Determination of the standard deviation for proficiency assessment from past participant’s performances

The “uncertainty function” introduced by Thompson et al. estimates the reproducibility standard deviation (SR) as a function of concentration. This model was successfully applied to a data set derived from three proficiency testing schemes aiming at the quantification of three toxic elements (cadmium, lead and mercury) in blood and urine. A threshold concentration was determined for each element. Below this concentration SR is found to be constant, while above it the reproducibility relative standard deviation is constant. This model allows the a priori estimation of standard deviation for performance assessment for proficiency testing rounds.JRC.D.5-Standards for Food Bioscienc

The Certification of the Mass Fractions of As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Sb, Se, Tl, V and Zn in Fly Ash, BCR-176R

This report describes the preparation and certification of the fly ash Certified Reference Material (CRM) BCR-176R. It replaces its exhausted predecessor, BCR-176. The CRM was processed and certified by the European Commission, Directorate General Joint Research Centre, Institute for Reference Materials and Measurements (IRMM), Geel, Belgium. The CRM was prepared from a fly ash collected in the electrostatic filters of a city waste incineration plant. After milling the resulting powder was filled in glass bottles containing 40 g powder. Certification of the CRM included testing of the homogeneity and stability of the material as well as the characterisation using an intercomparison approach. The new CRM has been certified for its content of As, Cd, Co, Cr, Cu, Fe, Ni, Pb, Sb, Se, Tl and Zn. Indicative values have been established for Hg, Mn, and V. This CRM is intended for use in quality assurance of measurements of heavy metals in fly ash and related matrices.JRC.D.2 - Reference material

Guidance Document on the Estimation of LOD and LOQ for Measurements in the Field of Contaminants in Feed and Food

The European Union Reference Laboratory (EURL) for Polycyclic Aromatic Hydrocarbons (EURL PAH), the EURL for Heavy Metals in Feed and Food (EURL HM), the EURL for Mycotoxins (EURL Mycotoxins), and EURL for Dioxins and PCBs in Feed and Food aim to provide with this document guidance to official food control in the EU on the estimation of the limit of quantification of analytical methods for the determination of individual substances in the field of contaminants in feed and food. The document focusses on estimation of the limit of detection (LOD) and/or limit of quantification (LOQ) of polycyclic aromatic hydrocarbons (PAHs), heavy metals (HM), mycotoxins, and polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs). The concept presented here consists of two major routes: The first route responds to the requirements for determination of PAHs, HMs and Mycotoxins. The second route corresponds to PCDD/F and PCB analysis, where results are calculated as sum-parameters and expressed in toxic equivalents (TEQs), converting thereby congener concentrations together with estimated LOQs using toxic equivalency factor (TEFs) into TEQs. Due to the nature of this more complex procedure, emphasis is put in the area of PCDD/F and PCB analysis on the LOQs, while LODs are of minor consequence. Terminology in this guidance document was adapted to the chemical analysis of contaminants in feed and food; hence, some of the general terms defined and used in international standards were replaced by more specific terms applicable to analytical chemistry. The presented statistical-mathematical approach is based on elements taken mainly from DIN 32645:2008-11 (DIN 2008) and ISO 11843-2:2000 (ISO 2000). This document covers only quantitative methods of analysis. The authors believe that LOD and LOQ values derived from the application of the presented experimental methodologies converge to a certain degree. Estimation of LOD/LOQ values based on blank measurements, and from calibration data is described. Signal-to-noise ratios are applied in the area of PCDD/Fs and PCBs. Mathematical terms and statistical background are presented as well. This guide document shall be applied systematically if measurement results are used for monitoring purposes and exposure modelling. However, authors are aware that precise knowledge of LOD/LOQ may not be required when assessing compliance with maximum levels exceeding LOD/LOQ. This guidance document shall be applied if maximum levels and analysis results are close to the expected LOQ.JRC.F.5-Food and Feed Complianc

EURL-FA Control Proficiency Test Report: Determination of the mass fraction of the total cobalt in compound feed for rabbits

