Proficiency Testing Rounds Research Articles

A New Design for Reference Values Assignment in Proficiency Testing for Fat and Crude Protein in Raw Milk for a Limited Number of Participants.

Proficiency testing (PT) allows food laboratories to endorse their competency to provide food safety guarantees to producers and consumers. One of the recommended methods for assigning reference values in PT with a small number of participants consists in considering the results that a laboratory obtains by means of a calibration test based on certified reference material (CRM). The present study delves into the results from eight PT rounds on the determination of fat and crude protein from raw milk, with modifications in the number of samples and the analysis sessions from that required by the ISO 13528:2022. The uncertainty criterion of the assigned value established by the ISO 13528:2022 standard was met by 93% of the participating laboratories, which allowed most participants to be evaluated through z-score. The assigned values were generally compatible with the results obtained by the participants. Thus, it can be concluded that the design for the assignment of the reference value is appropriate for PT with a limited number of participants. It is recommended for future PT to limit the uncertainty of the CRM according to their availability and to update the standard deviation of the proficiency assessment for the Mid-Infrared Spectroscopy method (MIR).

Experience of a proficiency testing program developed in Latin America for chemical analysis of coffee

Based on ISO 17043:2010, eight (8) proficiency testing (PT) rounds were organized for moisture, ash, caffeine, and total sugar analyses using commercial ground roasted pure coffee and roasted coffee with sugar added as PT materials as part of the Interlaboratory Food Analysis Rounds Program (PRIDAA, by its acronym in Spanish). Twenty-five (25) laboratories from Latin America participated in these PT Rounds. Results were evaluated using statistical procedures based on ISO 13528: 2016. The Z/Z′-scores used to evaluate the performance of laboratories were computed using the standard deviation for PT (σp) defined based on fitness-for-purpose, while the assigned values (mean, median, or robust mean) were obtained from the consensus of PT participants’ results. For ash and caffeine, 89 % and 88 % of PT participants achieved a satisfactory performance (|Z/Z’|≤2), respectively, as average of the eight (8) rounds. Only 75 % achieved a ‘‘satisfactory’’ performance in the case of total sugars and 83 % in the case of moisture. For total sugar and caffeine, results obtained with methods other than HPLC were not comparable to the assigned value defined as the consensus of the HPLC results. Significant improvements in the methodology were applied to the PT when the ISO 17043:2010 accreditation was achieved in 2020.

Quick and high-throughput quantification of β-agonist residues in bovine liver, meat, milk, kidney, poultry, and egg using dispersive solid phase extraction

A reliable liquid chromatography coupled to quadrupole-Orbitrap high-resolution mass spectrometry (LC-Q-Orbitrap HRMS) method was developed for the simultaneous identification and quantification of 13 β-agonist residues in bovine liver, meat, milk, kidney, poultry, and egg. Dispersive-solid phase extraction (d-SPE) using acetonitrile (ACN) was used to prepare the samples. The analyte in the extracts was separated on a reversed-phase Accucore aQ (50 mm × 2.1 mm, 2.6 μm) using a mobile phase of an aqueous solution containing 2 mM ammonium acetate and acetonitrile (ACN) 0.1 % formic acid. The method was validated in accordance with Commission Implementing Regulation (CIR) EU 2021/808 at six different concentrations ranging from 0.1 to 5 μg/kg. The mean recoveries ranged from 65 to 94 %, while repeatability and reproducibility values were all below 13 %. The linearity, as correlation coefficients (R2) ranged from 0.9955 to 0.9999. The decision limit (CCα) and detection capability (CCβ) ranges were 0.11–0.13 µg/kg and 0.12–0.15 µg/kg, respectively. The limits of detection (LOD) and limits of quantification (LOQ) were in the range of 0.004–0.048 μg/kg and 0.010–0.075 μg/kg, respectively. Of the 180 samples that were collected from local markets in Egypt, 21.11 % had β-agonist residues. The mean concentration (µg/kg) and detection frequency (%) of the most frequently found β-agonist in the samples were as follows: terbutaline (2.63 µg/kg and 90 %), ractopamine (5.14 µg/kg and 23.3 %). The method's applicability was verified by successfully completing two rounds of proficiency testing (PT).

