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A semi-preparative high-performance liquid chromatography process was evaluated as a tool to quantitatively determine the
purity or percentage mass fraction content (% m/m) of organic compounds. The method is simple and does not require the identification and subsequent quantitation of organic-related
structure impurities. A protocol was developed and tested on four reference materials certified for purity from 95% m/m to 99.3% m/m. Comparing the purity results of each certified reference material using the new approach with their respective certified
values showed no significant analytical bias. Semi-preparative high-performance liquid chromatography has proved the potential
to be a primary method directly traceable to mass with an uncertainty statement written down also in terms of mass with expanding
uncertainty ranging from 0.8% to 1.3% m/m compared to 0.3 to 2.0% m/m for the certified purity values at the 95% confidence interval. 相似文献
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Yoshitaka Shimizu Yoko Ohte Xinnu Bao Satoko Otsuka Yuko Kitamaki Keiichiro Ishikawa Toshihide Ihara Kenji Kato 《Accreditation and quality assurance》2008,13(7):389-396
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.
Presented at BERM-11, October 2007, Tsukuba, Japan. 相似文献
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Development of a solid-phase microextraction method for the determination of phthalic acid esters in water 总被引:1,自引:0,他引:1
Gabriela Prok?pkováKate?ina Holadová Jan PoustkaJana Hajšlová 《Analytica chimica acta》2002,457(2):211-223
Solid-phase microextraction method (SPME) coupled to GC/ECD has been developed and validated for the determination of phthalic acid esters (dimethyl-, diethyl-, di-n-butyl-, butylbenzyl-, di-2-ethylhexyl- and di-n-octyl phthalate) in water samples. Two types of coatings (PDMS, PA), altogether four different kinds of fibers have been investigated. Both parameters affecting the partition of analytes between a fiber coating and aqueous phase (i.e. extraction time, extraction temperature, agitation) and conditions of the thermal desorption in a GC injector were optimized. The final SPME method employing the polyacrylate fiber, extraction time 20 min, heating and stirring of the sample enabled the determination of all six phthalates in water samples. The method showed linear response over four orders of magnitude and the limits of quantification of the method ranged between 0.001 and 0.050 μg l−1. The repeatability expressed as R.S.D. was in the range 4-10% for the spiking level 7 μg l−1 of each analyte. The applicability of the developed SPME method was demonstrated for real water samples. 相似文献
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Purity certified reference materials (CRMs) are playing a key role in metrological traceability, because they form the basis
for many traceability chains in chemistry. Recently, the National Metrology Institute of Japan (NMIJ) has developed two purity
CRMs for creatinine (NMIJ CRM 6005-a) and urea (NMIJ CRM 6006-a), because the concentrations of these two compounds are frequently
measured in clinical laboratories for monitoring the renal functions. In the certification of purity CRMs, it is essential
that the materials have been thoroughly characterized for purity, and the purity should preferably be determined directly
by a primary method of measurements. In the development of these two CRMs, we used the purified materials as candidates. The
certified values were assigned based on the results of two different methods; acidimetric titration and nitrogen determination
by the Kjeldahl method. Since both methods cannot distinguish some impurities from the target compounds, major impurities
in the candidate materials were also identified, quantified, and subtracted. These CRMs can provide a traceability link between
routine clinical methods and SI units.
Presented at BERM-11, October 2007, Tsukuba, Japan. 相似文献
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Koichi Saito Masakazu Yato Takeshi Ito Yusuke Iwasaki Rie Ito Yasuhiko Matsuki Hiroyuki Nakazawa 《Accreditation and quality assurance》2008,13(7):373-379
In this study, optical purity measurement was performed on eight kinds of commercially available pesticide, namely, Dimethenamid-P,
Dichlorprop-P, Fluazifop-P butyl, Indoxacarb, Metalaxyl-M, Mecoprop-P, Quizalofop-P ethyl, and Uniconazole-P, in both enantiomer
and racemate forms. Chiral separation of each pesticide was achieved by using HPLC with a photodiode-array (PDA) detector
and a circular dichroism (CD) detector, which were connected in series. The chiral column used for the enantiomeric separation
was a normal phase Chiralpak AD-H column. The mobile phase was n-hexane, with various alcohols added as polar modifiers. The study included investigation of the effects on enantiomeric separation
of the percentage of alcohol used, the presence or absence of acid in the mobile phase, and the column temperature, and the
optimum detection wavelengths of both PDA and CD detectors. Enantiomeric excess (ee) was calculated as an expression of optical purity. As a result, the ee of some pesticides investigated was approximately (over 95%) in accord with the data provided by manufacturers. However,
the ee of Indoxacarb, Uniconazole-P, Quizalofop-P ethyl, and Fluazifop-P butyl was in the range 34.1–94.5%. These results suggest
that there is a need to conduct optical purity tests, in addition to a chemical purity test, for optically active pesticides.
