Lecture 7 Analytical Quality Control

1. IAEA Regional Training Course Sediment Core Dating Techniques - RAF/7/008 Project CNESTEN, Rabat, 05-09 July 2010 CNESTEN IAEA Lecture 7Analytical Quality Control Moncef Benmansour CNESTEN, Morocco

2. Content • Quality Assurance and Quality Control • Reliabilty of the Results • Internal programme • External programme • Examples

3. QA and QC • Quality (ISO) • The totality of features and characteristics of a product, process or service that bear on its ability to satisfy stated or implied needs • Quality assurance (ISO): • All those planned and systematic actions necessary to provide adequate confidence that a product, process or service will satisfy given quality requirements

4. QA and QC • Quality Control (ISO): • The Operational technique and activities that are used to satisfy quality requirement • The overall system of activities whose purpose is to control the quality of a product or service so that it meets the needs of users. The aim is to provide quality that is satisfactory, adequate, dependable and economic. It represents the mechanism established to control errors.

5. QA and QC • Good Quality control • Use of Reliable qualified personnel and well-maintained instrumentation • Use of appropriate standards for calibration • Use of Certified Reference Materiel or Reference Material • Analyses of blind and blank samples • Use of Control Chart

6. Terminology QA and QC: Basis • Quality assessment • The overall system whose purpose is to provide assurance that the quality control activities are being done effectively. It is a form of control in which intra-laboratory and inter-laboratory testing programs ply a major role • Good Laboratory Practices • GLP describes how a laboratory should work, how it should be organised and how it can produce valid data

7. Terminology QA and QC: Basis • Major items in a quality assessment programme • Facilities, organisation and personnel, • Equipment, consumables, chemicals, • Documentation • Sampling and storage • Laboratory analysis • Final results • Quality assessment

8. Reliabilty of the Results • Precision : Reproducibility • Precision refers to the repeatability of measurement. It does not require us to know the correct or true value • Accuracy : True Value • Accuracy refers to the agreement of the measurement and the true value

9. Reliabilty of the Results

10. Reliabilty of the Results • Uncertainty: • Uncertainty of a measured value is an interval around that value such that any repetition of the measurement will produce a new result that lies within this interval. This uncertainty interval is assigned by the experimenter following established principles of uncertainty estimation • Errors: • Error refers to the disagreement between a measurement and the true or accepted value

11. Internal Programme: Precision • Equipment performances • Stability of background • Stability of efficiency and energy resolution • All sources of uncertainties • Counting measurements • Standard sources • Physical and chemical preparation • Calibration • Correction factors • Analytical control of Samples • Internal standards: High and low activities • Blanks

12. Internal Programme: Precision • Use of control chart: • Graphical way to interpret test data and to monitor the measurement process or the status of an instrument • X Chart  • Single measurements : X • Mean value : Xmean • Upper Control Limit : UCL • Lower Control Limit LCL • Upper Warning Limit : UWL • Lower Warning Limit : LWL

13. Use of control chart:

14. Control Chart: FWHM ( keV)- Energy Resolution -

15. Control Chart: Efficiency: 662 keV

16. External Programme: Accuracy • Certified Reference Material • Intercomparison exercise ( IAEA/MEL) • Proficiency test ( IAEA/RMG)

17. Certified Reference Material

18. Interlaboratory test • The goal is to demonstrate that participating to intercomparison exercise and proficiency tests leads to improved quality of analytical results. • The result are of crucial interest for laboratories as these provide clear information of its measurement capabilities. • It would be pointed out that the participation is either voluntary or forced by external requirements (e.g. legal, accreditation, control bodies

19. External Programme: Accuracy • Intercomparison exercise: MEL/IAEA • Scope of the Intercomparison • Description of the material • Homogeinisation and Tests • Sample Dispatching and Data return • Evaluation of the results

20. Intercomparison exercice (IAEA/MEL): Example of 137Cs

21. Intercomparison exercice (IAEA/MEL): Example of 239, 240Pu

22. Intercomparison exercice (IAEA/MEL): Z score: value acceptable if I z I≤ 2

23. Proficiency test : IAEA Reference material group - Seibersdorf • Introduction: Obejective • Material and methods • Performance criteria

24. Proficiency test : IAEA Reference material group - Seibersdorf • Trueness and Precision • A: Acceptable • N: Not Acceptable • W: Warning

25. Proficiency test : IAEA Reference material group - Seibersdorf • Trueness

26. Proficiency test : IAEA Reference material group - Seibersdorf • Precision P ≤ LAP: Limit of Acceptable Precision

27. Proficiency test : IAEA Reference material group - Seibersdorf • Z score s

28. Proficiency test : IAEA Reference material group - Seibersdorf

29. Example: IAEA/PT, Analyse of 137Cs and 210Pb in soil sample

30. Example: IAEA/PT, Analyse of 137Cs and 210Pb in soil sample

31. Example: IAEA/PT, Analyse of 137Cs and 210Pb in soil sample

32. Example: IAEA/PT, Analyse of 137Cs and 210Pb in soil sample

33. Example: IAEA/PT, Analyse of 137Cs and 210Pb in soil sample • Source of errors