Interlaboratory Comparison Tests Research Articles

Boric acid as a reference substance in avoidance behaviour tests with Porcellio dilatatus (Crustacea: Isopoda)

Isopods are macrodecomposers in terrestrial ecosystems, contributing to soil organic matter breakdown and nutrient cycling. They have been considered sensitive in laboratory tests designed to evaluate contaminants effects and are considered likely candidates to have a standardized protocol for ecotoxicity tests. For this purpose, a reference substance should be proposed as positive control in laboratory tests. This work aimed to evaluate the avoidance behaviour of the isopod species Porcellio dilatatus to boric acid (H3BO3; BA). Interlaboratory comparison tests were carried out based on the ISO guideline for earthworms, using tropical artificial soil as substrate, in the concentrations of 0, 125, 250, 500, 750, 1000, 1300 and 1800 mg BA kg−1 soil. Avoidance behaviour was evaluated in group (six organisms per replicate) and in individual tests (one organism per replicate), in dual-section plastic boxes, which received control soil (not contaminated) in one side and tested soil (with BA) in another one. The percentage of organisms in each side was recorded after 48 h, and data were analysed using Fisher exact test (p < 0.05) and t-test. Results showed significant avoidance response in individual tests at 250 mg kg−1 and in group tests at 500 mg kg−1. Limited habitat function (< 20% of organisms) for both tests and laboratories were observed at the highest tested concentration of 1800 mg kg−1, indicating the low sensitivity of this species to BA in avoidance tests, if compared to other substances in literature. Results showed that BA can be used as reference substance until a better option will be proposed.

INTERLABORATORY COMPARATIVE TESTS OF METALLURGICAL MATERIALS

The experience of JSC «The Institute for Certified Reference Materials» (JSC «ICRM») in organizing and conducting inter-laboratory comparative tests (ICT) is considered. ICT are conducted to determine the values of certified characteristics of standard samples and examine the qualifications of the laboratories. Data on ICT carried out by JSC ISO in 2012 – 2017, as well as information on the ICT program for 2018 are presented. Some issues emerged upon accreditation of the JSC «ICRM» as a provider of inter-laboratory comparative tests are considered.

STUDY OF THE ACCURACY OF SPECTRAL ANALYSIS IN DETERMINATION OF ALUMINUM AND NICKEL IN STEEL BY THE RESULTS OF INTER-LABORATORY COMPARATIVE TESTS

The results of estimating the accuracy of spectral analysis of steel according to inter-laboratory comparative tests (ICT) conducted by JSC «ISO» to attest standard samples and examine qualification of the laboratories are considered. Data on the consistency of the results of spectral analysis and data of chemical methods and their comparison with analogous data of ICT of foreign standard samples are also presented.

THE INSTITUTE FOR CERTIFIED REFERENCE MATERIALS MARKS THE 55TH ANNIVERSARY OF FOUNDATION. DEVELOPMENT AND PRODUCTION OF CERTIFIED REFERENCE MATERIALS FOR METALLURGICAL PRODUCTION

The Institute for Certified Reference Materials (ICRM) is going to celebrate the 55 th anniversary in March 2018. The results of the ICRM activities in development and production of the certified reference materials (CRM) of raw materials and materials of metallurgical production over the past five years are considered. The nomenclature of the CRM produced by the ICRM includes raw materials (ores and concentrates, ferroalloys and ligatures, fluxes, refractories), metals (cast iron, steel, nickel-base alloys) and waste of metallurgical production (slags and metallurgical fly ashes). To approve the competence, the ICRM has been accredited as a producer of reference materials (RMP) in accordance with the requirements of the International Standard ISO Guide 34:2009 (ISO Guide 34). Testing analytical center of the ICRM (TC) applies both classical methods of chemical analysis (methods of «wet chemistry») and modern physicochemical and physical methods. TC is accredited in accordance with GOST ISO/IEC 17025 – 2009 in the National accreditation system. The competence of Testing Centre has been repeatedly approved by the results of inter-laboratory comparative tests for certification of reference materials produced abroad including those from the European Union (ECRM). The inter-laboratory tests (proficiency tests — PT) are performed by the Provider, ICRM accredited in the National Accreditation System for compliance with the requirements of GOST ISO/IEC 17043:2013. We consider and analyze contradictions in the statutory regulation and resulting difficulties encountered in the activities of producers of reference materials in Russia. The approval of reference materials to be used in the state system for ensuring the uniformity of measurements is possible only on the basis of positive test results. This procedure (RM testing for type approval purposes) has no analogues in the world practice. In accordance with the Russian legislation, the ICRM has got accreditation to perform RM testing for the type approval purposes in 2015. In 2013 – 2017 the Institute developed and certified 7 CRM sets of steel and 3 CRM sets of cast iron for spectral analysis (solids), and 46 CRM for chemical analysis (in dispersed form), including carbon and alloyed steel, cast iron, ferroalloys, ore and concentrates, metallurgical slags.

