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Measurement traceability is universally recognised as one of the basic prerequisites for comparability of results obtained in different laboratories and is a basic aspect of metrological sciences such as analytical chemistry. This requirement is underscored by the increasing adoption of standards and measurement quality systems, such as laboratory accreditation against ISO/IEC 17025. Testing laboratories ensure traceability of their measurement results by using appropriate reference standards for calibration of instruments and control of measurement processes. For routine work in the field of water analysis, these standards are usually commercial solutions or in-house solutions prepared from pure products. Therefore, laboratories should demonstrate that their use of reference standards is appropriate and sufficient, which can be done by participation in an appropriate proficiency-testing scheme. The paper reports how measurement traceability of results from field laboratories (nitrite nitrogen, nitrate nitrogen, chloride and sulphate; all in water) can be demonstrated by participation in a proficiency-testing scheme based on reference values. 相似文献
3.
In Japan, there was a drastic change in food control system, which was brought about by problems with BSE. Food Safety Basic Law was newly enacted and Food Hygiene Law, Japanese Agricultural Standards Law and so on were revised. Food Safety Commission was newly established for risk assessment, and Ministry of Agriculture, Forestry and Fisheries and Ministry of Health, Labor and Welfare were reorganized on food safety. National Food Research Institute (NFRI) works for improvement of technology for food analysis, development of technology to ensure food safety and so on. Objects of food analysis are inorganic elements, acrylamide, mycotoxins, functional components, genetically modified organisms, varieties of rice and so on. Proficiency testing schemes (PTs) were introduced to NFRI for reliability of food analysis. Certified reference materials (CRMs) of food related materials prepared in Japan, and PTs provided by Japanese organization were limited. It is requested for Japanese organizations to prepare new CRMs and provide many kinds of PTs for solution of peculiar problems. 相似文献
4.
The interlaboratory variability in the quantification of adsorbable organically bound halogens (AOX) in industrially contaminated
soil is presented. Three consecutive rounds of a proficiency testing scheme, in which between 88 and 119 routine laboratories
participated, yielded relative reproducibility standard deviations between 7 and 20% at AOX contents between 10.9 and 268 mg
kg−1. Nineteen laboratories with established proficiency were invited to participate in the certification of the AOX content in
three soil reference materials meant for the internal quality control in analytical laboratories. The certified values are
(1349 ± 59) mg kg−1, (80 ± 7) mg kg−1 and (102 ± 8) mg kg−1, respectively. 相似文献
5.
Metrological designs of experiment for proficiency testing (PT) with a limited number of participants are discussed. The designs are based on development of in-house reference materials (IHRMs) with traceable assigned values and fit-for-purpose uncertainties, used in a PT scheme as the measurement standards. When adequate certified reference materials (CRMs) are available, a comparative approach for IHRM development, using simultaneous analysis of IHRM and CRM test portions in pairs, is proposed for PT objectives. In the case where adequate CRMs are not available – for example, in the field of analysis of unstable aqueous systems – the function of the measurement standard for PT can be fulfilled by a synthetic IHRM prepared gravimetrically using non-adequate, non-aqueous CRMs or pure substances. The CRM or the pure substance is used as a spike for fortification of a natural water sample, while the natural water sample is used as a working IHRM for the spike determination. In this case the traceability chain is longer, since two IHRMs are added for one quantity determination, but it remains unbroken.Presented at the Second International Conference on Metrology –Trends and Applications in Calibration and Testing Laboratories, 4–6 November 2003, Eilat, Israel 相似文献
6.
Daniel Tholen Roderick Chappel Barbara Francis 《Accreditation and quality assurance》2006,11(8-9):400-407
International requirements for PT and EQA state that providers must demonstrate that samples are homogeneous and stable. However, testing for homogeneity and stability can be expensive, use samples that could otherwise serve as quality-control materials, and can also fail to detect significant inhomogeneity and instability. In some situations it may be preferable to use the results from participants to identify problems with sample lots, if historic results follow predictable distributions and a statistical decision rule can be produced. An unusually high proportion of incorrect results may indicate that samples were inhomogeneous or unstable. Conditions under which this can be demonstrated are discussed, and the efficacy of the proposal is demonstrated with two examples. This procedure is especially effective when there are a large number of participants and/or a historic small proportion of incorrect results. Providers who adopt this proposal will need to retain samples for testing and assume the risk of distributing bad samples.Presented at the Eurachem PT Workshop September 2005, Portorož, Slovenia 相似文献
7.
