Proficiency Testing Materials Research Articles

Evaluating proficiency testing implementation and identifying challenges that government comprehensive specialized hospital laboratories in northwest Ethiopia faced as they participated in the external quality assessment scheme: A document-based, interview-driven evaluation.

To assess the implementation of proficiency testing in the northwest Ethiopian government comprehensive specialized hospital laboratories, with a focus on identifying and understanding the challenges encountered during their participation in the external quality assessment scheme. A cross-sectional study was conducted among 3 comprehensive specializedhospitals in northwest Ethiopia, analyzing 41 documented laboratory test parameters from 2020 to 2022. In addition, face-to-face, in-depth interviews were carried out to identify the major challenges the participating institutions faced. The study covered a total of 41 tests across 9 cycles. Overall, proper implementation of proficiency testing was observed in 59.3% of the tests, with 61.8% maintaining consistent implementation status over 3 consecutive years. In addition, the overall performance of the laboratory was 54.3%, with a 68.7% participation rate. The predominantly identified challenges included the lack of participation, insufficient reagents and supplies, inadequacy of suitable proficiency testing materials, equipment malfunction and downtime, lack of management support, insufficient budget, and inadequate training and awareness. The results of this study highlight the ineffective implementation of proficiency testing. Contributing factors include personnel issues, equipment and supplies challenges, managerial shortcomings, difficulties with proficiency testing providers, budgetary constraints, and a lack of training and motivation.

Evaluation of a new Electrochemiluminescence Immunoassay System for Measuring High-Sensitivity Cardiac Troponin T.

The aim of this study was to verify the analytical performance of the UD90DT electrochemiluminescence immunoassay system (the UD90DT system) for measuring high-sensitivity cardiac troponin T (hs-cTnT). According to the Clinical and Laboratory Standards Institute guidelines, the imprecision, linearity, reference interval, limit of blank (LoB), limit of detection (LoD), and functional sensitivity (FS) of hs-cTnT using the UD90DT system were verified. The trueness was validated using the Proficiency Testing (PT) materials. The within-run and between-run coefficients of variations (CVs) of two hs-cTnT levels were 7.2% and 1.5%, and 7.1% and 2.6%, respectively. The biases of the PT samples (n = 6) all fell within the allowable total error. The linearity satisfied the requirements, with a slope of 0.9963 and an R12 value of 0.9998. The hs-cTnT levels of the healthy volunteers (n = 20) ranged from 3.0 ng/L to 7.7 ng/L. All blank calibrator measurements (n = 20) fell within the LoD claim, and none of the samples (n = 25) had a LoB value ≤ 3.0 ng/L. The FS was 5.3 ng/L. Furthermore, a good correlation between the UD90DT system and the Cobas e 601 module was observed for hs-cTnT. The analytical performance of hs-cTnT using the UD90DT system is acceptable and satisfies clinical needs.

Strategies for validation of a low-volume BCR::ABL p190 assay in the clinical laboratory

