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KIRTLAND AIR FORCE BASE ALBUQUERQUE, NEW MEXICO ...

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APPENDIX C<br />

analyzed with each sample batch. The method blank sample is carried through the complete<br />

sample preparation and analytical procedure. The method blank is used to document<br />

contamination resulting from the analytical process. For a method blank to be acceptable for<br />

use with the accompanying samples, the concentration in the blank of any analyte of concern<br />

should not be higher than the highest of either:<br />

― The method detection limit, or<br />

― Five percent of the regulatory limit for that analyte, or<br />

― Five percent of the measured concentration in the sample.<br />

Calibration Blanks—Calibration blanks are prepared with standards to create a calibration<br />

curve. They differ from the other standards only by the absence of analyte and provide the<br />

"zero-point" for the curve. A linear regression is established with a point at the origin. This is<br />

associated with an initial calibration.<br />

Internal Standards—Internal standards are measured amounts of certain compounds added<br />

after sample preparation or extraction. They are used in an internal standard calibration method<br />

to correct sample results suffering from capillary column injection losses, purging losses, or<br />

viscosity effects. Internal standard calibration is currently used for volatile and semivolatile<br />

organic extractables by GC/MS.<br />

Surrogates—Surrogates are measured amounts of certain compounds added before sample<br />

preparation or extraction for organic analyses. The amount spiked is dependent on the method<br />

of analysis. The recovery of a surrogate is measured to determine systematic extraction<br />

problems. Surrogates are added to all samples analyzed for chlorinated pesticides, GC/MS<br />

extractables, herbicides, explosives, petroleum hydrocarbons, and VOCs.<br />

Matrix Spikes—Matrix spikes are aliquots of samples to which known amounts of analyte have<br />

been added. They are subjected to the same sample preparation or extraction procedure and<br />

analyzed as samples. The amount of spike added will be as specified in the analytical method.<br />

Spikes are prepared and analyzed at a frequency of at least 1 per 20 project samples. The<br />

percent spike recovery measures sample matrix interference effects, and reflects the accuracy of<br />

the determination. Percent spike recoveries are calculated as follows:<br />

%REC =<br />

SR -USR<br />

SA<br />

x 100<br />

where,<br />

SR = the observed analyte concentration in the spiked sample<br />

USR = the analyte concentration in the original sample<br />

SA = the analyte concentration added to the spiked sample<br />

Duplicates and Matrix Spike Duplicates—Duplicates are additional aliquots of samples<br />

subjected to the same preparation and analytical scheme as the original sample. In cases<br />

where a stable, reproducible standard is available, matrix spike duplicates are substituted for<br />

duplicates. Duplicates (or matrix spike duplicates) are prepared and analyzed on a daily<br />

Kirtland AFB<br />

Quality Assurance Project Plan C-44 April 2004

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