Interlaboratory Test Research Articles

Ensuring the Validity of the Results by Participating in ILC Schemes—Case Study: The Determination of the Water-Soluble Chromium (VI) Content of Cement

The paper presents the mode in which an accredited laboratory, according to SR EN ISO/IEC 17025, monitors its performance by comparing the results with the results of other laboratories. This article aims to analyse the results of the participation of an accredited laboratory in two ILC schemes, one organized in France and the other in Romania, on cement, discussing only the results of the determinations of the water-soluble hexavalent chromium content. Although chromium (VI) is not present in large amounts in cement, it is responsible for allergic reactions on the skin of workers. Thus, in EU countries, the maximum amount of water-soluble Cr (VI) in bagged cement or in the products based on cement is limited to a maximum of 0.0002% by mass of cement. The Chromium (VI) results obtained by the lab must meet the requirements of the standard SR EN 196-10 for the repeatability and, where appropriate, the reproducibility. Questions about the validity of the results arise when the laboratory obtains satisfactory results in the ILC scheme, but the standard deviation of the scheme is higher than that recommended in the standard method. The elements of the novelty of this paper are the interpretation of water-soluble Cr (VI) results and the use of information obtained from participating in interlaboratory testing schemes tom improve the validity of laboratory results.

Fracture toughness of 3Y-TZP ceramic measured by the Chevron-Notch Beam method: A round-robin study

ObjectiveThis interlaboratory round robin test investigated the robustness of the Chevron-Notch Beam (CNB) test method and the effect of the processing and testing variations on the fracture toughness of a dental 3Y-TZP ceramic. MethodsThe round robin test was performed precisely following the procedures recommended in ISO 24370:2005 and applied on a commercial 3Y-TZP ceramic (product information). A total of 335 test specimens with dimensions 3×4 x 45 mm³ was equally distributed among 10 participating laboratories of varying experience in fracture toughness testing. A standard operating procedure was defined with either narrow processing tolerances or alternative (wider) processing tolerances (as proposed in ISO 24370). Fracture toughness data (series 2) was analyzed using one way ANOVA followed by post hoc Tukey HSD test and 95% Confidence Intervals (CI) were computed (p < 0.05). A further, preceding round-robin (series 1) test was conducted with - more possible variations of test conditions regarding CNB notch processing and storage conditions. Those results are summarized in the supplement and discussed with the actual ISO 24370 test. ResultsFracture toughness of the 3Y-TZP ceramic material, summarized over all laboratories was measured to KIc = 4.48 ± 0.11 MPam0.5 for the standard processing tolerance and KIc = 4.55 ± 0.31 MPam0.5 for the alternative tolerance. The results revealed a significant influence of cutting offset and notch geometry on KIc when using CNB method. The test medium also has a significant influence on KIc in terms of reduced fracture toughness under the influence of water. With defined testing conditions the number of valid tests and reduced standard deviation increased. In case of strictly following such standard operation procedures, KIc can be determined with high reliability. There is no difference between the involved laboratories, but significant influence of cutting offset on KIC was observed. SignificanceThe CNB method is suitable method for determination of KIc on fine-grained ceramics such as 3Y-TZP ceramic. By using tighter tolerances for processing and testing, i.e. closely following the ISO 24370 procedure, a highly-precise evaluation of fracture toughness with low data variation is achievable. The information of the storage medium should always be reported along with the data. CNB fracture toughness testing is an alternative method compared to Single-edge V-notch beam (SEVNB), especially for fine-grained ceramics.

Standards and Assessment of Construction Products: Case Study of Ceramic Tile Adhesives

This work attempts to draw attention to the importance of a multidimensional approach when creating standard requirements in the assessment of construction products with the example of ceramic tile adhesives (CTAs). CTAs are an essential group of building materials today, the continuous development of which has been noted since the 1960s. However, until 2001, i.e., the year when EN 12004 was published, there were no precise requirements for CTAs at the European level, which often made it difficult or, in extreme cases, even impossible to assess the product objectively. Under the provisions of EN 12004, for twenty years, the basis for the assessment and verification of constancy of performance (AVCP) of CTAs has been adhesion determined by tensile strength. The paper discusses the test methods, paying attention to their imperfections, including the impact of the materials used in measurements, i.e., concrete slab, ceramic tile, and water quality. The results of the multi-annual interlaboratory tests indicate that an essential factor that must be considered in the process of AVCP is test measurement uncertainty. Additionally, it should be remembered that uncertainty also occurs at other assessment levels. It also seems that the simple acceptance rule that does not consider the variability resulting from the measurement uncertainty is inadequate when assessing CTAs.