Abstract Background The low prevalence of samples positive for the BCR::ABL p190 (e1a2) fusion transcript (<1/week) can be a barrier for molecular test validation. The Cepheid Xpert BCR-ABL Ultra p190 Assay is a single-use cartridge-based RUO assay designed for the quantitative detection of BCR::ABL p190 from fresh specimens. The following study describes our validation strategy to overcome this barrier for implementing a quantitative molecular LDT. Methods This study was conducted in a hospital clinical laboratory setting between 2019 to 2023. RNA was extracted and frozen from peripheral blood (PB) and bone marrow (BM) samples that were sent in parallel to a reference lab for BCR::ABL p190 testing. High positive diagnostic specimens (>10% p190/ABL1) were presumptively identified as BCR::ABL FISH positive and p210 negative. Diagnostic specimens were diluted in known negative PB or BM to achieve %p190/ABL1 in various quantitative ranges. Reverse transcription, amplification, and quantitative real-time PCR were performed in a single reaction format (Cepheid Xpert cartridge®). For accuracy determinations, reported results of clinical samples from the reference lab were compared to the obtained values from our validation using extracted RNA only. Banked proficiency testing (PT) material was used to supplement qualitative and quantitative accuracy. For precision, Invivoscribe (IVS) control material (San Diego, CA) diluted in seven levels (12.5% to 0.0031%; 4-fold increments) and Maine Molecular Quality Controls (MMQCI, Saco ME) at 10%, 1%, 0.1%, 0.02%, 0% were run by at least three technologists and rotated amongst the 16 instrument modules. To evaluate linearity, IVS controls at 15 levels (100% to 0.003%; 2-fold increments) were assayed in triplicate. Limit of detection (LoD) was the minimum concentration at which the detection rate is 100% in 10 independent runs. For analytical specificity, high-positive p210 specimens (>10%) were evaluated for detection of p190. Results a total of 169 samples were analyzed (33 BM, 32 PB, 5 PT samples, 73 IVS controls, and 26 MMQCI controls). We found a correlation (linearity) between reference lab results and clinical/ control samples (R-squared ~0.88, P < 0.01). Overall Cohen’s kappa concordance for qualitative accuracy analysis was 0.80 (CI 95% 0.65-0.95). Sensitivity, specificity, and accuracy were 91%, 92%, and 91%, respectively. This assay showed precision in all levels of dilution (IVS and MMQCI samples) as previously established. LoD was 0.02%. Samples with high level of p210 /ABL remained negative with the p190 assay. Conclusion in the setting of low-volume assays optimized for fresh samples, such as for the detection of BCR::ABL p190, dilutions of clinical samples, banked frozen RNA extracts, PT samples, and commercial controls are important tools for validation of a quantitative LDT.

B-203 Development and Validation of an LC/MS/MS Method to Quantify Creatinine in Dried Blood Spots

Abstract Background Health disparities in diagnosis and treatment of chronic kidney disease (CKD) are apparent with Black, Brown, and socially disadvantaged people experiencing worse outcomes. Improving access to CKD screening may decrease disparities. Blood creatinine concentrations are a mainstay in CKD screening, as it is commonly used to estimate glomerular filtration rate. Creatinine is classically measured in serum/plasma using high-throughput chemistry analyzers. Dried blood spots (DBS) could offer a solution to under-screening, but require an alternative method since extraction from DBS retrieves minimal sample volume and is difficult to scale using conventional automation. The purpose of this study was to develop an LC/MS/MS DBS method to quantify creatinine and ultimately to increase screening access for underprivileged communities. Methods Creatinine was measured using a 100 × 2.1 mm Hypersil Silica column with an ABSciex API4000 MS/MS detector. A 5-point calibration curve was made using creatinine certified reference material (Cerilliant) and blank whole blood (UTAK) (target concentrations: 0.575, 0.975, 4.575, 10.575, 20.575 mg/dL). Calibrators were spotted onto Whatman903 cards and allowed to dry for at least 24-hours. A 6 mm punch was used for analysis of calibration points and patient samples. Once punched, water (50 ul) was added and the samples were incubated at 60°C for 15 min before shaking at 800 RPM. Acetonitrile with 2H-creatinine internal standard (IS; .06 mg/dL) was added and the mixture was shaken and centrifuged. The resulting supernatant was diluted to contain 20% water before injecting 10 uL. Creatinine was separated using an isocratic mobile phase (80% Acetonitrile, 20% DI water, 10 mM Ammonium Formate) and detected using MRM mode (Q1 114.0 m/z; Q3 86.8 m/z (quantifier) and 44.5 m/z (qualifier)). For the IS a Q1 of 117.0 m/z and Q3 of 89.9 m/z was applied and the extraction ratio of endogenous creatinine to IS was calculated to determine the concentration. Linearity was confirmed by running five levels of DBS calibration standards for five days. Imprecision was established by running 3 control levels five times for five consecutive days. Control material was purchased from BioRad and run as liquid. Accuracy was assessed using residual liquid CAP serum creatinine proficiency testing (PT) material in triplicate. DBS creatinine concentration determined by LC/MS/MS was compared to paired venous serum creatinine concentration determined by the Roche Cobas enzymatic creatinine assay (n = 63). Results Creatinine concentrations from 0.2–20 mg/dL were within the allowable nonlinearity of 0.075 mg/dL or 5.0% (y = 1.00x−0.010;R = 0.999). Intraday and interday precision was <2%and <3%, respectively for all levels (mean concentrations 1.00, 2.02, and 7.05 mg/dL). Residual CAP PT samples (n = 4) were within 2.5% of the peer group mean. Compared to venous results, DBS had a bias of −0.03 mg/dL (−3.573%) and a linear equation of (y = .904x +0.049; R = 0.83). Conclusion Preliminary results indicate that DBS are a viable sample source for measuring creatinine. Creatinine concentrations measured by DBS compared favorably with CAP PT. A clinically insignificant negative bias was seen when DBS creatinine concentration was compared to venous blood.

