Japan Calibration Service System Research Articles

Reliable purity assay of highly hygroscopic trichloroacetic acid for the development of high-purity reference material of NMIJ CRM 4074-a

Trichloroacetic acid is known as one of the harmful disinfection byproducts with chlorine of tap water and is regulated according to legally binding standards in Japanese Drinking Water Quality Standards. We developed a high-purity trichloroacetic acid reference material, NMIJ CRM 4074-a, with certified purity as a traceability source of standard solution supplied under the Japan Calibration Service System (JCSS). As trichloroacetic acid is hygroscopic, water could be the main impurity. Although all impurities in the sample can be possibly detected by the freezing point depression method (FPD), it was unclear for trichloroacetic acid whether water was detected by FPD owing to evaporation of water from the sample during fusion. Therefore, we confirmed that water in trichloroacetic acid was detected as an impurity by FPD. The procedure was validated from an increment of purity by FPD due to reduction of water content and an agreement of purity by FPD with those by neutralization titrimetry (NT) and mass balance approach (MBA), both methods were based on different measurement principles from FPD. The certified value was determined to be (0.999 ± 0.003) kg kg-1 from the purity assay by FPD and NT, and uncertainties due to the homogeneity and stability of the CRM were included in the expanded uncertainty. The reliability of the certified value was verified by the agreement of purities by FPD, NT, and MBA.

計量法トレーサビリティ制度(JCSS)により供給される標準物質について

計量法トレーサビリティ制度(JCSS)により供給される標準物質について

Chlorate ion standard solution established by multipath titration techniques

Analyses of chlorate ion are essential in evaluating water quality; however, there is no standard solution of chlorate ion characterized by a metrologically valid procedure. This paper describes the measurement procedures and assays of chlorate ions with the linkage to the International System of Units (SI) by multipath gravimetric titration techniques. Three different titration techniques were employed to assay chlorate ions: oxidimetric-reductometric back titration with an iron(II) solution standardized with standard potassium dichromate, precipitation titration with a silver nitrate solution standardized with standard sodium chloride, and oxidimetric-reductometric titration with a thiosulfate solution standardized with standard potassium iodate. The results obtained through three different reactions were in good agreement with each other within their uncertainties. A certified reference material of chlorate ions with the linkage to the SI was first established by evaluating the storage stability of the solution and estimating measurement uncertainties. The assay (mass fraction) of sodium chlorate was characterized by using a weighted mean of the results of three methods; 99.829% ± 0.029% (the value following ± gives a level of confidence of approximately 95%, coverage factor k = 2). Providing with the standard solution through Japan Calibration Service System (JCSS) under Japanese Measurement Act widely allows all analysts to obtain their reliable analytical results.

Quantification of elemental area densities in multiple metal layers (Au/Ni/Cu) on a Cr-coated quartz glass substrate for certification of NMIJ CRM 5208-a.

Area densities of Au/Ni/Cu layers on a Cr-coated quartz substrate were characterized to certify a multiple-metal-layer certified reference material (NMIJ CRM5208-a) that is intended for use in the analysis of the layer area density and the thickness by an X-ray fluorescence spectrometer. The area densities of Au/Ni/Cu layers were calculated from layer mass amounts and area. The layer mass amounts were determined by using wet chemical analyses, namely inductively coupled plasma mass spectrometry (ICP-MS), isotope-dilution (ID-) ICP-MS, and inductively coupled plasma optical emission spectrometry (ICP-OES) after dissolving the layers with diluted mixture of HCl and HNO3 (1:1, v/v). Analytical results of the layer mass amounts obtained by the methods agreed well with each another within their uncertainty ranges. The area of the layer was determined by using a high-resolution optical scanner calibrated by Japan Calibration Service System (JCSS) standard scales. The property values of area density were 1.84 ± 0.05μg/mm2 for Au, 8.69 ± 0.17μg/mm2 for Ni, and 8.80 ± 0.14μg/mm2 for Cu (mean ± expanded uncertainty, coverage factor k = 2). In order to assess the reliability of these values, the density of each metal layer calculated from the property values of the area density and layer thickness measured by using a scanning electron microscope were compared with available literature values and good agreement between the observed values and values obtained in previous studies.

