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QUALITY CONTROL REPORT <br />METHOD BLANK RESULTS: A method blank (MB) is a laboratory generated sample fre <br />of any contamination. The method blank assesses the degree to which th <br />laboratory operations ��nd procedures cause false -positive analytical results fo <br />your samples. The method blank results associated with your samples ai <br />attached. <br />LABORATORY CONTROL SPIKES <br />The LCS Program: <br />The laboratory c)ntrol spike is a well characterized matrix (organic pur <br />type II for water samples and contamination free sand for soil samples <br />which is spiked •with certain target parameters and analy^ed in duplicat <br />at approximately 10% of the sample load in order to assure the accurac <br />and precision o1 the analytical method. The results of the laborator <br />control spike associated with your samples are attached. <br />Accuracy is measured using percent recovery, i.e.: <br />(measured concentration) <br />Percent R.?covery --------------••---------- x 100 <br />(actual concentration) <br />Precision is me. sured using th,? relative percent difference (RPD) fro: <br />duplicate tests, i.e.: <br />% Recovery of Spike0) - % Recovery of Spike (2) <br />RPU------------------------------------------•---------- x 100 <br />($ Recovery of Spike(1) + % Recovery of Spike(2) )/2 <br />'Control limits 'or accuracy and precision are different for differev. <br />methods. They m:y also vary with the different sample matrices. They ar <br />based on labora.ory average historical data and EPA limits which ar <br />approved by tha Quality Assurance Department. McLaren Analytical <br />Laboratory rean;:.lyzes samples it the precision or accuracy is ou'. c <br />acceptance control limits. <br />- <br />McLaren <br />(DC3-CN2565A <br />