B-177 Quantitative Measurement of Vitamin B1 in Whole Blood using a Multiplex ESI-LC-MS/MS System

Abstract Background Vitamin B1 is a water-soluble vitamin required for human health. Thiamine diphosphate (TDP), the active form of vitamin B1, plays an essential role in biochemical pathways required for energy metabolism. TDP is analyzed routinely in the laboratory to assess the nutritional status of post-bariatric surgery patients and other individuals who are at risk of vitamin deficiency. In recent years, demand for vitamin B1 testing has increased dramatically, prompting development of a high throughput assay. Here, we present a method using protein precipitation and multiplex LC-ESI-MS/MS analysis at low pH with reversed-phase parameters that optimize chromatographic separation. The new method was validated for linearity, sensitivity, accuracy, imprecision, specificity, reproducibility, carryover, and stability. Method Whole blood samples were deproteinized using trichloroacetic acid (TCA) after the addition of stable-isotope-labeled TDP (d3-TDP) as an internal standard (IS). TDP was separated by reversed-phase chromatography on Waters XBridge™ Premier BEH C18 columns (2.1 × 100 mm, 2.5 µm) and analyzed on an Agilent StreamSelect™ LC-ESI-MS/MS platform. The StreamSelect™ system consists of four parallel Agilent Infinity Lab LC Series II instruments coupled to a single triple quadrupole mass spectrometer (6470B). TDP was found to interact with metal surfaces in the LC system, so the flow path was passivated using a deactivator solution which improved overall sensitivity and peak quality. TDP eluted in 3.15 ± 0.08 minutes; run times per column for a single stream and four streams were 9 min and 2.25 min, respectively. TDP was analyzed using positive electrospray ionization and multiple reaction monitoring mode with mass transitions of m/z 425.05 > 121.1 (quantifier) and m/z 425.05 > 304.00 (qualifier). Results The method was linear from 20 to 1000 nmol/L with an R2 > 0.99. Replicate analysis of low calibrators to evaluate assay sensitivity demonstrated accuracy within 10% and imprecision of ≤5%. Spike-recovery experiments showed an accuracy of ±15%. TDP measured in purchased, matrix-matched quality control (QC) and expired proficiency testing materials met the specified range for all samples. The intra- and inter-day assay imprecision was ≤3%. The cross-analyte interference study showed the analyte response in the IS-only blank was less than 10% of the LLOQ area. Also, the IS response at the ULOQ was ≤5% of the analyte area. Repeated injections of calibrators and QC materials across the four LC streams showed excellent parity (<2% imprecision). Re-injection reproducibility of extracted samples at 24 and 48 h was within ±2% of time zero concentration. Batch size tests indicated a high degree of robustness required to support the anticipated high testing volumes. Conclusions An accurate, specific, and high-throughput LC-ESI-MS/MS method was developed and validated to measure TDP in whole blood. Simple, quick sample preparation was employed for adaption to a high-throughput platform. StreamSelect™ using four parallel LCs reduced injection times to 2.25 min per sample and significantly minimized mass spectrometer idle time. The assay performance evaluations met our laboratory-developed test acceptance criteria for use in routine clinical laboratory analysis.

Comprehensive Evaluation of the NeoBase 2 Non-derivatized MSMS Assay and Exploration of Analytes With Significantly Different Concentrations Between Term and Preterm Neonates.