Proficiency of phenotypic drug susceptibility testing for Mycobacterium tuberculosis in China, 2008-2021.

To analyze the results of proficiency testing for anti-tuberculosis drug susceptibility testing (DST) in China. Number of laboratory participating the proficiency testing performed DST, and the sensitivity, specificity, reproducibility, and accordance rate were calculated from data of 13 rounds proficiency testing results for DST from 2008 to 2021. A total of 30 and 20 strains of Mycobacterium tuberculosis with known susceptibility results were sent to each laboratory in 2008 to 2019, 2020 and 2021, respectively. The number of participating laboratories ranged from 30 in 2009 to 546 in 2021. L-J DST was the predominant method. The specificity presented relatively higher than sensitivity. Improvement of specificity were observed for all drugs through the years, while sensitivity did not show improvement for amikacin and capreomycin. Accordance rate of pyrazinamide and kanamycin and reproducibility of capreomycin and pyrazinamide were not significantly improved through the years. Most of the participating laboratories significantly improved the quality of their DST through the consecutive rounds of proficiency testing except for second-line injectable drugs and pyrazinamide. The results highlight the importance of developing novel and/or improving existing methods for phenotypic DST for certain drugs.

Microbiology proficiency testing in fish and fishery products: detection of Listeria monocytogenes and Salmonella spp.

This paper presents the results of two proficiency testing (PT) rounds conducted by the Export Inspection Agency (EIA) Chennai laboratory in 2021 for food testing laboratories in India. The PT program was designed in accordance with ISO/TS 22117, a standard for proficiency testing in food microbiology, and targeted Listeria monocytogenes and Salmonella spp as the organisms of focus. The samples were found to be stable and recoverable during the analysis, and all PT sample packages were delivered to participant laboratories in good condition. The participant laboratories reported high sensitivity rates of 100% for PT round 061021M and 96.49% for PT round 050721M. The accuracy rate in PT round 061021M was 91.89% and 92.10% in case of PT round 050721M. However, there were some false positive and false negative results reported by some participant laboratories in both PT rounds, which may have been caused by operational errors or inconsistencies in analysis. During the PT round 061021M, out of a total of 38 participant laboratories, five laboratories reported false positive results and one laboratory reported a false negative result. Similarly, during the PT round 050721M, six laboratories reported false positive results which resulted in their results being deemed unsatisfactory.

Busulfan Interlaboratory Proficiency Testing Program Revealed Worldwide Errors in Drug Quantitation and Dose Recommendations.

The clinical outcomes of busulfan-based conditioning regimens for hematopoietic cell transplantation (HCT) have been improved by personalizing the doses to target narrow busulfan plasma exposure. An interlaboratory proficiency test program for the quantitation, pharmacokinetic modeling, and busulfan dosing in plasma was developed. Previous proficiency rounds (ie, the first 2) found that 67%-85% and 71%-88% of the dose recommendations were inaccurate, respectively. A proficiency test scheme was developed by the Dutch Foundation for Quality Assessment in Medical Laboratories (SKML) and consisted of 2 rounds per year, with each round containing 2 busulfan samples. In this study, 5 subsequent proficiency tests were evaluated. In each round, the participating laboratories reported their results for 2 proficiency samples (ie, low and high busulfan concentrations) and a theoretical case assessing their pharmacokinetic modeling and dose recommendations. Descriptive statistics were performed, with ±15% for busulfan concentrations and ±10% for busulfan plasma exposure. The dose recommendations were deemed accurate. Since January 2020, 41 laboratories have participated in at least 1 round of this proficiency test. Over the 5 rounds, an average of 78% of the busulfan concentrations were accurate. Area under the concentration-time curve calculations were accurate in 75%-80% of the cases, whereas only 60%-69% of the dose recommendations were accurate. Compared with the first 2 proficiency test rounds (PMID 33675302, October, 2021), the busulfan quantitation results were similar, but the dose recommendations worsened. Some laboratories repeatedly submit results that deviated by more than 15% from the reference values. The proficiency test showed persistent inaccuracies in busulfan quantitation, pharmacokinetic modeling, and dose recommendations. Additional educational efforts have yet to be implemented; regulatory efforts seem to be needed. The use of specialized busulfan pharmacokinetic laboratories or a sufficient performance in busulfan proficiency tests should be required for HCT centers that prescribe busulfan.

