A lab-on-valve analytical system includes a rotary sample preparation assembly having a stator and a rotor. The rotor includes a plurality of integral syringe pumps which can be aligned with passages formed within the stator. The stator passages can be connected with fluid inlet connector which connect the sample preparation assembly with fluid sources, and fluid outlet connectors which connect the sample preparation assembly with one or more wet chemical analytical devices. Some embodiments can include a mixer and optical sensor connected with the fluid outlets. One or more drive motors can be used to control simultaneous actuation of one or more of the syringe pumps, thereby providing for simultaneous delivery of metered volumes of fluid.