Presented at BERM-11, October 2007, Tsukuba, Japan. 相似文献
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Takeshi Saito Toshihide Ihara Masayoshi Koike Shinichi Kinugasa Yoshinori Fujimine Kazutoshi Nose Tetsuya Hirai 《Accreditation and quality assurance》2009,14(2):79-86
Quantitative nuclear magnetic resonance (qNMR) was used for the purity determination of neat compounds of persistent organic
pollutants (POPs). qNMR is a unique quantitative method that is not only traceable to the International System of Units (SI),
but it also does not require a standard of its own. The purities of the POP compounds determined in this work were traceable
to a single certified reference material (CRM), which is extremely attractive for reference material producers. The purities
observed by qNMR were equivalent to those observed by gas chromatography with flame ionization detection (GC/FID) or a differential
scanning calorimetry (DSC) combined with a thermogravimetric analyzer (TGA). The uncertainties obtained by the qNMR method
were comparable to being slightly larger than those observed by DSC. 相似文献
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The National Analytical Reference Laboratory has synthesized and characterized 67 anabolic steroid marker metabolites, both unlabelled and deuterated, and 37 key glucuronide and sulfate steroid conjugate pure substance reference materials. Work is also in process to establish their full traceability so that they can be issued as certified and primary reference materials. Both identity and purity have been rigorously characterized using a number of techniques and a primary method for purity assessment developed, based gas chromatography combined with flame ionization detection for the parent steroids and HPLC with evaporative light scattering detection for non-volatile steroid conjugates. Strategies for establishing traceability and for estimating measurement uncertainty are reported. The strategies described are considered applicable to a wide range of organic pure substance reference materials. 相似文献
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Xi Luo Chengxia He Feifang Zhang Hailong Wang Bingcheng Yang Xinmiao Liang 《Journal of separation science》2014,37(24):3656-3661
Heat‐shrink tubing, which shrinks in one plane only (its diameter) when heated, commonly used for sealing protection in electrical engineering, was found to be able to function as a solid‐phase microextraction coating. Its utility was demonstrated for the determination of phthalic acid esters in an aqueous solution combined with high‐performance liquid chromatography equipped with a UV absorbance detector. The preparation procedure was rather simple and only ~10 min was needed. The fiber cost is extremely low (~10 cent each). The parameters affecting the extraction were optimized. Heat‐shrink tubing fiber exhibited a significant enrichment effect for the three examined phthalic acid esters and up to 931‐fold enrichment factor was obtained. The limit of detection was <10 μg/L for all analytes. The operation repeatability and fiber‐to‐fiber reproducibility were 1.2–8.3 and 5.4–9.1%, respectively. It was successfully applied for the analysis of bottled drinking water with recoveries ranging from 90.1–100.5%. 相似文献
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Toussaint B Schimmel H Klein CL Wiergowski M Emons H 《Journal of chromatography. A》2007,1156(1-2):236-248
The certification of the purity of CRMs intended for calibration, where no other certified material already exists for comparison, raises principle questions on how to determine the purity of a "first" calibrant in the calibration hierarchy. We developed and certified two calibration CRMs for their purity in thyroid hormones taking into consideration inorganic residues, residual solvents and organic impurities detectable by HPLC-UV and HPLC-MS. IRMM-468 was certified for a thyroxine (T(4)) mass fraction of 98.6+/-0.7% and IRMM-469 was certified for a 3,3',5-triiodothyronine (T(3)) mass fraction of 97.1+/-0.7%. The approach we used aims to determine the purity of these two CRMs to the best of our knowledge and taking all scientific aspects properly into account for the estimation of an uncertainty related to the stated purity. 相似文献
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N. Majcen 《Accreditation and quality assurance》2003,8(3-4):108-112
The fact that various definitions and terminology applied to measurements in analytical chemistry are not always consistent
and straightforward, by not only answering the question ”what”, but also ”how”, leads to their various interpretations. This
results in non-uniform implementation of very basic and essential metrological principles in chemistry. Such a diverse situation
is not conducive to the endorsement of harmonised measurements all across the world, to serve as a tool for improving the
quality of life in its broadest sense for all its citizens. The discussion in this paper is focused on problems associated
with terminology and definitions of ’reference material’ and ’validation’. The role of reference materials in measurement
processes for purposes other than calibration and validation principles in analytical chemistry are also discussed in this
paper. Where possible, potential solutions are proposed, but more often, questions of essential importance are raised in order
to initiate international discussion which will hopefully lead to equally understandable answers.
