Proficiency Testing Schemes Research Articles

Results and Discussion on National Vaccine Proficiency Testing Schemes in 2020

OBJECTIVE: To acquire the knowledge of quality control performance through carrying out proficiency Testing Schemes (PTS) nationwide. METHODS: National Institutes for Food and Drug Control(NIFDC) schemed three PTS to evaluate the testing competence of participants from the aspects of safety and stability of vaccine products and pseudotyped virus-based neutralization assay, pseudotyped virus based neutralization assay(PBNA), which takes as a hand of COVID-19 vaccine development. RESULTS: Eighty-nine participants took part in the three PTS and the satisfaction rate stated as 96.9%, 96.4% and 76.0%. CONCLUSION: The testing ability and quality control performance of Official Medical Control Laboratories (OMCL), manufacturers and research institutes are acceptable. The testing results of sterile testing and aluminum assay of aluminum adjuvanted vaccine can be assured well, while the ability of PBNA needs to be improved by some manufacturers.

Proficiency testing for determination of pesticides residues in black tea: Comparison of three robust statistical approaches based on ISO 13528 to estimate the consensus values for small number of participants

In Indonesia, proficiency testing (PT) provider for determination of pesticides residues in tea is still limited. In addition, many proficiency testing schemes still use consensus value from participants’ results as the assigned value rather than reference assigned value due to some technical and economical issues. However, this mode of assigned value may lack of reliability when the number of participants are small and the test results are highly varied. In these conditions, many PT providers were not able to perform the statistical data evaluation causing the needed PT became unavailable. This study is aimed to investigate the suitable statistical approach in estimating the consensus value for small number of participants in PT for determination of pesticides residues in black tea. Three robust statistical approaches recommended by ISO 13528: variants of Algorithm A, Hampel method, and M estimator were compared to evaluate the participants’ data from the PT schemes organized by Research Center of Chemistry-LIPI in 2014 and 2015. All of the robust statistical approaches showed to be able to assess the performance of participants. The Hampel method and M estimator were the most adequate robust statistical approaches in obtaining the closest consensus values compared to the homogeneity test results, stability monitoring results, and the assigned valued in the real PT scheme, for endosulfan sulphate and bifenthrin, respectively.

Establishment of Traceability Chain For pH Measurement in Indonesia

As a consequence of the globalization of trade and industries, the presence of an accurate and traceable measurement has become very important for quality assurance of a product or service in the market, including pH measurement. pH measurement is a basic analysis used in a wide variety of applications, such as agriculture, wastewater treatment, industrial processes, research and development, and environmental monitoring. The reliable and comparable results of pH measurement are advantaged as one of the parameters for quality control that will affect the decision making. The Electrochemistry Laboratory under Deputy of National Measurement Standard – National Standardization Agency of Indonesia (SNSU–BSN) has a main duty to ensure the reliability, comparability, and traceability of pH measurements in Indonesia, as a commitment in building chemical metrology infrastructure. In this article, all the activities related to the establishment of traceability chain for pH measurement in Indonesia are comprehensively discussed. As of currently, the Electrochemistry Laboratory has successfully developed the secondary method for pH measurement using differential potentiometric cell, production of certified reference material (CRM) for buffer solution (oxalate, phthalate, phosphate, and borate buffer), dissemination by proficiency testing (PT) schemes for pH measurement, participation in the key comparison (KC) of APMP.QM-K91 for phthalate buffer, and claim submission for the Calibration Measurement Capabilities (CMCs) of phthalate buffer (pH 3.97-4.03) with expanded uncertainty 0.004.

