Methods and apparatus for facilitating the synthesis of compounds in a batch device are presented. Application of the batch type microfluidic devices to the synthesis of radiolabeled compounds is described. These methods and apparatus enable the selective introduction of multiple reagents via an enhanced rotary flow distribution valve through a single inlet port of the synthetic device. The sequential introduction of multiple reagents through a single inlet port allows an optimal delivery of highly concentrated reagents into the reactor and facilitates the synthesis of the desired products with a minimal loss of materials during transfers, which is critical to the synthesis of radiolabeled biomarkers.