The European Union Reference Laboratory for Feed Additive Control (EURL-FA Control) organised a proficiency test (EURL-FAC 2017-2) for the determination of the mass fraction of total cobalt in compound feed, to support the Commission Implementing Regulation (EU) No 131/2014 concerning the authorisation of various cobalt(II) compounds as feed additives. This proficiency test was open to National Reference Laboratories (NRLs) and official feed control laboratories (OCLs). The material used as test item was a commercially available compound feed for rabbits (containing the coated granulated cobalt (II) carbonate, 3b304 ) which, after appropriate processing, was bottled, labelled and dispatched to participants on June 21, 2017. The homogeneity and stability of the test item were evaluated and the assigned values were derived from the results reported by the selected expert laboratories. Twenty one NRLs and two OCLs from 21 countries - representing EU Member States and Norway - registered to the exercise and reported results at the end of August 2017. Laboratory results were rated using z' and zeta scores in accordance with ISO 13528:2015. A relative standard deviation for proficiency assessment (σpt) of 16 % of the assigned value was set according to the modified Horwitz equation. Twenty (out of 23) laboratories reported satisfactory results (according to the z' score). This confirms the ability of most NRLs in monitoring maximum levels set by the Commission Implementing Regulation (EU) No 131/2014 in this type of animal feed. The majority (74 %) of the participating laboratories provided realistic estimates of their measurement uncertainties.JRC.F.5-Food and Feed Complianc

IMEP-26: Determination of Brominated Flame Retardants in Plastic

This report presents the results of an interlaboratory comparison (ILC) which focussed on the determination of total bromine, total sum of polybrominated biphenyls (PBB), total sum of polybrominated diphenylethers (PBDE), brominated diphenylethers (BDE-47, BDE-99, BDE-183 and BDE-209) and decabrominated biphenyl (BB-209) in plastic. The test material used in this exercise was the Quality Control material (IRMM-310) from the Institute for Reference Materials and Measurements (IRMM) a poly(ethyleneterephthalate) (PET) granulated that has been fortified with commercially available technical mixtures of polybrominated diphenylethers and polybrominated biphenyls. The material was relabelled to avoid its recognition. Twenty-five laboratories from 15 countries registered to the exercise, from which 23 reported results. The informative values provided by the IRMM-310 material information sheet were taken as the assigned values and their associated uncertainties for all measurands. Studies to asses the adequacy of the selected test material regarding its homogeneity for all the selected measurands were undertaken Participants were invited to report the uncertainty of their measurements. Laboratory results were rated with z- and ζ-scores (zeta-scores) in accordance with ISO 13528. The standard deviation for proficiency assessment was fixed to 25 % of the respective assigned value by the advisory board of this ILC. The outcome of the exercise was illustrating quite well the difficulties laboratories do have to provide consistent values for the investigated measurands; the share of satisfactory z-scores ranged between 61 and 88 %. There was a clear tendency to underestimate most of the measurands. The most influencing variables, leading to the observed variability and lack of trueness, were investigated.JRC.DG.D.6-Food Safety and Qualit

Report of the Ninth Interlaboratory Comparison Organised by the European Union Reference Laboratory for Heavy Metals in Feed and Food - IMEP-109: Total Cadmium, Lead, Arsenic and Mercury as well as Methylmercury and Inorganic Arsenic in Seafood

