This UHPLC system works within a large range of pressures (up to 19,000 psi) and flow rates for applications that utilize particle-sized 2, 5, and 10um columns and packing materials that are the new sub-2um. A new and different need has developed with the modern advances in porous and pellicular shell packing materials since they have bigger sized particles and can work at higher flow rates with maximum efficiency. This X-LC-3000 is also efficient working with porous shell columns. A need for flow rates that are lower, from 250-750uL/min, has been created because UHPLC columns that are Fast and Responsive Gradients with sub 2um packing materials usually are designed as shorter, narrower columns (2.1mm ID x 50mm L) in contrast to more conventional analytical columns that are 4.6mm ID x 250mm L). Gradient formation and accuracy of pump metering is essential at lower flow rates to ensure quick, reproducible separations.