Interlaboratory comparison tests in mineralogical works

Introduction. Activities of FSBI “VIMS” are aimed at ensuring accuracy and comparability of the results of mineralogical analyses accompanying exploration and technological work. Evaluation of the research result quality is carried out with the help of various metrological instruments, one of which is an interlaboratory comparison test. Purpose. The purpose of interlaboratory comparison tests (ICTs) is to assess the results of X-ray quantitative phase analysis of an artificial mixture of minerals and to confirm the level of competence of testing laboratories. Methods. The procedure for conducting interlaboratory comparison tests is as follows: development of the programme and its approval; collecting and registering applications from laboratories, willing to participate in the ICT programme; preparation and simultaneous sending of control samples with accompanying information materials to those participating in the experiment; statistical processing of obtained results; drawing up, approval and circulation of documents confirming participation of the laboratories. The control sample is a homogenized artificial mixture of minerals (quartz, kaolinite, calcite and pyrite). The accuracy (quality) control of test results was carried out by X-ray quantitative phase analysis. Results . The ICT results showed a high level of competence of testing laboratories. For unreliable and unsatisfactory results percentages total less than 11%, the percentage for unfulfilled results is equal to zero. Interlaboratory comparison tests in mineralogical works are an important means for controlling competence of testing laboratories.

УЧАСТИЕ ЛАБОРАТОРИЙ В МЕЖЛАБОРАТОРНЫХ СЛИЧИТЕЛЬНЫХ (СРАВНИТЕЛЬНЫХ) ИСПЫТАНИЯХ. ОСНОВНЫЕ ТРЕБОВАНИЯ. ПРАКТИЧЕСКАЯ РЕАЛИЗАЦИЯ ТРЕБОВАНИЙ. ПЕРСПЕКТИВЫ

The topical issues of participation of laboratories in interlaboratory comparison tests, the requirements of the international standards ISO, requirements of transnational and national standards ISO, the national accreditation body are considered. The progress on the revision of the international standard ISO/IEC 17025:2005 and the order of the transition to the updated version of 2017 are described. The information about changes in the approach of the national accreditation body to organizations of interlaboratory comparison tests (ICT) is given. The immediate prospects for the russian providers of interlaboratory comparison tests (ICT) and testing laboratories accredited in the national accreditation system are defined.

Development of certified reference material of mineral composition of natural water designed to control of turbidity measurement accuracy

Introduction. The results of development of a certified reference material (CRM) of mineral composition of natural water are presented. A solution prepared from the material of the CRM specimen imitates mineral composition of natural surface water. The certified values are mass fractions of nitrate ions, chloride ions, fluoride ions, and total iron and turbidity according to formazine scale. Materials and methods. The certified values of mass concentrations of the components were determined using calculated experimental evaluation procedure;the certified turbidity value was determinedusing the certified turbidimetric method. Results. The relative expanded uncertainty (k = 2) of the certified turbidity values does not exceed 5 %, the same value for mass concentrationsis not more than 3.5 %. Relative standard uncertainty from heterogeneity does not exceed 1.0 %. The shelf life of the developed CRM is set to 3 years. Discussion and conclusion. Developed CRM was registered in the State Register of CRM's as GSO 10815-2016. The CRM is designed to control the accuracy of results of the certified characteristics measurements, including proficiency testing of laboratories using interlaboratory comparative tests. The CRM can be used for validation of measurement procedures.

