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Kuselman I.,The National Physical Laboratory of Israel INPL | Pennecchi F.,INRIM - Istituto Nazionale di Ricerca Metrologica | Burns C.,U.S. Food and Drug Administration | Fajgelj A.,International Atomic Energy Agency | de Zorzi P.,European Commission - Joint Research Center Ispra
Accreditation and Quality Assurance | Year: 2010

A metrological background for investigating out-of-specification (OOS) test results of chemical composition is discussed. When an OOS test result is identified, it is important to determine its root causes and to avoid reoccurrence of such results. An investigation of the root causes based on metrological concepts would be beneficial. It includes (1) assessment of validation data of the measurement process, (2) evaluation of the measurement uncertainty contributions, and (3) assessment of metrological traceability chains critical for measurement parameters and environmental conditions influencing the test results. The questions, how can the validation data be applied for this investigation, and how can measurement uncertainty contributions and/or metrological traceability chains change a probability of OOS test results, are analyzed. © 2009 Springer-Verlag. Source


Kuselman I.,The National Physical Laboratory of Israel INPL | Goldshlag P.,Laboratory for Pesticide Residue Analysis | Pennecchi F.,INRIM - Istituto Nazionale di Ricerca Metrologica | Burns C.,U.S. Food and Drug Administration
Accreditation and Quality Assurance | Year: 2011

A metrological approach is used for investigating multi-component out-of-specification (OOS) test results of pesticide residues concentration in tomatoes. As a case study, 169 test results were obtained in Israel in 2009. Five of the test results were OOS test results exceeding the national legal maximum residue limits (MRL). Only one of them was classified definitely (with more than 0.99 confidence) as caused by a farmer's/producer's problem. The other four OOS test results were probably metrologically related, i. e., compatible with MRL when considering the measurement uncertainty associated with the test results. A new parameter-the ratio of a test result to MRL-was proposed for analysis of tomatoes monitoring multi-residue data as a common statistical sample from the same population for different pesticide residues. Weibull distribution was found adequate for modeling the empirical distribution of the parameter values. Probability of future OOS test results was estimated, and global risks of farmer/producer and consumer/buyer were evaluated. Acceptance limits for the test results, such as "warning and action lines" in quality control charts, were calculated by taking into account the measurement uncertainties. © 2011 Springer-Verlag. Source


Kuselman I.,The National Physical Laboratory of Israel INPL | Shpitzer S.,The National Physical Laboratory of Israel INPL | Pennecchi F.,INRIM - Istituto Nazionale di Ricerca Metrologica | Burns C.,U.S. Food and Drug Administration
Air Quality, Atmosphere and Health | Year: 2012

A metrological approach is used for investigating out-of-specification (OOS) test results of total suspended particulate matter (TSP) mass concentrations in ambient air. As a case study, 496 test results of mass concentration of TSP in ambient air were obtained according to methods of the Environmental Protection Agency, USA. The samples, collected in 2009, came from the same geographic proximity in three stone quarries located in Israel. Twenty of the test results were OOS test results that exceeded the upper limit specified in the national air quality regulations. Investigation of the OOS test results indicated the fact that only 10% of these results (two out of 20) can be decidedly interpreted as witnesses of violations of the national air quality regulations. The other 90% were probably metrologically related, i. e., compatible with the national air quality regulations when considering the measurement uncertainty associated with the test results. Probabilities of future OOS test results and global risks of the stone producer and the consumer, who is defined as an inhabitant near a quarry, were estimated. Acceptance limits, resembling "warning and action lines" used in quality control charts, for air test results were calculated by taking into account the measurement uncertainty. © 2010 Springer Science+Business Media B.V. Source


Pankratov I.,National Water Monitoring Laboratory | Elhanany S.,National Water Monitoring Laboratory | Henig S.,National Water Monitoring Laboratory | Zaritsky S.,National Water Monitoring Laboratory | And 2 more authors.
Accreditation and Quality Assurance | Year: 2010

A proficiency testing (PT) scheme was developed for a limited number of analytical laboratories participating in the analysis of natural water in Israel. Three fit-for-intended-use reference materials (RMs) were prepared for a pilot PT from natural water: RM-blank and two in-house reference materials (IHRMs) with seven analytes fortified to achieve different levels of analyte concentrations. The measurands for the PT participants were the traceable spike values certified in the IHRMs, i.e., added mass concentrations of the analytes. The RM-blank and IHRMs were found to be homogeneous and stable over 11 days, the time necessary for the experimental part of the PT. The RMs were distributed to the PT participants as unknown test items similar to routine samples. The test results were evaluated using their deviations from the IHRM-certified values. Eight Israeli laboratories took part in the interlaboratory comparison. Individual laboratory performance and metrological compatibility of the PT results of the participants, as a local group of laboratories, were evaluated for every analyte. © 2010 Springer-Verlag. Source


Kardash E.,The National Physical Laboratory of Israel INPL | Kuselman I.,The National Physical Laboratory of Israel INPL | Pankratov I.,National Water Monitoring Laboratory | Elhanan S.,National Water Monitoring Laboratory
Accreditation and Quality Assurance | Year: 2013

A proficiency testing (PT) scheme was designed for measurements of pH and electrolytic conductivity (EC) of groundwater in Israel. A groundwater sample was used for preparation of test items fit-for-intended-use. The interlaboratory experiment was organized taking into account changes of the test item properties which occurred after sampling due to presence of CO2 in the groundwater. A total of 34 PT participants reported pH measurements results, while 29 of them reported results of EC measurements. The pH results were normally distributed. However, a significant bias of the pH consensus value of the PT participants from the metrologically traceable certified value (obtained by the National Physical Laboratory of Israel) was detected. This bias was caused by the drift of the measurement response due to water stirring and CO2 degassing from the sample during the measurement process. The bias of the EC consensus value from the metrologically traceable one was negligible, in spite of an abnormal distribution of the EC results of the PT participants. © 2013 Springer-Verlag Berlin Heidelberg. Source

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