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

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

Quality assurance (ISO): 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

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.

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

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

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

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

Reliabilty of the Results

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

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

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

Use of control chart:

Control Chart: FWHM ( keV) - Energy Resolution -

Control Chart: Efficiency: 662 keV

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

Certified Reference Material

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

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

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

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

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

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

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

Proficiency test : IAEA Reference material group - Seibersdorf Trueness

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

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

Proficiency test : IAEA Reference material group - Seibersdorf

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

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

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

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

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