A scoring metric for multivariate data for reproducibility analysis using chemometric methods

Process quality control and reproducibility in emerging measurement fields such as metabolomics is normally assured by interlaboratory comparison testing. As a part of this testing process, spectral features from a spectroscopic method such as nuclear magnetic resonance (NMR) spectroscopy are attributed to particular analytes within a mixture, and it is the metabolite concentrations that are returned for comparison between laboratories. However, data quality may also be assessed directly by using binned spectral data before the time-consuming identification and quantification. Use of the binned spectra has some advantages, including preserving information about trace constituents and enabling identification of process difficulties. In this paper, we demonstrate the use of binned NMR spectra to conduct a detailed interlaboratory comparison. Spectra of synthetic and biologically-obtained metabolite mixtures, taken from a previous interlaboratory study, are compared with cluster analysis using a variety of distance and entropy metrics. The individual measurements are then evaluated based on where they fall within their clusters, and a laboratory-level scoring metric is developed, which provides an assessment of each laboratory's individual performance.

The reproducibility of corrosion testing in supercritical water—Results of an international interlaboratory comparison exercise

A major challenge in supercritical water-cooled reactor development is the lack of a consistent alloy database. An international interlaboratory comparison test was organized to study the reproducibility of weight change data obtained for identical alloys under similar conditions in different facilities. This paper presents the test procedures, conditions, results, and additional characterization data. More variation in weight change was observed than expected. The scatter was small within the same laboratory, but large between different laboratories. Much of this variation appears to be attributable to differences in test facilities. The data generally agree on the relative ranking of the corrosion resistance.

Determination of Phosphine in Plant Materials: Method Optimization and Validation in Interlaboratory Comparison Tests

The optimization and validation of a method for the determination of phosphine in plant materials are described. The method is based on headspace sampling over the sample heated in 5% sulfuric acid. Critical factors such as sample amount, equilibration conditions, method of quantitation, and matrix effects are discussed, and validation data are presented. Grinding of coarse samples does not lead to lower results and is a prerequisite for standard addition experiments, which present the most reliable approach for quantitation because of notable matrix effects. Two interlaboratory comparisons showed that results varied considerably and that an uncertainty of measurement of about 50% has to be assessed. Flame photometric and mass spectrometric detection gave similar results. The proposed method is well reproducible within one laboratory, and results from the authors' laboratories using different injection and detection techniques are very close to each other. The considerable variation in the interlaboratory comparison shows that this analysis is still challenging in practice and further proficiency testing is needed.

A study on the utilization of the Youden plot to evaluate proficiency test results

Methods of utilizing the Youden plot obtained from interlaboratory comparison tests are proposed. The Youden plot is a powerful tool for visually evaluating between- or within-laboratory errors. However, there are no generally applicable methods to indicate the anomalies in the between- and the within-laboratory errors in qualitative terms. An evaluation frame was therefore developed in this study as an indication method. Moreover, the Youden plot is considered to be useful for visually assessing the comprehensive performance of laboratories using two types of results. Although the confidence ellipse has been proposed in ISO 13528:2005 for this purpose, robust determination of the parameters has not yet been implemented. In the present study, robust determination of one of the parameters, the correlation coefficient, was developed. Our proposals were analytically validated using two types of statistical models. In addition, the properties were evaluated through computational simulations. From the results obtained, it can be concluded that our proposals are practically applicable to actual interlaboratory comparison tests.

