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1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />ACZ Laboratories, Inc. August 10, 2007 <br />Quality Assurance Plan Version 12 <br />SOPAD018.08.07.12 Page 49 of 96 <br />12.2 Precision <br />Precision is defined as "the degree of mutual agreement characteristic of independent measurements as the <br />result of repeated application of the process under specified conditions." Matrix duplicates and spike <br />duplicates are analyzed with every batch of samples or as stipulated by the test SOP to determine the precision <br />associated with the analysis. If any method does not specify acceptance criteria for the RPD, then default <br />criteria of RPD < 20 is used (a value that rounds to 20 is acceptable). 5 The Relative Percent Difference <br />(RPD) as an absolute value is calculated as follows: <br />jRPD1 _ (S - D) x 100 Where: S =Sample Value <br />[(S + D) / 2] D = Duplicate Value <br />123 Other Calculations <br />• Solids Dilution Factor (assume 100% solid for "as received" samples): <br />Dilution Factor = V Where: V = Final digestate volume, in ml <br />(W)(% solid) W = Sample weight used, in g <br />%solid = %solid or air dry solid, as a decimal <br />• Sample Concentration for Solids: <br />? wet weight [biota tissue, fruit or vegetable matter, etc.]: mg/Kg = DF * C * V <br />W <br />? dry weight [plant matter, grasses, soil, sludge, etc.]: mg/Kg = SF * C * DF <br />Where: DF = instrument dilution factor <br />C = raw data value, in mg/L <br />V = Final volume of digestate, in L <br />W = sample weight used, in Kg <br />SF = soil dilution factor <br />• Percent Difference for Serial Dilution (SDL): <br />%Dj= I- (s 5)] x100 <br />I <br />Where: I = initial sample result <br />s = serial dilution result (raw data value) <br />For SDL calculations in LIMS, "s" is multiplied by 5 and the resulting "reg value" is compared <br />to the "found value" to calculate %D. <br />ADHS Information Update #87 (issued July 7, 2005) <br />2773 Downhill Drive 970-879-6590 <br />Steamboat Springs, CO 80487 www.acz.com