Machine learning techniques to estimate the degree of binder activity of reclaimed asphalt pavement

This paper describes the development of novel/state-of-art computational framework to accurately predict the degree of binder activity of a reclaimed asphalt pavement sample as a percentage of the indirect tensile strength (ITS) using a reduced number of input variables that are relatively easy to obtain, namely compaction temperature, air voids and ITS. Different machine learning (ML) techniques were applied to obtain the most accurate data representation model. Specifically, three ML techniques were applied: 6th-degree multivariate polynomial regression with regularization, artificial neural network and random forest regression. The three techniques produced models with very similar precision, reporting a mean absolute error ranging from 12.2 to 12.8% of maximum ITS on the test data set. The work presented in this paper is an evolution in terms of data analysis of the results obtained within the interlaboratory tests conducted by Task Group 5 of the RILEM Technical Committee 264 on Reclaimed Asphalt Pavement. Hence, despite it has strong bonds with this framework, this work was developed independently and can be considered as a natural follow-up.

Improving the quality of meat and canned products by production technology

This article provides an overview of qualification testing programs, inter-laboratory comparative tests and qualification testing in testing laboratories that analyze the safety of canned meat products. Organoleptic, physico-chemical, safety and microbiological studies were conducted, comparing Semipalatinsk canned meat products with other samples. According to the results of the study, the company's products turned out to be positive. It is proved that the main task is to produce high-quality products in order to meet the requirements of consumers. At the enterprise for the production of canned meat, measures were envisaged to ensure high-quality and safe products in accordance with the requirements of standards. The regulatory and technical requirements used by the enterprise in the production of canned meat were analyzed. In the market economy of the Republic of Kazakhstan, the development of individual entrepreneurship should be at a stable level in the food industry.

Study of P-Phenylenediamine (PPD) Concentrations after Hair Dye Mixing: A Call for Safety Reassessment

Para-phenylenediamine (PPD) is a chemical that is widely used in hair dyes. Multiple safety and regulatory agencies have categorized PPD as a potent sensitizer. In addition, PPD has carcinogenicity and genotoxicity attributes and, consequently, it is regulated at a maximal concentration of 2.0%. The aim of this study was to test whether the limit for PPD is surplus, and hence whether the consumer may be exposed to unnecessarily PPD levels. Experimentally, the analysis of PPD was performed using HPLC, where method validation and an inter-laboratory comparison test (ILC) were conducted to evaluate method performance. Thirty-three commercial products were analyzed, and five products were chosen to study the unconsumed PPD. Successfully, the implemented method confirmed its suitability and validity for the determination of PPD. For ILC results, PPD levels were 0.97 ± 0.04% and 0.92 ± 0.02%, quantified by our laboratory and an accredited laboratory, respectively. For all products, the initial concentration (T0) of PPD was lower than the regulatory limit. After 45 min, the content of PPD significantly reduced compared to T0. One product showed unconsumed PPD to be as high as 96% following the recommended dyeing time. In conclusion, the existence of high levels of unreacted PPD increases the likelihood of allergic events and elevates the risk of PPD-related chemicals. Collaborative efforts between industries, regulatory bodies, and health-related decision makers are deemed necessary to establish safe concentrations for PPD.

Report of RILEM TC 281-CCC: outcomes of a round robin on the resistance to accelerated carbonation of Portland, Portland-fly ash and blast-furnace blended cements.

