A 2 μL pump head, 1 mm external diameter plunger, and a pulse correction mechanism ensure the most reliable, accurate and stable solvent delivery at low μL/min flow rates. This results in a retention time and area value precision on par with conventional-scale HPLC. Recommended flow rate ranges are 0.2 to 200 μl/min for isocratic and 1.0 to 200 μl/min for gradient.