Adolf Zschunke 《Accreditation and quality assurance》1998,3(10):393-397
Global decisions made on the basis of chemical analytical results need global comparability. The concept of traceability
is important and necessary but not sufficient to achieve global comparability, especially for routine analysis in environmental
protection, health care and public safety. Sometimes comparability is only determined by the method. In this case validated
methods have to be known and recognized internationally. In addition, a minimum level of proficiency of the personnel producing
analytical results has to be guaranteed. Finally, a system of measures designed to build up trust is needed for worldwide
acceptance of analytical results. The method of self-declaration by the supplier of chemical analytical services has the advantage
of presenting specific responsibility and gaining a good reputation. Additional methods should be employed. The evaluation
of reference materials by specific quality criteria is mentioned as an example.
Received: 1 July 1998 · Accepted: 20 July 1998 相似文献
8.
The role of matrix reference materials in the process of demonstrating the degree of equivalence of measurement results obtained
from intercomparisons is outlined, reviewing exemplary selected experience gained at BAM regarding the determination of organic
contaminants in environmental matrices.
The specific characteristics of reference materials employed in the process of demonstrating equivalence between laboratories
in the course of proficiency testing as well as the development, comparison and validation of methods are elaborated. The
demand is for series of appropriately characterised samples which are fit for the purpose and it is seen from representative
examples that the utilisation of such tailor-made RM designed to tackle the specific need of an analytical problem dominates
over certified matrix reference materials in this context. Concluding, the role of certified matrix reference materials in
quality assurance is briefly looked at both from the user’s and providers’ points of view.
Received: 9 September 2002 Accepted: 16 December 2002
Presented at 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 R. Becker 相似文献
9.
C. Brera S. Grossi F. Debegnach B. De Santis V. Minardi M. Miraglia 《Accreditation and quality assurance》2006,11(7):349-355
This paper describes the interlaboratory study aimed at assessing the performance of 18 laboratories (14 national and 4 European) for Ochratoxin A (OTA) determination in cocoa powder samples. The study was tested at three levels of OTA covering the range in which presumably European regulatory limits could fall in the near future. For the extraction step, almost all laboratories used an aqueous solution of sodium hydrogen carbonate with the exception of one laboratory using dichloromethane consistently with the ELISA procedure adopted in the study. The clean-up step was performed by utilizing the immunoaffinity columns by the two main manufacturers (R-Biopharm Rhone and VICAM) and for the quantitative analysis, HPLC was used by all the participants except one using ELISA. From the output of the study, it can be concluded that at low level (0.19 μg/kg) 10 out of 18 (56%), at medium level (0.45 μg/kg) 11 out of 18 (61%), and at high level (1.45 μg/kg) 12 out of 18 (67%) results fell within the satisfactory ranges. This interlaboratory study provides an estimate of the performance of national and European laboratories involved in OTA determination in cocoa powder samples, which sounds extremely valuable in view of potential future legislation by the European Commission. 相似文献
10.
Quality-control materials in the USDA National Food and Nutrient Analysis Program (NFNAP) 总被引:1,自引:0,他引:1
Phillips KM Patterson KY Rasor AS Exler J Haytowitz DB Holden JM Pehrsson PR 《Analytical and bioanalytical chemistry》2006,384(6):1341-1355
The US Department of Agriculture (USDA) Nutrient Data Laboratory (NDL) develops and maintains the USDA National Nutrient Databank
System (NDBS). Data are released from the NDBS for scientific and public use through the USDA National Nutrient Database for
Standard Reference (SR) (). In 1997 the NDL initiated the National Food and Nutrient Analysis Program (NFNAP) to update and expand its food-composition
data. The program included: 1) nationwide probability-based sampling of foods; 2) central processing and archiving of food
samples; 3) analysis of food components at commercial, government, and university laboratories; 4) incorporation of new analytical
data into the NDBS; and 5) dissemination of these data to the scientific community. A key feature and strength of the NFNAP
was a rigorous quality-control program that enabled independent verification of the accuracy and precision of analytical results.
