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Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance.

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Presentation on theme: "Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance."— Presentation transcript:

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2 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching Metrology in Chemistry and Traceability of Analytical Measurement Results Ioannis Papadakis

3 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching Index  Needs for Metrology  Fundamentals of Metrology  International Measurement System  Traceability of analytical measurements results

4 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching Metrology – Science of Measurement  metrology includes all aspects both theoretical and practical with reference to measurements, whatever their uncertainty, and in whatever fields of science or technology they occur. Source:International Vocabulary of Basic and General Terms in Metrology, ISO, 1993

5 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching What is a Measurement ?  measurement is a ratio of an “unknown” to “known” quantity

6 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching Examples

7 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching Mars Climate Orbiter...confusion about units leads to crash...  On 23 September 1999 the Mars Climate Orbiter,one of the missions in a long-term program of Mars exploration, burned out completely.  The accident was not due to a technical problem, but the result of the different measurement units used by the NASA teams.  One team used the metric system for spacecraft operation, while the other used the English units. This information was critical to the maneuvers required to position the spacecraft in the proper Mars orbit and led to the loss of the orbiter.  The fate of the Mars Climate Orbiter clearly shows the need for standardization.

8 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching Difference $ 10 Million  A subsidiary of an oil company in the Far East analysed a batch of petrol. Their local lab established that the gum content (components in the gasoline that polymerize during combustion) was too much high.  On the basis of this analysis the company sold the batch to a trader for a much lower price.  The trader asked a second lab to perform an analysis in order to find out what he could do with the off-spec petrol.  He was very pleasantly surprised to find that the gasoline was actually on-spec and he was able to make a healthy profit selling the batch for the normal price.  The oil company only found out much later that the problem was not the petrol, but an error at their own lab. By then this error had already cost them $ 10 million. Source:Footprint of the Meter, NMi Communicabus, 1999

9 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching Alaska Pipeline  The 800-mile trans-Alaska pipeline pumps oil from the northern coast to the southern border of Alaska.  Construction started in 1973 and was completed 4 years later.  The pipeline was originally budgeted $ 900 million, but the cost escalated to exceed $ billion.  A steel manufacturer was awarded the multimillion dollar contract to supply steel for the pipeline with S content of less than 0.005%.  When several of the joint welds in the pipeline began to fail, it became clear that the S content was much higher than specified.  The poor quality of the steel, in part due to inadequate or lack of measurements, set the project back several millions of dollars, once again emphasizing the need for accurate measurements. Source:Footprint of the Meter,NMi Communicabus, 1999

10 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching Cholesterol Measurements  A high measurements uncertainty for cholesterol can lead to an unnecessary costly treatment or a higher health risk.  Reducing the measurement uncertainty from 23.7% in 1949 to 5% in 1995, saves to the Unites States alone $ 100 million every year in health care costs.  Standard reference materials played an important role in lowering the measurement uncertainty. Source:CITAC ‘99 Japan Symposium, Tsukuba, November 1999, W. May (NIST-USA)

11 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching Importance of Measurements  economic  political  social  environmental  scientific

12 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching Unreliable Measurements Lead to:  duplication of measurements  use of extra resources  lack of trust  negative economic impact  disasters/accidents

13 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching Metrology Users  industry (e.g. manufacturing)  commerce (e.g. disputes)  governments (e.g law implementation)  health and safety  environment protection  science / research  military services (e.g. navigation)  communications

14 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching … Lack of Standard … King’s foot

15 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching … Lack of Standard … Variations of One Unit of Length (Ell)  The “ell”, a unit originating from the custom of measuring cloth using one’s forearms, existed in many countries.  In order to make trade possible at all in these days, conversion tables were used. Source:Footprint of the Meter, NMi Communicabus, 1999

16 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching … Lack of Standard … countryell(m) England1.14 Scotland0.94 Germany0.6 Russia0.5 cityell(m) Vienna(A)0.78 Bruges (B)0.70 Amsterdam (NL)0.69 Source:Footprint of the Meter, NMi Communicabus, 1999

17 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching Meter Convention  diplomatic treaty  20th May 1875, in Paris  SI system  51 signatory countries  6 associate members

18 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching Meter Convention  international uniformity in measurement  common system of units  equivalent measurement standards  harmonised laws and regulations  mutual recognition of measurements aims

19 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching SI International System of Units

20 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching SI Base Quantities quantityunitsymbol  lengthmetrem  masskilogramkg  timeseconds  electric currentampereA  thermodynamic temperaturekelvinK  amount of substancemolemol  luminous intensitycandelacd

21 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching SI Derived Quantities quantityunitsymbol  speed, velocitymetre per secondm/s  densitykilogram per cubic metrekg/m 3  concentrationmole per cubic metremol/m 3 (of amount of substance) examples

22 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching Chemistry in SI  amount of substance (AoS)  agreed on 1971  Mole (mol) it is quite new !

23 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching Length corresponding to X number of wavelengths of an I 2 stabilized laser tape measure calibration 1 calibration 2 value Traceability of Length Measurements

24 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching analytical measurements need to be comparable in time and space traceability is the best way to achieve this

25 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching SI unit for amount of substance value amount content of X compound in solution Working Standard Reference Standard Traceability of Chemical Measurements

26 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching Problems...  absence of reference standards  absence of links to common basis  appropriate use of standards by laboratories  appropriate use of uncertainty

27 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching Traceability - Definition Traceability is defined as the property of the result of a measurement or the value of a standard whereby it can be related to stated references, usually national or international standards, through an unbroken chain of comparisons all having stated uncertainties. Source: International Vocabulary of Basic and General Terms in Metrology (ISO, 1993)

28 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching

29 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching Stated References  determination of amount of substance requires measurements of different properties  sample massmass reference  analyte identityDB of known compounds  analyte quantitationreference material

30 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching Stated Uncertainty  interval around the measurement result  uncertanty budget including:  uncertainties carried by the references  uncertainties introduced by the measurement process

31 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching Questions ?  Is the upper limit or lower limit of an uncertainty statement close to a legal limit, or does it reach beyond such a limit?  How much overlap is there between the uncertainty statement of similar measurements on the same or similar samples?  Do the uncertainty statements of measurements from different labs on the same sample overlap?

32 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching Stated Uncertainty  it is less important to have a particularly small uncertainty,  but more pertinent to have a good estimate of the uncertainty for answering such questions

33 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching Stated Uncertainty usually the contribution of the uncertainties carried by the references to the total uncertainty is small relative the contributions that originate from the measurement process

34 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching  in such cases results can be improved (in terms of uncertainty) only if measurement process is improved  thus, chemists are urged to concentrate on the measurement process they operate, which involves a thorough validation leading to valid results including a realistic uncertainty statement

35 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching Reference Materials  values carried by reference materials should be traceable to other references  the same features which are valid for the analytical laboratories are also valid for the reference materials producers

36 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching More Information       

37 Papadakis, I.: Metrology in Chemistry and Traceability © Springer-Verlag Berlin Heidelberg 2003 In: Wenclawiak, Koch, Hadjicostas (eds.) Quality Assurance in Analytical Chemistry – Training and Teaching Things to Remember  metrology in chemistry is still “young”  there is a lot to learn  traceability is not an aim by itself but it helps achieving reliable results  traceability can only be claimed if uncertainty statement includes all the uncertainties from references and the measurement procedure


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