IAEA quality control studies on determining trace elements in bioindicators

Twenty laboratories from 17 countries around the world participated in two analytical quality control exercises, coded NAT-5 and NAT-6, on determining trace and minor elements in plant bioindicator samples. 1398 laboratory mean values for 51 elements were submitted for two lichen and two moss materials. The submitted measurement results were evaluated as interlaboratory comparison (IC) exercises and as proficiency tests (PT) following standard procedures developed by the International Atomic Energy Agency (IAEA). The evaluations confirmed good performance of the participating laboratories for many elements. Furthermore, the laboratories performance based on IC criteria improved from the first exercise to the second one. Subsequent NAT-5 evaluation revealed systematic differences between the analytical values obtained non-destructively or after the total sample dissolution and the measurements following nitric acid sample dissolution (without the use of hydrofluoric acid) for some elements. The most critical elements for this kind of discrepancies appeared to be Al, Ca, Cr, Fe, Na, Ni, and Pb. After changing analytical methodologies in the concerned laboratories, more consistent values for those elements were obtained in NAT-6. This revised version was published online in August 2006 with corrections to the Cover Date.     

Findings of national proficiency test exercise for the determination of trace elements in edible mushroom reference material

This paper presents the results of the proficiency test exercise conducted in Pakistan for the determination of trace elements in mushroom reference material. Thirteen laboratories from different organizations of the country submitted trace elemental data on Al, As, Br, Ca, Cd, Ce, Cl, Co, Cr, Cs, Cu, Fe, Hg, K, Li, Mg, Mn, Na, P, Pb, Rb Sc, Si, Sm, Sr, Th, Zn. Results for Al, As, Br, Ca, Cd, Cl, Co, Cr, Cs, Cu, Fe, K, Mg, Mn, Na, Rb Sc, and Zn, in the mushroom material were reported by two or more participating laboratories and could be subjected to statistical evaluation. The original data of these trace elements was subjected to a computer program “Histo Version 2.1” provided by IAEA. The four outlier tests, i.e., Dixon, Grubbs, skewness and kurtosis were applied to the data sets. Consensus (overall) mean values, absolute standard deviation, relative standard deviation, standard error, median and range of values for these elements have been reported at a significance level of 0.05.     

Critical evaluation of laboratory performance from IAEA-452 (fish scallop) inter-comparison exercise results

The International Atomic Energy Agency Marine Environmental Laboratory (IAEA-MEL) conducted an intercomparison exercise for the “Trace elements and methyl mercury in fish scallop: IAEA-452” in 2009. The Neutron Activation Analysis (NAA) laboratory at PINSTECH, Pakistan took part in this exercise. Comparison with the IAEA results showed that of the 18 elements reported to the IAEA 7 had unacceptable z-scores while the data for two elements was questionable (2< |z-score| <3). Upon investigation it was discovered that the large number of elements having unacceptable z-scores was due to human error and the greater difficulty in analyzing biological samples which have low amounts of trace elements. Therefore selection of values corresponding to matrix matched reference materials (RMs), such as IAEA-436 and IAEA-407, and to non-interfering peaks the results obtained became comparable to the IAEA results with only the result for As having |z-score|> 3.     

Participation in IAEA proficiency test exercise on major,minor and trace elements in ancient Chinese ceramic (IAEA-CU-2006-06) using low power research reactor

A proficiency test (PT) exercise was offered by the International Atomic Energy Agency (IAEA) for major, minor and trace elements in Chinese ceramic reference material (IAEA-CU-2006-06). Neutron activation analysis (NAA) laboratory at PINSTECH, Pakistan participated in the exercise and submitted the results for 28 elements. The aim of participation was to develop a suitable methodology for accurate measurement of as many elements as possible in ceramic material using a low power reactor (PARR-2) as this would help future investigation in a project on the authenticity of art objects, for provenance, conservation and management of ancient cultural heritage of the country. After receiving the final report of the PT exercise, a critical review of our data and final scoring of each element is made to check the suitability of our methodology and reliability of the acquired data. Most of the reported results passed different statistical evaluation criterion such as relative bias, z-score and u-scores and ratio of our results and IAEA target values. One element (Yb) falls in the unacceptable range of relative bias and z-scores. Hf and Tb showed slightly high z-scores within the questionable range. Ho, Mo and Sn were determined during this study but their results were not submitted to the IAEA. The confidence of accuracy observed for most of the elements in ceramic material has made it mandatory to report their results as information values.     

Preparation and characterization of a proficiency test material “Polish mushrooms” supported by the International Atomic Energy Agency (IAEA), Vienna

Mushroom reference material has been prepared and characterized for use in proficiency test exercises within the frame of an IAEA Interregional Technical Cooperation Project. Laboratories from 14 countries provided results for homogeneity testing and the assignment of property values. The contents of 11 elements have been assigned. The material was used for conducting a proficiency test in Poland and the results obtained by Polish laboratories are presented and discussed.     

