Euramet 924 meeting 9./10. April 2008 (1)

Metrological Traceability and Dissemination Detlef Schiel, PTB

Euramet 924 meeting 9./10. April 2008 (2)

Questions

• What is metrological traceability?

• Why do we need metrological tracebility?

• How can it be realised?

Euramet 924 meeting 9./10. April 2008 (3)

Main tasks of the NMIs

• Realization of the units by national standards• Conservation of the standards• Dissemination of the standards

for the link with results of the field

Objective: Provision of the basis for reliable measurement results

Euramet 924 meeting 9./10. April 2008 (5)

Definition

• Property of the measurement result but not of an institution • Reference: definition of the unit through its practical realization• Calibration hierarchy required

Metrological traceability (after new VIM ):

Property of the measurement result whereby it can be related to a reference through an unbroken chain of calibrations, each contributing to the measurement uncertainty.

Euramet 924 meeting 9./10. April 2008 (6)

Traceability chain

SIThe mol is that amount-of-substance

which contains as many entities as there are in 12 g 12C. [n] = 1 mol

=)ZCu,(n

Primary (national)standard Z

n (Cu, Z)Amount of copper in a material Z

Cu

pur

M*wm

Comparison measurement

Uncertainty Values

Euramet 924 meeting 9./10. April 2008 (7)

Characterisation of elemental standards

ICP-OES, NAA, PAAVerification

CGHEGas and non-metal analysis

HR ICP MSMetal trace analysis

LA – ICP MSDissolution check

FI – ICP MS Improvement of sensitivity

Primary standardPurity statement

Uncertainty budget

Euramet 924 meeting 9./10. April 2008 (8)

BAM-A-primary-Cu-1

BAM-A-primary-Cu-1LOT B27F17

matrix impurity sum 'aboveum/2 'below' not underin % in mg/kg in mg/kg in mg/kg relevant nvestigation

mass fraction 99,9968 32,33 22,38 9,95 (estimate)abs. uncertainty 0,0005 5,27 3,84 3,61

H He< 2,1 < 0,001

Li Be B C N O F Ne< 0,31 < 1,1 < 3,2 0,04 0,2 1 < 2 < 0,001

Na Mg Al Si P S Cl Ar 0,002 < 0,05 < 0,07 < 0,002 < 2 5,4 < 0,6 < 0,001

K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr< 0,002 0,1 < 0,06 < 0,32 < 0,04 0,07 0,01 < 5 < 0,11 1,64 matrix 0,057 < 0,11 < 0,12 0,5 0,22 < 0,014 < 0,001

Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe< 0,05 < 0,014 < 0,03 < 0,015 < 0,02 < 0,06 < 0,001 < 0,03 < 1,6 < 0,014 11,3 < 0,015 < 0,05 0,14 1 < 0,22 < 0,09 < 0,001

Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn< 0,0057 < 0,017 < 0,002 < 0,003 < 0,003 < 0,12 < 0,009 < 0,004 < 0,007 < 0,007 < 0,008 < 0,03 < 0,005 0,47 0,23 < 0,001 < 0,001 < 0,001

Fr Ra Ac< 0,001 < 0,001 < 0,001

Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu< 0,0057 < 0,002 < 0,21 < 0,001 < 0,007 < 0,003 < 0,001 < 0,001 < 0,001 < 0,001 < 0,001 < 0,001 < 0,001 < 0,002

Th Pa U< 0,02 < 0,001 < 0,001

Euramet 924 meeting 9./10. April 2008 (9)

Pure materials for the realisation of the unit

Cu

Fe

Bi

Ga

Na

K

Ni

Pb

Mo

Si

W

Pure metals for the element analysis

Si-sphere for the re-determination of the Avogadro number NA

N = VSphere/ VAtom

n = N / NA= m / MNA = (M / m) (VSphere/ Vatom)

Euramet 924 meeting 9./10. April 2008 (10)

Traceability chain

Measurement Uncertainty

SIThe mol is that amount-of-substance

which contains as many entities as there are in 12 g 12C. [n] = 1 mol

Values

n (Cu, X)Amount of copper in XSample X

... Y)(Cu,

)X Cu,(=

n

n

Referencematerial Y

n (Cu, Y)Amount of copper in Y

...Z) (Cu,

) YCu,(=

n

n

Primary (national)standard Z

n (Cu, Z)Amount of copper in a material Z

=)ZCu,(nCu

pur

M*wm

Euramet 924 meeting 9./10. April 2008 (11)

Traceability system for elemental analysis

Measurement of the test laboratory

Precison measurement for the certification

Precision measurement of the element content

Purity determination

Gravimetrical preparation of the primary solution

sample XSample solution wX(E)

Secundary standard YCommercial sol., Urel= 0,3% wY(E)

Transferstandard TTransfer solution, Urel= 0,1% wT(E)

SIkg and mol NA

Primary standardPrimary solution, Urel= 0,05% wS(E)

Pure material, Urel= 0,01% wpur

diss

emin

atio

n

Euramet 924 meeting 9./10. April 2008 (12)

Traceability for real samples

Calibration (traceable)

Influence quantities

Validation using traceablereference values

Y = y ± U(y)Correction(Standards)

Euramet 924 meeting 9./10. April 2008 (13)

Traceability for real samples

Y = y ± U(y)

National standards (SI)

Trac

eabi

lity

by m

eans

of

cal

ibra

tion

mat

eria

l

Ver

ifica

tion

by m

eans

of

cer

tifie

d re

f. m

ater

ials

Euramet 924 meeting 9./10. April 2008 (14)

Comparability

CRM 1 orassigned or

consensus value

Lab 1

Lab 5

Lab 2

Lab 6

Lab 7

Lab 4

Lab 8

Lab 3

Euramet 924 meeting 9./10. April 2008 (16)

Link to the national standards

Test laboratories

National Standards (SI)

direkt

By means of CRMs or comparison measurements

Intermediate level

indirekt

Euramet 924 meeting 9./10. April 2008 (17)

Traceability structure in clinical chemistry

Dis

sem

inat

ion

Traceability

National Standards

Reference Laboratories

Field Laboratories

Internal External

Urel~ 5%

Urel~ 2%

Urel~ 0,5%

Euramet 924 meeting 9./10. April 2008 (18)

0.0

10.0

20.0

30.0

40.0

50.0

0.000 10.000 20.000 30.000 40.000 50.000

badd(Pb) / (µg/L)

βR

V(P

b) /

(µg/

L)

Proposal for getting reliable reference values

Matrix content from ring trail results (standard addition)

Euramet 924 meeting 9./10. April 2008 (19)

-20

-10

0

10

20

0 10 20 30 40 50

b(Pb) / (µg/L)

Ure

l / %

Reihe2

Reihe3

Reihe4

Reference values from gravimetry and ring trail results

( )( ) ( ) addRV0Pb;Pb ββββ +=±U

( ) ( )[ ] ( )Pb/PbPb IDMSIDMS βββ −

( ) ( )[ ] ( )Pb/PbPb IDMSIDMSRV βββ −

Euramet 924 meeting 9./10. April 2008 (20)

Conclusion

Metrology provides:

• internationally accepted reference points• link with the users measurement results • conformity to international requirements

by adding metrological concepts to existing QS

Euramet 924 meeting 9./10. April 2008 (21)

Thanks for your attentionThanks for your attention