Statistical Analysis of the Performance of Local Veterinary Laboratories in Molecular Detection (rRT-PCR) of Avian Influenza Virus via National Proficiency Testing Performed during 2020-2022.

For the early detection of avian influenza virus (AIV), molecular diagnostic methods such as real-time RT-PCR (rRT-PCR) are the first choice in terms of accuracy and speed in many countries. A laboratory's capability to perform this diagnostic method needs to be measured through external and independent assessment to ensure that the method is validated within the laboratory and in interlaboratory comparison. The Animal and Plant Quarantine Agency of Korea has implemented five rounds of proficiency testing (PT) for rRT-PCR targeting local veterinary service laboratories involved in the AIV national surveillance program from 2020 to 2022. In each round, a portion composed of six or more samples was selected from the entire PT panel consisting of H5, H7, and H9 viruses isolated in Korea and distributed to each participant, and at least one pair of samples was commonly included in each panel for interlaboratory comparison. During the five rounds of PT, a few incorrect and outlying results were detected that required immediate inspection or corrective actions. However, in the quantitative measurement of Ct values, the average standard deviation or coefficient of variation decreased as multiple PT rounds progressed, and a positive correlation between consecutive rounds of PT was observed since 2021. The better consistency or stability in the experimental performance appeared to contribute to the more harmonized results in the latest PTs, and it is assumed that the positive reaction of participants to the challenges of quantitative assessment reports showing their status intuitively might work. We need to continue operating the PT program for local laboratories because they play crucial roles at the front line of the national avian influenza surveillance program, and frequent changes in the human resources or environment for diagnosis in those laboratories are inevitable.

Evaluation of the 1R6F certified reference cigarette for proficiency testing of mainstream smoke parameters

A goal of the cooperative agreement between the U.S. Food and Drug Administration and the Center for Tobacco Reference Products (CTRP) at the University of Kentucky was to produce a standard reference cigarette for researchers to further tobacco science. The 1R6F certified reference cigarette for analytical testing was developed to be typical of an American blend cigarette. The cigarettes have been used in proficiency testing (PT) schemes under the supervision of the CTRP since 2016 for a variety of parameters. Data were compared from 8 rounds of PT schemes submitted by participating laboratories, which include various international stakeholders comprised of academic institutions, federal research/regulatory laboratories, tobacco product manufacturers, and independent contract testing laboratories. Evaluation of the datasets for harmful and potentially harmful constituents (HPHCs) within the mainstream smoke of the 1R6F certified reference cigarette included tobacco-specific nitrosamines (TSNA), tar, nicotine, and carbon monoxide (TNCO), and Benzo[α]pyrene (BαP). Of the datasets evaluated, less than 5 % resulted in either a warning or alert, and less than 2 % resulted in an alert. Comparisons across multiple PT rounds revealed no significant differences in the consensus means of the tested parameters. Evaluation of data submitted by participating laboratories for multiple proficiency test rounds shows that the 1R6F certified reference cigarette is an acceptable material as a control reference for the analysis of HPHCs which is imperative since some stakeholders may be required to participate in, and receive satisfactory results, from PT for accreditation purposes.

