Abstract: A valve assembly is disclosed which effectively partitions a syringe into proximal and distal chambers to provide a multi-chamber, sequentially dispensing syringe apparatus. The valve assembly may be effectively used with a variety of standard, currently available commercial syringes and pre-filled syringes. Incorporated in the valve assembly is a valved stopper having a valve (which may be a slit valve), an impact sensor which opens the valve upon impact between the valve assembly and internal distal end of the syringe and a gas separator which separates liquid from gas disposed in the proximal chamber to assure gas is not delivered therefrom. The valve assembly is displaced as a plunger of the syringe is displaced via communication through fluid in the proximal chamber of the syringe. The actuator has a latching feature which latches the valve to an open state after being opened by the impact sensor. The gas separator has a proximally disposed orifice which facilitates priming.