Accreditation and Quality Assurance最新文献

During the period 2021–2023, the Italian National Institute of Health (ISS) organised, in collaboration with the Italian Health Ministry, proficiency testing (PTs) for about 22 Italian and other EU laboratories involved in the monitoring programmes for Plant Protection Products (PPPs). The aim of the PTs was to determine the amount of active ingredient in various formulations of PPPs. Overall, the type of formulations to be analysed were soluble concentrate (SL), suspension concentrate (SC), capsule suspension (CS), emulsion water oil (EW), soluble water granule (SG), dustable powder (DP), water dispersible granule (WDG) and emulsion concentrate (EC). In 2021, the ISS organised PTs for the determination of Imazamox, Fenhexamid and Trinexapac-ethyl in three different PPPs as soluble concentrate (SL), suspension concentrate (SC), and capsule suspension (CS), respectively. In 2022, PTs for the determination of Bentazone, Spinosad and Tau-Fluvalinate were organised. For this PTs, commercial PPPs were obtained from the Italian market as SC, emulsion oil water (EW) and soluble water granule (SG). In 2023, the PT was organised to determine the active ingredient Trifloxystrobin, Deltamethrin and Cyprodinil in the commercial product as water dispersible granule (WDG), dustable powder (DP) and emulsion concentrate (EC), respectively. Homogeneity and stability, performed for all PT samples, fulfilled the acceptability criteria. The Jarque–Bera test was used to verify the hypothesis of normality of the data distributions before to calculate the z-score values. Laboratory performances, expressed in terms of z-scores, were satisfactory for almost all participants for all substances.

Valproic acid (VPA) is widely used for the treatment of epilepsy, bipolar disorder and other psychiatric diseases. Because of its narrow therapeutic window, monitoring the concentrations of VPA in patient’s serum is essential. In this paper, an isotope dilution-liquid chromatography-tandem mass spectrometry-(ID-HPLC–MS/MS) based candidate reference measurement procedure (RMP) for the quantification of VPA in human serum was established. After Samples pre-prepared by a simple protein precipitation method, the basic analytical performances of the candidate RMP was validated, including specificity, matrix effect, linearity, limit of quantitation (LOQ) and limit of detection (LOD), intra-and inter-batch precision, recovery rate, carryover, and stability. In order to make the measurement results of VPA traceable, we took all components that affect the accuracy of VPA measurement results into account to evaluate the corresponding uncertainties according to the GUM, including measurement imprecision, the purity of VPA standard, uncertainties caused by weighing during the preparation of calibrators and samples, matrix effect, recovery rate, carryover and sample stability. The candidate RMP separated VPA from potentially interferents in human serum and enabled measurement over a calibrated linear range from 2.60 to 203.57 μg/mL with a good correlation coefficient of 0.9995, and no significant matrix effects were observed. The intra-day and inter-day coefficients of variation (CV%) were 0.30–1.64% and 0.67–1.39%, respectively. The average recovery rates were between 94.55% and 96.93%. The LOD and LOQ were 0.23 μg/mL and 2.10 μg/mL, respectively. The expanded measurement uncertainties were 3.19% (k = 2) at 9.45 μg/mL, 3.14% (k = 2) at 48.86 μg/mL, and 2.95% (k = 2) at 97.23 μg/mL (k = 2), respectively.

The procedures used to assign values to certified reference gas mixtures and to evaluate their associated uncertainties, which are described in ISO 6143, and that were variously improved by Guenther and Possolo (Anal Bioanal Chem 399:489–500, 2011. 10.1007/s00216-010-4379-z), are further enhanced by the following developments: (i) evaluating and propagating uncertainty contributions derived from comparisons with historical reference gas mixtures of similar nominal composition; (ii) recognizing and quantifying mutual inconsistency (dark uncertainty) between primary standard gas mixtures used for calibration; (iii) employing Bayesian procedures for calibration, value assignment, and uncertainty evaluations; and (iv) employing state-of-the-art methods of meta-analysis to combine cylinder-specific measurement results. These developments are illustrated in examples of certification of two gas mixture Standard Reference Materials developed by the National Institute of Standards and Technology (NIST, USA). These examples serve only to demonstrate the methods described in this contribution and do not replace any official measurement results delivered in the certificates of any reference materials developed by NIST.