Advancing proficiency testing for ultra in resource-limited settings using dried tube specimen: A study by SRL-Uganda.

Proficiency testing (PT) has been hard to set up due to cost limitations and technical capacity. Conventional Xpert MTB/RIF PT programs use liquid and culture spots which require stringent storage and transportation conditions with cross-contamination chances prevalent. These setbacks prompted the use of dried tube specimens (DTS) for Ultra assay PT. For continuity of PT provision, stability of DTS and compatibility with testing protocols when kept for a long period needs to be established. DTS were prepared from known isolates inactivated using a hot air oven at 85°C. 100μl of bacterial suspensions were aliquoted and dried inside a Biosafety cabinet. Panel validation was done to establish the baseline Deoxyribonucleic acid (DNA) concentration in terms of cycle threshold (Ct) value. DTS aliquots were shipped to participants to test and report within six weeks. The remaining DTS were kept at 2-8°C and room temperature for one year with testing at six months. Twenty (20) DTS samples per set remaining at one year were heated at 55°C for two weeks before testing. The means of the different samples were compared to validation data using paired t-tests. Boxplots were designed to visualize the differences in the medians of the DTS. Overall mean Ct value increased by 4.4 from the validation to testing after one year at the different storage conditions. Samples heated at 55°C showed a 6.4 Ct difference from validation data. Testing done at six months on 2-8°C stored items showed no statistical difference. At all the remaining testing times and conditions, P-values were less than 0.008 although the absolute mean Ct when compared showed slight increments and accommodated differences for the detection of MTB and rifampicin resistance. Median values for samples stored at 2-8°C were lower compared to those at room temperature. DTS stored at 2-8°C remain more stable for one year compared to higher temperatures and can be consistently used as PT materials in more than one PT round for biannual PT providers.

Comparative Evaluation of Carboxyhemoglobin Quantification in Postmortem Whole Blood by CO-Oximetry and Headspace Gas Chromatography with Flame Ionization Detection and Atom Absorption Spectrophotometry.

A comparative evaluation of two methods used for carboxyhemoglobin (COHb) determination in postmortem whole blood was performed: carbon monoxide (CO)-oximetry measuring at 128 wavelengths and headspace gas chromatography with flame ionization detection (HS-GC--FID) where CO was determined after catalytic reduction of CO to CH4 and Fe was determined by atom absorption spectrophotometry (AAS, 248.3 nm). An aliquot of 100 µL whole blood was loaded into the CO-oximetry module. In the HS-GC--FID analysis, to 1.0 mL of whole blood, 3.0 mL of saponin solution was added, mixed and centrifuged. To 20 mL HS vials, 400 µL of the supernatant was added and the vials were immediately sealed. One milliliter of potassium hexacyanoferrat (III) solution was added through the HS septum and mixed. The samples were incubated at 70°C for 5 min. CO was separated using He as carrier gas and a CP-Molsieve 5 Å PLOT capillary column. Fe was determined using 400 µL of the saponin supernatant diluted to 10 mL by water. During a period of ∼3years, 124 postmortem whole blood samples were analyzed. Bland-Altman method comparison showed satisfactory agreement and no significant bias between the methods for the whole saturation range (5 to 85% COHb). Five samples, all with %COHb >40, showed deviations of more than 10% COHb in absolute terms. One sample, in the lower COHb range <10%, was false negative on the CO-oximetry method. The between-assay accuracy, reported as bias, at 60% COHb was -0.8% and -9.0%, and precision, reported as relative standard deviation, was 1.6% and 7.7%, for the CO-oximetry and HS-GC--FID-AAS methods, respectively. Both methods obtained satisfactory results in proficiency testing rounds, with z-scores <±2 (n = 11). This study showed that the CO-oximetry method based on the 128-wavelength principle and the HS-GC--FID-AAS method are comparable and satisfactory for %COHb determination in postmortem whole blood.