Many (inter)national standards exist to evaluate the resistance of mortar and concrete to carbonation. When a carbonation coefficient is used for performance comparison of mixtures or service life prediction, the applied boundary conditions during curing, preconditioning and carbonation play a crucial role, specifically when using latent hydraulic or pozzolanic supplementary cementitious materials (SCMs). An extensive interlaboratory test (ILT) with twenty two participating laboratories was set up in the framework of RILEM TC 281-CCC ‘Carbonation of Concrete with SCMs’. The carbonation depths and coefficients determined by following several (inter)national standards for three cement types (CEM I, CEM II/B-V, CEM III/B) both on mortar and concrete scale were statistically compared. The outcomes of this study showed that the carbonation rate based on the carbonation depths after 91 days exposure, compared to 56 days or less exposure duration, best approximates the slope of the linear regression and those 91 days carbonation depths can therefore be considered as a good estimate of the potential resistance to carbonation. All standards evaluated in this study ranked the three cement types in the same order of carbonation resistance. Unfortunately, large variations within and between laboratories complicate to draw clear conclusions regarding the effect of sample pre-conditioning and carbonation exposure conditions on the carbonation performance of the specimens tested. Nevertheless, it was identified that fresh and hardened state properties alone cannot be used to infer carbonation resistance of the mortars or concretes tested. It was also found that sealed curing results in larger carbonation depths compared to water curing. However, when water curing was reduced from 28 to 3 or 7 days, higher carbonation depths compared to sealed curing were observed. This increase is more pronounced for CEM I compared to CEM III mixes. The variation between laboratories is larger than the potential effect of raising the CO2 concentration from 1 to 4%. Finally, concrete, for which the aggregate-to-cement factor was increased by 1.79 in comparison with mortar, had a carbonation coefficient 1.18 times the one of mortar.Supplementary InformationThe online version contains supplementary material available at 10.1617/s11527-022-01927-7.

Unravelling reasons for variability in the OECD 306 marine biodegradation test

The recommended test for assessing if a chemical can be biodegraded in the marine environment is performed according to the Organisation for Economic Cooperation and Development Marine biodegradation test guideline (OECD 306). However, this test is known to generate highly variable test results when comparing interlaboratory test results for the same compound. One reason can be the relatively low bacterial content compared to the inoculum used for OECD readily biodegradation tests (OECD 301). Some of the variability in data obtained from OECD 306 tests can also be due to the flexibility on how to store the seawater inoculum before starting a test. Another variable in the seawater inoculum is the source of seawater used by different laboratories, i.e., geographical location and anthropogenic activities at the source. In this study, the effect of aging seawater and the source of seawater (sample time and depth) were investigated to determine differences in the biodegradation of the reference compound aniline. Aging the seawater before starting the test is recommended in OECD 306 to reduce the background levels of organic carbon in the water. However, it also functions to acclimatize the bacterial community from the environmental source temperature to the test temperature (normally 20 °C). Herein, the microbial community was monitored using flowcytometer during the aging process. As expected, the microbial community changed over time. In one experiment, aging significantly improved the biodegradation of aniline, while in two experiments, there was no significant difference in biodegradation. Interestingly however, there was significant variability in the biodegradation of aniline between sampling seasons and depths, even when all experiments were performed in the same lab, by the same operator and seawater obtained from the same source. This highlights the need for a more robust and consistent microbial inoculum source to reduce variability in seawater biodegradation tests.

Report of RILEM TC 267-TRM phase 2: optimization and testing of the robustness of the R3 reactivity tests for supplementary cementitious materials

The results of phase 1 of an interlaboratory test, coordinated by the RILEM TC 267-TRM “Tests for Reactivity of Supplementary Cementitious Materials” showed that the R3 (rapid, relevant, reliable) test method, by measurement of heat release or bound water, provided the most reliable and relevant determination of the chemical reactivity of supplementary cementitious materials (SCMs), compared to other test methods. The phase 2 work, described in this paper aimed to improve the robustness of the test procedure and to develop precision statements for the consolidated test procedure. The effect of the pre-mixing and mixing conditions, and the impact of the mix design on the test method robustness were assessed and fixed for optimal conditions to carry out the R3 heat release test. The effect of the drying step was evaluated to define the R3 bound water test procedure in more detail. Finally, the robustness of the consolidated final test methods was determined by an interlaboratory study to define the precision statements.

