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

Report of the Third Interlaboratory Comparison Organised by the Community Reference Laboratory for Heavy Metals in Feed and Food - Total Cd, Pb and Hg and Extractable Cd and Pb in Feed

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 its core tasks is to organise interlaboratory comparisons (ILCs) among appointed National Reference Laboratories (NRLs). This report presents the results of the third ILC of the CRL-HM which focused on the determination of total Cd, Pb and Hg and extractable Cd and Pb in 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 a commercial compound feed for fish provided by the Centro di Referenza Nazionale per la Sorveglianza e il Controllo degli Alimenti per Animali, Istituto Zooprofilattico del Piemonte. The material, naturally contaminated, was processed, bottled, labelled and dispatched by the Reference Materials Unit of the IRMM. The samples were dispatched on the second half of October 2007. Each participant received one bottle containing approximately 20 g of test material. Thirty-one participants from 25 countries registered to the exercise of which 31 submitted results for total Cd and total Pb, 28 for total Hg, 26 for extractable Cd and 24 for extractable Pb. The assigned values (Xref) were provided by IRMM using isotope dilution-inductively coupled plasma-mass spectrometry (ID-ICP-MS). The analytical uncertainty of Xref, uchar, was calculated according to the ISO Guide to the Expression of Uncertainty in Measurement (GUM)2. Homogeneity and stability studies were subcontracted to Bundesanstalt für Materialforschung und ¿Prüfung (BAM). The uncertainties of the respective assigned values, uref, were calculated combining the analytical uncertainty, uchar, with a contribution for the between-bottle homogeneity, ubb, and for the short term stability of the test material, usts. Participants were invited to report the uncertainty on their measurements. This was done by 29 laboratories for total Cd, 23 for total Pb, 25 for total Hg, 18 for extractable Cd and 13 for extractable Pb. Laboratory results were rated with z and zeta scores in accordance with ISO 135283. Standard deviation for proficiency assessment (also called target standard deviation) were calculated using the modified Horwitz equation and were 22 % of the assigned value for total Pb and Hg and for extractable Pb and 16 % of the assigned value for total and extractable Cd.JRC.D.4-Isotope measurement

IMEP-22 Sulphur in Petrol

EU Directive 2003/17/EC lays down requirements for the sulphur content in automotive petrol and provides criteria for appropriate methods of analysis to monitor compliance with these requirements.IMEP-22 studies whether the laboratories involved in petrol analysis in the frame of EU legislation are able to measure a sulphur content of 20.5 mg·kg-1. This value was certified by IRMM using a primary method of measurement. Involved in this interlaboratory comparison are also DG TAXUD and the European co-operation for Accreditation EA.JRC.D.4-Isotope measurement

IMEP-23: The Eight WFD PAHs in Water in Presence of Humic Acid

IMEP-23 is linked to the Water Framework Directive (WFD). It studied the capability of control laboratories to measure the eight WFD PAHs in the presence of humic acid in a water matrix. Humic acid simulates natural colloidal organic matter and is known to adsorb PAHs. This gives rise to various issues that are of large importance for the control laboratories. Participants' results were benchmarked against the IMEP certified reference values. On average 80 % of the z scores was satisfactory. Zeta scores were calculated for those laboratories who provided an uncertainty estimate. These were less satisfactory and this shows that many laboratories encounter difficulties to provide a reasonable uncertainty estimate.JRC.D.4-Isotope measurement

Visualizing orientation of retinal nerves and depolarization in the choroid using polarization-sensitive optical coherence tomography (Conference Presentation)

Polarization sensitive optical coherence tomography (PS-OCT) has been used to visualize the orientation of the nerves in the retinal nerve fiber layer (RNFL) and to visualize depolarization in retinas of healthy volunteers and age-related macular degeneration (AMD) patients. Optic axis orientation images clearly visualize the nerve fibers leaving the optic nerve head (ONH) in all radial directions in healthy volunteers. Depolarization images show depolarization of the RPE and for some cases, highlight another depolarizing layer at the boundary of the choroid and sclera

Comparability of PT Schemes - What did we Learn from COEPT?