Improving the quality of HIV rapid testing in Ghana using the dried tube specimen-based proficiency testing program.

BackgroundThe introduction of human immunodeficiency virus (HIV) antibody rapid testing (RT) in resource-limited settings has proven to be a successful intervention to increase access to prevention measures and improve timely linkage to care. However, the quality of testing has not always kept pace with the scale-up of this testing strategy. To monitor the accuracy of HIV RT test results, a national proficiency testing (PT) program was rolled out at selected testing sites in Ghana using the dried tube specimen (DTS) approach.MethodsBetween 2015 and 2018, 635 HIV testing sites, located in five regions and supported by the U.S. President’s Emergency Plan for AIDS Relief (PEPFAR), were enrolled in the HIV PT program of the Ghana Health Service National AIDS/STI Control Programme. These sites offered various services: HIV Testing and Counselling (HTC), prevention of mother-to-child transmission (PMTCT) and Antiretroviral Treatment (ART). The PT panels, composed of six DTS, were prepared by two regional laboratories, using fully characterized plasma obtained from the regional blood banks and distributed to the testing sites. The results were scored by the PT providers according to the predefined acceptable performance criteria which was set at ≥ 95%.ResultsSeven rounds of PT panels were completed successfully over three years. The number of sites enrolled increased from 205 in round 1 (June 2015) to 635 in round 7 (December 2018), with a noticeable increase in Greater Accra and Eastern regions. The average participation rates of enrolled sites ranged from 88.0% to 98.0% across the PT rounds. By round 7, HTC (257/635 (40.5%)) and PMTCT (237/635 (37.3%)) had a larger number of sites that participated in the PT program than laboratory (106/635 (16.7%)) and ART (12/635 (1.9%)) sites. The average testing performance rate improved significantly from 27% in round 1 to 80% in round 7 (p < 0.001). The highest performance rate was observed for ART (100%), HTC (92%), ANC/PMTCT (90%) and Laboratory (89%) in round 5.ConclusionThe DTS PT program showed a significant increase in the participation and performance rates during this period. Sub-optimal performances observed was attributed to non-compliance to the national testing algorithm and testing technique. However, the implementation of review meetings, peer-initiated corrective action, supportive supervisory training, and mentorship proved impactful. The decentralized approach to preparing the PT panels ensured ownership by the region and districts.

Control of Residues of Antimicrobial Substances by Screening Methods in Raw Milk Based on Participation in Proficiency Tests in Poland, 2017-2021.

Proficiency testing (PT) is an important tool for evaluation of the competences of laboratories which test milk for residues of antimicrobial substances. It also warrants the reliability of the obtained test results, which is important to the clients of a laboratory. In 2017–2021, the Polish National Reference Laboratory organized 10 rounds of proficiency testing on raw milk samples according to the ISO/IEC 17043 standard. The milk samples were fortified with selected antimicrobial substances. All participating laboratories used commercial receptor and/or microbiological diagnostic kits in the proficiency tests. The results obtained by the laboratories were compared to assigned results and were defined as compliant or non-compliant. In total, 7533 results were obtained, and 104 (1.4%) were assessed as non-compliant. The percentage of laboratories which obtained a positive result in proficiency tests ranged by testing round from 81.8% to 100%. Based on proficiency testing results, it can be concluded that laboratories carry out tests correctly. The proven proficiency by a laboratory increases the confidence of its clients in its service of antimicrobial residue monitoring in milk.

Results From a Proficiency Testing Pilot for Immunosuppressant Microsampling Assays.

