scholarly journals Proficiency Test for Chemical Laboratories for the Analysis of a Pesticide in a Formulated Product: Interlaboratory Study

2009 ◽  
Vol 92 (1) ◽  
pp. 271-278 ◽  
Author(s):  
Doyeli Sanyal ◽  
Anita Rani
Keyword(s):  
Proficiency Test ◽  
Robust Statistics ◽  
Graphical Representation ◽  
Sample Distribution ◽  
Testing Program ◽  
National Accreditation ◽  
Pesticide Formulation ◽  
Z Scores ◽  
Calibration Laboratories ◽  
Youden Plot

Abstract A multilaboratory proficiency testing program was conducted by the National Accreditation Board for Testing and Calibration Laboratories (India) and coordinated by the Institute of Pesticide Formulation Technology. This program was conducted to compare the performance of individual laboratories in the area of pesticide formulation (Chlorpyrifos 20 EC) analysis. A total of 24 laboratories in India participated. Analysis of 2 parameters (i.e., estimation of the active ingredient and the acidity) of 2 samples of Chlorpyrifos 20 EC was the objective of this program. Homogeneity tests were performed before sample distribution. Performance of the participating laboratories was evaluated by using new robust statistics given in the guidelines of the National Association of Testing Authorities, Australia. Results were collated and statistically computed to calculate the value of 2 types of Z-scores (Zwi and Zbi). In addition to the statistical analysis, a graphical representation such as the Youden plot was also generated to evaluate the performance of participating laboratories.

scholarly journals Aflatoxin Testing in Peanuts: A Proficiency Assessment Scheme for Chinese Analytic Laboratories

2009 ◽  
Vol 92 (2) ◽  
pp. 481-486 ◽  
Author(s):  
Lei Bao ◽  
Zhenmin Bao ◽  
Yibing Zhang ◽  
Chengzhu Liang ◽  
Ning Lu ◽  
...  
Keyword(s):  
Aflatoxin B1 ◽  
High Performance ◽  
Robust Statistics ◽  
Enzyme Linked Immunosorbent Assay ◽  
Target Analytes ◽  
Sample Stability ◽  
Inspection And Quarantine ◽  
Z Scores ◽  
Iso 13528 ◽  
Proficiency Assessment

Abstract This national assessment program was established by the China National Accreditation Service for Conformity Assessment (CNAS) to evaluate the aflatoxin-testing proficiency of a cross-section of Chinese laboratories. The Shan Dong Inspection and Quarantine Bureau of China conducted the assessment according to ISO 13528:2005 (E) and the International Harmonized Protocol for Proficiency Testing. The 77 laboratories that participated in the study had either been previously accredited by CNAS or were candidates for CNAS accreditation. The analytic samples for this testing scheme were prepared from naturally contaminated peanuts and diluted to approximately 10 g/kg for aflatoxin B1 and 18 g/kg for total aflatoxins. The Ss/p test (with a required result of Ss 0.3p) was used to evaluate the homogeneity of the test samples; sample stability was confirmed with a t-test. The performance of each laboratory was designated by a z-score that was calculated using robust statistics. The robust mean of the participants' results in this study was nearly coincident with the median. A modified Horwitz equation was used to determine the standard deviation. The study compared analytic results obtained by 5 different methods: high-performance liquid chromatography (LC), enzyme-linked immunosorbent assay, thin-layer chromatography, fluorometry, and LC with tandem mass spectrometry. A satisfactory performance rating required z-scores between 2 and 2 for the target analytes. Of the 73 laboratories that reported results for aflatoxin B1, 66 (90.4) performed satisfactorily. Of 32 laboratories that reported total aflatoxins (B1 B2 G1 G2), 30 (93.8) performed satisfactorily. Laboratories whose performance ratings were questionable or unsatisfactory were re-evaluated in a second interlaboratory comparison.

Laboratory performance and regulatory requirements.

1987 ◽  
Vol 33 (6) ◽  
pp. 1087-1102 ◽  
Author(s):  
M L Kenney
Keyword(s):  
Linear Regression ◽  
Proficiency Test ◽  
Clinical Laboratory ◽  
Group Practice ◽  
Federal Regulations ◽  
Test Results ◽  
Regulatory Requirements ◽  
Service Levels ◽  
Z Scores ◽  
Log Normal

Abstract We compared performance levels of four clinical laboratory groups defined by federal regulatory characteristics, to assess the appropriateness of selected regulations: laboratories in JCAH-accredited hospitals; non-doctoral-directed independent laboratories; state-regulated but federally exempt group-practice laboratories; and unregulated laboratories in physicians' offices (POLs). Federal regulations evaluated were those dealing with the doctoral directorship requirement and exemption of POLs from regulation. Quantitative analytes were compared by using linear regression on log-normal transformations of mean absolute-z scores of proficiency test results. The scope of services offered by laboratories was statistically related to performance in quantitative analytes. Confounding effects of scope-of-service levels were statistically controlled. Proportions of errors in qualitative analytes were compared. No pattern of statistically discernible differences in performance was found between hospital laboratories and non-doctoral-directed laboratories. Both regulated non-doctoral-directed laboratories and state-regulated but federally exempt group-practice laboratories demonstrated higher levels of performance than unregulated POLs.

