Chikungunya, a mosquito-borne viral disease caused by Chikungunya virus (CHIKV), infects humans through the bite of Aedes sp. mosquitoes, causing high fever. Diagnosis includes the detection of IgM antibodies against CHIKV by ELISA. Department of Health Research (DHR)—Indian Council of Medical Research (ICMR) implemented an External Quality Assurance Scheme (EQAS) through Proficiency Testing (PT) to ensure the accuracy and reliability of CHIKV-IgM-ELISA testing across a network of laboratories in India. The geographical distribution of the participant laboratories from the PT provider (PTP) can lead to delayed transportation while distributing the PT panels, which could result in disqualification of PT panels due to suspected sample degradation and thus necessitates expensive panel redistributions. This study evaluated panel quality by assessing homogeneity and stability across various temperatures and time periods that simulate real-world transit conditions. The results were analyzed in accordance with ISO 13528:2022. This study shows that the CHIKV-positive samples in the PT panel remained robust across all tested temperature ranges and time periods, maintaining 100
The fractional composition of particulate matter represents their fundamental property, which influences their use in specific applications. Therefore, it can be a subject of testing in accredited laboratories. It is often determined by measuring the masses of particulate matter fractions on sieves with graduated opening sizes. Such a measurement provides information on the representation of particles of a certain size for selected sieve openings. However, when we want to derive the cumulative percentage for any particle size of particulate matter, approximation methods must be used. These include, for example, a power model characterizing the fractional composition of particulate matter and an approximation polynomial passing through known values of the cumulative percentage. Both methods use measured data on sieves; therefore, measurement uncertainty must also be considered. This is also reflected in the evaluation of both approximation methods. The paper presents the methodology for evaluating the measurement uncertainty of the methods used and compares these methods also from the perspective of the use of analytical calculations and Monte Carlo simulation.
Routine petroleum product testing evaluates each parameter independently against its specification limit under a single-parameter compliance paradigm that implicitly assumes parameter independence. This study challenges that assumption, proposing that multi-parameter correlation structures carry diagnostic signals invisible to single-parameter review. An Isolation Forest (IF) model was fit to 10,120 full-test-panel samples (gasoline: 5432; diesel: 4688) from an ISO/IEC 17025-accredited testing laboratory in Guangdong, China (2018–2026), retaining 3,279 gasoline samples across 32 parameters and 3534 diesel samples across 22 parameters. Five alternative anomaly detection methods—MCD Mahalanobis distance, Local Outlier Factor (LOF), One-Class SVM (OC-SVM), PCA reconstruction error, and a shallow autoencoder—were compared at equivalent contamination settings (1.0
Blank matrix reference materials (RMs) are representative of a typical test matrix, but contain levels of target measurands below method limits of detection (LOD). In the absence of target measurands, conventional approaches used in the characterization of RMs are not applicable. Non-target analysis (NTA) using liquid chromatography–high-resolution mass spectrometry (LC–HRMS) enables collection of data on samples without prior information on the chemical constituents present. In this work, NTA was used to characterize CRM-Cyano-A, a blank cyanobacterial matrix (Aphanizomenon sp.) dietary supplement RM developed in support of cyanotoxin analysis methods. To provide extensive profile coverage, reversed-phase and hydrophilic interaction LC methods were used, and HRMS data were analyzed using metabolomics software. Information on thousands of chemical species was summarized and initially scrutinized to show that cyanobacterial toxins were not present above method LODs. The NTA data were then used to characterize the RM. Homogeneity was verified using data acquired on CRM units selected across the production series, examining compounds with varying polarities. Isochronous stability studies revealed changes in a broad range of matrix components, shedding light on the natural instability of the biological matrix, while facilitating selection of conditions for reference material transport and long-term storage. The NTA concept demonstrated is broadly applicable in biological and environmental RM development.
In order to ensure comparability of uncertainties for serum glucose quantified by ID-LC-MS/MS, a comprehensive uncertainty evaluation method was established, especially associated with weighing. A set of class E2 weights were weighed under repeatability conditions, then the indication error, standard deviation and uncertainty of each weight were combined to the uncertainty of repeatability ( u_rep.rel ). The relationship between the indications and certified mass of all weights was established by linear least square fitting, then the uncertainties of slope and temperature coefficient were combined to the uncertainty of linearity ( u_L.rel ). Test load at least Max/3 was used to evaluate the uncertainty of eccentricity ( u_ecci.rel ). Uncertainties of the densities for weights, samples and air were combined to the uncertainty of buoyancy correction factor( u_B_u.rel ). The contribution of u_rep.rel , u_L.rel , u_ecci.rel and u_B_u,rel to the combined uncertainty of weighing ( u_c(m_s).rel ) were then calculated. At low weighing mass (≤112.7 mg), u_rep.rel is the maximum uncertainty contribution, whereas u_B_u.rel becomes the major contribution for higher mass (>20 g). When weighing object is 1.9497 g, both u_rep.rel and u_B_u.rel are significant uncertainty contributors. Other contributions which are less than 10 u_c(m_s).rel were 0.0652 and 0.0515 u_c(m_s).rel based on ID-LC-MS/MS, only u_rep.rel and/or u_B_u.rel should be taken into account.
