I am attempting to determine the amount of chrysene (228.3 g/mol) contained in a creosote-coated lumber sample. A 1.03 part per trillion chrysene standard gave a peak area of 349.0 fluorescence units*s by HPLC. I extract a 1.995 g portion of the wood sample with 50.0 mL of toluene. A 500 uL portion of extract was diluted to 5.00 mL and analyzed using the same method as the standard. The chrysene peak in the dilute extract gave a peak area of 2560 fluorescence units*s.

Is this internal or external calibration?

What is the concentration of chrysene in the unknown sample (ppb w/w)?