Evaluation of Pre-Analytical and Analytical Methods for Detecting SARS-CoV-2 in Municipal Wastewater Samples in Northern Italy

(1) Background: The surveillance of SARS-CoV-2 RNA in urban wastewaters allows one to monitor the presence of the virus in a population, including asymptomatic and symptomatic individuals, capturing the real circulation of this pathogen. The aim of this study was to evaluate the performance of different pre-analytical and analytical methods for identifying the presence of SARS-CoV-2 in untreated municipal wastewaters samples by conducting an inter-laboratory proficiency test. (2) Methods: three methods of concentration, namely, (A) Dextran and PEG-6000 two-phase separation, (B) PEG-8000 precipitation without a chloroform purification step and (C) PEG-8000 precipitation with a chloroform purification step were combined with three different protocols of RNA extraction by using commercial kits and were tested by using two primers/probe sets in three different master mixes. (3) Results: PEG-8000 precipitation without chloroform treatment showed the best performance in the SARS-CoV-2 recovery; no major differences were observed among the protocol of RNA extraction and the one-step real-time RT-PCR master mix kits. The highest analytic sensitivity was observed by using primers/probe sets targeting the N1/N3 fragments of SARS-CoV-2. (4) Conclusions: PEG-8000 precipitation in combination with real-time RT-PCR targeting the N gene (two fragments) was the best performing workflow for the detection of SARS-CoV-2 RNA in municipal wastewaters.

Development of Avocado Reference Material for Pesticide Residue Analysis.

Pesticide quantitation in foods relies on the availability of matrix reference materials, which, however, are scarce because of the general instability of pesticides. In particular, no avocado reference material has been developed. This research aimed to develop a reference material to support the determination of pesticide residues in avocado. Avocado was spiked with 11 selected pesticides at levels of 0.01-0.35 mg/kg. The production process included the assessment of between-unit heterogeneity, stability during dispatch, and best storage conditions according to ISO 17034. Reference values were estimated through an interlaboratory comparison study involving laboratories of demonstrated competence and adhering to ISO/IEC 17025. The corresponding expanded uncertainties were calculated as 4-19% in compliance with the Guide to the Expression of Uncertainty in Measurement. The reference material was sufficiently homogeneous and stable at 4°C during the entire study period (365 days) for most of the pesticides, and at 40°C during 10 days, but it was unstable at 50 and 60°C during 10 days. Four pesticides showed downward trends; however, this behavior was considered in the uncertainty budget. As this material complied with all requirements of proficiency testing, it was used in an interlaboratory proficiency test designed to investigate analytical performance and assist laboratories in improving the quality of measurement results. The presented material can be used for the development of novel analytical methods or in-house reference materials and adds to the scarce supply of reference materials for the determination of pesticides in vegetable matrixes with high oil contents and intermediate water contents. A novel reference material has been developed for the reliable and accurate quantitation of multiple pesticides in avocado, allowing researchers to avoid the preparation of in-house reference materials for this purpose.

Determination of glucosamine in functional food samples by high performance liquid chromatography (HPLC-FLD)

A simple, rapid and specific method using high performance liquid chromatography with fluorescence detector (HPLC-FLD) was developed for quantification of glucosamine in supplements after derivatization with 9-fluorenylmethyl chloroformate (FMOC-Cl). The chromatographic separation was achieved on a C18 column (150 mm &amp;times; 4.6 mm &amp;times; 5 &amp;micro;m) using a gradient mobile phase containing acetonitrile and water at a flow rate of 1.0 mL/min. The FLD detector was operated at excitation and emission wavelengths of 265 and 315 nm, respectively. The analytical method was validated for specificity, linearity, accuracy, and precision. The detector response for glucosamine was linear over the selected concentration range from 6.7 to 135 ppm with a correlation coefficient of 0.9988. The repeatability (RSD, n = 6) and reproducibility (RSD, n = 4) were from 2.54 to 3.23 % and from 2.24 to 3.07 %, respectively. The recovery was between 98.0 and 101.5 %. In addition, we also joined the interlaboratory proficiency testing program (code: H21.11) organized by the National Institute of Food Control with good result (z-score value was - 0.89 &amp;lt; 2). The method was successfully applied for the analysis of glucosamine in 15 supplement samples.

