of-substance content of a complexing agent expressed as EDTA based on the coulometric titration with electrogenerated Hg ions

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