Proficiency Testing Materials Research Articles

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.

Matrix Effects in Proficiency Testing Materials Influence the Accurate Measurement of Gamma-Glutamyltransferase Activity.

A consensus on an accurate method to measure γ-glutamyltransferase (GGT) activity for clinical purposes has not been achieved among practicing clinical laboratories. To improve analytical trueness, we evaluated the influences of matrix effects in proficiency testing (PT) materials on the measurement of GGT activity in human serum samples. Five fresh frozen human samples (FFS1-5) and five lyophilized proficiency testing materials (Lyo1-5) were distributed to 23 participating clinical laboratories for the measurement of GGT activity. Target GGT activity values for the samples were obtained by using previously approved reference methods. The results obtained by the Beckman Coulter Unicel DxC 800 Synchron analyzer were compared to the target values assigned by two reference laboratories, and the commutability of the lyophilized materials was evaluated according to Clinical and Laboratory Standards Institute (CLSI) guideline EP14-A2. The relative bias between the results obtained by the Beckman Coulter analyzer and the reference target values ranged from -27.2% to -18.0% for FFS1-5 and from 9.1% to 2.5% for Lyo1-5. Non-commutability of all lyophilized samples falling outside of the 95% prediction interval was observed. The results obtained for the lyophilized PT materials were deemed acceptable within the total allowable errors, suggesting that matrix effects may impart a false sense of confidence that clinical analytical systems are performing very well. A primary reference measurement procedure on fresh frozen serum provides a valuable method for evaluating the trueness of results measured by PT.

A Multilaboratory Commutability Evaluation of Proficiency Testing Material for Carbamazepine and Valproic Acid: A Study Within the Framework of the Dutch Calibration 2000 Project.

Medical laboratories are required to participate in interlaboratory comparisons of the analyses they perform. The materials used in these comparisons need to be of sufficient quality so that the comparison provides a picture of the performances. One of the main characteristics of the testing material is commutability, which is the ability of a material to yield the same numerical relationships between results of measurements as those relationships obtained when the same procedures are applied to patient samples. The aim of this study was to assess the commutability of 3 different matrices for the preparation of proficiency testing material (PTM) for the analysis of carbamazepine and valproic acid. Patient samples and PTM containing various concentrations of carbamazepine and valproic acid were collected, prepared, and shipped to different laboratories for analysis. Reported results for patient samples from each laboratory were plotted against results for patient samples of each of the other laboratories, and the corresponding regression line was calculated. The distance of results from PTM to the regression line is a measure for commutability. The distance is expressed as a multiple of the SDwl (average within-laboratory SD as calculated from external quality assessment scheme results) and referred to as relative residual. A commutability decision limit of 2 SDwl was set. For carbamazepine and valproic acid, a total of 78 and 105 laboratory couples respectively could be formed. The number of relative residuals for liquid human serum outside the commutability decision limit was 1, 4, and 0 for low, medium, and high concentrations of carbamazepine, respectively and 3, 1, and 0 for low, medium, and high concentrations of valproic acid, respectively. In both liquid and lyophilized bovine sera, the number of relative residuals outside the commutability decision limit was between 2 and 15 and between 6 and 21 for carbamazepine and valproic acid, respectively. Although not all results for PTM with carbamazepine and valproic acid are within the commutability decision limits, a preference for human serum can be seen.

Preparation of an infant formula proficiency testing material and assessment of its homogeneity and stability

The European Union Reference Laboratory for Chemical Elements in Food of Animal Origin (EURL-CEFAO) is a proficiency testing (PT) provider accredited according to ISO Guide 43-1 and later to ISO/IEC 17043:2010. It organizes exercises devoted to expert laboratories of the EU Member States. PTs are proposed taking into account matrices, analytes, maximum levels (MLs) ruled in Commission Regulation (EC) 1881/2006 (and following amendments) and discussions about new or modified MLs. Following this approach, an exercise was organized in 2012 on the measurement of the cadmium (Cd) and lead (Pb) mass fraction in powdered infant formula based on animal proteins (17th PT). One of the goals was to prepare a material containing Cd around the probable new ML so as to allow participants to test their performance at such a level. The procedure to produce the PT material was set on the basis of the EURL long experience in preparing freeze-dried samples and was tested on a preliminary batch. Homogeneity and stability of the PT material were evaluated through procedures based on international standards. For all tests, a standard deviation for proficiency assessment (σpt), more restrictive than that from the Horwitz equation (σH), was used. The mass fraction of Cd and Pb in the material was proven to be homogeneous and stable for 15 months. These results are extremely satisfactory taking into account the low mass fraction proposed and the restrictive standard deviation for proficiency assessment used to perform the tests. Furthermore, the PT was particularly useful considering that Commission Regulation (EC) 1881/2006 has been recently amended [CR (EU) 488/2014] with the introduction of the new ML for Cd in infant formulas consistent with the mass fraction value proposed in the 17th PT.

