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w i • Each of the calibration standards is introduced into the Gcros system using the technique to be used for introduction of actual samples Cie . 2- to S-ul liquid injections, purge r a trap, etc _) . R serxea of Calibration Factors CCF•s) is calculated for each analyte, at each standard concentration, for the mass peak of interest that is specific for that analyte. amount introduced 1 o The Cr - ------------------ (for multiresponse total response ' compounds use the total area of all peaks used for quantitation) . o If the percent relative standard deviation (XRSO) 1 between the CF`s is less than 2SX ower the working range, linearity through the origin can be assumed and an average CF can be used for quantitation. a If this criteria is not net, the standard analyses must be repeated if quantitation is to be performed . 1 The working average Calibration factor must be verified an each working day by the introduction of one or more calibration standards . The frequency of verification is method specific, and varies from once per day to an average of once every f i ue samples . a If the response of any analyte varies from the predicted response by more than +!- 20x, a new calibration curve must be prepared for that analyte . CRl -R2? - -------- x 100 a The Percent Difference e where R1 R1 the cF from the first analysis, and R2 - the CF from the second analysis . o Internal Standard Calibration Procedures For each analyte, or group of analytes, five concentration levels of standards are prepared by adding aliquots of one or more stock standards to volumetric flasks . In addition, a known and constant amount of one or more internal standards (IS•s)is added to each volumetric flask and they erethen diluted to volume with an appropriate esoluent. One of the standards should be at a concentration near the method detectian limit. The other concentrations should define the working range of the system. 1• 16