Analytische Chemie
Filtern
Dokumenttyp
Sprache
- Englisch (11)
Referierte Publikation
- nein (11)
Schlagworte
- Inter-laboratory comparison (11) (entfernen)
Organisationseinheit der BAM
Eingeladener Vortrag
- nein (8)
The TiO2 material selected for the present inter-laboratory comparison (ILC) was the bipyramidal anatase UT001 batch synthesized hydrothermally by University of Turin in the frame of the EU/FP7 Project SETNanoMetro and carefully prepared on TEM grids by BAM to be distributed to the ILC participants. A clear measurement protocol including data analysis and reporting (including an xls reporting template) has been also prepared by BAM. 14 of 18 participants have measured and reported results which have been already checked by BAM as being conform to the agreed protocol. After receiving the last results (of 4 participants) the ILC data evaluation will be carried out by BAM in line with agreed ISO/TC229 procedures as for the other case sudies.
A proposal of an inter-laboratory study (ILC) on determination of size and shape distribution of TiO2 nanoparticles (NPs) by transmission electron microscopy is presented. The anatase NPs synthesized in a controllable fashion within the EU/FP7 project SETNanoMetro can be considered as shape-defined (bipyramidal) and are offered to complete the list of case studies already in progress within ISO/TC229/JWG2. The main points of the measurement procedure are presented as well as a proposed procedure to evaluate the size and shape according to the standard operation procedure already developed within SETNanoMetro is discussed. Potential ILC participants and a plan with next step to be carried out are proposed.
The presentation goes into the characterization of TiO2 engineered nanoparticles within EU/FP7 SETNanoMetro Project and the nanomaterial classification according to the EC definition tested within EU/FP7 NanoDefine Project. Further, ISO/TC 229/JWG 2 activities related on ISO standards in development and inter-laboratory comparisons on measurement of nanoparticle size and shape distribution by SEM and TEM are discussed.
First results of an inter-laboratory comparsion launched in the frame of ISO/TC 229 'Nanotechnologies' / JWG 2 'Measurement and Characterization' are presented and the further data treatment discussed.
Feret min, Feret and Aspect Ratio of bipyramidal TiO2 nanoparticles as determined according to the measurememnt protocol distributed by BAM are compared for all 17 participants for the first time. The inclusion of the case study into the ongoing ISO/TC 229/JWG 2 project on Measurement of size and shape distribution of nanoparticles by TEM is discussed.
Microbeam analysis data are of continuously improving quality, this owing mainly to developments in instrumentation (hardware and software) and computer performance. The knowledge and skills of the operators must be also kept correspondingly updated. To be deemed as technically competent, the laboratories must be accredited according to an accreditation scheme, mostly following ISO/IEC 17025.
International standards are able to provide requirements, specifications, guidelines or characteristics of methods, instruments or samples with the final goal that these can be used consistently in accredited laboratories. In the field of electron microscopy and microbeam Analysis standardisation and metrology are terms that are encountered rather seldom at major conferences and scientific publications. Several ISO standards already published and used successfully by a large part of the electron microscopy and microbeam analysis community. For example, file formats such as EMSA/MSA for spectral-data exchange or tagged image file format (TIFF) for SEM images; procedures for the specification of X-ray spectrometers, the specification of certified reference materials (CRMs), and for measurement of average grain size by electron backscatter diffraction (EBSD); and guidelines for calibrating image magnification in SEM or TEM. A main task of ISO technical committee TC 202 ‘Microbeam Analysis’ is to identify feasible projects/proposals needed to be developed into new international standards, particularly in respect to recent technology, such the silicon drift detector (SDD).
As far as the metrological aspects are regarded, The International Bureau of Weights and Measures (BIPM) through the Consultative Committee for the Amount of Substance (CCQM) is concerned with the metrological aspect in Chemistry and Biology. In particular, the Surface Analysis Working Group (SAWG) assists in identifying and establishing inter-laboratory work to test the consistency as well as to improve the traceability of spatially resolved chemical surface analysis at the micro and nanoscale. Examples of recent projects on quantitative microbeam analysis at low energies, such as the quantification of light elements such as carbon and nitrogen will be presented.
The significant sources of measurement uncertainty will be emphasized. These are: quality of the unknown and the reference materials used, the quantification model, instrumental parameters like take-off-angle, spectrometer efficiency, and particularly the beam current. The crucial importance of working with uniform and well-defined measurement and data evaluation protocols will be discussed in compliance with the ISO document “Guide to the expression of uncertainty in measurement (GUM)”.
Another international platform where pre-standardisation work can be organised is VAMAS (Versailles Project on Advanced Materials and Standards). International collaborative Projects aim at providing the technical basis for harmonised measurements, testing, specifications, and standards to be further developed at ISO level. One key point of VAMAS activities is constituted by inter-laboratory comparisons for high-quality data. In the field of microbeam analysis, the technical working area (TWA) 37 Quantitative Microstructural Analysis deals with corresponding projects. Good ideas, e.g., on analysis at low energies, are particularly encouraged by directly contacting the author. Support and guidance will be supplied.