A method for quantification of volatile organic compounds in blood by SPME-GC-MS/MS with broader application: From non-occupational exposure population to exposure studies.

Humans are continuously exposed to volatile organic compounds (VOCs) as these chemicals are ubiquitously present in most indoor and outdoor environments. In order to assess recent exposure to VOCs for population-based studies, VOCs are measured in the blood of participants. This work describes an improved method to detect 12 VOCs by head-space solid-phase microextraction gas chromatography coupled with isotope-dilution mass spectrometry in selected reaction monitoring mode (SPME-GC-MS/MS). This method was applied to the analysis of trihalomethanes, styrene, trichloroethylene, tetrachloroethylene and BTEX (benzene, toluene, ethylbenzene, m-xylene, p-xylene, o-xylene) in a population-based biomonitoring study (Canadian Health Measures Survey). The method showed good linearity (>0.990) in the range of 0.010-10μg/L and detection limits between 0.007 and 0.027μg/L, precision better than 25% and good accuracy (±25%) based on proficiency testing materials. Quality Control data among runs over a 7 month period showed %RSD between 14 and 25% at low levels (∼0.03μg/L) and between 9 and 23% at high levels (∼0.4μg/L). The method was modified to analyze samples from a pharmacokinetic study in which 5 healthy volunteers were exposed to single, binary and quaternary mixtures of CTEX (chloroform, ethylbenzene, toluene and m-xylene), thus the expected concentration in blood was 1 order of magnitude higher than those found in the general population. The method was modified by reducing the sample size (from 3g to 0.5g) and increasing the upper limit of the concentration range to 395μg/L. Good linearity was found in the range of 0.13-395μg/L for toluene and ethylbenzene and 0.20-609μg/L for m/p-xylene. Quality control data among runs over the period of the study (n=13) were found to vary between 7 and 25%.

Benzo[a]pyrene 분석용 토양 숙련도 표준시료 개발에 관한 연구 - 후보 표준물질의 인증을 위한 균질성, 안정성 평가를 중심으로 -

This study was implemented as a part of the experiment to develop two kinds of soil-based Benzo[a]pyrene (BaP) proficiency testing materials (PTMs) for soil analysis. A test was carried out for the check of solubility of the reference material (high purity reagent) using several solvents. Another test was also conducted for the evaluation of homogeneity and stability of two kinds of candidate soil reference materials. The test analysis of BaP in terms of the candidate materials was conducted according to the Standard Soil Analytical Methods by Ministry of Environment. Dissolution of the reference material was shown to vary depending on solvent type and was higher in the order of Dichloromethane > Acetone > Acetone/MeOH (9 : 1) > Nhexane. In addition, the slope on calibration curve for BaP standard solutions was largest on BaP standard solutions prepared with dichloromethane of the tested solvents. Such tendency appeared egually in the commercial BaP standard solution. Therefore, it is thought to be reasonable to use dichloromethane as the solvent in case of the standard stock solution that is used for the measurement of BaP concentration in soil. ISO 13528 and IUPAC protocol were used for verification of homogeneity on the two kinds of soil candidate materials, Both candidate materials were sufficiently homogeneous. Stability assessment of the two candidate materials was made according to ISO Guide 35 and the result showed that both batches did not have any long-term and short term stability issues that might occur during shipping. However, monitoring results of BaP concentration in soil showed that BaP concentration of the two batches measured at 15 days after the sample preparation was reduced by about 24~37% compared with that of the samples measured on 0 day of the sample preparation. Identification was done with several treatments such as irradiation and sterilization etc. The major cause was shown to be irradiation to the samples.

복합악취 검사기관의 숙련도시험을 통한 희석배수 산정과정에서의 오류 사례 분석

The aim of this study is to analyze error cases induced during the proficiency test of certified odor measurement agencies. In the case of the homogeneity test performed in three panel groups, the geometric mean dilution factor of the site boundary PTMs(proficiency testing materials) was 1.4 ± 0.2, 1.7 ± 0.2, 1.8 ± 0.1 and that of the outlet PTMs was 3.7 ± 0.2, 3.7 ± 0.3, 3.7 ± 0.3, respectively. In the case of the stability test for 72 h, the geometric mean dilution factor of the site boundary PTMs was 1.6 ± 0.1 and that of the outlet PTMs was 3.6 ± 0.1. Among error cases induced during the proficiency test of certified odor measurement agencies, the proportion of error cases was in the order of case II(discontinuance of estimation)(40.0%) > case I(error on estimation procedure by panelist)(33.3%) > case III(miswriting of estimation result)(13.3%) > case IV(miswriting of dilution factor) and V(writing of wrong estimation result)(6.7%). Therefore, it seems likely that additional education related to error cases II and I is required.

