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' Section 8 . ONSITE Environmental Laboratories, Inc Revision 0 ' Quality Assurance Plan February 15, 1996 Page I of 1 ' 8.0 CALIBRATION Two types of calibration are discussed in this section > Operational calibration is routinely performed as part of instrument usage, such as the ' development of a standard curve for use with an atomic absorption spectrophotometer Each specific operational calibration procedure is described the SOP for the test being performed and is summarized in Appendix E, Table I ' > Periodic calibration is performed at prescribed intervals for equipment which can be calibrated at routine intervals, such as balances, ovens, or equipment This equipment has a distinct, single purpose urut and which is relatively stable in performance The ' specific calibration process for each piece of equipment is described in the Maintenance Log for that item and is summarized in Appendix E, Table 2 ' 8 1 Standard Preparation Logs Standard Prep logs are maintained that indicate how and when a calibration or QC standard was prepared, the intermediate concentrations, and by whom The logs also allow traceability back to the primary standard used An example of a standard preparation log is attached as Appendix F 82 Initial Setting of Retention Time Windows for GC ' If major changes in the instrument have occurred or a test procedure has not been previously performed at ONSITE, the laboratory is required to establish retention time acceptability windows by making at least three injections of all single component ' standard mixtures over the course of a 72 hour period Serial injections over less than a 72 hour period may result in retention time windows that are too tight ' The acceptance windows are established by calculating the standard deviation of the retention times from the three injections for each single component standard Plus and minus three times the standard deviation of the absolute retention time for each ' standard is used to define the retention time window However, the experience of the analyst, in consultation with the Laboratory Director or the Quality Assurance Program Advisor, may weigh heavily in the interpretation of chromatograms and the setting of ' windows In those cases where the standard deviation for a particular standard is zero, the laboratory substitutes the standard deviation of a close eluung, strrular compound to develop a valid retention time window 1 Word 6 0 loelsec$doc