Therapeutic drug monitoring (TDM) of immunosuppressive drugs is important for the prevention of allograft rejection in transplant patients. Several hospitals offer a microsampling service that provides patients the opportunity to sample a drop of blood from a fingerprick at home that can then be sent to the laboratory by mail. The aim of this study was to pilot an external quality control program. Fourteen laboratories from 7 countries participated (fully or partly) in 3 rounds of proficiency testing for the immunosuppressants tacrolimus, ciclosporin, everolimus, sirolimus, and mycophenolic acid. The microsampling devices included the following: Whatman 903 and DMPK-C, HemaXis, Mitra, and Capitainer-B. All assays were based on liquid chromatography with tandem mass spectrometry. In round 2, microsamples as well as liquid whole blood samples were sent, and 1 of these samples was a patient sample. Imprecision CV% values for the tacrolimus microsamples reported by individual laboratories ranged from 13.2% to 18.2%, 11.7%-16.3%, and 12.2%-18.6% for rounds 1, 2, and 3, respectively. For liquid whole blood (round 2), the imprecision CV% values ranged from 3.9%-4.9%. For the other immunosuppressants, the results were similar. A great variety in analytical procedures was observed, especially the extraction method. For the patient sample, the microsample results led to different clinical decisions compared with that of the whole blood sample. Immunosuppressant microsampling methods show great interlaboratory variation compared with whole blood methods. This variation can influence clinical decision-making. Thus, harmonization and standardization are needed. Proficiency testing should be performed regularly for laboratories that use immunosuppressant microsampling techniques in patient care.

Analytical Uncertainty in Animal Feed Laboratories: A Current Evaluation of AAFCO Proficiency Testing Data for Select Analytes

The animal feed regulatory community utilizes analytical variations (AVs) that account for the normal variability that occurs within and between laboratories. The AV was created using the Association of American Feed Control Officials (AAFCO) proficiency testing (PT) program results and represent the coefficient of variation times 2 (2 CV). This study was performed to assess the accuracy of the published AVs within the association’s Official Publication (OP) using AAFCO PT data from 2014 to 2020. This study also reevaluated the current AV values by applying the concept of the measurement uncertainties including the expanded uncertainty (U), Horwitz value, and 2 CV for the assessment of the label guarantees. Although greater variations were observed at lower concentrations, the majority of data points from the PT rounds showed an acceptable reproducibility for the select analytical methods except for cobalt, fat, fiber, moisture, and selenium where 2 CV was higher than the current AAFCO AV. Regression models were developed based on the 95% tolerance interval of expanded uncertainty and 2 CV and were validated using the 2019-2020 AAFCO PT data. The validation data fell within the expanded uncertainty and 2 CV model bounds indicating the new models were fit-for-purpose and accurately characterized current AAFCO PT data. The study results imply the AAFCO AV and its issues need to be better understood to improve an accuracy and traceability of the laboratory’s measurement and thus regulatory decisions to help animal feed producers and processors lower economic losses.

Provision of chemical proficiency testing round on corn-based snack food for laboratories in the Asia-Pacific

Provision of chemical proficiency testing round on corn-based snack food for laboratories in the Asia-Pacific

Proficiency testing for SARS-CoV-2 in assuring the quality and overall performance in viral RNA detection in clinical and public health laboratories

Diagnostic testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has undergone significant changes over the duration of the pandemic. In early 2020, SARS-CoV-2 specific nucleic acid testing (NAT) protocols were predominantly in-house assays developed based on protocols published in peer reviewed journals. As the pandemic has progressed, there has been an increase in the choice of testing platforms. A proficiency testing program for the detection of SARS-CoV-2 by NAT was provided to assist laboratories in assessing and improving test capabilities in the early stages of the pandemic. This was vital in quality assuring initial in-house assays, later commercially produced assays, and informing the public health response. The Royal College of Pathologists of Australasia Quality Assurance Programs (RCPAQAP) offered three rounds of proficiency testing for SARS-CoV-2 to Australian and New Zealand public and private laboratories in March, May, and November 2020. Each round included a panel of five specimens, consisting of positive (low, medium or high viral loads), inconclusive (technical specimen of selected SARS-CoV-2 specific genes) and negative specimens. Results were received for round 1 from 16, round 2 from 97 and round 3 from 101 participating laboratories. Improvement in the accuracy over time was shown, with the concordance of results in round 1 being 75.0%, in round 2 above 95.0% for all samples except one, and for round 3 above 95.0%. Overall, participants demonstrated high capabilities in detecting SARS-CoV-2, even in samples of low viral load, indicating excellent testing accuracy and therefore providing confidence in Australian and New Zealand public and private laboratories test results.

