Developed to feed fuming nitric acid to continuous-flow synthesis reactors, the DS-1a pump features two independently-driven syringes, each with its own distribution valve. The syringes can be controlled independently to allow the pump to deliver two different fluids, or can be slaved together and driven 180° out of phase to enable continuous, pulseless flow. With standard 5 ml syringes, the DS-1a is capable of delivering flow rates from <50 µL/min to 15 ml/min. Extremely high resolution stepper motor drive (65535 steps/stroke) enables flow rates to be controlled to better than 0.1% for flows above 0.1 ml/min. The pump connects to a computer with a standard USB-A cable. The DS-1a software allows computer control from either a stand-alone Windows application or using the provided LabVIEW libraries. All wetted parts are either glass, PTFE or PCTFE. The fluid ports use 1/4-28 flangeless chromatography fittings and 1/8 inch OD PFA or FEP tubing (provided). The pump is exceptionally compact (115 x 190 x 200 mm) and takes up minimal space in your chemical hood. Optional accessories include 1 mL and 12.5 mL syringes, which extend the operating flow rate ranges for the pumps.