The ‘moving-injection technique,’ based on an electrically actuated HPLC valve, injects very small samples (ca. 0.008 μl) directly onto HPLC columns. The injected samples have lower than usual injector variance contribution because laminar flow sample dilution with the mobile phase is eliminated. This technique can also be used to control the size of sample injection. Samples of 6- to 100-μl size can be injected from a single 100-μl loop when a data system is used to control the electric valve actuator.