Received: 2 November 2002 Accepted: 3 February 2003
Acknowledgements
The author is grateful to Aleš Fajgelj for his comprehensive comments on the topic described in this paper. Sincere thanks
also to Philip Taylor, Ewa Bulska, Emilia Vassileva, Miloslav Suchanek and Margreet Lauwaars for their contribution during
fruitful discussions on validation.
Presented at the CERMM-3, Central European Reference Materials and Measurements Conference: The function of reference materials
in the measurement process, May 30–June 1, 2002, Rogaška Slatina, Slovenia
Correspondence to N. Majcen 相似文献
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K. Ishikawa N. Hanari Y. Shimizu T. Ihara T. Maeda A. Nomura T. Yarita K. Kato K. Chiba 《Accreditation and quality assurance》2008,13(7):397-408
Certified reference materials (CRMs) are playing an increasingly important role in environmental monitoring in Japan. The
National Metrology Institute of Japan (NMIJ)/National Institute of Advanced Industrial Science and Technology (AIST) has been
developing CRMs of organic calibration solutions since 2003, and has issued several NMIJ CRMs. The development of these materials
was conducted at the NMIJ in cooperation with candidate material producers. The freezing-point depression method was principally
adopted for assessment of the purity of starting materials to give reliable certified values. Gas chromatography with flame
ionization detection (GC–FID) and/or high-performance liquid chromatography (HPLC), which are based on independent principles
and whose levels of accuracy are well evaluated, were applied in combination with other methods to avoid any possible analytical
bias. Purity assessment is outlined for two typical examples, 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (p,p′-DDD) and 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (p,p′-DDT), which were used as starting materials for a CRM under development. Methods adopted for gravimetric preparation and
ampouling of solutions were qualified and optimized to reduce the uncertainties of certified values due to these factors.
Furthermore, a new experimental scheme for assessment of stability and preparation variation is proposed for the proper estimation
of uncertainties.
Presented at BERM-11, October 2007, Tsukuba, Japan. 相似文献
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André Lagerwaard J. R. W. Woittiez J. J. M. de Goeij 《Fresenius' Journal of Analytical Chemistry》1995,351(8):786-789
A method for the determination of Cr in biological materials with high accuracy is reported for use as an independent reference method. It is based on radiochemical neutron activation analysis (RNAA) in combination with an individual yield determination based on the online yield principle. A precision of better than 4% between replicate determinations was achieved by application to biological materials with Cr contents on the 100 g·kg–1 level. Analytical characteristics of the method offer good perspectives for Cr assays at lower levels. 相似文献
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B. M. Gawlik F. Ulberth H. Langenkamp G. Bidoglio M. Grasserbauer 《Accreditation and quality assurance》2004,9(4-5):221-225
The need for standardisation and harmonisation of measurements increases with the progress of the European integration process. One of the areas for which the need for harmonisation has been emphasised is the protection of the soil compartment. While knowledge of problems associated with soils is increasing in Europe, based on soil surveys, monitoring systems and data networks, the corresponding (analytical) data is not often comparable, which limits its value for policy development. In this context, the European Commission has invited the Member States to investigate the possibility for a harmonisation of European standards in the fields of soil, sludge and biodegradable waste (compost). Furthermore, the development of new reference materials for both the validation of these new methods and their successful implementation on a routine basis is required. This paper shows some selected examples for which the development of horizontal standards may be worth investigating. In addition, it discusses and proposes the vehicle of (C)RMs for the implementation of a common measurement system for soil, related to these horizontal standards. It also raises some open questions and sheds light on future perspectives and challenges.Presented at BERM-9 – 9th International Symposium on Biological and Environmental Reference Materials, June 15–19, Berlin, Germany 相似文献
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