Interlaboratory comparisons to demonstrate the competence of two similar mobile laboratories

In order to maintain the RENAR (Romanian Accreditation Association) accreditation, each accredited laboratory must periodically participate in interlaboratory testing programs carried out with specialized providers or similar laboratories. In December 2021, an interlaboratory comparison in the field of environmental protection was organized by INCD ISEMEX PETROȘANI. The current paper examines the similarity of results of two auto-laboratories, in similar sampling points to demonstrate the competence of accredited laboratories. During the interlaboratory test session, immission measurements (nitrogen dioxide, nitrogen monoxide, carbon monoxide and sulphur dioxide), ambient noise measurements and determination of suspended dust concentration were performed. The main objective of the interlaboratory tests is to comply with limits established by the bilateral testing protocol, and all these results can be processed and achieved in situ due to systems endowing the auto-laboratories, which integrate all the measurements performed in situ. Results of the study indicate very close values found by the two mobile laboratories, which leads to the performance requirement for all components analysed, namely coefficients of variation below 20%.

Potentiometry for Cyanide Detection Applied to Fisheries Regulation

Illegal cyanide fishing is practiced by some fishers to capture agile and otherwise inaccessible reef fishes easily. Economic incentives had prevented discontinuation of the practice despite regulations present. Aside from the well-known toxicity of cyanide, it is a concern whether the fish is for ornamental purposes or human consumption that cyanide is being used because of the environmental damage it can cause by killing off non-target species. Currently, the cyanide content of fish is determined using an ion-selective electrode (ISE), with distillation as the mode of extraction of cyanide from tissues. This paper reports a modification of ASTM Method 500-CN-E, a method originally used to test for cyanide content in the wastewater. This paper outlines the process of determining the applicability of the method modification for analysis of fish tissue samples, in which no standard method was designed specifically for the matrix mentioned above. Although percent recoveries for cyanide at 0.05-10 mg/L range in spiked distilled water matrices are in line with the American Society of Testing and Materials (ASTM) results (90-105%), cyanide recoveries in spiked fish tissue matrices at the same concentration range are appreciably lower (~60-80%). For regulatory purposes, it serves as a temporarily acceptable method to detect cyanide-laden fish until a suitable method can be validated on international standards. However, to be accepted as a standard method, additional modifications may be needed or proven in inter-laboratory tests that the recovery of cyanide in fish is consistently low.

Inter-laboratory testing as a strategy for external quality assessment for qualitative detection of SARS-CoV-2 by real-time RT-PCR testing in India.

To implement the strategy of test, track and treat to tackle the ongoing COVID-19 pandemic, the number of real-time RT-PCR–based testing laboratories was increased for diagnosis of SARS-CoV-2 in the country. To ensure reliability of the laboratory results, the Indian Council of Medical Research initiated external quality assessment (EQA) by deploying inter-laboratory quality control (ILQC) activity for these laboratories by nominating 34 quality control (QC) laboratories. This report presents the results of this activity for a period of September 2020 till November 2020. A total of 597 laboratories participated in this activity and 86 per cent of these scored ≥90 per cent concordance with QC laboratories. This ILQC activity showcased India’s preparedness in quality diagnosis of SARS-CoV-2.

Structure-borne sound sources in buildings – Estimating the uncertainty of source properties and installed power from interlaboratory test results

A low immission due to structure-borne sound sources is a major component of the acoustic quality inside buildings. After many years of research, methods have been standardised to characterise such sources (EN 15657) and to predict their impact in buildings (EN 12354-5). This contribution is dedicated to the question what the uncertainty of the source descriptors and the predicted installed sound power is. To answer this question, an interlaboratory test with an artificial source was performed. Altogether seven laboratories participated, and estimates for the uncertainties of the source quantities could be deduced from the measurement results. Additionally, measurements were performed with a standardised structure-borne sound source, the ISO tapping machine, by all participating laboratories. The measured source quantity for this source turned out to be in good agreement with the theoretically predicted values thereby validating this theoretical prediction.

Значение испытательных и экспериментальных центров в научно-техническом развитии (на примере транспортной отрасли)

The article aims to study the role of testing centers in the scientific and technological development of railways. The object of the study is the Experimental Railway Loop of the Railway Research Institute (JSC VNIIZhT). In 2022 the Institute celebrates the 90th anniversary of continuous testing of the latest models of railway equipment. To analyze the activities of the Experimental Railway Loop, the Technology Readiness Assessment (TRA) methodology was used, which in the article is adapted to analyze the activities of scientific and experimental organizations. Interpretations of product and process technologies are presented, from their perspective the testing activities of the Experimental Ring are considered. The stages of the Experimental Railway Loop’s development were studied: auxiliary test site; interlaboratory railway testing ground; industry polytechnic testing ground; international testing and exhibition center; catalyst for scientific and technological progress on the railways. Based on the results of the analysis, directions for improving the activities of the Experimental Railway Loop in the interests of the development of Russian railway transport were formulated. The study of the activities of the Experimental Railway Loop leads to the conclusion about the critical role of the railway test sites in the scientific and technological development of the country and makes it necessary to improve the activities of such sites.

