An apparatus and method for injection of one or more chemical components into a reaction chamber are disclosed. The apparatus includes a reaction chamber for receiving one or more libraries (26) in a fixed position relative to the chamber and configured to form a sealed enclosure. An injection manifold (28) is located within the reaction chamber and selectively movable relative to the libraries (26). The injection manifold (28) is configured for receiving at least one fluid transfer line coupled to an external source for injection of one or more chemical components into the reaction chamber.