Round-Robin Tests with Relocatable Coverslips Improve Asbestos Fibre Counting.

Asbestos fibre counting by phase-contrast microscope is subject to many sources of variation, including those dependent on the analyst. In this study, asbestos sample slides prepared with relocatable coverslips have been used for fibre counting among voluntary analysts to evaluate their proficiency. One slide of amosite and one of chrysotile were distributed to all the analysts, and three proficiency testing rounds were conducted for amosite and four for chrysotile. Each relocatable coverslip has a report in which are reported for each viewing field both the number of certified fibres (Verified Fibres) and a drawing representing the shape and position of the individual fibres. In the first round, the analysts were asked to report only the number of fibres counted in each of the predesignated fields of view. In the other rounds, subsequently developed, the analysts had to report the number and the position of the fibres for each field. The reported number of fibres and their position in each of the designed fields were evaluated against their respective verified fibres, to identify types of error. Discrepancies between reported fibres and verified fibres in each field of view have been used to evaluate the proficiency of the analysts. The discrepancies can be positive (D+) or negative (D-) depending on whether the analyst counts, for a specific field of view, more or less fibres compared to the verified fibres. The score is calculated using the following equation: Score = (1 - ∑D+ + ∑│D-│/VF) × 100. An analyst obtaining a score of ≥60, which corresponds to (∑D+ + ∑│D-│)/VF ≤ 0.40, is proficient. The number of laboratories that participating in this study varied from 13 to 17 depending on the rounds. For amosite fibre counts, the results were generally good compared to a proficiency score of 60. The major error made by analysts was the counting of fibres shorter than 5 µm, where this error was of 62% of extra fibres and accounted for 8% over-estimation of amosite fibres. For chrysotile, a score of ≥50 has been used to consider an analyst as proficient. The results of chrysotile fibres showed that in the first round all analysts counted less than fifty per cent of the verified fibres. In the second round 10 analysts out of 13 reached a score of ≥50, 8 of 16 in the third and 10 of 12 in the fourth. For chrysotile fibres, the error relating to the counting of fibres shorter than 5 µm was of 56% of extra fibres, but the error that most influenced the results was the number of oversight-missing fibres. This type of error accounted for 97% of the missing fibres and for the 29% under-estimation of the chrysotile fibres. For amosite fibre counting, results of this study show an improvement of the analyst's performance. For the chrysotile fibre count, although there is a significant improvement in the comparison between some rounds, this is not continuous over time.

Interlaboratory collaboration to determine the performance of the Randox food diagnostics biochip array technology for the simultaneous quantitative detection of seven mycotoxins in feed

An inter-laboratory collaborative study was performed to evaluate the performance of the Biochip Array Technology (BAT) Myco 7 method. The Myco 7 Array is a method which simultaneously and quantitatively detects 20 mycotoxins including aflatoxins B1, B2, G1 and G2, ochratoxin A, deoxynivalenol, zearalenone, fumonisin B1, B2 and B3 and T-2 and HT-2 toxin. The BAT Myco 7 method was collaboratively evaluated by nine government and private Association of American Feed Control Officials (AAFCO) laboratories. Samples were analysed in a proficiency testing round format. Seventeen blind samples were analysed on the same equipment using Myco 7 kits. 99% of the results fell within an acceptable Z-score range of -2|&lt;Z&lt;|+2. Deoxynivalenol had a 100% Z-score pass rate, while a 99% pass was recorded for aflatoxins, zearalenone, ochratoxin A and fumonisins. T-2 toxin had a 97% Z-score pass rate. HorRat analysis for reproducibility used a range of 0.3&lt;|HorRat|≤2. The target was met for deoxynivalenol, zearalenone, T-2 and HT-2 toxin, and aflatoxins B1, B2, G1 and G2 assays. Fumonisins and ochratoxin A assays had a 93% and 94% pass, respectively. The reproducibility co-efficiency of variation was between 16 and 20% meeting set criterion of &lt;40% and is, therefore, fit-for-purpose for use in the AAFCO control programs for mycotoxins.