scholarly journals The Data Evaluation of Interlaboratory Comparisons for Calibration Laboratories

2021 ◽  
Author(s):  
Oleh Velychko ◽  
Tetyana Gordiyenko
Keyword(s):  
Measuring Instruments ◽  
Interlaboratory Comparisons ◽  
Technical Competence ◽  
Optimal Method ◽  
National Accreditation ◽  
Testing Laboratories ◽  
Accredited Laboratories ◽  
Processing Algorithms ◽  
Calibration Laboratories ◽  
Data Processing Algorithms

National accreditation agencies in different countries have set quite strict requirements for accreditation of testing and calibration laboratories. Interlaboratory comparisons (ILCs) are a form of experimental verification of laboratory activities to determine technical competence in a particular activity. Successful results of conducting ILCs for the laboratory are a confirmation of competence in carrying out certain types of measurements by a specific specialist on specific equipment. To obtain reliable results of ILC accredited laboratories, it is necessary to improve the methods of processing these results. These methods are based on various data processing algorithms. Therefore, it is necessary to choose the most optimal method of processing the obtained data, which would allow to obtain reliable results. In addition, it is necessary to take into account the peculiarities of the calibration laboratories (CLs) when evaluating the results of ILС. Such features are related to the need to provide calibration of measuring instruments for testing laboratories. The evaluation results for ILCs for CLs are presented. The results for all participants of ILCs were evaluated using the En and z indexes. The obtained results showed that for the such ILCs it is also necessary to evaluate the data using the z index also.

scholarly journals Evaluation of the Use of Microtracers™ in a Proficiency Testing Program

2019 ◽  
Vol 102 (3) ◽  
pp. 767-775 ◽  
Author(s):  
Nancy Thiex ◽  
Mark Carlson ◽  
Robert Kieffer ◽  
Amy Kieffer ◽  
David Eisenberg ◽  
...  
Keyword(s):  
Quality Control ◽  
Proficiency Testing ◽  
Proficiency Test ◽  
Feed Additives ◽  
Chi Square ◽  
Testing Program ◽  
Test Items ◽  
Production Run ◽  
Relative Standard ◽  
Splitting Process

Abstract Background: An effective proficiency testing program must utilize accurate splitting procedures to ensure that customers receive equivalent (by some measure) test items. When test items are not equivalent, it becomes impossible to separate variation among laboratories from variation among test items, and the program cannot achieve its objectives. Therefore, there is a critical need to validate the splitting process used to manufacture test items. Objective: The incorporation of MicrotracersTM was investigated for validating the splitting process used in the Association of American Feed Control Officials Proficiency Testing Program and as a potential quality control event for a production run. Methods: Microtracers were incorporated into six production runs. From each run, 12 test items were randomly selected for evaluation. Proficiency test materials were prepared from commercially available feedstuffs using base animal feeds and feed additives. The tracers were incorporated into base feed with other additives, recovered, and counted from the randomly selected test items. Results: Uniformity of test items was evaluated with the following two statistical methods: (1) relative standard deviation (RSD) of particle counts according to a Poisson distribution and (2) a Pearson’s Chi-square test. RSDs for counts (per mass basis) ranged from 2.49 to 4.13%, and Chi-square P values ranged from 0.0097 to 0.3740 over the six sets. Conclusions: Microtracers were determined to be a potential tool for validating the splitting process used to manufacture proficiency test items and a tool for incorporating quality control events into the manufacture of proficiency test items. Highlights: The authors offer suggestions for proficiency testing programs.

A study on the utilization of the Youden plot to evaluate proficiency test results

2013 ◽  
Vol 18 (3) ◽  
pp. 161-174 ◽  
Author(s):  
Katsuhiro Shirono ◽  
Kosei Iwase ◽  
Hiroshi Okazaki ◽  
Masaru Yamazawa ◽  
Kazuhiro Shikakume ◽  
...  
Keyword(s):  
Proficiency Test ◽  
Test Results ◽  
Youden Plot

Robust Statistics Analysis of Proficiency Test Result of Cement Chemical Composition

2012 ◽  
Vol 238 ◽  
pp. 96-100
Author(s):  
Yan Jia ◽  
Xiao Tian Cheng ◽  
Dong Wei
Keyword(s):  
Statistical Analysis ◽  
Chemical Composition ◽  
Proficiency Test ◽  
Robust Statistics ◽  
Composition Analysis ◽  
Test Plan ◽  
Statistics Analysis ◽  
Chemical Composition Analysis ◽  
Test Result

Test result of cement chemical composition was obtained from the participating laboratory through organizing and performing the cement proficiency test plan. After performing the robust statistical analysis to the result, the test proficiency of the laboratory is evaluated, the proficiency of each laboratory on chemical composition analysis and test is objectively reflected.

Robust Statistics Analysis of Proficiency Test Result of Cement

2019 ◽  
Vol 2 (1) ◽  
pp. 79
Author(s):  
Shwet Vashishtha ◽  
D. V. S. Prasad ◽  
R. N. Lokesh
Keyword(s):  
Proficiency Test ◽  
Robust Statistics ◽  
Statistics Analysis ◽  
Test Result
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