• Analytical Science and Technology
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• v.30 no.5
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• pp.226-233
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• 2017

In general, quantitative chemical analysis in various areas including food, the environment, in vitro diagnostics, etc., requires traceability in order to increase the reliability of the measurements. Measurement traceability is a property of an unbroken chain of comparisons relating an instrument's measurements to SI units. Purity analysis is the first process for establishing traceability to SI units in chemical measurements. The purpose of this study is to develop and validate a method of purity assignment for establishing the traceability of $17{\beta}$-estradiol measurements in an in vitro diagnostics field. The establishment of this method is very important as it can be applied to the development of CRM and to the analysis of the purity of other hormones. The method of assignment of the purity of $17{\beta}$-estradiol was developed using the mass balance method and was validated through participation in an International comparison. In the mass balance method, impurities are categorized into four classes as follows: total related structure impurities, water, residual organic solvents, and nonvolatiles/inorganics. In this study, total related structure impurities were characterized by a gas chromatography-flame ionization detector (GC-FID) and a high-performance liquid chromatography-ultraviolet (HPLC-UV) detector, water content was determined by a Karl-Fisher coulometer, and total residual solvents and nonvolatiles/inorganics were checked simultaneously by thermogravimetric analysis (TGA). The purity of the $17{\beta}$-estradiol was 985.6 mg/g and the expanded uncertainty was 2.1 mg/g at 95% confidence. The developed method can be applied to the development of certified reference materials, which play a critical role in traceability.

• Journal of the Korean Magnetic Resonance Society
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• v.24 no.1
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• pp.30-37
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• 2020

Quantitative nuclear magnetic resonance (qNMR) has been gaining attention as a purity assessment method. In particular, qNMR is recognized as the primary method to realize the Internal System of Units (SI) in organic analysis. The capability of quantitative analysis is recognized as the beginning of NMR development. NMR signals are proportional to the number of nuclei and qNMR has been used in various fields, such as metabolomics and food and pharmaceutical analysis. However, careful sample preparation and thorough optimization of measurement parameters are required to obtain accurate and reliable results. In this review, quantitative methods used in qNMR are discussed, and the important factors to be considered also introduced. The recent development of qNMR techniques including combination with chromatography and, multidimensional NMR are also presented.

• Analytical Science and Technology
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• v.32 no.6
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• pp.225-232
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• 2019

Traceability establishment in chemical measurements is a like a linkage established through an unbroken chain from the measured results to the international system (SI) of units. The primary process for traceability establishment is the purity assignment of a target material to be measured. In this study, we studied the purity assignment of 17α-hydroxyprogesterone (17-OHP). The presence of 17-OHP is indicative of congenital adrenal hyperplasia (CAH) and it builds up due to the deficiency of 21-hydroxylase and 11β-hydroxylase enzyme in the human blood. The purity assignment of 17-OHP was performed by the mass balance method, in which the impurities are categorized into four classes: total related structural impurities, water, residual organic solvents, and nonvolatiles/inorganics. The total related structural impurities were characterized by HPLC-UV; water content was determined by Karl-Fisher coulometer; and the total residual solvents and nonvolatiles/inorganics were determined by TGA. The purity of 17-OHP from a commercial manufacturer was calculated as 993.30 mg/g, and the expanded uncertainty was 0.58 mg/g. The proposed method was validated by uncertainty evaluation and comparing with the actual value of purity.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1492-1493
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• 2007

This paper represents the development of national standard(NS) for switching impulse(SI) voltage measuring system rated 500 kV. A traceability of the NS to the international standard could be achieved by the intercomparison test with PTB(Physikalisch-Technische Bundesansalt). According to the IEC 60060-2, a measurement uncertainty was assessed. As a result of the tests, the measurement uncertainty and the characteristics of step response were satisfied with the requisite for NS.

• Bulletin of the Korean Chemical Society
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• v.31 no.5
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• pp.1149-1154
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• 2010

Liquid chromatography/mass spectrometry using isotope dilution method has been established as a primary method for the measurement of cortisol in human serum. Verification of this method was accomplished by the participation in Consultative Committee for Amount of Substance-Metrology in Chemistry (CCQM) pilot study. Two levels of cortisol certified reference materials were prepared and certified by the established method. They were used as sample materials for the proficiency testing. The expanded uncertainty in the measurement of cortisol in human serum was approximately 1.2% at 95% confidence level. The results of the proficiency testing showed a good precision among the participants, but some bias to the certified values. This means that commercial field laboratories should keep traceability chain to SI unit through available reference measurement procedures and/or available reference materials.