Improving the quality control of drinking water in Nicaragua through proficiency testing in a metrological multilateral cooperation project

The United Nations General Assembly explicitly recognized the human right to water and sanitation and acknowledged that drinking water is essential to the realization of all human rights in a 2010 resolution. Supporting and strengthening the quality infrastructure in countries throughout the world guarantees more reliable water quality analyses, thus reducing the risks to consumers’ health. The present paper describes a multilateral cooperation project developed in Nicaragua to improve the country's quality infrastructure and, in turn, the quality control of drinking water. The project was developed with the support of National Metrology Institutes (NMIs) from the Inter-American Metrology System (SIM), the Physikalisch Technische Bundesanstalt (PTB) and the participation of research institutes and laboratories in Nicaragua. Several mechanisms such as awareness seminars, workshops, metrological screenings, peer review of the laboratories’ quality systems, and organizing proficiency testing (PT) were used to successfully achieve the cooperation goal. As a result, technical infrastructure for the organization of PT rounds in Nicaragua was implemented to evaluate the relevant physicochemical parameters such as pH, chloride (Cl−), and nitrate (NO3−) in drinking water. The results from the PT rounds which took place during the two-year cooperation project showed substantial improvement in the performances of the participating laboratories, and therefore, in their measurement methods. Finally, this article shows how multilateral cooperation projects can strengthen the quality infrastructure, improving and ensuring the quality control of drinking water.

Quality Control of Busulfan Plasma Quantitation, Modeling, and Dosing: An Interlaboratory Proficiency Testing Program.

Personalizing busulfan doses to target a narrow plasma exposure has improved the efficacy and lowered the toxicity of busulfan-based conditioning regimens used in hematopoietic cell transplant. Regional regulations guide interlaboratory proficiency testing for busulfan concentration quantification and monitoring. To date, there have been no comparisons of the busulfan pharmacokinetic modeling and dose recommendation protocols used in these laboratories. Here, in collaboration with the Dutch Association for Quality Assessment in Therapeutic Drug Monitoring and Clinical Toxicology, a novel interlaboratory proficiency program for the quantitation in plasma, pharmacokinetic modeling, and dosing of busulfan was designed. The methods and results of the first 2 rounds of this proficiency testing are described herein. A novel method was developed to stabilize busulfan in N,N-dimethylacetamide, which allowed shipping of the proficiency samples without dry ice. In each round, participating laboratories reported their results for 2 proficiency samples (one low and one high busulfan concentrations) and a theoretical case assessing their pharmacokinetic modeling and dose recommendations. All participants were blinded to the answers; descriptive statistics were used to evaluate their overall performance. The guidelines suggested that answers within ±15% for busulfan concentrations and ±10% for busulfan plasma exposure and dose recommendation were to be considered accurate. Of the 4 proficiency samples evaluated, between 67% and 85% of the busulfan quantitation results were accurate (ie, within 85%-115% of the reference value). The majority (88% round #1; 71% round #2) of the dose recommendation answers were correct. A proficiency testing program by which laboratories are alerted to inaccuracies in their quantitation, pharmacokinetic modeling, and dose recommendations for busulfan in hematopoietic cell transplant recipients was developed. These rounds of proficiency testing suggests that additional educational efforts and proficiency rounds are needed to ensure appropriate busulfan dosing.