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10.2.5 Establishment of Acceptance limits <br />Accuracy <br />Secti c. r. 14 c, . <br />Revie. ion Nc, <br />tete. <br />Page 4. C <br />for Precision and <br />Multi -Tech uses the formulas presented in Standard Methocs and <br />tree U.S. EPA :uaIity Assurance handbooi for calculeticn.s cf <br />precis c and accuracy. <br />Pcr every bete^ :f samples analyzed, a `e-•escf nr-a,.,P;`z a - e <br />analyzed in cor•unct.ion to access the precision, accuracy, and <br />validity of analysis. These data are reviewed by laboratory <br />anal ytical rerzc-nell , supervisors, the Anal yti cel Cil rector , and <br />the Quality Assu-ence Officer before release to the client. <br />For estimate of accuracy both spiked blank samples and rr.etrix <br />spike sample-ecOveries ere evaluated, allowing for the <br />cetermination of doth accuracy of method er:d ectuel serrmple :etch <br />accuracy. Precis`cn is measured and monitored using ranee control <br />for duplicate ceirs and rel etive percent difference. the <br />following formulas and protocols are used to calculate precision <br />and accuracy data, and subsequently to establish QC limits. Once <br />QC limits are established for each analysis (based on tate <br />veneration), res -Its should be within a two standard deviation <br />range for both precision and accuracy in order to qualify as <br />credible and therefore acceptable data. QC limits are updated <br />after every twentieth QC result recorded, if possible. Results <br />which do not fail within the two standard deviation range ere <br />further examined to determine whether corrective action is <br />necessary (e.g. the sample matrix does not fit the data base <br />matrix). Results which fail outside a three standard deviation <br />range require corrective action and are not used in the <br />calculation of the next set of QC limits. For corrective action <br />procedures, the client is referred to Section 10.4 of this <br />document. <br />