真空計測における Japan Calibration Service System：計量法に基づく校正事業者登録制度（JCSS）への取り組み，「誤差」から「トレーサビリティー」と「不確かさ」へ

This article describes the reason why ULVAC, Inc. tried to become the JCSS calibration Lab, and also describes the advantage to our vacuum gauge users. When operating ISO/IEC 17025 and getting traceability of measurement we needs to understand the concept of uncertainty of measurement. Understanding the difference of the concept of “measurement error” and “uncertainty of measurement” leads to understanding the concept of the traceability of measurement.

Elemental Analysis of Biodiesel by Inductively Coupled Plasma Optical Emission and Flame Atomic Absorption Spectrometries

ABSTRACTThe extraction of 21 elements from biodiesel using aqueous acid and alkaline solutions was investigated as pretreatment to permit their determination by inductively coupled plasma optical emission spectrometry and flame atomic absorption spectrometry. Al, Ca, Cd, Cu, K, Mg, Mn, Na, V, and Zn were completely extracted from the biodiesel fuel with aqueous acid solution, and Na was completely extracted with alkaline solution. Extraction characteristics varied from element to element; however, 100 ± 5% recoveries were obtained with a 30-s extraction procedure. Therefore, although biodiesel is an organic lipophilic material, these elements were determined in aqueous solution. The extracted elements were determined based on traceable Japan calibration service system standards. Accurate analysis of biodiesel was performed using the reported protocol.

Certification of reference materials for the determination of alkylphenols.

Certified reference materials (CRMs) are playing an increasingly important role in national and international standardizing activities. In Japan, primary standard solutions for analyses of endocrine disrupters are supplied under the national standards dissemination system named the Japan Calibration Service System (JCSS). For the traceability on reference materials used for preparation of the primary standard solutions based on the JCSS, the National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology (NMIJ/AIST) has developed and certified high-purity reference materials of alkylphenols as NMIJ CRMs, such as 4-n-nonylphenol, 4-tert-octylphenol, 4-n-heptylphenol, 4-tert-butylphenol, and 2,4-dichlorophenol. Thereafter, it is essential to determine the alkylphenols by using these solutions based on the JCSS for environmental monitoring and risk assessments because analytical values obtained by using the solutions can ensure the reliability and traceability of the chemical analyses.

FIVE PROFICIENCY TESTING PROGRAMS FOR THE JCSS WEIGHT CALIBRATION LABORATORIES

The Japan Calibration Service System (JCSS) organized in 1993 accredits the measurement capability of calibration laboratories and ensures the traceability to the national measurement standards. As an essential part of accreditation of the measurement capability of calibration laboratories for the weights, the International Accreditation Japan (IAJapan) of National Institute of Technology and Evaluation has been operating the JCSS proficiency testing programs with the technical support of the National Metrology Institute of Japan (NMIJ/AIST). Up to now, five proficiency testing programs have been carried out for the JCSS weight calibration laboratories in the range of 2 mg to 10 kg. The proficiency testing programs organized by the IAJapan were carried out in accordance with ISO/IEC Guide 43 (JIS Q 17043), and the NMIJ was responsible for the technical aspect as a reference laboratory. This paper describes the methods of the five proficiency testing programs during the period from 1997 to 2009, and outlines assessment of the measurement capability of the JCSS weight calibration laboratories.