The use of proficiency testing schemes (PTS) by laboratories as an integral part of their quality system has been increasing in recent years. Accreditation bodies, regulators and the laboratories’ customers are increasingly using results from PTS in their relationship with laboratories. There are many PTS available in Europe in analytical chemistry; EPTIS indicates over 400. The comparability of these PTS is now a real issue, as many organisers of PTS move into new markets. The COEPT project has systematically demonstrated (in four technical sectors – water, soil, food and occupational hygiene), that there are many similarities between PTS in each sector. For example, nearly all use the z-score as a performance index. One significant difference between many PTS is the value used for the term s in the z-score equation, and this gives a range of evaluations for the same data point. Despite this, the agreement between PTS in the same sector for the evaluation of data is approximately 85%. COEPT has given us a basis for establishing the comparability of PTS and showing us where further harmonisation could occur.JRC.D.4-Isotope measurement

IMEP-24 Analysis of Eight Trace Elements in Toys

The International Measurement Evaluation Program (IMEP) organized the IMEP-24 interlaboratory comparison after reports in the media about high levels of lead in toys. The aim of this comparison was to verify the laboratories' capacity to evaluate trace-element levels in a possible toy-like material according to the European Standard EN 71-3:1994. As test material, it used a former certified reference material containing levels of antimony, arsenic, barium, cadmium, chromium, mercury, lead and selenium around the limits set in the standard. Four expert laboratories confirmed the reference values (Xref) for all elements but Hg, and established a reference value for Hg. The scatter of the results reported by the participants was large, as expected, but showed a close to normal distribution around the reference values for five of the eight trace elements. The spread of results was mainly attributed to sampling and sample preparation. One major issue observed in this exercise was the lack of legislative rules about how to report the result, or, more specifically, the use of the analytical correction, which was introduced in EN 71-3:1994 to achieve consistent interpretation of results and which is to be applied when values are equal to or above the maximum limits set in the standard. Its application by the participants was very inconsistent and led to problems in their evaluation. There is clearly a need for clarification and for more formal regulations with regard to result reporting in order to minimize the risk of confusion. Participants were also asked to give their opinion with regard to the acceptability of the test material for the market. The majority correctly considered the material as non-compliant. However, almost one-third incorrectly assessed the material as compliant.JRC.DG.D.6-Food Safety and Qualit

IMEP-23: The Eight EU-WFD Priority PAHs in Water in the Presence of Humic Acid

Recently, the International Measurement Evaluation Programme (IMEP) organized an interlaboratory comparison on total concentrations of eight polycyclic aromatic hydrocarbons (PAHs) in natural inland waters. It was carried out in support to the European Union Water Framework Directive (EU-WFD) that lists these eight as priority substances. As sample matrix, we used groundwater spiked with humic acid as a model for the colloidal substances that are present in natural inland waters. Humic substances can adsorb PAHs, but we found that some laboratories did not apply analytical procedures that sufficiently accounted for this. One of these laboratories was involved in establishing the reference values. We show how this impacted on the reliability of their measurements. Many participants accepted our invitation to report their measurement uncertainties. We assessed their results against our reference values and uncertainties, and provided z and zeta scores. Although the overall measurement capability appears satisfactory, there is room for improvement of analytical procedures as regards the use of measurement standards.JRC.D.5-Food Safety and Qualit

Optic axis uniformity as a metric to improve the contrast of birefringent structures and analyze the retinal nerve fiber layer in polarization-sensitive optical coherence tomography

A new metric is used to improve the contrast of birefringent structures in biological tissue using polarization-sensitive optical coherence tomography. This metric, optic axis uniformity (OAxU), is based on the optic axis of birefringence and quantifies the uniformity of the optic axis direction. OAxU provides surprisingly strong contrast for fibrous structures such as muscle and the retinal nerve fiber layer (RNFL). We used OAxU for automatic segmentation of the RNFL in human eyes. From the segmentation, en face images of RNFL thickness and RNFL birefringence were created. The measured birefringence values are consistent with earlier reports

IMEP-24: Analysis of Eight Heavy Metals in Toys According to EN 71-3:1994

The Institute for Reference Materials and Measurements (IRMM) of the Joint Research Centre (JRC), a Directorate-General of the European Commission, operates the International Measurement Evaluation Programme (IMEP). It organises interlaboratory comparisons (ILC's) in support to EU policies. This report presents the results of an ILC which focussed on the determination of soluble antimony, arsenic, barium, cadmium, chromium, lead, mercury, and selenium according to European Standard EN 71-3:1994. The principle of the procedure in EN 71-3:1994 consists in the extraction of soluble elements from toy material under the conditions simulating the material remaining in contact with stomach acid for a period of time after swallowing. Forty participants from eighteen countries registered to the exercise, of which 33 reported results for As, 35 for Ba and Se, 37 for Cr, Pb, and Sb, 38 for Hg, and 39 for Cd. For seven measurands the test material had already been certified in the past. The validity of the certificate was reconfirmed and the certified values were taken as the reference values for this ILC. As no certified value was available for Hg, the mean value of the results provided by four expert laboratories was used together with the corresponding uncertainty. Participants were invited to report the uncertainty on their measurements. This was done by 35 of the 39 laboratories having submitted results in this exercise. Laboratory results were rated with z and zeta scores in accordance with ISO 13528. The standard deviations for proficiency assessment were based on the analytical correction laid down in EN 71-3:1994.JRC.D.8-Food safety and qualit