Sometimes, analytical laboratories receive requests with a small number of determinations and/or samples or outside the typical scope of analytical services. As a result, they may not have historical data on the performance of the required analytical procedures and/or appropriate reference materials. Under these conditions, it is difficult or uneconomical to use traditional quality control charts. This is the so-called start-up problem of these charts. Quesenberry’s Q charts are appropriate in these situations because they do not require a prior training phase. In the first part of this series of publications, the fundamentals and the algebraic expressions of the Q charts were presented for the individual measurements for the mean (four cases) and for the variance (two cases). This experimental study was carried out with data from quality control of mass fractions of Co in a serpentinite CRM and SiO₂ in a laterite CRM, by ICP-OES. The performance of Q charts is discussed in two situations: when the analytical process showed a clear systematic error from the beginning and when small shifts in mean and variance occurred simultaneously. In the first situation, performances of Q charts for the mean depended on the case: two of them were very sensitive even in the short run and the other two were insensitive and useless. In the second situation, the Q charts showed delayed alarms, but with a comparable behavior to the chart for individual measurements and the moving range of two. EWMA charts associated to Q charts were an excellent complement.

The present paper outlines a joint proficiency testing (PT) programme established between the Asia–Pacific Metrology Programme (APMP) and the Asia Pacific Accreditation Cooperation (APAC). This programme aims to assess the analytical performance and enhance measurement proficiencies in laboratories across various economies, with a focus on the quantification of benzoic acid in fish sauce. This PT programme was organised by the Government Laboratory, the designated institute of metrology in chemistry for Hong Kong, China (GLHK). A comprehensive invitation extended to both APMP and non-APAC members resulted in the participation of 41 laboratories from 19 different economies. The metrological reference value for benzoic acid, provided by GLHK, was determined utilizing isotope-dilution mass spectroscopy (IDMS) with traceability to the International System of Units (SI). This SI-traceable reference value enhances the quality of participants’ measurements and promotes the awareness of traceability among the participants, enabling a more accurate evaluation of their results. Concurrently, this approach facilitates the building of measurement capabilities among participants, fostering more robust connections between metrology institutes and testing laboratories. The programme also revealed a notable deficiency in the understanding of statistical concepts among some participants, including the coverage factor, degrees of freedom, standard uncertainty, and expanded uncertainty. Proper interpretation of zeta-scores or E_n scores based on measurement uncertainties, when analysed alongside z-scores, proves to be indispensable for an accurate assessment of the participants’ measurement competencies and their ability to evaluate measurement uncertainty. The assessment of participants’ performances, taking into account measurement uncertainties, serves as a benchmark for participants to gauge the validity of their measurement uncertainty evaluations.

Purity-evaluated inorganic materials, which are potential primary reference materials (PRMs) in chemistry, are crucial to the production of inorganic calibration solutions with metrological traceability to the International System of Units (SI). Purity evaluation is typically performed by individually assaying all possible impurities (gaseous and nongaseous) in a material, but technical challenges and the lack of resources are creating bottlenecks in developing effective purity assay procedures. This study describes a nongaseous impurity assay procedure developed and used at Korea Research Institute of Standards and Science (KRISS) to evaluate the purities of inorganic PRMs. Inductively coupled plasma mass spectrometry (ICP-MS) is used to assay more than 60 impurity elements in a single day, and external glow discharge mass spectrometry (GDMS) data are used to complement ICP-MS data. All aspects of the impurity assay procedure, including sample preparation, instrument operation, and data treatment, are described in detail. It is shown that the procedure is applicable to high-purity Al, As, Cu, NaCl, Se, Si, and Zn, and that a target relative uncertainty of 0.005 % for purity values can be satisfied even if individual impurity data are quite uncertain. Particular emphasis is on clearly specifying the measurand and target uncertainty for developing a fit-for-purpose assay procedure, as they determine the acceptable level of assay quality and help preventing misinterpretation of assay results.