Quantum Efficiency Measurement of Lamp Phosphors in Accordance with Radiometric Standards

To measure the quantum efficiencies of lamp phosphors, a JCSS (Japan Calibration Service System) traceable measurement method that uses a polychromator, with improved optical design to reduce stray light, and an integrating sphere has been developed. To verify the measurement accuracy of this method, a monochromator, which has a 0 - 45°incident optical system, was used. The BRDF (Bidirectional Reflectance Distribution Function) of the phosphor was measured by a goniophotometer. A comparison was made between these JCSS traceable measuring devices on the 260-400 nm wavelength characteristics of the internal quantum efficiency of the blue phosphor BAM (BaMgAl10O17:Eu2+) , which has excitation characteristics up to 400 nm. The results agreed within 4 % of the difference of the measured values. This is a good agreement considering that it was a composite measure and that the uncertainty of the spectral irradiance standard in the spectral region is lower than 3 %. It has also been established that the proposed method using a polychromator and an integrating sphere shows sufficient measurement accuracy.

Characterization of a certified reference material (NMIJ CRM 8301-a) for determination of Cu in bio-ethanol

A certified reference material (CRM) was characterized for the determination of copper (Cu) in bio-ethanol samples. The material for the CRM was made from rice by fermentation and refined by distillation, which was further added with Cu acetate and acetic acid. Because the ionization of Cu in inductively coupled plasma mass spectrometry (ICP-MS) was affected by the content of ethanol in the sample, matrix matched methods were developed for the determination of Cu, where the bio-ethanol samples were 10-times (v/v) diluted to 1molL−1 nitric acid solution. All of the standard solutions for calibration were also adjusted to 1molL−1 nitric acid solution with 10% (volume fraction) ethanol. Determination of the concentration of Cu in the sample was carried out by gravimetric standard addition ICP-MS, isotope dilution (ID-) ICP-MS, and graphite furnace atomic absorption spectrometry (GF-AAS). The property value of Cu was calculated based on the weighted mean of the observed values by these methods, with the reciprocal of the uncertainty of each method as the weight. The deviation factor of sampling for characterization was also taken into consideration for calculating the certified value. The combined uncertainty (3.79%, relative value) of the certified value was calculated as a combination of the uncertainties of homogeneity (3.53%), analytical method (0.64%), method-to-method variance (1.16%), and calibration standard (0.35%). The certified value of Cu in the CRM was (53.7±4.1) ngg−1 (property value±expanded uncertainty, k=2), which is traceable to the International System of Units (SI units) via the Japan Calibration Service System (JCSS).

Preparation and certification of hijiki reference material, NMIJ CRM 7405-a, from the edible marine algae hijiki (Hizikia fusiforme).

A certified reference material, NMIJ CRM 7405-a, for the determination of trace elements and As(V) in algae was developed from the edible marine hijiki (Hizikia fusiforme) and certified by the National Metrology Institute of Japan (NMIJ), the National Institute of Advanced Industrial Science and Technology (AIST). Hijiki was collected from the Pacific coast in the Kanto area of Japan, and was washed, dried, powdered, and homogenized. The hijiki powder was placed in 400 bottles (ca. 20 g each). The concentrations of 18 trace elements and As(V) were determined by two to four independent analytical techniques, including (ID)ICP-(HR)MS, ICP-OES, GFAAS, and HPLC-ICP-MS using calibration solutions prepared from the elemental standard solution of Japan calibration service system (JCSS) and the NMIJ CRM As(V) solution, and whose concentrations are certified and SI traceable. The uncertainties of all the measurements and preparation procedures were evaluated. The values of 18 trace elements and As(V) in the CRM were certified with uncertainty (k = 2).