PROFESSIONAL LEVEL VERIFICATION: CALIBRATION OF MEASURED BULBS FOR MEDICAL LABORATORIES

The round of proficiency testing scheme for calibration of volumetric flasks was conducted by an accredited provider of proficiency testing - Metrology Center of SE “Kharkovstandardmetrology”. Report on the results of the round of the proficiency testing scheme № SM 38422000-9 19/08-II / 19 for calibration of volumetric flasks was published on the official website of the provider (http://khsms.com/primaryactivity/metrology/about/type/ remont / id / 23).When analyzing the documents based on the calibration of the volumetric flask provided by the participants of the round of proficiency testing scheme, the use of one calibration method was indicated - gravimetric, at the same time the participants use different methods of calibration which, in turn, is reflected in the form of significantly different extended uncertainties.The analysis of the obtained results testifies to the need to create and use a standardized calibration technique, which will provide a unified and clear approach to the conduct and report of calibration results of measuring utensils in general, and volumetric flasks in particular. The basis of such a technique can be the method of calibration by gravimetric method, which is set out in the European document EURAMET Calibration Guide No. 19 Version 3.0 (09/2018).Taking into account the use of the results of the calibration of volumetric flasks, including by medical laboratories, we believe that the creation and use of a standardized calibration method for volumetric glassware, and in particular volumetric flasks, not only meets the modern metrological needs of calibration customers, but will also improve the metrological support of critical activities of medical laboratories.

Proficiency-Testing Scheme for Detection and Enumeration of Campylobacter in Poultry Meat

Proficiency-Testing Scheme for Detection and Enumeration of Campylobacter in Poultry Meat

Inter-laboratory proficiency testing of the measurement of gypsum parameters with small numbers of participants

Conducting proficiency tests with large numbers of participants are not a problem because the ISO standard 13528:2015 describes many indicators that allow for proper assessment. However, there are proficiency testing (PT) schemes that involve only few participants. In such situations, the same difficulties exist for the selection of proper indicators and the criteria for assessing the participants' achievements. The Institute for Chemical Processing of Coal in Zabrze, Poland organised a round of PT of the determination of gypsum parameters. The results from six participants from Polish research entities and independent laboratories and methodology for the organisation this PT are presented. The performance evaluation criteria were determined using participants results due to the inability to use the metrologically valid procedure. The performance of the participants was evaluated using z′ and zeta scores.

Optimizing hepcidin measurement with a proficiency test framework and standardization improvement.

Hepcidin measurement advances insights in pathophysiology, diagnosis, and treatment of iron disorders, but requires analytically sound and standardized measurement procedures (MPs). Recent development of a two-level secondary reference material (sRM) for hepcidin assays allows worldwide standardization. However, no proficiency testing (PT) schemes to ensure external quality assurance (EQA) exist and the absence of a high calibrator in the sRM set precludes optimal standardization. We developed a pilot PT together with the DutchEQA organization Stichting Kwaliteitsbewaking Medische Laboratoriumdiagnostiek (SKML) that included 16 international hepcidin MPs. The design included 12 human serum samples that allowed us to evaluate accuracy, linearity, precision and standardization potential. We manufactured, value-assigned, and validated a high-level calibrator in a similar manner to the existing low- and middle-level sRM. The pilot PT confirmed logistical feasibility of an annual scheme. Most MPs demonstrated linearity (R2>0.99) and precision (duplicate CV>12.2%), although the need for EQA was shown by large variability in accuracy. The high-level calibrator proved effective, reducing the inter-assay CV from 42.0% (unstandardized) to 14.0%, compared to 17.6% with the two-leveled set. The calibrator passed international homogeneity criteria and was assigned a value of 9.07±0.24nmol/L. We established a framework for future PT toenable laboratory accreditation, which is essential to ensure quality of hepcidin measurement and its use in patient care. Additionally, we showed optimized standardization is possible by extending the current sRM with a third high calibrator, although international implementation of the sRM is a prerequisite for its success.

Matrix Reference Materials Development for Food Safety Application in Philippine Products

<p>The development of RMs was pioneered in the Philippines by the Industrial Technology Development Institute (ITDI) - DOST as part of its vision to establish metrological traceability and support the RMs needs of chemical testing laboratories in the country. Food safety issues for chemical testing of Philippine products were prioritized in this activity as these could affect the health of consumers and trade issues. Reference methods used for the provision of reference value was developed and validated for contaminants like histamine and benzoic acid in canned tuna and mango juice respectively. The materials were prepared and characterized and found to be homogeneous and stable for at least six (6) months. The reference value assigned to these RMs was done using a higher order method like isotope dilution technique coupled with Liquid Chromatography-Triple Quadrupole Mass Spectrometry (LCMSMS). Results were also cross-checked using gravimetric technique for High Performance Liquid Chromatography (HPLC) analysis. Certified RMs purchased from Metrology Institutes were also used to further support traceability of measurements. Philippine product RMs were developed for histamine and benzoic acid. The measurement traceability was disseminated by ITDI to local testing laboratories through the Proficiency Test schemes organized and conducted for the said analytes. </p>

Analysis of six different homologues of phosphatidylethanol from dried blood spots using liquid chromatography-tandem mass spectrometry.