The Institute for Reference Materials and Measurements (IRMM) of the Joint Research Centre (JRC), a Directorate General of the European Commission, operates the European Union Reference Laboratory for Heavy Metals in Feed and Food (EU-RL-HM). One of its core tasks is to organise interlaboratory comparisons (ILCs) among appointed National Reference Laboratories (NRLs). This report presents the results of the ninth proficiency test (PT) of the EU-RL-HM which focused on the determination of total cadmium, lead, arsenic and mercury as well as methylmercury and inorganic arsenic in seafood. The test material used in this exercise was the Certified Reference Material (CRM) DOLT-4, dogfish liver of the National Research Council of Canada (CNRC). The material was relabelled to prevent recognition by the participants and was dispatched the second half of May 2010. Each participant received one bottle containing approximately 20 g of test material. Thirty-eight laboratories from 27 countries registered to the exercise of which 38 reported results for total Cd, 36 for total Pb, 33 for total As, 36 for total Hg, five for methylmercury and 10 for iAs. The assigned values for total Cd, Pb, As, Hg and methylmercury are the certified values taken from the DOLT-4 certificate. An attempt was made to establish an assigned value for inorganic As (iAs) using the results provided by a group of five laboratories expert in the field, following a similar approach to that used in IMEP-1071, a PT on total and inorganic arsenic in rice. Contrary to what was observed in IMEP-107, the results obtained by the expert laboratories for iAs was method dependent, therefore no assigned value could be established. The uncertainties of the assigned values, uref, were taken directly from the CRM certificate as provided by the producer for total Cd, Pb, As, Hg and methylmercury. Participants were invited to report the uncertainty of their measurements. This was done by the majority of the laboratories taking part in this exercise. Laboratory results were rated with z- and ¿-scores (zeta-scores) in accordance with ISO 135282. Since the concentration of iAs seems to be method dependent according to the results obtained by the expert laboratories, no scoring was provided to the laboratories that submitted results for iAs. The standard deviation for proficiency assessment (also called target standard deviation) was fixed to 15% by the advisory board of this ILC, on the basis of the outcome of previous ILCs organised by the EURL-HM and on the state-of-the-art in this field of analysis. Between 80 and 97.5 % of the laboratories performed satisfactory for total Cd, As, Hg and methylmercury. Regarding total Pb, 70 % of the laboratories scored satisfactory.JRC.DG.D.6-Food Safety and Qualit

Report of the Second Interlaboratory Comparison Organised by the Community Reference Laboratory for Heavy Metals in Feed and Food: Total Cd, Pb and Hg in Mineral Water

The Institute for Reference Materials and Measurements (IRMM) of the European Commission's Directorate-General Joint Research Centre holds the Community Reference Laboratory for Heavy Metals in Feed and Food (CRL-HM). One of the core tasks is to organise interlaboratory comparisons (ILCs) among appointed National Reference Laboratories (NRLs). This report presents the results of the second ILC of the CRL-HM which focused on the determination of the total Cd, Pb and Hg content in mineral water. The test material used in this exercise was a commercial mineral water purchased in Belgium at a local supermarket. The material was spiked with Cd, Pb and Hg, rebottled and dispatched by the Reference Material Unit of the IRMM. The samples were dispatched on the first half of May 2007. Each participant received two sets of samples containing one bottle per set. Each bottle contained approximately 100 mL of test material. Twenty participants from 17 countries registered to the exercise of which 20 submitted results for Cd and Pb and 19 for Hg. The assigned values were those obtained from the gravimetric measurements used to spike the material. The homogeneity and stability studies were subcontracted to the University of Natural Resources and Applied Life Sciences (BOKU) in Vienna. The uncertainty of the assigned values was calculated combining the uncertainty of the spiking procedure with a contribution for the between-bottle homogeneity and for long-term stability of the test material. Participants were invited to report the uncertainty on their measurements. This was done by all them. Laboratory results were rated with z and zeta scores in accordance with ISO 135281. Standard deviation for proficiency assessment (also called target standard deviation) for Cd, Pb and Hg was 10% of the assigned value.JRC.D.4-Isotope measurement

IMEP-30: Total Arsenic, Cadmium, Lead, and Mercury, as well as Methylmercury and Inorganic Arsenic in Seafood - Interlaboratory Comparison Report

This report presents the results of an ILC which focussed on the determination of total As, Cd, Pb , and Hg, as well as methylmercury and inorganic arsenic in seafood. The test material used in this exercise was the Certified Reference Material (CRM) DOLT-4, dogfish liver of the National Research Council of Canada (NRC). Each participant received one bottle containing approximately 20 g of test material. Fifty-seven laboratories from 29 countries registered to the exercise and all of them reported results. The assigned values and their associate uncertainties for total As, Cd, Pb, Hg and Methylmercury are the certified values taken from the DOLT-4 certificate. An attempt was made to establish an assigned value for inorganic As (iAs) using the results provided by a group of five laboratories expert in the field. Unfortunately, contrary to what was expected, the results obtained by the expert laboratories for iAs showed a large spread and no assigned value could be established.JRC.DG.D.6-Food Safety and Qualit

IMEP-37: Determination of pesticides in grapes - Interlaboratory Comparison Report

