METROLOGY PERSPECTIVE - Standards Australia · 8. Have the results of measurements using the...

METROLOGY PERSPECTIVE

4 July 2012

Jan Herrmann

WG2, NT-001

Metrology

People make decisions involving [nano]technologies. Researchers, manufacturers, workers,

regulators, consumers, …

They need [nanoscale] measurements that are

fit for purpose, accurate, recognised.

“To measure is to know.”

(Lord Kelvin)

//upload.wikimedia.org/wikipedia/commons/a/a0/Lord_Kelvin_photograph.jpg

Metrology

questions

1. Why are we measuring ?

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

measured?

Measurand (VIM): Quantity intended to be measured

Several published lists of physical/chemical properties

relevant for safety testing of nanomaterials: EC / SCENIHR (2009)

“Risk Assessment of Products of

Nanotechnologies”

OECD WPMN Sponsorship program (2010)

Series on the Safety of Manufactured

Nanomaterials, No. 27

ISO/TR 13014:2012 (ISO/TC229 WG3, PG5)

“Nanotechnologies -- Guidance on

physico-chemical characterization

of engineered nanoscale materials

for toxicologic assessment”

Set of physical-chemical properties

• Agglomeration/aggregation

• Water solubility

• Crystalline phase

• Dustiness

• Crystallite size

• Representative TEM picture(s)

• Particle size distribution

• Specific surface area

• Zeta potential

• Surface chemistry

• Photocatalytic activity

• Pour density

• Porosity

• Octanol-water partition coefficient

• Redox potential

• Radical formation potential

Nanometrology

challenges Nano properties cannot be extrapolated from the macro scale.

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 V Coleman

ZnO V Coleman

How to describe

ensembles of

[nano-]objects?

30 nm

Au V Coleman

Al2O3

T Tsuzuki ZrO

T Tsuzuki

CeO2

T Tsuzuki

100 nm

ZnO 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

diameter?

Choose a measurand that matches the application.

Be aware of limitations of methodology/infrastructure.

Sphere of same

2D projection area Sphere of same

hydrodynamic

mobility

Sphere of same

surface area Sphere of same

sieve aperture

Sphere of same

sedimentation

rate

Sphere of

same mass

Sphere of

same volume

dec

ds

dsieve

dsed

dw

dv

dh

ISO/TC229 –

IEC/TC113

JWG2

Metrology SG 1. Has the system / body / substance that will be subjected to the

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?

Metrology Checklist (N095) for use in preparation and evaluation of ISO/TC229 NWIPs and WDs

ISO/TC229 –

IEC/TC113

JWG2




restrictive?




defined property?











ISO/IEC Guide 99:2007 (JCGM 200:2008);

International vocabulary of metrology —

Basic and general concepts

and associated terms

(VIM), 3rd edition.

ISO/TC229 –

IEC/TC113

JWG2




restrictive?




defined property?











ISO/IEC Guide 99:2007 (JCGM 200:2008);

International vocabulary of metrology —

Basic and general concepts

and associated terms

(VIM), 3rd edition.

ISO/TC229 – IEC/TC113 JWG2_N096

Guidelines on the metrological content

in the documentation of measurement

methods

Metrology

When developing standards/regulations/guidelines

for [nano]technologies that involve measurements …

talk to a [nano]metrologist !

“To measure is to know.”

(Lord Kelvin)

//upload.wikimedia.org/wikipedia/commons/a/a0/Lord_Kelvin_photograph.jpg

THANK YOU

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