Interlaboratory comparison for determination of ochratoxin A by ELISA in maize (running title: Determination of ochratoxin A in maize)

Participation in interlaboratory comparison and proficiency testing schemes is important for laboratories to control the work quality. In this study, a sample of naturally contaminated maize was analyzed for the content of ochratoxin A (OTA) in three laboratories in Serbia. Participating laboratories used enzymatic immunoaffinity method (ELISA) for the determination of OTA and selection of the ELISA kit was free. Between-laboratory precision was acceptable as evidenced by Cochran?s C test. Moreover, z-scores for all three laboratories were z &lt; ? 2, which is considered acceptable. Used OTA confirmation methods were thin-layer chromatography (TLC) and high-pressure liquid chromatography (HPLC), with fluorescence detector. The results of different methods were comparable.

Study on the Interlaboratory Comparison Test of the Electronic Test Method for Raw Silk

To establish an international standard on the electronic testing method for raw silk, the interlaboratory comparison tests of the electronic testing method for raw silk are done. Five lots of soaked silk are sampled and tested by four machines of the same type in four labs, 13 items including the defects and evenness information of each lot of silk are measured. The analysis of variance and multiple comparison procedure are used to find whether there exist significant differences among the four machines; and the result shows that there are no significant differences among the machines in testing these items except for the item of IPMe by optical sensor. The reason for the difference is analyzed, and the measure for dismissing the difference is proposed.

Metrological support of water-environmental control

Analysis is given to the source of errors, invalidating the results of laboratory studies of water and the standards, norms, and regulations for ensuring the accuracy (validity and accuracy) of methods and results of measurements. The accreditation of laboratories, and their use of the means of measurements and reference standards, admitted for use in accordance with the established order, as well as the participation in interlaboratory comparison tests are shown to be necessary but not sufficient conditions for providing customers with reliable measurement data. To obtain measurement results with an error satisfying the established standards, one should demonstrate conscious and competent attitude toward the measurement problem in accordance with the basic ISO/MEK 17025 standard. It is shown that, under the conditions of increasing value of fresh water in the world, the metrological support of water-environmental control becomes an urgent and specific scientific problem. Therefore, it is proposed to develop water qualimetry—the direction of scientific and applied studies, making it possible to evaluate the characteristics of measurement errors in the characteristics under control to ensure their lying within the established limits with a specified probability.

Testing the proficiency of analytical laboratories by means of inter-laboratory comparison tests – an important element in assurance of the uniformity of measurements

The role of proficiency testing of laboratories through inter-laboratory comparison tests in an effort to assure the uniformity of measurements is considered.

Odor and Odorous Chemical Emissions from Animal Buildings: Part 1. Project Overview, Collection Methods, and Quality Control

Livestock facilities have historically generated public concerns due to their emissions of odorous air and various chemical pollutants. Odor emission factors and identification of principal odorous chemicals are needed to better understand the problem. Applications of odor emission factors include inputs to odor setback models, while chemical emission factors may be compared with regulation thresholds as a means of demonstrating potential health impacts. Acompanion study of the National Air Emissions Monitoring Study (NAEMS) included measurements necessary for establishing odor and chemical emission factors for confined animal feeding operations. This additional investigation was conducted by the University of Minnesota, Iowa State University, West Texas A&M Agri-Life Center, and Purdue University. The objectives were to (1) determine odor emission rates across swine and dairy facilities and seasons using common protocols and standardized olfactometry methods, (2) develop a chemical library of the most significant odorants, and (3)correlate the chemical library with the olfactometry results. This document describes the sampling and quality assurance methods used in the measurement and evaluation of odor and chemical samples collected at two freestall dairy farms, one sow (gestation/farrowing) facility, and one finishing pig site. Odor samples were collected in Tedlar bags and chemical samples were collected in sorbent tubes at barn inlet and exhaust locations using the NAEMS multiple-location gas sampling systems. Quality assurance protocols included interlaboratory comparison tests, which were evaluated to identify variations between olfactometry labs. While differences were observed, the variations among the labs and samples appeared random and the collected odor data were considered reliable at a 0.5% level of statistical significance. Overall, the study took advantage of groundbreaking opportunities to collect and associate simultaneous odor and chemical information from swine and dairy buildings while maintaining accordance with standard methods and comparability across laboratories.