Comparison of neutron activation analysis with other analytical techniques for the determination of inorganic constituents of milk powder

The contribution of different analytical techniques to the results of a recent IAEA intercomparison (A-11) of the determination of the inorganic constituents of a milk powder sample is discussed. In all, 43 laboratories from 24 countries reported results on 40 elements, “recommended” concentrations for 14 elements were established. NAA was the most important of the 9 techniques used in this run, it contributed 40% of all the results and all the results for 7 elements. Accuracy and precision of NAA proved to be good compared to those of other methods.     

Round Robin “Impurities in Uranium Matrix”: A Success for CETAMA and IAEA

The safeguard of nuclear material is of paramount importance to the IAEA which increasingly uses this information for characterization purposes in order to strengthen the verification of declared nuclear material and to identify the origin of samples from mines. IAEA tasked CETAMA to conduct a round robin with objective to evaluate the capability of laboratories to measure impurities in uranium with concentration levels between 1 and 500 ppm relative to uranium. This round robin was attended by 17 international laboratories from the nuclear industry and safeguards community. The results are mainly obtained by ICP-MS (14) and ICP-AES (3). The synthesis of this round robin were helpful in identifying anomalies and will allow the IAEA to better set realistic measurement performance targets for ICP-MS and ICP-AES.     

The establishment of quality systems in veterinary diagnostic testing laboratories in developing countries: experiences with the FAO/IAEA External Quality Assurance Programme

Quality systems, established to internationally accepted standards, are one mechanism that can assist in evaluations of the sustainability of technology transfer, the proficiency of the user, and the reliability and comparability of data generated, resulting in potential enhancement of laboratory credibility. The means of interpreting existing standards and implementing quality systems in developing country veterinary diagnostic laboratories has become a significant adjunct to the technology transfer element within the Food and Agriculture/ International Atomic Energy Agency, FAO/IAEA programme. The FAO/IAEA External Quality Assurance Programme (EQAP) is given as an example for an initial step towards enhancing the “quality” culture in developing country veterinary laboratories. In 1995 the EQAP began as an effort to assure that test results emanating from laboratories using FAO/IAEA ELISA kits for animal disease diagnosis are valid. For this purpose 15 international external quality-assurance rounds have been performed to date for a variety of animal diseases e.g. Rinderpest, brucellosis, trypanosomosis, and foot-and-mouth disease (FMD). Results indicate that the EQAP is a valuable tool in the assessment of both the results provided by, and use of the ELISA kits provided through, the joint FAO/IAEA programme. Furthermore EQAP can assist laboratory diagnosticians to enhance quality control/quality assurance (QC/QA) procedures for conducting FAO/IAEA ELISAs and to advise on the implementation of similar QC/QA procedures in other laboratory activities. Based on the experiences made during the implementation of the EQAP a proposal for establishing a quality system standard was ratified through the World Organization for Animal Health (OIE) general conference in May 2000. The OIE Standard On Management And Technical Requirements For Laboratories Conducting Tests For Infectious Animal Diseases is based on ISO 17025 and provides a clear formula for establishing quality systems in veterinary diagnostic laboratories world-wide.     

Multielement analysis by total reflection X-ray fluorescence spectrometry for the certification of lichen research material

 Total reflection X-ray fluorescence spectrometry was applied for the certification of IAEA lichen-336. The elements Ca, Mn, Fe, Cu, Zn, Rb, Sr and Pb were determined simultaneously. The concentrations range from 1.8 mg/kg for Rb to 2360 mg/kg for Ca. The results were compared with those of other methods and laboratories having participated in this certification for the International Atomic Energy Agency (IAEA): emission spectrometry, mass spectrometry, atomic absorption spectrometry, X-ray spectrometry, neutron activation analysis and voltammetry. The results determined by TXRF are in good agreement with the overall means of accepted values and differ from the means by 1 to 10%. Received: 1 September 1996/Revised: 15 October 1996/Accepted: 22 October 1996     

Analytical Intercomparison Exercises and Harmonization within Environmental Laboratories from Developing Countries

Abstract

Since the early 60's, the IAEA implements a Quality Assurance (QA) programme for the Member States. As part of this programme, the IAEA organized more than 150 analytical intercomparison exercises and produced more than 70 Certified Reference Materials for a wide range of determinands, encompassing radionuclides, trace elements, petroleum hydrocarbons, pesticides and PCBs. From the IAEA — Marine Environment Laboratory in Monaco, analytical Quality Assurance services are provided for non-nuclear contaminants in marine materials.