Proficiency Testing of Complex Odors with Artificial Proficiency Testing Materials for air dilution olfactory method

Proficiency Testing of Complex Odors with Artificial Proficiency Testing Materials for air dilution olfactory method

BTEX 분석용 토양 숙련도 표준시료(PTMs) 개발에 관한 연구

In this study, two kinds of soil-based proficiency testing materials (PTMs), NICE-012L and NICE-012R were prepared and certified for Benzen, Toluene, Etylbenzene and Xylene with evaluation of uncertainties. In order to analyse BTEX (Benzen Toluene Etylbenzene Xylene) for the candidate materials, GC/MS was used after pretreatment according to methods of soil analysis by Ministry of Environment. For the homogeneity test among bottles in terms of candidate materials, ISO 13528 and IUPAC Protocol were used and according to the result, both candidate materials showed sufficient homogeneity. Also, the stability test over the candidate materials was accessed according to the ISO Guide 35 by classifying short-term and long-term stability and the result showed that both candidate materials showed decent stability. The reference values of the two candidate materials depending on BTEX components were derived from the average of the 11 samples that were used for verification of the samples’ homogeneity. Uncertainty of measurement was combined by uchar that was caused by a characteristic value, ubb that was caused by between-bottle homogeneity, and ustab that was caused by stability, and then combined uncertainty (uPTM) was multiplied to the coverage factor (k) derived from the effective degree of freedom from each factor that leads to expanded uncertainty (U) in about 95% of confidence level. The proficiency testing materials developed through this study were supplied to National Institute of Environmental Research (NIER) and utilized as an external proficiency testing materials for evaluating analysis capacity of soil agencies with specialty in terms of soil analysis approved by Minister of Environment.

복합악취 숙련도 평가를 위한 시험용 시료로서 현장시료의 타당성과 이를 이용한 숙련도 평가

복합악취 숙련도 평가를 위한 시험용 시료로서 현장시료의 타당성과 이를 이용한 숙련도 평가

The study on VOCs PTMs (Proficiency Testing Materials) as a complex malodor sample for air dilution olfactory method

The study on VOCs PTMs (Proficiency Testing Materials) as a complex malodor sample for air dilution olfactory method

The current status and future of medical laboratory quality regulation and accreditation in Ghana

High-quality and reliable laboratory services are important components of effective and well-function- ing health systems. Accurate, reliable and timely medical laboratory testing is crucial to patient care and disease surveillance. Unfortunately, in many sub-Saharan African countries, medical laboratory systems are adversely affec- ted by the unavailability of medical laboratories, poor laboratory infrastructure and lack of well-trained personnel (1). Quality in the laboratory is only achieved in a sys- tematic way through the implementation of a quality management system. The results of the study showed that approximately 60 % of the 78 respondents were unaware of the requirements of ISO 15189:2007. A trial of proficiency testing, termed 'blind proficiency testing', was carried out in which 19 laboratories determined the concentrations of urea and cholesterol in a proficiency testing material. Of the 19 laboratories that determined the concentration of urea, 63 % produced satisfactory results with scores between -2 and ?2. Similarly, 63 % of the participating laboratories obtained satisfactory z scores for cholesterol determination. Some of the laboratories that obtained sat- isfactory scores for urea determination had unsatisfactory scores for cholesterol determination and vice versa. It is recommended that the Ghanaian government pass a law and establish a standard to regulate medical laboratories in Ghana in order to improve quality in a significant way.

A Universal Influenza A and B Duplex Real‐time RT‐PCR Assay

A high throughput universal influenza A and B duplex real‐time RT‐PCR was developed to meet effectively the heightened surveillance and diagnostic needs essential in managing influenza infections and outbreaks. Primers and probes, designed to target highly conserved regions of the matrix protein of influenza A and the nucleoprotein of influenza B, were optimized using the high‐throughput LightCycler 480 II system. Analytical sensitivity and specificity were characterized using RNA transcripts diluted serially, archived non‐influenza respiratory viruses, and proficiency test samples. Eighty‐nine clinical samples were tested in parallel against existing influenza A and B monoplex assays. Once validated, the duplex assay was applied prospectively on 2,458 clinical specimens that were later subtyped. In April 2011, the emergence of an influenza B variant necessitated the inclusion of an additional modified probe for influenza B and revalidation of the revised protocol. The lower detection limits of the assay were 50 copies/PCR. There was no cross‐reactivity against any non‐influenza respiratory virus and all proficiency testing materials were identified correctly. The parallel testing revealed a 98.9% overall agreement. Routine application of the assay revealed high sensitivity and specificity for the detection of influenza A/H1N1/2009, A/H3N2 and influenza B. Assay Cq values correlated well between the pre‐ and post‐revision protocols for influenza A (r2 = 0.998) and B (r2 = 0.999). The revised protocol detected three additional novel influenza B variant cases in 200 specimens reported previously as influenza B negative. This in‐house assay offers a highly sensitive and specific option for laboratories seeking to expand their influenza testing capacity. J. Med. Virol. 84:1646–1651, 2012. © 2012 Wiley Periodicals, Inc.