Phosphatidylethanol (PEth) is a direct biomarker for alcohol consumption consisting of a fraction of different ethanol-modified, homologue phospholipids. The aim of this study was to validate an ultra-high-performance liquid chromatography-tandem mass spectrometry method to quantitate six different homologues of PEth (16:0/18:1, 16:0/18:2, 16:0/20:4, 18:0/18:1, 18:0/18:2, and 18:1/18:1) from dried blood spots (DBSs). DBSs were prepared volumetrically (20 μL of whole blood) and extracted with 1 mL of methanol (0.02 ng/μL internal standards). PEth homologues were separated on a BEH C18 column (2.1 × 150 mm, 1.7 μm) using methanol and ammonium acetate buffer (25 mM) in a 7 min isocratic run. Multiple reaction monitoring mode was used for the detection of PEth and the internal standards. Calibrators (10-1000 ng/mL) and quality controls (40, 400, and 700 ng/mL) were prepared from spiked whole blood; external control samples were obtained from proficiency testing schemes. After a comprehensive validation of the method, quantitative patterns of the different homologues were investigated in PEth positive samples (n = 57) from patients in a transplant setting. Satisfactory chromatographic separation, sensitive detection, and reliable quantification of the PEth homologues in DBSs can be achieved using the liquid chromatography-tandem mass spectrometry (LC/MS/MS) procedure. Validation results, including accuracy, linearity, recovery, matrix effects, and in-process stability, complied with international standards, and the analytical performance of the procedure was not affected by the hematocrit of the blood samples. Different quantitative patterns of the investigated PEth homologues were observed in authentic samples from liver transplant patients. This method will enable the study of the kinetics of six PEth homologues simultaneously and investigate the meaning of the homologues' distribution in individuals.

Practical approach to develop a multi-group screening method for detection of mycotoxins, pesticides and veterinary drugs in food.

A multi-group screening method to detect residues of veterinary drugs in meat and environmental contaminants in wheat flour has been developed using liquid chromatography coupled to quadrupole-Orbitrap high-resolution mass spectrometry (LC-HRMS). The procedure was tested for over 300 representative compounds (173 veterinary drugs, 122 pesticides and 9 mycotoxins) analysing in parallel negative and positive (spiked) samples according to European validation rules. The Screening Target Concentrations (STCs) were chosen conservatively with respect to the method purposes. Interpretation of results was based on retention time, mass accuracy of precursor and MS2 spectral library. Evaluating the percentage of false negative results, 280 out of the 304 analytes were detectable at the STCs (false compliant rate ≤ 5%). In wheat flours, incurred levels of mycotoxins, deoxynivalenol and 3-acetyldeoxynivalenol, higher than STCs, were frequently found, whereas in meat, the most detected veterinary drugs were antibiotics generally at negligible concentrations (<10 μg kg-1 ). Finally, seven test materials from proficiency test schemes were successfully tested.

A liquid chromatography-high resolution mass spectrometry method for the determination of thirty-three per- and polyfluoroalkyl substances in animal liver.

An analytical method for the quantification of thirty-three perfluoroalkyl and polyfluoroalkyl substances (PFASs) in animal liver was developed applying the isotopic dilution methodology with twenty-one labelled isotopologues of native compounds. The proposed protocol involved the determination of short and long aliphatic chain PFASs (C4C18) extracting liver with acetonitrile followed by two clean-up steps. The instrumental analysis was performed with liquid chromatography coupled to high-resolution mass spectrometry. The acquisition method combined full MS/dd-MS2, t-SIM/dd-MS2 and SIM experiments with variable resolution in order to maximize in one chromatographic run accuracy, sensitivity and selectivity. An eight-level validation study was performed evaluating linearity, trueness, precision, quantification and detection limits. Trueness was from 94 to 126% with intra-laboratory reproducibility lower than 20%. Limits of quantification were in the range 2-100 pg g-1, except for 2,3,3,3-tetrafluoro-2-(1,1,2,2,3,3,3-heptafluoropropoxy)-propanoic acid, HFPO-DA (500 pg g-1). The analysis of a certified reference material (IRMM-427) and participation in a proficiency test scheme (FAPAS - 0687) confirmed these satisfactory performances. Finally, the application of the developed procedure to detect PFASs in sixteen liver samples of farm animals revealed that chicken was the less contaminated species.