Despite the popularity of the NeoBase 2 Non-derivatized MSMS assay (PerkinElmer, Turku, Finland), there are no reports of its comprehensive evaluation, including the ability to distinguish transient tyrosinemia of the newborn (TTN) from tyrosinemia type 1 (TYR 1) using succinylacetone (SUAC). No newborn screening (NBS) cutoffs for preterm neonates in the Korean population have been suggested. We evaluated the NeoBase 2 assay and identified analytes requiring different cutoffs in preterm neonates. Residual NBS dried blood spot samples and proficiency testing (PT) materials of the Newborn Screening Quality Assurance Program and the Korean Association of External Quality Assessment Service were used. Precision, accuracy, limit of detection (LOD), lower limit of quantification (LLOQ), linearity, recovery, carryover, and performance of SUAC were evaluated. Cutoffs were determined, and analytes requiring different cutoffs in preterm neonates were investigated. Mean CVs for within-run and between-day precision were within 15%. Accuracy analysis indicated high agreement with in-house derivatized assay results and results of other PT participants. All analytes demonstrated acceptable LOD, LLOQ, and linearity. Recoveries were acceptable, except for SUAC. Carryover was negligible. Cutoffs were established for all analytes; Tyr, adenosine, and C20:0-lysophosphatidylcholine required different cutoffs in preterm neonates. Differential diagnosis of TYR 1 and TTN was successful with simultaneous Tyr and SUAC measurement. The NeoBase 2 assay demonstrated satisfactory performance. The additional analytes provide a wider diagnostic coverage, and the simultaneous measurement of Tyr and SUAC is efficient in excluding TYR 1. The new cutoffs for preterm neonates may decrease false-positive rates, without compromising diagnostic sensitivity.

Sigma metrics of Alinity ci system - a study on thirty-nine clinical chemistry and immunoassay parameters.

Sigma metrics in an invaluable and inexpensive tool used in laboratories to monitor analytical quality of the assays. Alinity ci platform is a relatively recent analytical system launched by Abbott Diagnostics, and as such performance studies on it are few. We have calculated sigma metrics of 39 clinical chemistry and immunoassay analytes on two Alinity ci systems. Sigma metrics were calculated using results of method validation studies. Coefficient of variation (CV) was calculated according to CLSI EP 15 guidelines. Bias was calculated using three different methods i.e.,proficiency testing material, alternate method comparison with existent analyzers and linearity experiment. Total allowable error limits were kept similar to or less than the ones used in reference studies. All analytes except blood urea nitrogen (BUN) demonstrated greater than six sigma value across one or more levels and methods. No analyte amongst clinical chemistry and immunoassays was at below three sigma class. Amongst electrolytes, sodium was below three sigma class at two levels by proficiency testing method, although it was above four sigma class by other two methods. Sigma levels obtained were comparable to those reported in previously published studies. Acceptable sigma metrics were achieved for all clinical chemistry, immunoassays and electrolytes on Alinity ci. Sigma metrics is an objective and well established cost effective tool to tailor internal quality control practices. This study determines sigma metrics for a wide range of high throughput assays. Long term assay performance needs to be monitored.

Participation in the College of American Pathologists Laboratory Accreditation Program Decreases Variability in B-Lymphoblastic Leukemia and Plasma Cell Myeloma Flow Cytometric Minimal Residual Disease Testing: A Follow-up Survey.

