Accreditation and Quality Assurance最新文献

Accurately determining the calorific value of aviation kerosene is crucial for optimizing aircraft engine efficiency and design testing. However, current measurement methods exhibit significant uncertainties, necessitating an assessment of the uncertainty associated with measuring the calorific value of aviation kerosene to establish precise results. The present paper introduces the oxygen bomb calorific value measurement method and the probability box model, proposing an improved aviation kerosene calorific value uncertainty evaluation method by combining it with the MCM method. An uncertainty evaluation model based on GUM method, MCM method, and improved MCM method is established in conjunction with experimental data. The analysis of different models demonstrates that the improved MCM method effectively considers the uncertainty of corresponding distribution parameters of variables based on their own uncertainties, providing a reliable approach for calculating the heating value uncertainty of aviation kerosene.

A large variety of statistical methods can be used for proficiency testing (PT) programs in various areas of laboratory testing. Statistical methods described in ISO 13528 and other international standards address PT in a wide variety of applications. The most significant difference in statistical techniques is whether performance evaluations are determined from the participant results using consensus statistics from the current round, or whether the performance criteria are determined independently. For schemes evaluated by consensus, the next most significant factor is the experience of both the scheme and its participants. This is evidenced in the proportion of results reported by participants who lack competence, are newly enrolled, or do not understand the instructions provided. For example, statistical techniques that are necessary for novel schemes (e.g. run for the first time) may not be appropriate for a similar scheme after several rounds with the same participants. Similarly, different techniques may apply for closed schemes that have regular technical review of a limited group of experienced laboratories. Techniques that make allowances for high levels of “contamination” from incompetent or inexperienced participants, such as the z’ score with consensus assigned values, should not be used in experienced schemes using consensus statistics. Other techniques that are more sensitive to small systematic errors should be employed for closer monitoring of experienced laboratories, including statistical techniques that consider the measurement uncertainty of the results. Mature PT schemes and closed schemes for special purposes should evaluate the measurement uncertainty of participant results in any PT scheme used by laboratories that make decisions on conformity assessment, or where improvement of participant agreement is an objective for the scheme. Oversight bodies that require compliance with ISO/IEC 17043 should consider these recommendations, to better ensure global compatibility of measurements.

Lead exposure is a well-known health concern, affecting children worldwide. We aim to assess children’s blood lead levels (BLLs), and the association of risk factors with elevated BLL in children since the phase-out of leaded gasoline. We enrolled 8085 outpatient children to assess their blood lead levels, and the associations with social-demographic factors. Social-demographic information was obtained by using questionnaires. Multivariable linear and logistic regression models were performed to explore the associations between social-demographic factors and elevated BLLs. The geometric mean BLL was 15.96 μg/L. The prevalence rates of elevated BLLs (≧ 100 μg/L and ≧ 50 μg/L) were 2.0 % and 10.9 %, respectively. BLLs in boys were higher than that in girls (P < 0.001). Girls had a lower risk of BLLs above 50 μg/L than boys (OR = 0.83, 95 % CI 0.71–0.96). Father’s occupation as a skilled laborer or professional worker and living in the suburbs significantly contributed to the elevated BLLs ( ≧ 50 μg/L), with the ORs of 1.39 (1.06–1.81), 1.33 (1.01–1.75) and 1.24 (1.02–1.50), respectively. Our results suggested that children who lived in suburbs and whose fathers were skilled laborers and professional workers were more likely to have BLLs above 50 μg/L.

The purpose of this study was to develop a rapid, sensitive, and precise RP-HPLC (Reverse-Phase High-Performance Liquid Chromatography) method for the estimation of asiaticoside (AC) using the analytical quality by design (AQbD) approach. Initially, important AQbD prerequisites like analytical target profile (ATP) and critical analytical attributes (CAAs), such as theoretical plates and tailing factor, were defined. The final chromatographic conditions for the analysis of AC consist of stationary phase {A COSMOSIL 5C18-MS-II packed column (250 mm × 4.6 mm i.d, 5 µm)}, mobile phase was S_mix {Methanol and Acetonitrile (40:25)}, and Orthophosphoric acid buffer (0.025 % OPA) in the ratio of 65:35 v/v at a flow rate of 1.0 mL/min and detection wavelength was 205 nm. The diversity in CAAs with different inputs was explained using the Ishikawa fishbone diagram. Taguchi design was selected as the first screening design to choose the critical material attributes (CMAs) that influence the method development. Subsequently, for more systematic optimization of the chromatographic technique and evaluation of CAAs, central composite design (CCD) was employed. In conclusion, the findings of the present study validated the utility of AQbD in the systemic design of a liquid chromatographic method with fine sensitivity for AC estimation in pharmaceutical products.