Influence of bitumen emulsion on the curing behaviour of standardised cold bitumen emulsion mortars

This research was part of the RILEM TC 280-CBE interlaboratory testing aiming to characterise the role of mortars as mesoscale model systems and establish a link between the properties of bitumen emulsions and the performance of cold bitumen emulsion-based mixtures for structural layers. The objective of this specific work was to investigate the curing behaviour of such mortars with the reference volumetric composition prepared with different types of emulsions and sands. This approach enabled the preparation of specimens that could be successfully demoulded immediately after compaction and tested by indirect tension. The curing was characterised by comparing the evolution of water content and indirect tensile strength. The results showed that the estimated long-term indirect tensile strength at 5 °C of the mortars was in the range from 1.14 to 1.52 MPa. They also highlighted the importance of intrinsic properties of cationic emulsions and of their compatibility with sand particles.

Interlaboratory Validation of Toxicity Testing Using the Duckweed Lemna minor Root-Regrowth Test.

Simple SummaryDuckweed (Lemna minor) is commonly used as a phytotoxicity test organism, adopted by the main international standardization organizations (ISO, OECD, USEPA, ASTM). For duckweed tests, measurements of fronds or biomass are usually preferred with a standard exposure period of at least 7 days. The proposed root- regrowth test differs from other internationally standardized methods in several important aspects: (a) the test can be performed within 72 h; (b) the test vessel was a 24-well cell plate; (c) the required volume of test water samples was 3 mL; (d) roots were excised before exposure and newly developed roots then measured. The validation of the new test method by interlaboratory comparison tests confirmed that the Lemna root bioassay is valid and reliable. The root growth test is therefore a valuable tool for rapid toxicity screening of wastewater effluents and hazardous pollutants in natural waters because it is simple to perform, quick to conduct, cost-effective to operate, and can have operational benefits for testing time, since management decisions need to be made promptly in the event of unpredictable pollution events.The common duckweed (Lemna minor), a freshwater monocot that floats on the surfaces of slow-moving streams and ponds, is commonly used in toxicity testing. The novel Lemna root- regrowth test is a toxicity test performed in replicate test vessels (24-well plates), each containing 3 mL test solution and a 2–3 frond colony. Prior to exposure, roots are excised from the plant, and newly developed roots are measured after 3 days of regrowth. Compared to the three internationally standardized methods, this bioassay is faster (72 h), simpler, more convenient (requiring only a 3-mL) and cheaper. The sensitivity of root regrowth to 3,5-dichlorophenol was statistically the same as using the conventional ISO test method. The results of interlaboratory comparison tests conducted by 10 international institutes showed 21.3% repeatability and 27.2% reproducibility for CuSO4 and 21.28% repeatability and 18.6% reproducibility for wastewater. These validity criteria are well within the generally accepted levels of <30% to 40%, confirming that this test method is acceptable as a standardized biological test and can be used as a regulatory tool. The Lemna root regrowth test complements the lengthier conventional protocols and is suitable for rapid screening of wastewater and priority substances spikes in natural waters.

Use of standard samples for qualification inspections of testing laboratory for analysis safety of meat and meat products

This article provides insights into qualification testing, interlaboratory comparative testing, and qualification testing programs in testing laboratories that analyze the safety of meat and meat products. Samples with codes OK-MB- 21 were used as a model for interlaboratory comparisons. The uniformity and stability of the CC code was assessed in accordance with GOST R 50779.60-2017 “Statistical methods. Application in proficiency testing through interlaboratory testing ”. Seven laboratories participated in the proficiency testing program. The test preparation procedure was described and the test results determined whether each sample tested was satisfactory or questionable. Participants with unsatisfactory results are encouraged to identify the causes of the alarms, take corrective actions and document them, and identify and eliminate the causes of the unsatisfactory results.