There are different ways how to prove the quality of the results obtained by electron microscopy and related microanalysis techniques, e.g. use of validated standard operation procedures, participation in proficiency testing exercises, use of certified reference materials, etc. International standards are able to provide requirements, specifications, guidelines or characteristics of methods, instruments or samples with the final goal that these can be used consistently in accredited laboratories. In the field of electron microscopy and microbeam analysis standardization and metrology are terms which are encountered rather seldom at major conferences and scientific publications. Nevertheless, spectra formats like EMSA/MSA for spectral-data exchange or tagged image file format (TIFF) for SEM, guidelines for performing quality assurance procedures or for the specification of X-ray spectrometers as well as of certified reference materials (CRMs) in EPMA, or measurement of average grain size by electron backscatter diffraction (EBSD), or guidelines for calibrating image magnification in SEM or TEM are ISO standards already published and used successfully by a large part of the electron microscopy and microbeam analysis community. A main and continuous task of ISO/TC 202 and its subcommittees is to identify and evaluate feasible projects/proposals needed to be developed into new international standards, particularly in respect to recent but established technology, such the silicon drift detector (SDD) EDS one.
Another international platform in the frame of which pre-standardization work can be organized is VAMAS (Versailles Project on Advanced Materials and Standards). International collaborative projects involving aim at providing the technical basis for harmonized measurements, testing, specifications, and standards to be further developed at ISO level. One key point of VAMAS activities is constituted by inter-laboratory comparisons for high-quality data. In the field of microbeam analysis, the technical working area (TWA) 37 Quantitative Microstructural Analysis deals with corresponding projects. Good ideas, e.g. on analysis of low-Z materials/elements and at low energies are particularly encouraged by directly contacting the author. Support and already available guidance will be supplied.
The progress in activities on Microbeam Analysis under VAMAS/TWA 37 is reviewed. Particularly the liaison with the new projects within the ISO technical committee TC 202 is presented and discussed with respect to the possibility of identifying and launching related VAMAS projects. Need of more promotion for the engagement of more participants from industry and academia at national, European and international level is highlighted. Also, the competition with the other technical working areas (on 'nano' or materials-related) is critically discussed.
Characterization of Nanoparticles: Measurement Processes for Nanoparticles surveys this fast growing field, including established methods for the physical and chemical characterization of nanoparticles. The book focuses on sample preparation issues (including potential pitfalls), with measurement procedures described in detail. In addition, the book explores data reduction, including the quantitative evaluation of the final result and its uncertainty of measurement. The results of published inter-laboratory comparisons are referred to, along with the availability of reference materials necessary for instrument calibration and method validation. The application of these methods are illustrated with practical examples on what is routine and what remains a challenge.
In addition, this book summarizes promising methods still under development and analyzes the need for complementary methods to enhance the quality of nanoparticle characterization with solutions already in operation.
The main outcomes of the EMPIR project nPSize are presented and the suitability of the new capabilities (e.g. reference materials, measurement procedures, VAMAS inter-laboratory comparisons) to be standardized and implemented in accredited analytical laboratories is discussed. Complementation and/or filling gaps of published and ongoing standardisation projects on size, shape and number concentration measurements under ISO/TC 229/JWG 2 are offered.
A case study on the TEM analysis of the size and shape distribution of TiO2 bipyramidal nanoparticles prepared on TEM grids was included in the recently published ISO standard ISO 21363. It was agreed to organize at a later stage a second inter-lab comparison with the nanoparticles distributed to the participants as a liquid suspension. Protocols for uniform nanoparticle deposition on suited supports developed and optimized within the EMPIR nPSize project are also prepared to be distributed. For this, we have chosen the VAMAS platform (www.vamas.org) which offers an excellent international infrastructure of laboratories with high competence in nanoparticle measurement. The VAMAS technical working area dedicated to nanoparticle measurement is TWA 34 ‘Nanoparticle populations’. For this type of nanoparticles, the size and shape distributions are the primary parameters to be reported. Due to the good deposition protocols developed, an automated image analysis is enabled (in contrast to the manual analysis of irregular TiO2 nanoparticles.
In parallel with the TiO2 nanoparticle exercise, two spherical SiO2 nanoparticle samples with bi-modal size distributions (nominal relative number concentrations of 1:1 and 10:1) are prepared for a second VAMAS inter-lab comparison. Here, the nanoparticle concentration is the primary parameter to be measured. For the imaging methods it is targeted to measure the relative nanoparticle concentrations of the two modes. For the absolute nanoparticle concentration to be measured by imaging methods it is necessary to control the volume of the liquid suspension deposited on the substrate and to obtain such a homogeneous nanoparticle deposition on the substrate which allows to count (or extrapolate) all the deposited particles.