Results of recently organized worldwide intercomparison exercises using the sample materials IAEA-142 (mussel tissue homogenate) and IAEA-140 (seaweed homogenate), show that some progress was achieved worldwide in the analyses of the more common environmental contaminants. However, results also show that difficulties in obtaining accurate data for trace elements and especially for organic contaminants are still widespread, particularly in developing countries. Therefore, the success of international cooperative programmes as well as of many regional environmental monitoring programmes, depends on improved quality and comparability of data which has to be achieved still through reinforced Quality Assurance programmes. To this aim, the IAEA/UNEP/IOC-UNESCO inter-agency programme on marine pollution promotes the adoption of Reference Methods for harmonization of techniques used in developing and developed countries, organizes frequent intercomparison exercises, and produces certified marine Reference Materials which are made available to laboratories worldwide.     

Preparation and characterization of a new set of IAEA reference air filters using instrumental neutron activation analysis, proton-induced X-ray emission and Rutherford backscattering

A new set of reference air filters was prepared for proficiency testing of laboratories involved in air pollution studies organized by the International Atomic Energy Agency (IAEA). The set consists of one filter loaded with airborne particulate matter (APM) and one blank filter. Target values and their standard deviations were established using instrumental neutron activation analysis (INAA) and proton induced X-ray emission (PIXE) with proven accuracy. Rutherford backscattering (RBS) was used to help in deriving the necessary corrections in PIXE. Losses of individual elements from APM due to the wet deposition procedure were evaluated.     

Towards accreditation of clinical biochemistry in the public sector on the island of Mauritius

Medical laboratories of the public sector as well as of the private sector on the island of Mauritius are preparing for accreditation. The clinical laboratory of the Central Health laboratory of the Ministry of Health and Quality of Life has undergone a pre-assessment by experts of the International Atomic Energy Agency (IAEA) through the aegis of a project targeted to members of the Africa Region. Several shortcomings were identified and respective corrective actions were recommended for implementation within a given time frame. In addition to ensuring the competence of the laboratory, accreditation has various positive aspects such as an increased awareness of the staff to quality and better training opportunities. The pre-assessment exercise has provided a gap analysis, which is an important aspect in the preparation towards accreditation.     

Establishment of a quality system for nuclear analytical laboratories

Comprehensive Quality Control (QC) and Quality Assurance (QA) Program is stated on the quality policy, organization, methods and records for nuclear analytical laboratories which are necessary for improvement of productivity, to upgrade the performance, credibility and reputation. The proper and complete identification of quality elements for management and technical requirements are being written in Quality Manual as well as analytical and organizational procedures and working instructions according to ISO 17025 standard. Technical ability of gamma, X-ray and a/b laboratories in the Center has been checked by participation in proficiency test, critical technical variables, and quality results. Performance of quality system has been controlled by external audit inspection, progress reports and service to clients. The present study is a framework of the model project of IAEA, coded RER/2/004, which has resulted self-sustainable accreditation from the national body, TURKAK. This revised version was published online in August 2006 with corrections to the Cover Date.     

Characterization of a potato reference material for major, minor and trace elements

Summary A potato reference material (RM) was prepared for the analytical quality control program to be employed by the Sub-network on Trace Elements in Food of the FAO European Co-operative Network on Trace Elements. Approximately 50 kg of commercially available potato granules prepared from baked, mashed and roller-dried potatoes, containing 2.8% ash and 3 mg/kg added butylhydroxyanisole was purchased. The granules were carefully homogenised in large glass cylinders followed by division into 50 g portions into numbered acid-washed bottles. The bottled material was tested for homogeneity by taking ten bottles throughout the bottling line and determining by validated atomic absorption spectrometric methods 1.0 g samples for seven mineral elements. Homogeneity for Mg, Ca, Zn, Fe, Mo, Ni and Cd was better than 5%. An international network on experienced, high-quality reference laboratories was established to conduct an interlaboratory comparison study on the determination of 14 mineral elements in the RM. A total of seven methods based on independent analytical principles were employed by the reference laboratories. After excluding outlying analytical results, the criteria defined by the IAEA were used for classification of the overall medians obtained through the interlaboratory comparison study. The relative standard deviations for the 95% confidence limits of the medians were as follows: P=4.2%, K=0.7%, Na=4.7%, Ca=5.5%, Mg=2.4%, Fe=9.3%, Mn=4.0%, Zn=3.6%, Cu=4.7%, Mo=23%, Ni=22%, Cr=19%, Pb=11% and Cd=4.6%. With the exception of Cr, all of the recommended concentration values obtained for the above indicated elements fell into category A, i.e. values recommended with a high degree of confidence according to the classification criteria of the IAEA. The present RM is the only certified potato RM currently available for mineral elements.