Clause 6.5 of the ISO/IEC 17025:2017 standard describes the requirements for the metrological traceability of measurement results of a testing or calibration laboratory. Subclause 6.5.2 describes three ways to establish traceability to the International System of Units (SI). However, it is not technically possible to trace the bacterial strains used in a microbiology laboratory to the SI unit. So, when selecting a bacterial strain in a microbiology laboratory for quality assurance purposes, the laboratory needs to fulfill the subclause 6.5.3 (a) of the ISO/IEC 17025:2017 standard i.e., the laboratory needs to utilize a certified bacterial strain provided by a competent producer. So, when procuring a bacterial strain to fulfill this subclause, we need to ensure two points; (a) the bacterial strain is certified and (b) the producer is competent. A certified bacterial strain produces well-defined biochemical reactions and possesses a defined genomic sequence. There are various well-known certified bacterial strains, such as American Type Culture Collection (ATCC) strains, National Collection of Type Cultures (NCTC) strains etc. The laboratory also needs to make sure that the producer of these certified bacterial strains is competent, i.e. ISO 17034 accredited. Only when these two conditions are met, a microbiology laboratory can safely assume that it meets the requirements of subclause 6.5.3 (a) of the ISO/IEC 17025:2017 standard. For a particular bacterial species, from the vast number of strains available, the laboratory also needs to consider which specific strain to procure. The purpose of this article is to discuss why a testing microbiology laboratory needs bacterial reference materials and how it should select a bacterial reference material for quality assurance purposes from the ISO/IEC 17025:2017 standard point of view.

Leather is a versatile and widely used material, employed in various products such as fashion, footwear, furniture and automotive industries. The quality of leather products is critical in ensuring their safety, durability and aesthetic value verified through reliable and accurate testing. However, obtaining reliable leather test results can be challenging due to the complexity of the material and the test methods involved. Metrological traceability is a significant aspect of quality assurance, for ensuring results are comparable, consistent and accurate over time and across different laboratories. This paper will look at how the Polymer Laboratory of Kenya Bureau of Standards’ Testing Services Department demonstrates metrological traceability of leather tear tests results.

The Laboratory identified ISO 3377-1:2011 [IULTCS/IUP 40 Leather—physical and mechanical tests—determination of tear load. International Organization for Standardization, Geneva, Switzerland] as the appropriate reference measurement procedure for determination of tear load. Leather fibre material obtained from cowhide was tested for single-edge tear, result obtained was 6.6 ± 0.7 N. This result was then compared to assigned value for tear (8.1 ± 0.64 N) obtained through consensus of results from participating laboratories all using reference measurement procedure ISO 3377-1:2011|IULTCS/IUP 40 [8]. This comparison allowed the Laboratory to establish a traceability chain that connects its measurement result and any associated uncertainties to the SI unit of force, i.e. newton (N) through calibrated equipment.

Istituto Zooprofilattico Sperimentale delle Venezie (IZSVe) organizes qualitative and quantitative proficiency testing (PT) schemes—in the frame of the AQUA project—in different fields of technical competence. AQUA schemes for Salmonella, rabies, and avian influenza are performed by the national and international reference centres hosted by IZSVe. These PT are accredited according to ISO/IEC 17043:2010, since 2012. This manuscript aims to illustrate the methodology used in mapping the AQUA activities, identifying risks, and evaluating the risk management strategies implemented over the past decade. The goal is to provide a practical example of our experience in effective risk management. The mitigation actions put in place demonstrated the ability of IZSVe to minimize identified risks or at least keep them under control. In order to revise the quality management system in accordance the ISO/IEC 17043:2023 standard within the planned three-year transition period, the Institute has completed the first step of the transition processes: conducting a gap analysis and definition of the transition plan. A significant enhancement in the new edition of the standard is the increased emphasis on risk analysis. The organization believes that the methodology outlined in this document is applicable to the new regulatory context; however, it will be necessary to re-evaluate the risks associated with to each process in light of the new requirements.