The Use of Static Telecytology Applications for Accreditational Purposes

This study aims to examine the feasibility of developing a proficiency testing scheme for cytology labs wishing to be accredited according to ISO 15189:2012, by using low cost telemedical applications. Two hundred forty-eight fine-needle aspiration specimens from patients preoperatively aspirated under ultrasonographic guidance and 208 pap smears with histological confirmation were retrospectively selected from the department's registry. Three diagnostic categories of cytological reports were used. Ten characteristic images from each case were transferred via file transfer protocol to password-protected accounts for remote review by three independent cytopathologists. Contributor's and reviewer's diagnoses were collected, recorded and statistically evaluated. No significant difference in diagnostic accuracy could be detected between the diagnoses proffered on the basis of digitized images and conventional slides.

Environmental monitoring of total mercury content in different marine compartments after cold vapor generation and inductively coupled plasma mass spectrometry determination

Analytical procedure for environmental and seafood safety monitoring of total mercury content, based on the external calibration methodology and cold vapor generation inductively coupled plasma mass spectrometry determination, was validated according to the requirements of international guidelines and standards. Marine samples with varying levels of mercury: marine biota, marine sediment and costal sea waters were used in this study. A full validation approach in line with the ISO/IEC 17025 and Eurachem guidelines was followed. With this in mind, blanks, selectivity, working range (1.2 ng kg−1 to 240 ng kg−1), linearity (0.9991), recovery (97 % to 103 %), repeatability (< 2.5 %), intermediate precision (< 3.5 %), limit of detection (0.72 ng kg−1) and limit of quantification (1.10 ng kg−1) were systematically assessed. The uncertainty of measurement results was estimated according to the recommendations of the Guide to the expression of Uncertainty in Measurement. The relative expanded uncertainty was in the range between 14.2 % and 15.8 % (k = 2) for marine biota and sediment samples, respectively, and rise up to 32.8 % (k = 2) on the total mercury mass fraction in costal seawater at the level of 5 ng kg−1. The major contribution to the combined uncertainty was found to come from the uncertainty associated with the correction for recovery and procedural blanks. The performance of validated procedure was demonstrated by its application to the low-level Hg content seawater samples, received in the frame of Proficiency Testing Scheme, conducted by the Quality Assurance of Information in Marine Environment Monitoring in Europe. The result for total mercury content in marine sediment IAEA-475 was used as the contribution of the IAEA in the characterization campaign of the IAEA-475 candidate certified reference material. The demonstrated SI traceability of obtained results is a prerequisite for their further comparisons with monitoring data obtained in different place and time.

SUN-LB46 Differences in IGF-I Concentrations Between European and US Populations - Consequences for Reference Intervals

Background: IGF-I is the most widely used biomarker for management of GH related diseases. Reproducible assays and method-specific reference intervals (RIs) are crucial determinants of its clinical utility. Assay validation and RIs based on >15,000 subjects were published for the IDS iSYS IGF-I assay (J Clin Endocrinol Metab 2014). We now analyzed distribution of IGF-I results obtained in routine samples analyzed by accredited laboratories in the US and Europe, all using the IDS iSYS assay. Methods: All results from routine IGF-I measurements during the past 5 years in 4 laboratories were included (US lab n=778,173 males/710,752 females; European labs (Germany/Belgium, n=23,220 males/40,183 females). Assay performance across laboratories was confirmed through proficiency testing schemes and exchange of patient samples. We constructed RIs adjusted for age/sex from European and US cohorts separately using a modified Hoffmann approach (Am J Clin Pathol 2015), and compared to the originally published RIs (n=6697 males/8317 females, adults from Europe). A subset of US samples was used to compare IGF-I between regions with lower (Colorado) and higher (Alabama) mean body mass index (BMI). Results: Lower limits (LLs) of RIs calculated from routine results are superimposable to LLs from the original publication for all ages and sexes, regardless whether IGF-I results were from Europe or the US. For groups with sufficient n, upper limits (ULs) of RIs calculated from European routine data were also not statistically different from the originally published central 95%. However, a striking difference exists in calculated ULs from data of European and US origin: For ages 10-18 years, calculated UL on average was 149.3 ng/mL (34.6%) higher in boys and 94.9 ng/mL (19.8%) in girls from the US. In adults (19-95 years), calculated UL on average was 45 ng/mL (20.3%) higher in males and 29.7 ng/mL (13.8%) in females from the US. Within the US, mean IGF-I was significantly higher in samples from Colorado (lower mean BMI) than in Alabama (p<0.0001) across age- and sex groups, although the difference between the two states was smaller than between each of them and Europe. Conclusion: This study provides evidence that in sufficiently large datasets, both, direct sampling (as in the original publication) and the indirect Hoffmann algorithms provide statistically comparable RI limits and may be considered as accurate representation of results distribution in the disease-free populations. More importantly, we demonstrate that even with tight cross-correlation and continuous monitoring of IGF-I assay performance RIs generated in different populations can be different. Notably, in our extremely large study, the difference between Europe and the US was clinically relevant only at the UL. Although our study cannot reveal the cause of the difference, we suggest using adapted RIs for the US.