Minimal residual disease (MRD) testing by flow cytometry is ubiquitous in hematolymphoid neoplasm monitoring, especially B-lymphoblastic leukemia (B-ALL), for which it provides predictive information and guides management. Major heterogeneity was identified in 2014. Subsequently, new Flow Cytometry Checklist items required documentation of the sensitivity determination method and required lower level of detection (LLOD) inclusion in final reports. This study assesses Laboratory Accreditation Program (LAP) participation and new checklist items' impact on flow cytometry MRD testing. To survey flow cytometry laboratories about MRD testing for B-ALL and plasma cell myeloma. In particular, enumerate the laboratories performing MRD testing, the proportion performing assays with very low LLODs, and implementation of new checklist items. Supplemental questions were distributed in the 2017-A mailing to 548 flow cytometry laboratories subscribed to the College of American Pathologists FL3 Proficiency Testing Survey (Flow Cytometry-Immunophenotypic Characterization of Leukemia/Lymphoma). The percentage of laboratories performing MRD studies has significantly decreased since 2014. Wide ranges of LLOD and collection event numbers were reported for B-ALL and plasma cell myeloma. Most laboratories determine LLOD by using dilutional studies and include it in final reports; a higher proportion of LAP participants used these practices than nonparticipants. Several MRD testing aspects vary among laboratories receiving FL3 Proficiency Testing materials. After the survey in 2014, new checklist items were implemented. As compared to 2014, fewer laboratories are performing MRD studies. While LLOD remains heterogeneous, a high proportion of LAP subscribers follow the new checklist requirements and, overall, target LLOD recommendations from disease-specific working groups are met.

Commutability of proficiency testing material containing amitriptyline and nortriptyline: A study within the framework of the Dutch Calibration 2.000 project

BackgroundExternal quality assessment schemes (EQAS) can provide important information regarding accuracy and comparability of different measurement methods if the sample matrices are composed of commutable material. The aim of this study was to assess the commutability of different matrices for the material used in an EQAS for amitriptyline and nortriptyline. MethodsProficiency testing material (PTM) and patient samples containing amitriptyline and nortriptyline were prepared, collected, pooled, and distributed to participating laboratories for analysis. Low, medium and high concentrations of both drugs in liquid pooled human, lyophilized human and lyophilized bovine serum were tested in this study. The measurement deviation of the PTM results to the patient serum regression line were normalized by dividing trough the average within-laboratory SD (SDwl) derived from the results reported in the official EQAS, resulting in a relative residual. The commutability decision limit was set at 3 SDwl. ResultsWith 10 laboratories participating in this study, 45 laboratory couples were formed. All matrix types delivered several relative residuals outside the commutability decision limit. The number and the magnitude of relative residuals for both drugs were lower for liquid human sera as compared to lyophilized human and bovine sera. ConclusionsThe PTM used for amitriptyline and nortriptyline is preferably prepared with human serum, although not all relative residuals are within the commutability decision limit.

Development of interlaboratory comparison test samples and reference materials for the quality assurance of air composition measurements

Introduction. The article presents an approach to the development of interlaboratory comparison test samples and respective reference materials for use in the metrological assurance of measurements of hazardous substances in the ambient air. Materials and methods. Solid and liquid sorbents, as well as air filters were used in the experiments. Measurement methods comprised photometry, atomic absorption spectrometry, inductively coupled plasma atomic emission spectrometry. Results. An optimized algorithm for developing multi-purpose test samples that can be used for the metrological assurance of a large number of methods for analysing ambient air is presented. Discussion and conclusions. The described approach has been used to develop test samples for laboratory proficiency testing and respective reference materials, which can be used in the certification of procedures for analysing ambient air quality, calibration of measurement instruments, as well as in the internal and external quality control of results obtained during ambient air quality measurements.

31. The PT alphabet soup: LDT, FDA, NGS, non-NGS, @#$!%

The performance of laboratory testing has recently come under increased scrutiny as part of important and ongoing debates on regulation and reimbursement of laboratory developed tests (LDTs), including next generation sequencing (NGS). The College of American Pathologists (CAP) is a well- recognized provider of external proficiency testing (PT) materials that provide a mechanism for laboratories to fulfill Clinical Laboratory Improvement Amendments. The CAP Molecular Oncology Committee has examined the overall performance of laboratories across specific single analytes as well as NGS PT surveys.

