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1 <br /> o An Systems <br /> 1 The atonic absorption systems are calibrated daily by an <br /> i <br /> external standard calibration process . Specific nethods may <br /> t impose variations and/or different acceptance criteria upon this <br /> calibration. These specific requirements are found in the <br /> CNrMUCST SRP covering the particular method in question . <br /> 1 o Daily External Standard Calibration Procedure: <br /> ror each anaivte. or group of analytes, to be analyzed, <br /> Initial calibration standards„ at three to four different <br /> concentrations, are prepared by adding aliquots of one or more <br /> stock standards to uolunetric flasks and diluting to volume <br />» with an appropriate solvent. One of the standards should be <br /> at concentrations near the detection limits of the method . <br /> Continuing calibration standards, containing the same <br /> analyte(s) as the calibration standards, are prepared in the <br /> same manner, but at approximately the mid-point of the <br /> w calibration standard concentration ranges . <br /> Each of the appropriate Initial calibration standards, <br /> followed by an appropriate blank solution, are introduced into <br /> the !1A system in replicate using the technique used for the <br /> introduction of actual samples. The nn system calculates a <br /> set of response factors based on the syten response to both <br /> the standards and blank, and displays the results as a <br /> calibration curve . This is followed by replicate introductions <br /> of the appropriate continuing calibration standard . The <br /> continuing calibration standard is analyzed after every ten <br /> samples . <br /> r <br /> o Acceptability of system generated calibration curves <br /> is made by visual inspection of the curves . <br /> o If the curves are judged unacceptable, the <br /> calibration standards are reanalyzed . <br /> 1 <br /> o Results from the replicates of each sample or standard <br /> must have a percent relative standard deviation (XRS0) <br /> less than or equal to 2OX. <br /> o If this criteria is not net, the sample or <br /> 1 standard analysis i+ust be repeated . <br /> o Results from the continuing calibration standards must <br /> fall within F/- 13% of the expected value . <br /> o It this criteria is not net, the standard <br /> 1� analysis must be repeated . <br /> o If the standard still does not meet the criteria, <br /> the entire standardization procedure is repeated . <br /> 22 <br /> 1 <br />