• Bulletin of the Korean Chemical Society
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• v.20 no.8
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• pp.910-916
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• 1999

A current interest in chemistry concerns traceability of analytical measurements to the International System of Units (SI) and the proper estimation of their uncertainties in accordance with the internationally agreed guide provided by the International Organization for Standardization (ISO). Isotope dilution mass spectrometry (IDMS) is regarded as a primary method, which make the measurement results traceable to SI units without significant empirical correction factors. Our laboratory, as the national standards institute of Korea, participated in an intercomparison of environmental analysis, pp'-DDE in corn oil, which was organized by the CCQM under supervision of the CIPM to test feasibility of IDMS as a primary method for the trace analysis of organic compounds. In this report, we provide basic equations used for the calculation of the concentration of the analyte in a sample and a precise description of the processes for the evaluation of the uncertainties of the measurement results. Also, we report the experimental conditions adopted to improve the accuracy of the IDMS measurement. The principles contained in ？？Guide to the Expression of Uncertainty in Measurement'' provided by ISO are followed for the uncertainty evaluation.

• Proceedings of the KIEE Conference
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• 2003.10a
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• pp.261-263
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• 2003

This paper represents the development of national standard(NS) for switching impulse(SI) voltage measuring system rated 500 kV. A traceability of the NS to the international standard could be achieved by the intercomparison test with CSIRO of Australia. According to the IEC 60060-2, a measurement uncertainty was assessed. As a result of the tests, a measurement uncertainty and step response characteristics were satisfied with the requisite for NS.

• Mass Spectrometry Letters
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• v.11 no.4
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• pp.108-112
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• 2020

A certified reference material (CRM) for the analysis of nutrient elements in an edible mushroom (Ganoderma lyceum) powder has been developed (KRISS CRM 108-10-011). The mass fractions of calcium (Ca), iron (Fe), and zinc (Zn) were measured by isotope dilution inductively coupled plasma mass spectrometry (ID ICP/MS). To dissolve the fungi cell wall of mushroom consisted of chitin fibers, sample preparation method by single reaction chamber type microwave-assisted acid digestion with acid mixtures was optimized. The mean measurement results obtained from 12 sample bottles were used to assign as the certified values for the CRM and the between-bottle homogeneities were evaluated from the relative standard deviations. The certified values were metrologically traceable to the definition of the kilogram in the International System of Units (SI). This CRM is expected to be used for validation of analytical methods or quality control of measurement results in analytical laboratories when they determine the mass fractions of elements in mushroom or other similar samples.

• Mass Spectrometry Letters
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• v.8 no.3
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• pp.53-58
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• 2017

Glycated hemoglobin ($HbA_{1c}$) has been commonly used to screen and diagnose for patients with diabetes mellitus. Here the accelerated procedure of microwave-assisted sample treatment from acid hydrolysis to enzyme digestion followed by isotope dilution liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS) was optimized and applied to measure $HbA_{1c}$ in an effort to speed up analysis time. First, two signature peptides of $HbA_{1c}$ and hemoglobin $A_0$ were certified with amino acid analysis by setting optimized acid hydrolysis conditions to $150^{\circ}C$, 1.5 h and $10{\mu}M$ sample concentration in 8 M hydrochloric acid. Consequently, the accurate certified peptides above were used as calibration standards to implement the proteolytic procedure with endoproteinase Glu-C at $37^{\circ}C$, 700 W for 6 h. Compared to the traditional method, the microwave heating not only shortened dramatically sample preparation time, but also afforded comparable recovery yields. The optimized protocol and analytical conditions in this study are suitable for a primary reference method of $HbA_{1c}$ quantification with full SI-traceability and other similar proteins in complex biological samples.

• Journal of Sensor Science and Technology
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• v.32 no.6
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• pp.447-454
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• 2023

The Korea Laboratory Accreditation Scheme (KOLAS) operates accreditation programs for ensuring measurement traceability with the International System (SI) of Units - the highest calibration standard that measurements can be tested against. As of September 2023, there are 70 KOLAS-accredited laboratories in the Republic of Korea that specialize in humidity calibration. Among them, 32 KOLAS laboratories, along with one laboratory not affiliated with KOLAS, participated in the proficiency test (PM 2023-11) for relative humidity transducers in 2023. This proficiency test was conducted within a relative humidity range of 20-90% at a temperature of approximately 20 ℃, taking into consideration the calibration and measurement capability (CMC) of the participating laboratories. The primary objective of the proficiency test was to establish the measurement equivalence between each participating laboratory and the reference laboratory, by calculating the number of equivalence (En). When |En| was less than 1, the measurements from the participating and reference laboratory were equivalent. Out of the 33 participating laboratories, 32 successfully met this criterion and passed the proficiency test.