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In this study, the results obtained by 19 laboratories participating in 2 editions of the interlaboratory comparison (ILC) determining 2 properties of ceramic tiles adhesives (CTAs), i.e., initial tensile adhesion strength and tensile adhesion strength after water immersion following EN 12004, were analyzed. The results show that participating laboratories maintain a constant quality of their work. The use of z-score analysis, under ISO 13528, allows for classifying 89.5% to 100% of laboratories as satisfactory, depending on the measurement’s kind and edition. The remaining laboratories are classified as questionable. The investigation of the predominant mode of failure of the CTA’s samples tested in the two editions shows significant differences. From the perspective of laboratories, the goal of the ILC has been achieved. From the standpoint of a manufacturer who evaluates a product’s properties when placing it on the market, the results indicate the necessity of a particular treatment of the product evaluation process because the variability of the obtained results is significant. It increases the possibility of the product failing to meet the assessment criteria verified by the construction market supervision authorities. The manufacturer must consider all possible variations in the risk analysis, including the ILC results, to improve the assessment process of CTAs.

Quality assurance measures ensure competence and reliability in the laboratories procedures from patient specimen receipt (pre-analytical phase), specimen handling and testing (analytical phase), to the analysis and reporting of patient results (post-analytical phase). However, when faced with new challenges such as Coronavirus pandemic, the virology laboratory has to dynamic and responsive as well as able to adapt existing protocols, implement new technologies in response to the risks posed by the most recent threats to public health, while ensuring that the quality of the testing services provided, demonstrates clinical utility and meets appropriate regulatory requirements

A long-term, envisioned, objective of the Customs laboratories (CLEN), is the acquisition of harmonization of tasks and laboratory practices and procedures. One such task was the enrichment of the CLEN methods with their performance characteristics (PChs). The aim of this investigation was to define a valid statistical estimation procedure of the (PChs) (Repeatability and Reproducibility limits) from existing Proficiency Testings’ (PT) data, whose implementation could become the basis for all the other CLEN methods. The procedure was based on the estimation of the in-between reproducibility, considered to represent the systematic error of all the variations between and within laboratory, promoting thus Harmonization. There was no rejection of any data and hence, there was no need to follow any statistical rejection rules. The effectiveness and validity of the results was assessed and supported by the conformance to the AOAC minimum analytical requirements and the verification to the comparison with standard methods. The estimation and evaluation of data for the Butyric Methyl Esters (BAME) and Total fat in biscuits and chocolates, were found to be for BAME at concentration range (1.7–4.0)%m/m, repeatability (r) 0.14 and Reproducibility (R) 0.38 and Total fat at concentration range (10–20)%, repeatability (r) 0.28 and Reproducibility (R) 0.84 and for Total fat at concentration range (20–30)%, repeatability (r) 0.48 and Reproducibility (R) 1.07,though, in the milk products of high protein content, for (BAME) and Total Fat below 1.5%, methods, gave not conforming results. It is suggested that implementation of this estimation procedure will be of great benefit for CLEN laboratories, not only for the method acceptance, but for further investigation in different matrices, aiming to amendments and hence Harmonization. It is proposed that this procedure is reliable and can be implemented to any CLEN method, provided that sufficient PT data are available.

This article presents the results of the interlaboratory comparison (ILC) study of the following four characteristics of ceramic tile adhesives (CTAs): initial tensile adhesion strength, tensile adhesion strength after heat ageing, tensile adhesion strength after immersion in water, and tensile adhesion strength after freeze–thaw cycles. The results showed that the objective of the ILC was achieved—the z-score analysis carried out following ISO 13528 allowed for classifying all results obtained by 23 laboratories out of 27 as satisfactory. The results of the remaining four laboratories were rated worse. Despite the achieved goal, the ILC notes high heterogeneity of the results in terms of failure patterns, as well as significant differences between the lowest and the highest values of tensile adhesion strength for various measurement conditions. The results of the ILC were discussed in terms of the possibility of including them in the risk analysis conducted by the manufacturer. The results of the ILC are also valuable information for market surveillance authorities, who, in the authors’ opinion, should be more cautious about results on samples taken from the market. The ILC results for CTAs are also a valuable recommendation for a possible revision of EN 12004.

10 páginas, 2 figuras, 5 tablas.-- et al., Chemical oxygen demand (COD) is a critical analytical parameter in waste and wastewater treatment, more specifically in anaerobic digestion, although little is known about the quality of measuring COD of anaerobic digestion samples. Proficiency testing (PT) is a powerful tool that can be used to test the performance achievable in the participants’ laboratories, so we carried out a second PT of COD determination in samples considered “difficult” to analyze (i.e. solid samples and liquid samples with high concentrations of suspended solids). The results obtained (based on acceptable z-score values) may be considered satisfactory. When compared with the results of a previous similar scheme, the overall performance improved by around 30%, again demonstrating that analytical performance can be improved by regular participation in PT.

Chemical oxygen demand (COD) is a critical analytical parameter in waste and wastewater treatment, more specifically in anaerobic digestion, although little is known about the quality of measuring COD of anaerobic digestion samples. Proficiency testing (PT) is a powerful tool that can be used to test the performance achievable in the participants laboratories, so we carried out a second PT of COD determination in samples considered ‘‘difficult’’ to analyze (i.e. solid samples and liquid samples with high concentrations of suspended solids). The results obtained (based on acceptable z-score values) may be considered satisfactory. When compared with the results of a previous similar scheme, the overall performance improved by around 30%, again demonstrating that analytical performance can be improved by regular participation in PT.