ARCHIVED REPORTS_1996_2 - Laserfiche WebLink

Home Browse Search

FS Section No: 8 Page: 3 of 5 Revision No: 2.0 Date: January 15, 1994 8.3.6 Selection of Calibration Levels Two standards should be included per order of magnitude of concentration of the calibration curve. For example 0.1, 1.0, 10.0 has 2 standards per order magnitude (0.1 and 1.0? 1.0 and 10.0). In cases where instrumentation spans several orders of magnitude, the SOP for that method may not require this policy. 1 1:: I .. 11. 1 ..1 1 ill ` i4a1 . t JI. 4 1 11 li. 1 f i 1 4, 1 .: 1 WA L141,1 1. i 1: 1 .' 8.3.7 Calibration Analysis Sequence The calibration must progress from the analysis of the lowest to highest standard unless the instrumentation does not permit it. A blank must be analyzed after the highest calibration standard. If the analysis requires an initial high standard to set the gain, a blank must be run before starting with the low calibration standard unless the instrumentation does not permit it. 8.3.8 Calibration Acceptance Criteria In general, for inorganics, the calculated value for standards must be wit 10% of the expected value. However, the value determined by the calibration curve for the lowest standard must be wit +/- 50% of the true value and if the calibration is linear through the ori (at less than +/- 1/2 the detection limit). For organics, if a linear regression is used, a single average response factor may be used. The percent relative standard deviation for the individual response factors must be less than the ( maximum value listed for the method in the SOP. 8.3.9 Calibration Check Compounds (CCC) and Initial Calibration Verifications (ICV°s) The CCC or ICV is used to check the validity of the initial calibration. This standard is composed of some or all of the same analytes used for calibration but from a different source than the calibration standard. The standard should be at a concentration near the midpoint of the curve. In many cases FGL uses a Laboratory Control Sample (LCS) as an ICV. In this case the LCS verifies both the calibration and sample preparation. FGL uses control charts for LCSIs and acceptance ranges for many analytes have been statistically derived. Please see table 5-1 for acceptance limits. If calculated acceptance criteria are not listed, the general acceptance range is +/-25% of the true value for organics and +/-10% for inorganics. 8.3.10 Continuing Calibration Verifications (CCV) The CCV is used to verify continuing calibration validity without having to completely restandardize the instrument. Refer to specific EPA methods or SOPS to determine whether this is required. The continuing calibration standard should be near the mid -point of the calibration curve. If calculated acceptance criteria are not listed, the general acceptance range is +/-25% of the true value for organics and +/-10% for inorganics.