Proficiency-testing scheme for haloanisoles and halophenols in oak wood

Haloanisoles are responsible for musty or mouldy off-flavours in wine. These molecules are extremely odorous and they alter wines in an irreversible way. The origin of haloanisoles can be attributed to the biodegradation of halophenols, which can be found in winery environments. Various materials including oak products (wood tanks, barrels, chips, staves) may be contaminated by haloanisoles and halophenols. Once polluted, these materials may release these molecules into wine. Requests for analyses of haloanisoles and halophenols in oak wood have gradually increased in recent years, above all from the coopers, who want to prove the quality of their products. However, the lack of an official testing method is an obstacle for the performance monitoring of laboratories. In response to these challenges, BIPEA organises, since October 2013, regular proficiency-testing schemes (PTS) for the detection and quantification of these molecules in oak wood. For each test, the statistical treatment of laboratories’ results is performed according to ISO 13528. These PTS enable the participating laboratories to compare with each other, draw up a general inventory of their analytical skills and improve their performances for the detection and quantification of haloanisoles and halophenols in oak wood.

Proficiency Testing Schemes for Food Nutrition Analysis in Japan (2017-2018)

This paper deals with proficiency testing schemes for food nutrition analysis in Japan. In schemes in 2017 and 2018, 65 and 73 organizations participated, respectively, and more than 70% of the participants were public organizations responsible for a nutrition-labeling compliance test. The food matrices were pork and chicken sausages, and analytes were protein, fat, ash, moisture, carbohydrate, energy, sodium, salt equivalent, calcium (2018 only), and iron (2018 only). The organizations reporting inadequate laboratory values in one or more nutrients for mandatory declaration (energy, protein, fat, carbohydrate, or salt equivalent) were 11 and 15% of all organizations and 9 and 13% of public organizations in the 2017 and 2018 schemes, respectively. The approximate relative standard deviations for proficiency assessment (RSDr) were as follows: protein, 2%; fat, 3%; ash, 2%; moisture, 0.5%; carbohydrate, 9%; energy, 1%; sodium (salt equivalent), 4%; calcium, 7%; and iron, 7%. Notably, the large RSDr value for carbohydrate may cause inconsistency among laboratories in compliance tests for foods containing several grams or less of carbohydrate per 100 grams.

Continual Improvement of the Reliability of EML4-ALK Rearrangement Detection in Non–Small-Cell Lung Cancer: A Long-Term Comparison of ALK Detection in China

The results of EML4-ALK testing are critical to manage ALK tyrosine kinase receptor inhibitor treatment. Thus, the accurate detection of ALK rearrangement is increasingly becoming a matter of serious concern. To address this issue, a long-term EML4-ALK proficiency testing (PT) scheme was launched in China in 2015, serving as an educational tool for assessing and improving the testing quality of EML4-ALK fusion detection. Responses across 20 different PT samples interrogating three different variants and wild-type samples were collected between 2015 and 2019. Performance was analyzed by evaluating the detection methods, kits, and pre-analytic practices used to further display the landscape of changing conditions of the reliability of EML4-ALK testing. During the 5 years, 3224 results reported from 988 laboratories were evaluated, with an overall error rate of 5.36%. Along with an increasing number of participating laboratories, the error rate within each of the different methods showed a significantly downward trend over the years. No obvious differences in the error rates were found regarding the testing methods or kit manufacturers. Moreover, the individual performance of the laboratories improved when they participated in more PT scheme rounds. The data demonstrated that the performance of individual Chinese laboratories for EML4-ALK testing continuously improved over time by participating PT schemes, regardless of their method. However, care must be taken in standardized operations and validations.

