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Eingeladener Vortrag
- nein (31)
Reliable and efficient methods for detecting genetically modified organisms (GMOs) are essential for establishing an effective system for traceability all along the supply chain from seed producers to final consumers. The latter is especially meaningful in European Union and other countries where strict legislations on GMOs were set up. Performance of the methods used in laboratories around the world should be uniform, in order to obtain reliable and comparable results. Accreditation is a suitable system for harmonising procedures in each testing laboratory. In this paper, key elements for the accreditation of molecular biology methods for GMO detection according to ISO/IEC 17025 are described. The procedures described are also valuable for the accreditation of molecular methods for all laboratory diagnostics where qualitative and quantitative characterisation of nucleic acids is needed.
Die Norm ISO/IEC 17025, die im Allgemeinen die Grundlage der Laborakkreditierung darstellt, verlangt u.a. auch die Rückführung analytischer Ergebnisse auf SI-Einheiten (SI: Système internationale d'unités). Dazu bieten sich im Prinzip zwei Wege an:
1. Verwendung von Primärnormalen zur Kalibrierung oder von Primärmethoden,
2. Verwendung von zertifizierten Referenzmaterialien.
Die Verwendung von zertifizierten Referenzmaterialien (ZRM) setzt voraus, dass diesen ZRM ein (oder mehrere) auf SI rückführbarer zertifizierter Wert (z.B. Massenanteil) mit dazugehöriger Unsicherheit zugewiesen wurde.
Ein möglicher Weg, dies zu erreichen, der von BAM und EMPA in Zusammenarbeit mit der Fa. Fluka für Kalibrierstandards (Anionen- und Kationenlösungen, Urtitersubstanzen) beschritten wurde, wird hier beschrieben.
Zertifiziert wurden
- Kationen-Standardlösungen (1000 mg/L) für Spektrometrie
- Anionen-Standardlösungen (1000 mg/kg) für Ionenchromatographie
- Urtitersubstanzen (> 99,5 %) für Titrimetrie
Die Materialien wurden bei Fluka hergestellt, die Überprüfung der Homogenität der abgefüllten Charge erfolgte bei der EMPA. SI-rückführbare Zertifizierungsanalysen wurden in der EMPA sowie in der BAM mit zwei unterschiedlichen analytischen Methoden durchgeführt. Dabei kamen neben spektrometrischen und chromatographischen Verfahren auch klassische Methoden wie Titrimetrie und in Einzelfällen Gravimetrie zum Einsatz. An ausgewählten Beispielen werden Messverfahren, Berechnung der Messunsicherheit und Rückführung auf SI gezeigt.
The preparation and analysis of the oxygen mass fraction of three pure copper reference materials (BAM-379/1, BAM-379/2, BAM-379/3) intended for the calibration of spark emission spectrometry are described here. Data of homogeneity testing and round robin certification in collaboration with 12 independent laboratories from metalworking industry and research are reported. Problems with the establishment of traceability in this special case are discussed.
The key comparison CCQM-K33 was organized by the Inorganic Analysis Working Group of the CCQM to test the abilities of the national metrology institutes to measure the mass fractions of minor elements in steel. Elements to be analysed were Cr, Mn, Ni and Mo in low alloy steel. The National Metrology Institute of Japan (NMIJ), the National Institute of Standards and Technology (NIST) and the Federal Institute for Materials Research and Testing (BAM) acted as the coordinating laboratories. The participants used various measurement methods, though many of them used ICP-AES. Generally speaking, the agreement of the results was very good for each measurand.
The capabilities of National Metrology Institutes (NMIs) and selected outside expert laboratories of determining the mass fractions of the main and minor elements Cu, Pb, Sn, Fe, and Ni in a lead-containing brass were assessed. This pilot study P76 was organized as an activity of the Inorganic Analysis Working Group of CCQM and was piloted by the Federal Institute for Materials Research and Testing (BAM). In total 12 laboratories (four NMIs and eight outside labs) submitted results, some of them more than one set of results per element. The laboratories were free to choose any analytical method they wanted to use for the analysis. Consequently various methods of measurement were employed: inductively coupled plasma optical emission spectrometry (ICPOES), inductively coupled plasma mass spectrometry (ICPMS), instrumental neutron-activation analysis (INAA), titrimetry, flame atomic-absorption spectrometry (FAAS), spectrophotometry (MAS), electrogravimetry, and gravimetric analysis. After testing for homogeneity within BAM, a certified reference material of lead-containing brass was used as test sample without informing the participants about the source of the material. The agreement of the results for all elements investigated was acceptable and mean values calculated from the results of all participants were close to the certified mass fractions of the CRM used as test sample. No statistically significant differences between the results of the NMIs and those of the non-NMIs could be observed.