Custom-made food-control composites and/or commercially available certified reference materials were sent to the laboratories,
blinded, with the samples. Data for these materials were essential to ongoing monitoring of analytical work, to identify and
resolve suspected analytical problems, to ensure the accuracy and precision of results for the NFNAP food samples. 相似文献
11.
Katherine M. Phillips Wayne R. Wolf Kristine Y. Patterson Katherine E. Sharpless Karen R. Amanna Joanne M. Holden 《Accreditation and quality assurance》2007,12(3-4):126-133
Certified reference materials (CRMs) play a critical role in validating the accuracy of nutrient data for food samples. A
number of available food CRMs of differing matrix composition have assigned concentrations for various nutrients, along with
associated uncertainty intervals (UIs) for those values. These CRMs have been used extensively in the United States Department
of Agriculture’s (USDA) ongoing National Food and Nutrient Analysis Program (NFNAP) to monitor the accuracy of assays of key
foods and nutrients consumed in the United States. A total of 690 assigned values for individual nutrients, including proximates,
vitamins, macroelements, microelements, fatty acids, amino acids, and selected phytochemicals (e.g., carotenoids), were compiled
from the certificates of analysis for 63 CRMs, and the specified UI in each case was expressed as a percentage of the assigned
certified or reference concentration. Across all nutrients, 63.5% of the UIs were less than 10% of the assigned value, 25.5%
were 10–20%, and 11% were greater than 20% of the assigned value. The UIs for proximates, minerals, and trace elements were
most consistently less than 10% of the assigned value. The relative uncertainties were significantly higher for vitamins,
suggesting greater challenges in measuring and certifying these components. These high UIs (greater than 10% assigned value)
in the best available reference materials are likely to be indicative of the precision and accuracy that can be obtained by
current measurement systems for these components. These data suggest that care must be taken in choosing CRMs to monitor food
composition analysis, including evaluating what levels of uncertainty are required in assigned values and which analytical
measurement systems for food components need closer examination and improvement.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Presented at ‘BERM-10’, April 2006, Charleston, SC, USA. 相似文献
12.
Proficiency testing (PT) results have been used to improve traceability in chemical drinking water analysis. With a generalized
least-square regression the mass concentrations of As and Sb were calculated in a drinking water that had been used to prepare
proficiency testing samples by a spiking procedure. From the mass concentrations in the matrix and the spiked amounts, reference
values with an uncertainty budget could be calculated without the need for reference measurements. The degree to which these
reference values can be regarded as traceable is discussed. The results showed slight deviations in some samples between reference
values and consensus means. 相似文献
13.
Edmond J. Baratta 《Accreditation and quality assurance》2001,6(2):84-86
The U.S. Food and Drug Administration's (FDA) Radionuclides in Food Program was reinstituted in 1973, expanded in 1975 and
again in 1990, to its present status. The need for reference materials for radionuclides in food samples was recognized as
early as 1962. There were no available reference materials for these types of samples at that time. The materials developed
to assure that the results being obtained were acceptable were primarily milk, water and food. The radionuclides of interest
were iodine-131, cesium-137 and other short-lived radionuclides found in fission products. These were first issued through
the then Health, Education and Welfare Department's Analytical Quality Control Program and, later, in 1970 through the Environmental
Protection Agency (EPA). In November 1998, the EPA discontinued this program. The FDA is proposing to reinstitute part of
this program, as a primary laboratory, traceable to the National Institute of Technology (NIST) and included in this, the
FDA proposes to supply the States and/or their contractors with low-level standards and with milk- and water intercomparison
samples. It will also use these results where possible as collaborative studies to validate some of the more recent methods
adopted by the American Society for Testing and Materials (ASTM), American Public Health Association (APHA) and Association
of Official Analytical Chemists International (AOAC, Int'l.) The FDA will also supply low-level standards to compliment these
programs as did the EPA. It is expected that these samples will serve as performance evaluation samples for the States programs. 相似文献
14.
