10.6 Daily Calibration
10.6.1 Summary. Prior to the analysis of samples and blanks but after tuning criteria have been met, the
initial calibration of each GC/MS system must be routinely checked by analyzing a daily calibration standard to
ensure that the instrument continues to remain under control. The daily calibration standard, which is the nominal
10 ppbv level calibration standard, should contain all the target compounds.
10.6.2 Frequency. A check of the calibration curve must be performed once every 24 hours on a GC/MS
system that has met the tuning criteria. The daily calibration sequence starts with the injection of the BFB. If
the BFB analysis meets the ion abundance criteria for BFB, then a daily calibration standard may be analyzed.
10.6.3 Procedure. The mid-level calibration standard (10 ppbv) is analyzed in a GC/MS system that has
met the tuning and mass calibration criteria following the same procedure in Section 10.5.
10.6.4 Calculations. Perform the following calculations.
[Note: As indicated earlier, the area response of the primary quantitation ion is used unless otherwise
stated.]
10.6.4.1 Relative Response Factor (RRF). Calculate a relative response factor (RRF) for each target
compound using the equation in Section 10.5.4.1.
10.6.4.2 Percent Difference (%D). Calculate the percent difference in the RRF of the daily RRF
(24-hour) compared to the mean RRF in the most recent initial calibration. Calculate the %D for each target
compound using the following equation:
where: RRF = RRF of the compound in the continuing calibration standard. c
= Mean RRF of the compound in the most recent initial calibration.
10.6.5 Technical Acceptance Criteria. The daily calibration standard must be analyzed at the
concentration level and frequency described in this Section 10.6 and on a GC/MS system meeting the BFB
instrument performance check criteria (see Section 10.4).
The %D for each target compound in a daily calibration sequence must be within ±30 percent in order to proceed
with the analysis of samples and blanks. A control chart showing %D values should be maintained.
10.6.6 Corrective Action. If the daily calibration technical acceptance criteria are not met, inspect the
system for problems. It may be necessary to clean the ion source, change the column, or take other corrective
actions to meet the daily calibration technical acceptance criteria.
Daily calibration acceptance criteria must be met before any field samples, performance evaluation (PE) samples,
or blanks are analyzed. If the % D criteria are not met, it will be necessary to rerun the daily calibration sample.