How do you extract imiquimod from blood?

You can extract imiquimod from blood using Strata X-C. Imiquimod contains several basic sites (pKa 5.86 and 2.92). Although a reversed phase sorbent such as C18 or Strata X can be used for its extraction, a cation exchange sorbent will provide higher selectivity, allowing a much stronger wash to eliminate matrix interferences more effectively. The general Strata X-C protocol is a great starting point.  As for sample pretreatment, dilute 500 uL of whole blood sample with 3 parts of MeCN containing 1% formic acid. Vortex and centrifuge. Collect supernatant and dilute with equal amount of DI water for SPE loading.  Please collect and analyze load and wash fractions from the SPE method to monitor analyte movement throughout the method. The method can be further optimized based on initial results.