Preparation of pooled blood samples to use as a proficiency Testing material for hemoglobin a1ctesting byturbidimetric Inhibition immunoassay

Preparation of pooled blood samples to use as a proficiency Testing material for hemoglobin a1ctesting byturbidimetric Inhibition immunoassay

Analysis of the influence of panel characteristics on odor measurement based on the air dilution olfactory method in Korea

This study was to objectify differences in the results of odor testing according to the characteristics of panel members that participate in air dilution olfactory method (ADOM) testing. When differences in the results of olfactory testing were reviewed in relation to characteristics of the panelists, the result of entire panels for the site boundary Proficiency Testing Materials (PTMs) showed no difference according to panelist sex, age, smoking status, and past participation in ADOM tests. As for the outlet PTMs, distinct differences appeared in relation to the smoking status and age of panelists. The frequency distribution for all the panelists (Dev(D/Ttotal)) showed a form similar to a normal distribution, so it is thought to be more appropriate for the review of effect of panelist characteristics on the result of air dilution olfactory tests. In addition, the ADOM testing method implemented as the standard method for odor compounds in Korea (Dev(D/T3)) will have to be implemented along with a concurrent assessment, for the purpose of identifying the effect of panelist characteristics on administrative dispositions against malodors. Keywords: Odor, Olfactory sense, Olfactory test, Panelists, Proficiency testing materials

Measurement uncertainty: requirements set in the accreditation standards

Measurement uncertainty is of high importance to all testing and calibration laboratories and those involved in sampling activities. Its evaluation requires good understanding of the method implemented and realisation of all factors contributing to it. It is required that the users of the results fully understand the meaning of uncertainty stated on test reports and calibration certificates and, when needed, ask for clarifications. Laboratories, both the accredited ones and those being prepared towards their accreditation, need to take this into account when evaluating the uncertainty of their results. Competent authorities need to consider the stated uncertainty to compare the result with a legislative limit. The producer can decide on adjustments needed. The consumer may find it more difficult to understand how this “uncertain component” of the results could affect their health, safety or economic rights. This article describes the relevant requirements of the accreditation standards referring both to testing and calibration laboratories and to proficiency testing and reference material producers. Further to this, the article explains why all these factors have to be considered by a laboratory.

Multicenter Laboratory Comparison of Iohexol Measurement

Iohexol is utilized for measurement of kidney glomerular filtration rate (GFR). Until recently, there have not been available proficiency standards to assist in calibrating a laboratory's results. In view of a shift in calibration at the University of Rochester Medical Center (URMC) laboratory, serving as Central Biochemistry Laboratory for the CKiD study, we performed a multi-centered laboratory comparison. Two batches of 30 fortified sera and patient samples from serum or heparinized plasma were sent for duplicate analysis to URMC, University of Minnesota (UMN), Mayo Clinic, and University of Lund. Five proficiency testing materials from Equalis AB were also provided. Iohexol calibration was performed using dilutions of Omnipaque™ 300 and concentrations measured by HPLC or LC-MS/MS (Mayo). UMN and Lund agreed well. URMC calibration was 11-13% lower, and Mayo was 4-8% lower for fortified samples. URMC corrected calibration was 3-8% higher for these samples. When measured values were adjusted for the results of the Equalis samples, all laboratories agreed within 1-2% on all iohexol concentrations. For 12 URMC calibrator lots from 11/ 2006 to 3/ 2016, the factor quantifying the underestimation of measured to true iohexol concentration was 0.89. If each concentration were divided by 0.89, the calculated GFRs would be reduced by 10-11%. GFR results for CKiD were adjusted for this shift in calibration. Regular examination of iohexol proficiency testing materials, free exchange of samples among laboratories, and standardized dilution of the stock iohexol for calibration would help to bring more universal agreement to this assay.

The evaluation of homogeneity and stability of proficiency testing materials in indoor air quality test

The evaluation of homogeneity and stability of proficiency testing materials in indoor air quality test

Glucose-6-phosphate dehydrogenase enzyme stability in filter paper dried blood spots

