CALIBRATION AND QUALITY CONTROL:
8. Calibrate daily with at least six working standards covering the range of the samples.
a. Add known amounts of analyte or calibration stock solution to eluent in 10-mL volumetric
flasks and dilute to the mark.
b. Analyze together with samples and blanks (steps 11 and 12).
c. Prepare calibration graph (ratio of peak area of analyte to peak area of internal standard vs.
mg analyte).
9. Determine desorption efficiency (DE) at least once for each batch of charcoal used for sampling
in the calibration range (step 8). Prepare three tubes at each of five levels plus three media
blanks.
a. Remove and discard back sorbent section of a media blank sampler.
b. Inject a known amount of analyte or DE stock solution directly onto front sorbent section
with a microliter syringe.
c. Cap the tube. Allow to stand overnight.
d. Desorb (steps 5 through 7) and analyze together with working standards (steps 11 and 12).
e. Prepare a graph of DE vs. mg analyte recovered.
10. Analyze three quality control blind spikes and three analyst spikes to insure that the calibration
graph and DE graph are in control.