Erratum to: Mass balance method for purity assay of phthalic acid esters: development of primary reference materials as traceability sources in the Japan Calibration Service System

Purity assay of high-purity materials (HPMs) of phthalic acid esters (PAEs) was carried out by means of a mass balance method. In this method, chromatographic methods such as gas chromatography-flame ionization detector (GC-FID) and/or high-performance liquid chromatography (HPLC) in combination with other methods such as Karl-Fischer (KF) titration and vacuum evaporation (VE) were applied. The sum of the impurities estimated by these methods allowed the estimation of the purity of the main component by difference. Seven PAEs with varying side chain structures and levels of impurities were analysed on a systematic way in which impurities were classified into several groups in terms of their abundance, availability of qualitative information and availability of authentic compounds, etc. The absolute quantity of each impurity was determined by GC-FID and/or HPLC based on the calibration made by the authentic compounds of impurities whenever available. The purities in mass fraction of these PAEs were certified at the National Metrology Institute of Japan (NMIJ), and the PAEs were registered as primary reference materials playing an essential role in linking the metrological traceability of the Japan Calibration Service System (JCSS) to the International System of Units (SI).

Mass balance method for purity assay of phthalic acid esters: development of primary reference materials as traceability sources in the Japan Calibration Service System

Mass balance method for purity assay of phthalic acid esters: development of primary reference materials as traceability sources in the Japan Calibration Service System

Recent activities on neutron standardization in Japan

NMIJ provides national standards on neutron fluence as well as neutron emission rate in Japan. The neutron fluence standards are established for thermal neutrons, monoenergetic neutrons at seven energies from 24 keV to 14.8 MeV, radionuclide-source neutrons from 252 Cf and 241 Am-Be. The neutron emission standards are provided for these radionuclide sources. These are basically prepared in accordance with ISO 8529-1. Worldwide consistency of the standards has been supported by participating in key comparisons organized by BIPM. NMIJ issues calibration certificates accepted worldwide within the range specified in our calibration and measurement capabilities listed in the BIPM web page. The development of the 19 MeV neutron field is in progress to complete standardization in 2011. The radionuclide-source neutron fluence standards were extended in 2008 so that calibrations are also available in terms of ambient/personal dose equivalent. The Japan calibration service system has launched to improve the traceability of neutron measurement in Japan. A new thermal neutron calibration field is developing with a guided beam at the research reactor JRR-3M of JAEA. Aiming at the establishment of the 20-100 MeV high-energy neutron standard, comparison studies are currently being conducted between the cyclotron facilities TIARA of JAEA and CYRIC of the Tohoku University. -1 ) in Japan. We report the present status and recent activities of these neutron standards.

Purity Evaluation of Alkylphenol Primary Standards Based on Japan Calibration Service System by Subtraction Method

In the development of organic reference materials, a purity evaluation by the freezing point depression method, which is regarded as one of primary methods of measurement, is used to ensure traceability to the International System of Units (SI). However, because this method is difficult to apply to some organic compounds, a subtraction method based on chromatographic techniques under ISO Guide 35 : 2006 was developed for purity evaluation. The subtraction method was based on subtracting every impurity detected from 1. Since the detection of every impurity is impossible, validation of the subtraction method is necessary. To validate our subtraction method based on chromatographic techniques, the purities of 4-n-nonylphenol, 4-n-heptylphenol, and 2,4-dichlorophenol were determined using both the subtraction and freezing point depression methods, and then compared. The purities obtained by the subtraction method were comparable, within the range of uncertainties, to the purities determined using the freezing point depression method. Moreover, validation of our subtraction method was confirmed using international comparisons, which play an important role in ensuring mutual recognition of national reference materials, related to purity evaluation. Therefore, these data suggest that our subtraction method used for purity evaluation of alkylphenols is a reliable technique.

Quantum Efficiency Measurement of Lamp Phosphors in accordance with Radiometric Standards

To measure the quantum efficiencies of lamp phosphors, a JCSS (Japan Calibration Service System) traceable measurement method that uses a polychromator, with improved optical design to reduce stray light, and an integrating sphere has been developed. To verify the measurement accuracy of this method, a monochromator, which has a 0 - 45°incident optical system, was used. The BRDF (Bidirectional Reflectance Distribution Function) of the phosphor was measured by a goniophotometer. A comparison was made between these JCSS traceable measuring devices on the 260-400 nm wavelength characteristics of the internal quantum efficiency of the blue phosphor BAM (BaMgAl10O17:Eu2+) , which has excitation characteristics up to 400 nm. The results agreed within 4 % of the difference of the measured values. This is a good agreement considering that it was a composite measure and that the uncertainty of the spectral irradiance standard in the spectral region is lower than 3 %. It has also been established that the proposed method using a polychromator and an integrating sphere shows sufficient measurement accuracy.