Ten years of proficiency testing reveals an improvement in the analytical performance of EU National Reference Laboratories for genetically modified food and feed

National Reference Laboratories (NRLs) in the Member States of the European Union (EU) monitor the implementation of the EU legislation on the presence of genetically modified organisms (GMOs) in food and feed. The EU Reference Laboratory for GM Food and Feed (EURL GMFF) supports the harmonisation of measurement procedures and the improvement of the analytical performance of these laboratories, among others through the organisation of a proficiency testing (PT) scheme. The PT results reported over 10 years have been analysed using common criteria applied to the reported data. The outcome revealed a gradual decrease of the relative standard deviation within the sets of the reported data with time. The extent of the deviation of the results from the assigned value also diminished between 2010 and 2019. The average deviation from the assigned value was independent of the GM content in the later PT rounds but it was affected by the complexity of the test item matrix. Performance scores were calculated for all results reported by the 62 NRLs. The number of unsatisfactory performance scores obtained decreased with time. The trends observed indicate an improvement in the analytical performance and an increased harmonisation of GMO testing within the EU enforcement laboratories.

Model of uncertainty for the variability of water microbiological enumeration in a proficiency testing scheme

Data processing of microbial enumeration expressed as colony counts requires the use of specific statistical approaches due to the particular aspect of the analyte and the consideration of the variability related to the growth of microorganisms. A challenging matter in the organization of proficiency testing (PT) schemes for water microbiology is to provide representative, homogeneous and stable enough samples with the aim of assessing participants’ performance but also characterizing the accuracy of measurement. As a consequence, the proficiency testing design may help to make clear distinction between the different sources of variation and facilitate the subsequent error analysis associated with the analytical procedures of the participants. Besides, the statistical tools may be selected to provide explicit outcomes which enable the participants to interpret the data in line with other existing indicators such as those arising from validation studies or measurement uncertainty procedures in the laboratory quality assurance system. In this paper, the suitability of a Poisson–Gamma hierarchical generalized linear model is tested in order to evaluate the interlaboratory error, the batch homogeneity and the repeatability error from water microbiology PT. A probabilistic approach deriving from the negative binomial distribution is proposed for assessing the participating laboratories performance in terms of generalized z-score.

Features of the Functioning of the National Metrological System in the Health Sector

The legislative requirements for metrological support in the healthcare sector, the issues of ensuring metrological traceability and the hierarchical scheme of calibrations and measurements in laboratory medicine according to the recommendations of JCTLM and their adaptation at the national level are considered. The features of the provided metrological control of measuring instruments for medical purposes, including when conducting their compliance assessment with the requirements of technical regulations. The current state of affairs in the confirmation of the technical competence of medical laboratories, including the need for their participation in proficiency testing schemes through inter-laboratory comparisons, in the transition from certification to accreditation is considered.&#x0D; The analysis of the used methods and means of calibration and reference measurements proposed by JCTLM and other leading orga­nizations in the field of laboratory medicine is observed. Information is provided on the work carried out by the SE «Ukrmetrteststandart» for metrological support of medical measuring instruments. The necessity of legal improvement, the regulatory and methodological base of the metrological system in the field of healthcare is substantiated. As a result of the work performed, the authors consider:&#x0D; &#x0D; the legislative base of metrological support in the field of healthcare is not perfect and in need of refinement of the profile of the central executive authorities in order to build technically sound organizational and regulatory frameworks for metrological support in this area;&#x0D; proficiency testing through interlaboratory comparisons in the field of laboratory medicine is an effective tool for confirming the technical competence of the laboratory. Laboratories should parti­cipate in proficiency testing schemes on a regular basis. Proficiency testing providers should pay particular attention to the method of determining reference values of indicators in proficiency testing samples, using predominantly metrologically sound procedures based on the use of standards, certified reference materials and/or reference measurement methods;&#x0D; the heads of medical laboratories should be careful about the choice of suppliers of legal acts in the metrology.&#x0D;