An Introduction to Quality Assurance in Analytical Science Dr Irene Mueller-Harvey Mr Richard Baker Mr Brian Woodget

Part 4 - Regulation and Accreditation Contents: Accreditation (slide 3,4) ISO 17025 (slides 5-7) Inter-laboratory proficiency testing (slides 8-11) Evaluating analytical quality (slides 12-13) The presentation contains some animation which will be activated automatically (no more than a 2 second delay), by mouse click or by use of the ‘page down’ key on your keyboard.

Accreditation Accreditation is defined as: Formal recognition that Certificate Accreditation is defined as: Formal recognition that a testing laboratory is competent to carry out specific tests

Accreditation – which standard? A number of universally recognised Accreditation systems ISO 9000 applicable mostly to manufacturing & services - emphasis on records and customer service Good laboratory (GLP) and good manufacturing practice (GMP) recognised for pharmaceutical and clinical measurements - emphasis on records, procedures, reproducibility ISO 17025 used by analytical laboratories for work outside the health sector - emphasis on valid data, traceability, comparisons and data recognition in a court of law

ISO 17025 Accreditation Main features of accreditation Guarantee to customers: work to agreed standards Laboratory: independent & stringent assessment Agreed & specified methods used All measurements traceable to national & international standards

ISO 17025 Accreditation How do you become accredited? 1 Install a quality system in the laboratory that complies with the ISO 17025 requirements; 2 Decide on the schedule of tests that are to be accredited 3 Apply to the United Kingdom Accreditation Service (UKAS); 4 Have a ‘Pre-assessment’ visit from the UKAS assessors; 5 Have a formal Assessment visit from UKAS; 6 Clear any non-compliances they find; 7 Become Accredited for the chosen schedule of tests

ISO 17025 Accreditation How do you remain accredited? pay an annual subscription perform satisfactorily in inter-laboratory proficiency tests undergo and pass regular horizontal and vertical audits Mostly concerned with the overall quality management system Will trace sample paths from initial acceptance to final report

Inter-laboratory Proficiency Tests Many laboratory tests are used for international or national standard and regulations, for example: food labelling, water quality, animal feeds, pesticide residues. The authorised laboratories must show that their results are comparable with others doing the same tests.

Participation in proficiency testing schemes offer the Proficiency Schemes (1) Participation in proficiency testing schemes offer the following benefits: Show labs how well they compare with others; Help them to reduce the overall variability in testing; Give the regulatory authorities and consumers confidence that their quality criteria are meaningful

Organisers of such schemes must Proficiency testing (2) Organisers of such schemes must ensure that: all participating labs receive identical samples; a ‘true’ value is assigned for the result of a test (for example it may be the mean of all participants’ results); participants do not know the ‘true’ result before they do the test.

Proficiency testing (3) From the results submitted by the participating laboratories, the organisers can: rank the laboratory’s performance by calculating its “z-score”; identify the laboratories that can produce acceptable results for the test; show divergent laboratories how they need to improve their performance of the test.

Calculation of ‘z’ scores A laboratory’s z-score is calculated from: -10 -8 -6 -4 -2 2 4 6 8 10 1 Laboratory identity number z-score A laboratory’s z-score is calculated from: [(x - X)/SD] x = the lab result X = the true or accepted result SD = target value for the standard deviation The graph above shows the ‘z’ scores obtained by 120 laboratories who participated in a particular proficiency testing scheme The best performing laboratories have ‘z’ values close to zero. The acceptable range is +2 to -2

Variation of CV with analyte level We can expect a CV to be: approx. 5% at a 1g/l level and approx. 15% at a 0.001g/l level +60 +50 +40 · +30 Coefficient of variation (CV) or relative standard deviation (RSD) [ % ] +20 · · · · +10 · · · · -10 -20 -30 · -40 -50 -60 10% 0.1% 1 ppm 1 ppb 10-1 10-3 10-6 10-9 Concentration