Water content variation of p-n-heptylphenol reference material

Water content variation of candidate p-n-heptylphenol (HP) reference material (ampoule form) for preparation of a primary standard solution based on the Japan Calibration Service System, a national standards dissemination system, under the Measurement Law of Japan, was examined by a Karl-Fischer water content meter. As prepared samples, liquid-phase HP and upper, middle, and lower layers of solid-phase HP were measured since characteristic phase transition occurs near room temperature (melting point: 28.98 °C). As a result of water content in liquid- and solid-phase HP, water content variation among three layers of solid-phase is found in within ampoules, though water content variation of liquid-phase is not found. Between-ampoule variation of water content is also found using total ampoules of liquid-phase HP used to eliminate within-ampoule variation. Moreover, water content variation is secondarily confirmed by the results of the amount-of-substance fraction of HP based on a differential scanning calorimeter. From these results in this study, it is concluded that within- and between-ampoule variations of water content may depend on phase transition and water loss during ampouling of candidate reference material, respectively.

Preparation and certification of arsenate [As(V)] reference material, NMIJ CRM 7912-a

Arsenate [As(V)] solution reference material, National Metrology Institute of Japan (NMIJ) certified reference material (CRM) 7912-a, for speciation of arsenic species was developed and certified by NMIJ, the National Institute of Advanced Industrial Science and Technology. High-purity As(2)O(3) reagent powder was dissolved in 0.8 M HNO(3) solution and As(III) was oxidized to As(V) with HNO(3) to prepare 100 mg kg(-1) of As(V) candidate CRM solution. The solution was bottled in 400 bottles (50 mL each). The concentration of As(V) was determined by four independent analytical techniques-inductively coupled plasma mass spectrometry, inductively coupled plasma optical emission spectrometry, graphite furnace atomic absorption spectrometry, and liquid chromatography inductively coupled plasma mass spectrometry-according to As(V) calibration solutions, which were prepared from the arsenic standard of the Japan Calibration Service system and whose species was guaranteed to be As(V) by NMIJ. The uncertainties of all the measurements and preparation procedures were evaluated. The certified value of As(V) in the CRM is (99.53 +/- 1.67) mg kg(-1) (k = 2).

Development of primary standard for hydrocarbon flow and traceability system of measurement in Japan

It is of importance to establish the hydrocarbon flow standard which acts as the basis for vast dealings and taxation for hydrocarbons, enforcement of the policy on energy savings and high quality management of industries. As a result of investigation into calibration methods, reliability, and effectiveness, the specification of the national primary standard and the traceability system for hydrocarbon flow in Japan was designed. We took the technical initiative in establishing the traceability system using JCSS (Japan Calibration Service System) as basis of the national primary standard in the limited region of flow rates and various kinds of liquids. The national primary standard of high accuracy and safety has been developed. This project was evaluated through verification of international consistency by way of international key comparisons.

Development of certified reference materials of high-purity volatile organic compounds: purity assay by the freezing-point depression method

For accurate measurement of concentrations of substances by instrumental analysis, reliable calibration standards are needed. In Japan, national reference materials are supplied under the national standards dissemination system named the Japan Calibration Service System (JCSS). In JCSS, calibration standards for the analysis of environmental pollutants are supplied. For the traceability to the SI of reference materials for calibration in JCSS, the National Metrology Institute of Japan (NMIJ) is developing high-purity reference materials of volatile organic compounds (VOCs) as NMIJ CRMs. The freezing-point depression method, which has potential as a primary method of measurement, is employed for the determination of property value. In this paper, a development scheme of certified reference materials of high-purity VOCs is described.