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Charakterisierung eines Kartoffel-Referenzmaterials für Haupt-, Neben- und Spurenelemente

     

Certifying the chemical composition of a biological material — a case study

A worldwide laboratory intercomparison was organized by the International Atomic Energy Agency's Analytical Quality Control Services (AQCS) involving the determination of trace elements in plant materials used for human consumption. The National Institute of Standard and Technology (NIST) Standard Reference Materials Program donated 5 kg of spinach designated for the production of the future Standard Reference Material SRM 1570a to this intercomparison; the AQCS provided a similar amount of cabbage. For the study, 150 units of each material were distributed and 114 laboratories reported results on both materials to AQCS. The results for the spinach, encompassing more than forty elements, have been compiled and evaluated; estimates of the elemental concentrations were made based on statistical evaluations, principles of analytical procedures and the laboratory performance indicated by the results on the cabbage material. Satisfactory estimates were obtained for 27 elements. Comparison with IAEA laboratory and NIST reference data did not reveal any significant bias that might have been introduced by the intercomparison approach or its evaluation.     

Certification of trace and major elements and methylmercury concentrations in a macroalgae (Fucus sp.) reference material, IAEA-140

A marine reference material, IAEA-140, prepared with a macroalgae (Fucus sp.) was recently produced by the International Atomic Energy Agency and certified for trace and major elements and for methylmercury (MeHg). Certification of this material was achieved as an outcome of an international analytical intercomparison study which resulted in 116 independent sets of results reported by participants from 54 countries. The statistical evaluation of the collected data and the criteria used for assignment of the mean and uncertainty values are described. The analysis of data allowed to certify concentration values for 24 elements and MeHg, and to provide information values for another 10 elements. Regarding the elements which could be given certified values, between two and eight different instrumental methods were used to measure metal concentrations, and four independent analytical procedures were used to measure MeHg concentrations. In order to assess the results of the certification procedure, a comparison was made between the certified values obtained from the world-wide intercomparison results and the values obtained from a small subgroup of well-qualified laboratories. The means and 95% confidence intervals for reference values obtained by the two methods are similar for most elements showing that the usual method of certification used by the IAEA, based on large groups of participants, is indeed pertinent.     

Evaluation of laboratory performance using proficiency test exercise results

The IAEA conducted the IAEA-CU-2006-06 Proficiency Test (PT) on “The determination of major, minor and trace elements in ancient Chinese ceramic” in 2006. The results of this PT showed that of the 21 analytes reported by our laboratory 9 failed the precision criteria. Therefore the results reported by our laboratory along with the results of other laboratories which carried out analysis using neutron activation analysis (NAA) were studied. It was found that the major factor contributing towards data falling in the “Warning” category, failing the precision criteria was the high uncertainties cited in the certificates of the reference materials (RMs) used for quantification of data. In this regard, it is recommended that synthetic standards should be prepared and used on a routine basis especially for the measurement of the elements K, Eu, Lu, Ta, Tb and Yb.     

Quality system implementation in Member States of the IAEA

The International Atomic Energy Agency (IAEA), through its Technical Co-operation Programme, has supported the establishment of many nuclear analytical and complementary laboratories in Member States. This included the development of capabilities for the use of various nuclear analytical techniques that include alpha, beta, and gamma spectrometry; radiochemical analysis; neutron activation analysis; energy dispersive X-ray fluorescence analysis; and total reflection X-ray fluorescence. As economic, ecological, medical, and legal decisions are frequently based on laboratory results, they need to be based on accepted national and international standards.The IAEA has taken up this important issue to enhance and foster the competitiveness of nuclear analytical laboratories with the consideration that non-nuclear capabilities are equally important. The projects aim at enhanced quality awareness, a concise system for documentation, establishment of standard operating procedures, procedures for validation of methods, surveillance of method performance, systems for sample management, regular qualification of personnel, client liaison and safety. These projects follow the ISO/IEC 17025 standard and promote participating laboratories to maintain a self-sufficient quality system by which they might be able to obtain national accreditation.This contribution describes the general concept of these projects and discusses some of the results achieved.     

Investigation of air pollution in Chile using biomonitors

A project has been undertaken to carry out a long term study on atmospheric air pollution in Chile using biomonitors. Samples of different species of lichens were collected in clean areas (native forest), analyzed and transplanted to the Santiago Metropolitan Area. In addition, samples of Tillandsia recurvata were collected in the Metropolitan Area for comparison purposes. The preparation of the samples was done under controlled, cryogenic conditions and analyzed by neutron activation analysis and solid sampling atomic absorption spectrometry. As part of the routine QA/QC procedures, the analytical laboratories, have participated in intercomparison runs organized by the IAEA for the determination of trace and minor elements in two lichens samples. The present paper describes the activities carried out within the framework of this project. This revised version was published online in July 2006 with corrections to the Cover Date.