Figure 4From: A selective pretreatment method for determination of endogenous active brassinosteroids in plant tissues: double layered solid phase extraction combined with boronate affinity polymer monolith microextractionOptimization of sampling conditions. (A) Effect of pH on the BR extraction efficiencies. (B) Effect of acetonitrile content in sampling solution on the BR extraction efficiencies. (C) Effect of sampling flow rate on the BR extraction efficiencies. The sampling solution was spiked with five BRs standard solution (4 ng for each BR).Back to article page