The Estimation of Uncertainty by the Utilization of Validation and Quality Control Data; Lead in Gasoline by AAS

摘要

This protocol was developed to estimate the uncertainty of measurement of a chemical analysis by utilizing in-house validation studies and quality control data. The approach was to generate an estimate of the uncertainty across the analytical concentracion range. This was to be expressed as a mathematical equation or factor that could be inserted into a Laboratory Information Management System (LIMS) and thus produce an uncertainty estimate from an entered analytical result.The aim is to identify as many sources of uncertainty as possible and account for them by appropriatte precision and trueness studies. Any additional sources of uncertainty are evaluated by other means such as calibration certificates, published dana, etc.. It is not necessary to evaluate every source of uncertainty if they are deemed insignificant, unless there are a large number of them. Uncertainty components that are less than one third of the largest component are not evaluated in detail. A preliminary estimate of the contribution of each component or combination of components to the uncertainty is made and those that are not significant eliminated . The uncertainty contributions is expressed as standard deviation, and combined according to the appropriate rules, to give a combined standard uncertainty. Coverage factor ( 2 for normal distribution) is applied to give an expanded uncertainty.