15.
A. Baldan Adriaan M. H. van der Veen Daniela Prauß Angelika Recknagel N. Boley Steve Evans Derek Woods 《Accreditation and quality assurance》2001,6(4-5):164-167
Many proficiency tests are operated with a consensus value derived from the participants’ results. Apart from technical issues,
one of the reasons often mentioned is that proficiency tests operated with consensus values would be cheaper than those using
reference values obtained from a priori characterisation measurements. The economy of a proficiency test must of course be balanced by the need of the participants,
and the quality of the comparison in general. The proficiency tests selected in this study had both a reference value and
a consensus value, one of which was used for assessing the performance of the participating laboratories. In this work, both
a technical and an economical assessment of how the comparisons were operated is made. From the evaluation, it follows that
usually the use of consensus values does not necessarily reduce the costs of a proficiency test. However, frequently it may
be observed that the quality of the assessment of the laboratories is better with a reference value.
Received: 11 October 2000 Accepted: 3 January 2001 相似文献
16.
Olaf Rienitz Detlef Schiel Bernd Güttler Michael Koch Ulrich Borchers 《Accreditation and quality assurance》2007,12(12):615-622
Metrologically traceable reference values add an essential benefit to interlaboratory comparisons: unlike consensus values,
they can be used to establish national and international comparability. Furthermore, the participating laboratories obtain
a reliable and unbiased benchmark to check their results for accuracy. Usually, metrologically traceable reference values
are obtained by so-called primary methods which demand excessive efforts at great expense. Within the framework of two national drinking-water interlaboratory comparisons
(proficiency testing rounds), a new approach to provide metrologically traceable reference values was applied. It is solely
based on existing data which were collected during the comparison itself. Lead (Pb) measurements serve as an example to show
how metrologically traceable reference values were derived from the lead amount added during sample preparation and the amount
of lead already present in the drinking-water matrix used to prepare these samples. Within this approach, the matrix content
is calculated in a way similar to a standard addition experiment. An uncertainty budget for the reference value was set up
which describes the link to the corresponding SI units. Isotope dilution mass spectrometry (IDMS) as a primary method was
used to validate this approach in the case of cadmium, chromium, copper, lead, and nickel. 相似文献
17.
A. Uldall 《Accreditation and quality assurance》1996,1(5):218-222
The clinical routine laboratory generally utilizes cheap, easy and rapid measurement procedures ("methods") in order to meet
the requirement for the production of many analytical results (500–3000 per day) of hundreds of different types. The measurement
procedures are optimized for the analysis of native patients' samples, but are frequently sensitive to deviation of the composition
of the matrix from that in normal fresh samples. The inherent lack of stability of patient samples means that control samples
need to be stabilized. The method of stabilization is critical. Furthermore, the method of "spiking" samples with pathological
material is a matter of concern. Generally, minimally processed patients' samples should be used in external quality assessment
(EQA) schemes. Consensus values are currently the most popular for use as a guide to the best results from participating laboratories
in EQA schemes; these often work fairly well. However, the uncertainty and traceability of this type of value is unknown,
and in some cases may even be misleading, tending to preserve bad routine methods when these are dominant in the participating
laboratories. Reference measurement procedure (RMP) values are recommended to provide scientifically based information, to
facilitate the proper choice of methods in the routine laboratories, and to validate the suitability of control materials
in EQA schemes. The present paper provides selected examples from a study comparing consensus values with RMP values on lyophilized
sera, and also presents results on a fresh frozen thawed serum for the study of commutability.
Received: 8 November 1995 Accepted: 8 May 1996 相似文献
18.