Standardization and Monitoring of Laboratory Performance and Quality Assurance by Use of the Less-Sensitive HIV Incidence Assay

The Performance Evaluation Program for HIV-1 incidence tests provided quality assurance services to laboratories conducting the serological testing algorithm for recent HIV seroconversion by use of a modified less-sensitive version of the Vironostika HIV-1 MicroElisa System assay. We report on the performance of the assay using proficiency testing and quality control materials tested from 2001 to 2008. Two sets of 5 blinded serum panels using common calibration and quality control materials were tested. The mean, standard deviation, and coefficient of variation were calculated. Results were analyzed for misclassifications: false recent HIV infection errors (long-term infection classified as HIV infection less than 1 year), false long-term infection errors (HIV infection less than 1 year classified as long-term infection), and differences in standardized optical density means and variances over time. The false recent error rate was 1.26% (n = 2219). The false long-term error rate was 0.25% (n = 1618). No significant trends were observed for misclassification rates by year, and no significant trend in the standardized optical density over 7 years was observed. Laboratories using the less-sensitive Vironostika HIV-1 assay produced consistent results by use of a common calibrator and quality control materials.

O3-S1.05 Quality assurance of syphilis testing in a rural health facility using dried tube specimens (DTS)

BackgroundAssuring the quality of a diagnostic test is important in healthcare. For syphilis testing, this includes proficiency testing of previously well characterised serum samples by health workers blinded to the...

중금속분석용 하천수 매질표준물질을 이용한 숙련도 결과 평가

In this study, river water-based reference materials (RMs), NIER-I08RW and NIER-I09, for trace metal analysis were prepared and certified for Pb, Cd, Cr and Cu with evaluation of uncertainties. The RMs were confirmed to be homogeneous enough to be used as proficiency testing materials since within-bottle homogenieties of the RMs were lower than 0.3 times of targeted standard deviation of proficiency testing. The RMs were distributed to environmental testing laboratories for the proficiency testing and the variation of Z scores of the proficiency testing results were compared for different assigned values. The relative bias, , deviations between reference values and consensus values, were lower than 1 except for cadmium of NIERI08RW. The results showed both values were in a good agreement and only 2.9% of Z scores changed by using a different assigned values such as consensus and reference values.

Use of proficiency testing materials for the calculation of detection and quantification limits in the analysis of organochlorine compounds in human serum

A method for the calculation of the limits of detection (LD) and quantification (LQ) for the analysis of organochlorine compounds in serum is described. The method is based on the analysis of proficiency testing materials, an external quality assessment for selected pollutants, and the study of the signal/noise ratio of chromatograms obtained from GC-ECD injection. This method provides representative results for matrix effects, instrumental variability and extraction recoveries in the analysis of serum samples.

A rapid and fully-automated method for the quantitation of tricyclic antidepressants in serum using turbulent-flow liquid chromatography–tandem mass spectrometry

BackgroundWe describe a fully-automated turbulent-flow liquid chromatography–tandem mass spectrometry method for the detection of tricyclic antidepressant drugs (amitriptyline, desipramine, imipramine, and nortriptyline) in serum. MethodsHuman serum and an internal standard were injected directly onto a Cyclone-P online solid-phase extraction (SPE) column (0.5×50mm). Following removal of serum proteins and other components the analytes were transferred to a Hypersil Gold C-18 (50×3mm) analytical column. Elution occurred with a gradient of water and acetonitrile each with 0.1% formic acid. Analytes were ionized and detected over a 3.5min analysis time by electrospray-ionization mass spectrometry with selected reaction monitoring (SRM). Matrix effects were well-characterized and carryover, precision, linearity, recovery and limits of detection and quantitation were evaluated. ResultsThe simple and complex precision CVs for all compounds were ≤16%. The limits of detection and quantitation for all drugs were ≤3ng/ml and <20ng/ml, respectively. Recoveries were between 97 and 114%. Slopes for method comparison plots were all >0.96. Proficiency testing materials had values within 2 SDI of peer group means for all drugs. ConclusionBased on validation data, this is a specific, sensitive fully-automated method for rapid quantitation of tricyclic antidepressants in serum.