ObjectivePrior to initial distribution of Glucose-6-phosphate dehydrogenase (G6PD) proficiency testing (PT) materials, we evaluated G6PD enzyme stability in dried blood spots (DBS) under various temperature and humidity environments to develop storage and usage guidelines for our new materials. Design & methodsWe prepared fresh G6PD-normal DBS materials and conducted stability evaluations of daily use and short and long-term storage under various temperature and humidity environments. ResultsG6PD DBS PT materials retained 92% of initial activity after 30days of use at 4°C. Materials stored at −20°C and 4°C with desiccant for 30days retained 95% and 90% of initial activity, respectively. When stored for one year at −20°C or six months at 4°C specimens retained >90% of initial activity. Specimens stored at 37°C with desiccant lost 10% activity in three days. At the end of 30days, specimens stored under ‘Extreme’—humidity >50% without desiccant— conditions at 37°C assayed below the NSQAP cut off for G6PD. Humidity exacerbated loss of enzyme activity with increasing temperature and time duration. ConclusionData suggest that G6PD PT materials can be stored at 4°C and used for up to one month and can be stored at −20°C for one year and yield >90% enzyme activity. Exposure to warm temperatures, especially with elevated humidity, should be avoided. Desiccant should always be used to mitigate humidity effects.

First evidence of high urinary 1-hydroxypyrene level among rural school children during smoke haze episode in Chiang Mai Province, Thailand

Smoke haze from biomass burning has been a crisis in northern Thailand. There have been plenty of reports on ambient PM10 and PAHs but not on individual exposure during smoke haze episodes. The present study aimed to quantify urinary 1-OHP, a predominant biomarker of PAH exposure, among 200 rural school children in Om Koi and Mae Chaem districts, Chiang Mai Province, northern Thailand. Questionnaires for information regarding environmental exposure and health diaries were given out. Urine samples were collected to measure 1-OHP using high-performance liquid chromatography-fluorescence detection, HPLC-FLD (HP1100 Series/HP1046A). Proficiency testing materials were obtained from the participation of German External Quality Assessment Scheme (G-EQUAS, Erlangen, Germany) and analyzed as part of the method validation of our urinary 1-OHP method. The median urinary 1-OHP level in the school children from Om Koi District was significantly higher than that in Mae Chaem District (0.70 versus 0.24 μmol/mol cr). The present study showed the evidence that urinary 1-OHP level among school children from the selected study sites during haze episode in northern Thailand is higher than those reported in other region of Thailand and other countries.

Assuring the Quality of Next-Generation Sequencing in Clinical Microbiology and Public Health Laboratories

Clinical microbiology and public health laboratories are beginning to utilize next-generation sequencing (NGS) for a range of applications. This technology has the potential to transform the field by providing approaches that will complement, or even replace, many conventional laboratory tests. While the benefits of NGS are significant, the complexities of these assays require an evolving set of standards to ensure testing quality. Regulatory and accreditation requirements, professional guidelines, and best practices that help ensure the quality of NGS-based tests are emerging. This review highlights currently available standards and guidelines for the implementation of NGS in the clinical and public health laboratory setting, and it includes considerations for NGS test validation, quality control procedures, proficiency testing, and reference materials.

Commutability of proficiency testing material containing tobramycin: a study within the framework of the Dutch Calibration 2.000 project.

Results from external quality assessment schemes (EQASs) can provide information about accuracy and comparability of different measurement methods, provided that the material used in these schemes behave identical to patient samples among the different methods, a characteristic also known as commutability. The aim of this study was to assess the commutability of different matrices for the material used in an EQAS for tobramycin. Proficiency testing material (PTM) and patient samples containing tobramycin were prepared, collected, pooled, and distributed to participating laboratories for analysis. Low, medium, and high tobramycin concentrations in liquid human, liquid bovine and lyophilized bovine serum were tested in this study. The patient serum results of every laboratory were plotted against each of the other laboratories, and the distances of the PTM results to the patient serum regression line were calculated. For comparison, these distances were divided by the average within-laboratory standard deviation (SDwl) of the results reported in the official EQAS for tobramycin, resulting in a relative residual. The commutability decision limit was set at 3 SDwl. With 10 laboratories participating in this study, 45 laboratory couples were formed. For human serum, only one relative residual for high concentrations of tobramycin was found outside the commutability decision limit. For liquid and lyophilized bovine sera, the number of relative residuals outside the decision limit was between 15 and 18 for low, medium, and high tobramycin concentrations. The PTM used for tobramycin is preferably prepared with human serum.