C30J_Topic_3_Internal_Quality_Control

C30J_Topic_3_Internal_Quality_Control - Topic 3: Internal...

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Topic 3: Internal Quality Control (ICQ) in Analytical chemistry laboratories. Pure and Applied Chemistry, 67(4), 649-666, 1995. ICQ is the routine practical procedures that enable the Laboratory to accept results as “fit for purpose”. Achieve IQC by analysing reference materials and duplicates during an analytical run. Analytical “run” includes test materials, reference materials, duplicates, blanks, randomly ordered, and done over a period of time during which there are constant systematic errors (hopefully = 0) and consistent random errors. Reference (control) materials must be representative of the test materials – analyte concentrations, matrix composition, physical states. - reasonable to assume that if the results are good for the reference materials then they are also good for test materials. - reference materials must be traceable, either directly of indirectly, to certified reference materials or a recognized empirical reference method. End 6 2009 {empirical - provable or verifiable by experience or experiment}
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Topic 3: Internal Quality Control ICQ) in Analytical chemistry laboratories cont. Analysts must recognize the “standard of accuracy” required for the effective use of the data. Accuracy cannot be quatified. - accuracy : the closeness of the result of a measurement to a true value of the measurand. To use a result for a decision the precision must be stated. Definitions: Quality Assurance – “All those planned and systematic actions necessary to provide adequate confidence that a product or service will satisfy given requirements for quality”. Bias: the difference between the expectation of the test results and an accepted reference value. eg (x i - µ) in the t-test for determining the number of samples to be taken. Error: result of a measurement minus the true value. Trueness: closeness of the agreement of a population average and the accepted reference value. Traceability : “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”. .
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Internal Quality Control is part of the Quality Management System ISO 9001 + ISO 17025 Report (x ± 2s) units Samples & Information Methods Quality Assurance Programme Document the Quality : Document procedures and activities. Conduct Quality Control analyses and activities. Store data appropriately. Monitor quality control results. Organizational infrastructure – training, lab environment, safety, documented appropriate analytical methods, sample ID and integrity, reagents, purchasing, maintaining and calibrating equipment, …
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Internal Quality Control in Practice: based on the use of reference (control) materials to monitor trueness and duplicates to monitor precision and that the analytical process is under “statistical control”.
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This note was uploaded on 02/23/2011 for the course CHEMISTRY C30J taught by Professor Vaugnrattray during the Spring '11 term at University of the West Indies at Mona.

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C30J_Topic_3_Internal_Quality_Control - Topic 3: Internal...

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