Certification of a set of pure copper reference materials - analytical challenges and pitfalls
(2007)
Certification of the mass fractions of Pt, Pd and Rh in a used car catalyst reference material
(2009)
The high economic value of catalysts containing the platinum group elements platinum, rhodium and palladium as active components causes the need to be able to measure the precious metal loading with small uncertainty and to have suitable certified reference materials fulfilling high demands on the quality of the certified values. In European Reference Material ERM®-EB504, a used cordierite-based car catalyst material, mass fractions of platinum, palladium and rhodium were certified. The raw material was milled, homogenised and annealed before analysis. Seventeen laboratories experienced in precious metals analysis participated in the certification interlaboratory comparison, most of them analysing with inductively coupled plasma optical emission spectrometry using different sample pretreatment techniques. Homogeneity testing was carried out using X-ray fluorescence spectrometry. The certified mass fractions of Pt, Pd and Rh and their expanded uncertainties (k = 2) in ERM®-EB504 are (1777 ± 15), (279 ± 6) and (338 ± 4) mg/kg respectively.
Three methods for direct solid sampling of bulk material namely IR laser ablation, glow discharge and spark OES, were compared with respect to analytical figures of merit obtained for elemental analysis with atomic spectrometry. Matrices investigated were copper, pressed doped copper powder, and magnesium alloys. For the vast majority of analytes, statistical equivalence regarding precision (usually ≤ 5%) and the performance of the calibrations between the compared methods was demonstrated.
Standards for Metal-analysis
(2002)
Within the framework of a German government project (initiated by the Federal Environment Agency) to check the compliance of commercially available batteries with the German Battery Ordinance concerning their heavy metal contents, 18 different types of commercially available zinc-air button cells were analysed for their cadmium, lead and mercury contents. After microwave assisted dissolution with aqua regia, Cd and Pb were determined using inductively coupled plasma mass spectrometry (ICP-MS), and Hg was determined using inductively coupled plasma optical emission spectrometry (ICP OES) and atomic absorption spectrometry. Cd contents were found to be much lower than the permitted limits; Pb contents were also found to be below the limits. Hg contents were found to be near the limits, and in one case the limit was exceeded.
The objective of this work was to test the compliance of commercially available batteries with the German Battery Ordinance, a project of the German government that was initiated by the Federal Environment Agency. Different types of commercially available dry cells were analysed for their cadmium, lead and mercury contents. The dry cells underwent mechanical pre-treatment, separation of the different components and microwave-assisted digestion before determination of the heavy metals. Mercury is sometimes added to prevent the generation of gaseous hydrogen from the electrochemical process. Lead could be present since it is sometimes used as an alloying element of zinc. Cadmium has no technical importance and is an undesirable impurity. None of the batteries contained higher heavy metal mass fractions than the permissible limits.
The degree of equivalence within the participating national metrology institutes for the measurement results of the mass fractions of the analytes Cr, Cu, Fe, Mn and Zn in an aluminium alloy was assessed. This interlaboratory comité consultatif pour la quantité de matière key comparison (CCQM-K42) was organised as an activity of the Inorganic Analytical Working Group of CCQM. In total seven laboratories participated, six of them for all analytes. Measurands were the mass fractions of the analytes in a range of 0.05 and 0.2%. As an outcome the consistency of the results for all elements investigated was acceptable, hence satisfactory comparability was established. An aluminium based certified reference material—undisclosed to the analysts which one it was—was used as test sample. For the purpose of this study homogeneity was tested at BAM. Each laboratory was free to choose any analytical method they wanted to use for the analysis. Consequently various methods of measurement were employed: instrumental neutron activation analysis, X-ray fluorescence spectrometry (XRF) using fused cast-bead method combined with reconstitution technique, inductively coupled plasma optical emission spectrometry (ICP OES) and inductively coupled plasma mass spectrometry. Metrological traceability of the measurement results to the SI unit had to be demonstrated. Therefore, methods such as spark OES or XRF (without fused cast-bead technique)—both of them being most important methods for the analysis of metals and alloys in industrial laboratories—could not be used in the frame of the key comparison.
