Method of metered switching for a high-performance liquid chromatography sample injector

A method of metered switching for a high-performance liquid chromatography sample injector, comprising:

• in a load mode of a high-performance liquid chromatography sample injector, injecting a sample into the high-performance liquid chromatography sample injector until a sample loop thereof is filled with the sample, wherein the sample loop is not in fluid communication with an outlet port of the high-performance liquid chromatography sample injector in the load mode;
• switching the high-performance liquid chromatography sample injector into an injection mode wherein, in the injection mode, the sample loop is in fluid communication with a source of pressurized mobile phase and with the outlet port such that the pressurized mobile phase pushes the sample through the sample loop and out of the outlet port;
• and
• switching the high-performance liquid chromatography sample injector back into the load mode at a selected time corresponding to a desired volume of the sample to be dispensed from the outlet port, wherein a time-dependent correspondence between a flow rate of the pressurized mobile phase and the desired volume of the sample for the sample loop is known.