From 2008 to 2020, the Ministry of Food and Drug Safety (MFDS) and the Korea Research Institute of Standards and Science (KRISS) jointly conducted a proficiency testing (PT) program for the analysis of pesticide residues in kimchi cabbage and ginseng powder. This collaborative effort marked a significant milestone in South Korea, being the first instance of employing metrologically traceable assigned values, determined via isotope dilution mass spectrometry (IDMS), in PT programs. The focus was on a selective range of pesticides, including diazinon, chlorpyrifos, p,p’-DDE, γ-HCH (lindane), α-endosulfan, and β-endosulfan. Each biennial PT program centered on two of these pesticides with participating laboratories reporting their mass fractions in provided samples. PT samples were prepared meticulously prepared in powder form by KRISS, ensuring homogeneity and stability, integral for the accuracy of the testing. The paper elaborates on the intricate processes involved in PT sample preparation and the rigorous assignment of values. To evaluate laboratory proficiency, the Horwitz equation was utilized as a general mode to set for standard deviations in proficiency assessment. An in-depth review of seven PT programs conducted over this period demonstrates the significant role these programs played in advancing the measurement competencies of laboratories, underscoring the novelty and impact of this long-term collaborative effort.

Proficiency testing is an essential tool, which laboratories may use to demonstrate their competence, enabling them to evaluate their performance for specific measurements, tests or calibrations by comparison with results of other laboratories. The pressure therefore to consistently perform ‘well’ in proficiency tests may lead participants to consider colluding with other labs or falsifying data, in order to ensure a high standard of performance. The requirements for the accreditation of proficiency testing schemes to the ISO/IEC 17043 standard place a responsibility on the providers of proficiency testing to consider the possibility of collusion within their schemes and to take measures to discourage or prevent it. A survey of proficiency testing providers has been performed to gather a range of opinions on the ‘state’ of collusion within their schemes. The options available to providers for prevention of collusion and the difficulties of detection are also discussed.

For a laboratory following the ISO/IEC 17025:2017 standard, establishing a calibration programme is a requirement as per Clause 6.4.7. Clause 6.4.6. of the ISO/IEC 17025:2017 standard states that measuring equipment shall be calibrated when its measurement accuracy or measurement uncertainty affects the validity of the test results and/or when establishment of the metrological traceability of the test results is required. Equipment commonly used in a conventional food microbiology laboratory include biosafety cabinets or laminar flow cabinets, balances, diluters, homogenizers or blenders or mixers, pH meters, autoclaves, incubators, refrigerators, freezers, deep freezers, thermostatically controlled water baths, sterilizing ovens, temperature-monitoring devices such as thermometers, micropipettes, dispensers, vortex mixers, centrifuges, hot plates, and stop watches. The standard ISO 7218:2007/Amd 1:2013 provides guidance on which equipment requires calibration but sometimes, the accreditation body establishes more stringent guidelines which the conformity assessment body needs to follow. So, equipment that requires calibration may differ between conventional food microbiology laboratories accredited by different accreditation bodies. In this practitioner’s report, the author discusses the points a conventional food microbiology laboratory needs to consider when establishing a calibration programme.

The number of reference materials (RMs), including certified reference materials (CRMs) characterized for qualitative properties, has steadily increased in recent years. In response, the Technical Committee for Reference Materials of the International Organization for Standardization, ISO/TC 334, developed ISO 33406 to provide guidance to reference material producers (RMPs) on producing qualitative RMs. ISO 33406 builds on the general requirements in ISO 17034:2016 for RMP competence and offers specific guidance on value assignment, assessment of homogeneity and stability, statement of metrological traceability, and measurement uncertainty evaluation for RMs with qualitative property values.

According to clause 7.2.1.5, it is essential that a laboratory that follows the ISO/IEC 17025:2017 standard verifies standard methods or validated alternative methods before it starts using them. In 2021, the International Standard Organization published the ISO 16140-3:2021 standard. This standard provides guidelines for verification of reference methods and validated alternative methods in a single food microbiology laboratory. By using the guidelines provided in the standard, we performed the method verification of Compact Dry BC, a ready-to-use media for quantification of Bacillus cereus in foods or raw materials. This Compact Dry BC method was validated by MicroVal according to the ISO 16140-2:2016 standard and revealed to be at least equivalent to the reference method “ISO 7932: 2004—Microbiology of food and animal feeding stuffs—Horizontal method for the enumeration of presumptive Bacillus cereus—Colony count technique at 30 °C”. For implementation verification, the laboratory selected dried infant formula samples, while for food item verification, the laboratory chose dried infant formula, canned fish, breakfast cereal, sliced meat and pie samples. Intralaboratory reproducibility standard deviation (S_IR) obtained by the laboratory was 0.055 log₁₀ CFU, while the acceptable S_IR is ≤ 0.341 log₁₀ CFU. Estimated bias (eBias) for dried infant formula, canned fish, breakfast cereal, sliced meat and pie samples were also found to be ≤ 0.5 log₁₀ CFU for low, medium, and high inoculum levels. Therefore, as per the criteria set by the ISO 16140-3:2021 standard, the Compact Dry BC method is suitable to use in our laboratory for enumeration of presumptive B. cereus in a broad range of food.