Phillips KM Wolf WR Patterson KY Sharpless KE Holden JM 《Analytical and bioanalytical chemistry》2007,389(1):219-229
Over a 6.5-year period a total of 2554 values were reported by nine laboratories for 259 certified or reference nutrient concentrations
in 26 certified reference materials (CRM) submitted to contract laboratories, blinded, as part of the qualifying process for
analytical contracts and in the routine sample stream as part of the National Food and Nutrient Analysis Program. Each value
was converted to a Z′-score, reflecting the difference from the assigned value related to the combined expected analytical uncertainty plus the
uncertainty in the CRM value. Z′-scores >|3.0| were considered unacceptable. For some nutrients (Na, folate, dietary fiber, pantothenic acid, thiamin, tocopherols,
carotenoids, monounsaturated, and polyunsaturated fatty acids), >20% of Z′-scores were >|3.0|. For total fat, vitamin C, and niacin >25% of Z′-scores were >|2.0|. Components for which CRM data were
best (more than 90% of Z′-scores <|2.0|) were Mg, P, Mn, Se, and vitamin B12. In some cases deviations from assigned values were not uniform across
laboratories and materials. For Na almost all high Z′-scores were for low-Na matrices, suggesting analytical problems related to concentration.
Figure Z′-scores for vitamins in certified reference materials
Disclaimer: Certain commercial equipment, instruments, or materials are identified in this paper in order to specify the experimental
procedure adequately. Such identification is not intended to imply recommendation or endorsement by the National Institute
of Standards and Technology, or the United States Department of Agriculture, nor is it intended to imply that the materials
or equipment identified are necessarily the best available for the purpose. 相似文献
19.
Shahida Waheed Asma Rahman Naila Siddique Shujaat Ahmad Matthias Rossbach 《Accreditation and quality assurance》2007,12(6):311-316
The results from a proficiency test exercise for the determination of natural levels of radionuclides in mushroom reference
material carried out by laboratories in six different countries are discussed. These laboratories submitted data on seven
radionuclides, namely 134Cs, 137Cs, 40K, 90Sr, 241Am, 226Ra, and 210Po. However, only the data received for three of these radionuclides could be statistically evaluated to obtain consensus
mean values and confidence intervals (at a significance level of 0.05). The contents of 134Cs, 137Cs and 40K were quantified as 4.4, 2,899 and 1,136 Bq/kg, respectively. 相似文献
20.
Analyses of waste water are routinely performed to monitor the level of contamination. To verify the quality of such determinations
the National Institute of Chemistry, with the support of the Ministry of Environment and Spatial Planning and the Slovenian
Accreditation Agency, organizes interlaboratory comparisons. Over the last 3 years, five interlaboratory trials named "MPP-Waste
Water" were organized. Each round attracted around 50 participants, mostly from Slovenia and some from abroad, which enabled
the testing of SIST ISO methods or alternative methods. We prepared samples for determination of harmful substances that are
important for the characterization of waste water; physico-chemical parameters (pH), global parameters – chemical oxygen demand
(COD), biochemical oxygen demand (BOD5), metals (mercury, cadmium, copper, nickel, lead and chromium (VI)), nutrients (ammonia and total phosphorus), anions (chloride,
nitrite, nitrate, sulphate) and toxicity to Daphnia magna. For the analysis of each parameter we prepared two samples at two different concentration levels. The materials used in
the proficiency testing were carefully prepared and their homogeneity and stability were verified. The purpose of this scheme
was to enable participants to check their day-to-day analytical performance. The results should enable the participants to
improve the quality of their analyses.
Received: 24 October 2002 Accepted: 2 January 2003
Acknowledgments We would like to thank the Ministry of Environment and Spatial Planning and the Ministry for Education, Science and Sport for providing financial support. We would like to thank members of the Technical Committee: Mrs. Marjana Kovacˇicˇ, Dr. Katja Otrin-Debevc, Prof. Dr. Marjan Veber and Mrs. Boža Gregorc for their valuable support. Special thanks are due to Dr. Adrian Van der Veen who helped us in running the first PT.
Presented at 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 M. Cotman 相似文献
Received: 24 October 2002 Accepted: 2 January 2003
Acknowledgments We would like to thank the Ministry of Environment and Spatial Planning and the Ministry for Education, Science and Sport for providing financial support. We would like to thank members of the Technical Committee: Mrs. Marjana Kovacˇicˇ, Dr. Katja Otrin-Debevc, Prof. Dr. Marjan Veber and Mrs. Boža Gregorc for their valuable support. Special thanks are due to Dr. Adrian Van der Veen who helped us in running the first PT.
Presented at 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 M. Cotman 相似文献