Situationsbeschreibung bezüglich der Einhaltung der Schwermetallverbote der Batterieverordnung zu
erhalten. Nach geltenden Vorschriften dürfen die Gehalte folgende Grenzwerte nicht überschreiten:
5 ppm Quecksilber (Hg; Knopfzellen: 20000 ppm Hg), 250 ppm Cadmium (Cd) und 4000 ppm Blei
(Pb).
Dazu wurden Mignon-Zellen (Alkali-Mangan, Zink-Kohle), Monozellen (Alkali-Mangan, Zink-Kohle),
Knopfzellen verschiedener chemischer Systeme (Alkali-Mangan, Zink-Luft, Lithium, Silberoxid),
eingebaute Batterien (herausnehmbar und fest eingebaut) von unterschiedlichen Herstellern aus
unterschiedlichen Orten sowie Bezugsquellen auf ihren Gehalt an Cadmium, Blei und Quecksilber
untersucht. Von jedem Batterietyp wurden zwei Exemplare, insgesamt 310 Proben analysiert. Anhand
eines Probenahmeplans wurden Batterien in vier Regionen Deutschlands im Einzelhandel, bei
Straßenhändlern sowie auf Flohmärkten und im Versandhandel käuflich erworben.
Für Rundzellen (Alkali-Mangan, Zink-Kohle) sowie Knopfzellen (Zink-Luft, Lithium, Silberoxid, Alkali-
Mangan) wurden unterschiedliche Analysenstrategien entwickelt. So wurden die Knopfzellen nach
Möglichkeit komplett gelöst und analysiert, bei den Rundzellen kam nur eine mechanische Zerlegung
mit anschließender Analyse von Teilproben in Frage. Die Knopfzellen sowie die Teilproben der
Rundzellen wurden mit Hilfe eines Säureaufschlusses mit Mikrowelle gelöst, zur Bestimmung der
Elemente wurden abhängig vom Gehalt ICP-MS, ICP OES sowie ein automatischer
Quecksilberanalysator verwendet, einzelne unlösliche Graphitteile aus Zink-Kohle Batterien wurden
mit direkter Feststoff-ICP OES analysiert.
Als Ergebnis der Studie wurde erhalten, dass nur in zwei von 155 untersuchten Batterietypen der
Gehalt an Quecksilber leicht oberhalb des Grenzwertes von 2 % lag, für Blei und Cadmium wurden
keine Grenzwertüberschreitungen festgestellt. Bei den beiden Batterien, bei denen eine
Grenzwertüberschreitung vorlag, handelte es sich um Zink-Luft-Knopfzellen, die vom Hersteller als Hgfrei
deklariert waren. Unterschiede nach Bezugsort von Batterien desselben Typs und Herstellers bzw.
nach verschiedenen Größen von Batterien desselben chemischen Systems eines Herstellers konnten
nicht gefunden werden.
The aim of the project was to describe the situation concerning the compliance with the existing
limits for heavy metal content in commercially available batteries in Germany on the basis of a
representative sample. The allowed limits which not have to be exceeded are: 5 ppm of mercury (Hg;
button cells: 20000 ppm Hg), 250 ppm of cadmium (Cd) and 4000 ppm of lead (Pb).
Several batteries of different size such as AA batteries (alkaline/manganese, zinc/carbon), D
batteries (alkaline/manganese, zinc/carbon) and button cells of different chemical systems (zinc-air;
lithium; alkaline/manganese, silver oxide) were analysed for cadmium, lead and mercury. The test
batteries came from different producers and were bought on different places in Germany. From each
battery type two specimen were investigated, in total 294 samples. Following a sampling plan the
batteries were purchased in four regions in Germany by retail, by mail order or on flew markets.
