•
Number of potential synthetic PDE5 inhibitors:
–
more than 100 known analogs
Analytical Challenges
–
more than 50 analogs reported as adulterants
•
Availability of reference standards
•
Inventiveness of adulterators:
–
exotic analogs
i
f
l
–
m xtures o ana ogs
–
embedding of adulterants into capsule walls
•
Complex and variable dietary supplement matrices
Fitness for Purpose
(1) Screening Method
(2) Identification/Determination Method
