Abstract: A pipetting device for use with a pipette tip containing a solid phase reaction support, comprising a cylinder, a plunger movable within the cylinder between a retracted and an extended position, and a seal disposed between the plunger and cylinder for holding the plunger as it moves. The plunger has a central passageway within an upper portion of the plunger communicating with a side egress port on the plunger, the plunger movable between a retracted position, for aspirating and dispensing liquid reagent wherein the port remains above the seal, and an inserted position wherein the port is positioned below the seal for allowing fluid (e.g., washing solution or inert gas) to be introduced into the cylinder and tip. In an apparatus and method, an array of such devices is used, each fitted with a pipette tip having a solid support retained therein, for performing high-throughput and parallel chemical synthesis of biopolymers (e.g., oligonucleotides or peptides).