I try to develop a SPME extraction, but instead of using desorption (is not available into our laboratory), I use extraction in ethyl acetate.

To check if I have analytes extraction on the SPME fibers:

First, I put the SPME fibers into 100ppm standard solution. Then, the SPME fibers are insered in 2 mL of ethyl acetate. Then, I inject into GC-MS 1ul from the ethyl acetate solution with the analyte sample. (I have obtained chromatographic peaks)

Second: I spray 100ppm standard solution over a textile material. Then I put the SPME fiber in direct contact with the textile surface. Then, the SPME fibers are insered in 2 mL of ethyl acetate. Then, I inject into GC-MS 1ul from the ethyl acetate solution with the analyte sample. (I have obtained chromatographic peaks)

How do I calculate my recovery?

Thank you for your help!