A High-Performance Liquid Chromatographic-Tandem Mass Spectrometric Method for the Determination of Ethyl Glucuronide and Ethyl Sulfate in Urine Validated According to Forensic Guidelines

Ethyl glucuronide (EtG) and ethyl sulfate (EtS) are powerful markers for alcohol intake and abuse. Several analytical procedures for the quantification of EtG and EtG in serum and urine have been developed so far. Many of the published methods show limits of detections (LODs) or limits of quantifications (LOQs) for EtG in urine within the range of 0.1 mg/L or higher. Since this is the actual cutoff value for proving abstinence in Germany, problems may occur if urine samples are highly diluted. In this paper, the validation of a highly sensitive, fast and simple LC-MS-MS for the determination of EtG and EtS in urine is described. The calibration curves for EtG and EtS is linear over the whole range (0.025-2.0 mg/L). Very low detection limits can be achieved (LOD: EtG 0.005 mg/L, EtS 0.005 mg/L; and LOQ: EtG 0.019 mg/L, EtS 0.015 mg/L). All data for selectivity, precision and accuracy, recovery, as well as for the processed sample and the freeze/thaw stability, comply with the guidelines of the German Society of Toxicological and Forensic Chemistry. Strong matrix-related effects can be compensated for by using an internal standard. Finally, the applicability of the procedure is proven by analysis of 87 human urine samples and by successful participation in interlaboratory comparison tests.

Identification of weak spots in the metrological investigation of dynamic machine behaviour

Both the measurement of frequency response functions and the modal analysis are established tools for the measurement of the dynamic compliance of machine tools. State of the art measurement technique enables an allocation of dynamic weak points of the machine structure and optimization of the machine design on the basis of these measurement results. In recent applications the metrological investigation is used for the parameterization and the verification of simulation models to describe the dynamic behaviour of machine tools, which demands high standards regarding to the quantitative quality of measurement results. This paper describes the interlaboratory comparison test, which has been carried out at well-known German research institutes and was initiated by the Laboratory for Machine Tools and Production Engineering (WZL) of the RWTH Aachen. In this regard, the question is discussed, to what extent the compliance behaviour of machine structures under real process conditions corresponds to behaviour, determined in metrological investigation under idealized test conditions.

중금속분석용 폐수표준물질 제조 및 실험실간 비교평가

In this study, the wastewater-based reference material (RM) was prepared and certified for 7 trace metal elements with evaluation of uncertainties. The RM was distributed to 25 laboratories for the interlaboratory comparison testing. The certified values and expanded uncertainties were derived using ISO guideline 35 and the standard uncertainties for homogenieties were 0.43~2.67% of certified values. The analytical results from the interlaboratory comparison testing showed normal distributions and the robust means from the interlaboratory comparison testing were higher than the certified values of the RM for all analytes.

Assessment of international inter-laboratory comparison tests for the diagnosis of classical swine fever from 1998 until 2007

The inter-laboratory comparison tests for classical swine fever (CSF) laboratory diagnosis organised by the European Community Reference Laboratory for CSF are regularly performed within European Union Member States. The objective of this study was to evaluate the results of the inter-laboratory comparison tests carried out over the last decade, from 1998 until 2007, by using a statistical approach. A set of five or six lyophilised sera was sent to participants. These included sera containing CSF antibodies, sera containing antibodies against ruminant pestiviruses, sera containing CSF virus and negative sera. This study focused on the results of the diagnostic reference methods for CSF: the neutralisation test for the detection of CSF antibodies (including its interpretation) and virus isolation for the detection of CSF virus. For the detection of CSF antibodies, results were closest to what was expected by the Community Reference Laboratory when only neutralisation tests were performed. The percentage of correct results decreased as soon as the results of CSF antibody enzyme-linked immunosorbent assay were included or when sera with antibodies to ruminant pestiviruses were added to the panel. The results for the detection of CSF antibodies are still valid today, as no additional method has been introduced recently. Regarding CSF virus detection, CSF virus isolation is well established but on the way to being superseded as the reference test by reverse-transcription polymerase chain reaction.