METROLOGY PERSPECTIVE Jan Herrmann WG2, NT-001 4 July 2012
Metrology “To measure is to know.” (Lord Kelvin) People make decisions involving [nano]technologies. Researchers, manufacturers, workers, regulators, consumers, … They need [nanoscale] measurements that are fit for purpose, accurate, recognised.
Metrology 1. Why are we measuring ? questions What is the purpose of the measurement ? 2. What should be measured ? What is the quantity that matters ? 3. How accurate does the result need to be ? How is the purpose affected by the accuracy ? 4. What can actually be measured ? What methodology/infrastructure is available ? 5. How accurate is the measurement result ? What is the uncertainty budget of the measurement ? 6. How comparable is the measurement result ? Is the measurement traceable to a reference ?
What should be Measurand (VIM): Quantity intended to be measured measured? Several published lists of physical/chemical properties relevant for safety testing of nanomaterials: EC / SCENIHR (2009) “Risk Assessment of Products of Nanotechnologies” Set of physical-chemical properties OECD WPMN Sponsorship program (2010) Agglomeration/aggregation • Series on the Safety of Manufactured Water solubility • Crystalline phase Nanomaterials, No. 27 • Dustiness • ISO/TR 13014:2012 (ISO/TC229 WG3, PG5) Crystallite size • “Nanotechnologies -- Guidance on Representative TEM picture(s) • physico-chemical characterization Particle size distribution • Specific surface area of engineered nanoscale materials • Zeta potential • for toxicologic assessment” Surface chemistry • Photocatalytic activity • Pour density • Porosity • Octanol-water partition coefficient • Redox potential • Radical formation potential •
Nanometrology Nano properties cannot be extrapolated from the macro scale. challenges Enormous variety of nanomaterials and characterisation techniques, growing rapidly. No consensus about which properties are most relevant, e.g. for risk assessment. Statistical relevance of measurement results for ensembles of nano-objects is often limited. Interaction of nanomaterials with their environment is crucial, but often not well understood. Number of methods available for analysing nanomaterials in matrices (e.g., in tissue, soil, food) is very limited. Physico-chemical metrology of nanomaterials is still in its infancy. 60 nm Au ZnO V Coleman V Coleman
How to describe ensembles of [nano-]objects? 30 nm 100 nm Au Al 2 O 3 ZrO V Coleman T Tsuzuki T Tsuzuki CeO 2 ZnO T Tsuzuki V Coleman Complex particle systems require complex descriptors. “Size” is (almost) never enough ! Guidance: ISO 9276 Series, e.g., ISO 9276-6:2008 “Representation of results of particle size analysis -- Part 6: Descriptive and quantitative representation of particle shape and morphology”
What is the ‘right’ particle Sphere of same Sphere of diameter? Sphere of same 2D projection area same mass hydrodynamic d w d ec mobility d h Sphere of d v same volume d sed Sphere of same d s sedimentation rate Sphere of same d sieve surface area Sphere of same sieve aperture Choose a measurand that matches the application. Be aware of limitations of methodology/infrastructure.
ISO/TC229 – Metrology Checklist (N095) IEC/TC113 for use in preparation and evaluation of ISO/TC229 NWIPs and WDs JWG2 1. Has the system / body / substance that will be subjected to the Metrology SG measurement procedure clearly been described, including its state? 2. Is the definition of the system / body / substance not unnecessarily restrictive? 3. Is the measurand clearly described? 4. Has it been clearly indicated whether the measurand is operationally or method defined, or whether the measurand is an intrinsic, structurally defined property? 5. Is the measurement unit defined? Are the tools required to obtain metrological traceability available? 6. Has the method already been validated in one or more laboratories? 7. Are any quality control tools available to enable the demonstration of a laboratory's proficiency with the test method? 8. Have the results of measurements using the proposed method already been published in peer-reviewed journals by several laboratories? 9. Is the instrumentation required to perform the test widely available? 10. Does the document propose a measurement uncertainty budget?
ISO/TC229 – Metrology Checklist (N095) IEC/TC113 for use in preparation and evaluation of ISO/TC229 NWIPs and WDs JWG2 1. Has the system / body / substance that will be subjected to the Metrology SG measurement procedure clearly been described, including its state? 2. Is the definition of the system / body / substance not unnecessarily restrictive? 3. Is the measurand clearly described? 4. Has it been clearly indicated whether the measurand is operationally or method defined, or whether the measurand is an intrinsic, structurally defined property? 5. Is the measurement unit defined? Are the tools required to obtain metrological traceability available? 6. Has the method already been validated in one or more laboratories? 7. Are any quality control tools available to enable the demonstration of a laboratory's proficiency with the test method? 8. Have the results of measurements using the proposed method already been published in peer-reviewed journals by several laboratories? 9. Is the instrumentation required to perform the test widely available? 10. Does the document propose a measurement uncertainty budget?
ISO/TC229 – Metrology Checklist (N095) IEC/TC113 for use in preparation and evaluation of ISO/TC229 NWIPs and WDs JWG2 1. Has the system / body / substance that will be subjected to the Metrology SG measurement procedure clearly been described, including its state? 2. Is the definition of the system / body / substance not unnecessarily ISO/IEC Guide 99:2007 (JCGM 200:2008); restrictive? International vocabulary of metrology — 3. Is the measurand clearly described? Basic and general concepts 4. Has it been clearly indicated whether the measurand is operationally or and associated terms method defined, or whether the measurand is an intrinsic, structurally (VIM), 3rd edition. defined property? 5. Is the measurement unit defined? Are the tools required to obtain metrological traceability available? 6. Has the method already been validated in one or more laboratories? 7. Are any quality control tools available to enable the demonstration of a laboratory's proficiency with the test method? 8. Have the results of measurements using the proposed method already been published in peer-reviewed journals by several laboratories? 9. Is the instrumentation required to perform the test widely available? 10. Does the document propose a measurement uncertainty budget?
ISO/TC229 – Metrology Checklist (N095) IEC/TC113 for use in preparation and evaluation of ISO/TC229 NWIPs and WDs JWG2 1. Has the system / body / substance that will be subjected to the Metrology SG measurement procedure clearly been described, including its state? 2. Is the definition of the system / body / substance not unnecessarily ISO/IEC Guide 99:2007 (JCGM 200:2008); restrictive? International vocabulary of metrology — 3. Is the measurand clearly described? Basic and general concepts 4. Has it been clearly indicated whether the measurand is operationally or and associated terms method defined, or whether the measurand is an intrinsic, structurally (VIM), 3rd edition. defined property? 5. Is the measurement unit defined? Are the tools required to obtain metrological traceability available? 6. Has the method already been validated in one or more laboratories? ISO/TC229 – IEC/TC113 JWG2_N096 7. Are any quality control tools available to enable the demonstration of a Guidelines on the metrological content laboratory's proficiency with the test method? in the documentation of measurement 8. Have the results of measurements using the proposed method already methods been published in peer-reviewed journals by several laboratories? 9. Is the instrumentation required to perform the test widely available? 10. Does the document propose a measurement uncertainty budget?
Metrology “To measure is to know.” (Lord Kelvin) When developing standards/regulations/guidelines for [nano]technologies that involve measurements … talk to a [nano]metrologist !
THANK YOU
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