This report presents the results of a proficiency test exercise (PT) which focussed on the determination of pesticides in grapes in support of Regulation 396/2005/EC of the European Parliament and of the Council on maximum residue levels of pesticides in or on food and feed of plant and animal origin. Eighty-seven participants from thirty-three different countries registered to the exercise, of which eighty-one reported results. From these eighty-one participants, forty were from EU countries while forty-one were from outside the EU. The test item was a grapes sample spiked with 20 selected pesticides. The assigned values were obtained as the average of results reported by five expert laboratories having demonstrated experience in the analysis of pesticides in vegetable and fruit matrices. The standard uncertainties related to the assigned values (Uref) were calculated by combining the uncertainty of the characterisation (Uchar) with a contribution for homogeneity (Ubb) and for stability (Ust). Uchar was calculated following the ISO guide 35. Laboratory results were rated with z- and zeta (ζ-) scores in accordance with ISO 13528 and ISO 17043. The z-score compares the participant's deviation from the reference value with the standard deviation for proficiency assessment (σp) used as common quality criterion, the ζ-score states if the laboratory result agrees with the assigned value within the respective uncertainty. The standard deviation for the proficiency assessment, σp, was set by the advisory board of this PT at 25% for the 20 measured pesticides based on previous experience with similar measurands. Participants were not scored for triadimenol due to the large Uref associated to the assigned value. According to the results obtained in the frame of the IMEP-37 study, the participants performed satisfactorily for the 19 scored pesticides ranging from 81 % (carbendazim) to 97 % (azoxystrobin, penconazole, pyrimethanil) of satisfactory z-scores. When analysing the results of the group of non-EU countries separately, similar results were obtained. It can be concluded that the performance in this PT is satisfactory for the laboratories world-wide.JRC.D.5-Standards for Food Bioscienc

IMEP-111: Total Cadmium, Lead, Arsenic, Mercury and Copper and Extractable Cadmium and Lead in Mineral Feed - Report of the Eleventh Interlaboratory Comparison Organised by the European Union Reference Laboratory for Heavy Metals in Feed and Food

The Institute for Reference Materials and Measurements (IRMM) of the Joint Research Centre, a Directorate-General of the European Commission, operates the European Union Reference Laboratory for Heavy Metals in Feed and Food (EU-RL-HM). One of its core tasks is to organize interlaboratory comparisons (ILCs) among appointed National Reference Laboratories. This report presents the results of the eleventh proficiency test (PT) of the EU-RL-HM which focused on the determination of total Cd, Pb, As, Hg and Cu and extractable Cd and Pb in mineral feed according to Directive 2002/32/EC of the European Parliament and of the Council on undesirable substances in animal feed. The test material used in this exercise was the Certified Reference Material (CRM) BCR-032, Moroccan phosphate rock. The material was relabelled to prevent identification by the participants and was dispatched the second half of October 2010. Each participant received one bottle containing approximately 100 g of test material. Thirty-one laboratories from 26 countries registered to the exercise of which 28 reported results for total Cd and total Pb, 25 for total Hg and total Cu, 23 for total As and for extractable Cd and extractable Pb. The assigned values (Xref) for total Cd, As and Cu are the indicative values taken from the BCR-032 certificate. The assigned values (Xref) for total Pb, total Hg and for extractable Cd and Pb were provided by IRMM using isotope dilution-inductively coupled plasma-mass spectrometry (ID-ICP-MS). For total Cd, As, Hg and Cu and for extractable Cd, the uncertainty of the assigned values (uref) was calculated by combining the uncertainty of the characterization (uchar) and a contribution for between-bottle homogeneity (ubb) (which was calculated from the certification report). For total and extractable Pb the number of replicates performed to establish the assigned value was higher (11 replicates) than for the other measurands (6 replicates). Since the aliquots were taken from different bottles, it was assumed that uchar included a contribution for the homogeneity. For total Cd, As and Cu, uchar were taken from the CRM certificate as indicated by the producer. For extractable Cd the same uchar as for total Cd was used. For total Pb and Hg and for extractable Pb, uchar was calculated according to the ISO Guide for the Expression of Uncertainty in Measurement (GUM). Participants were invited to report the uncertainties of their measurements. This was done by the majority of the laboratories taking part in this exercise.JRC.DG.D.6-Food Safety and Qualit