Different strategies for the analysis of AA and D batteries (alkaline/manganese, zinc/carbon) and
for button cells (alkaline/manganese, zinc-air, lithium, silver oxide) were developed. Button cells were
dissolved completely whenever possible. From the bigger types only subspecimens were analysed
after mechanical destruction. Button cells and the subspecimens of the bigger batteries were
decomposed with acid in a microwave oven. For the analysis of the heavy metals ICP-MS, ICP OES
and an automatic mercury analyser were used depending on the content of the interesting element.
Some graphite parts from zinc/carbon batteries were analysed using solid sampling ICP OES.
The result of the study was that only two of 147 batteries had Hg-contents slightly higher than the
limit of 2 %. Pb- and Cd-contents were below the limits for all batteries investigated. The two
batteries with higher Hg-contents were both zinc-air button cells declared by the manufacturer to be
mercury-free. Differences between batteries of the same kind and producer purchased at different
places or between batteries of different size but same producer and same chemical system could not
be detected.
The mass fraction of potassium hydrogen phthalate (KHP) from a specific batch was certified as an acidimetric standard. Two different analytical methods on a metrological level were used to carry out certification analysis: precision constant current coulometric and volumetric titration with NaOH. It could be shown that with a commercial automatic titration system in combination with a reliable software for the end-point detection it is possible to produce equivalent results with the same accuracy in comparison to a definite method handled by a fundamental apparatus for traceable precision coulometry. Prerequisite for titrations are that a high number of single measurement are applied which are calibrated with a high precision certified reference material.
Certification of a set of pure copper reference materials - analytical challenges and pitfalls
(2007)
22 trace elements in a set of six pure copper reference materials intended for the calibration of spark emission and X-ray fluorescence spectrometers were analysed in a certification interlaboratory comparison using different analytical methods. He materials was prepared by alloying different quantities of the interesting elements Ag, Al, As, Bi, Cd, Co, Cr, Fe, Mg, Mn, Ni, P, Pb, S, Sb, Se, Si, Sn, Te, Ti, Zn, and Zr to a pure copper to get reference samples with graded element mass fractions.
Results and problems of the analytical determinations performed during the interlaboratory comparison for certification are presented. Special regard is paid to the dissolution procedure of the copper matrix and interferences from insoluble residues. Additionally questions related to the traceability of the certified values are discussed since solid sampling methods were also used for certification analysis of some elements.
The special importance of the analysis of non-metals in high purity metals, which will serve as national standards for elemental analysis in Germany, is illustrated for oxygen and nitrogen. The typical range of the mass fraction of oxygen and nitrogen in these materials is below 10.MU.g/g, often close to 1.MU.g/g. The two methods applied at BAM for these measurements are classical carrier gas hot extraction (HE) and carrier gas hot extraction after activation with photons (PAA-HE). The approach, the methods and their advantages and limitations are discussed. Comparative results from the measurement of oxygen and nitrogen in Cu, Fe, Ga, Pb, Sn and W are presented. (author abst.)
Production of Inorganic RM
(2015)
The unique optical properties, such as size-tunable absorption and emission, caused semiconductor nanocrystals to attract a great deal of interest for recent technological developments. For the evaluation of semiconductor nanocrystals as new materials for various applications like optoelectronic devices, knowledge of the structure–property relationships is indispensable, but still presents a challenge. Here, we address these challenges for thioglycolic acid-capped CdTe nanocrystals with a focus on the quantification of thiol ligands, identification of the ligand shell structure and their influence on the optical properties of these nanocrystals. We present the use of a simple analytical technique, the Ellman's test, and ICP-OES analysis for the study of the surface chemistry of these nanomaterials. Together with theoretical calculations, the results of these studies show the strong influence of the amount of Cd–thiolates present in the ligand shell on the concentration-dependent emission properties, thereby providing the basis for a better understanding of the chemical nature of the NC–ligand interface. In this context, the present work contributes to the establishment of a clearer picture and better control of the surface chemistry, which will provide the basis for the design of highly emitting nanocrystals and the prediction of their applicability.