A sample injector configured to introduce a sample fluid into a mobile phase, wherein the mobile phase is to be driven by a mobile phase drive through a separation unit for separating compounds of the sample fluid in the mobile phase, the sample injector comprising: at least a portion of an analysis path between the mobile phase drive and the separation unit, said portion of an analysis path being suitable for transporting fluids at high pressure; a metering device being operable for intaking a metered amount of the sample fluid into the sample injector; an injection needle drivable for immersing into the sample fluid; and a sample loop in fluid communication with the injection needle for accommodating the sample fluid upon being intaken by the metering device via the injection needle; a fluidic valve being switchable for operating the sample injector selectively in: a flushing mode (600; 1300, 1500) in which the metering device is switched at least temporarily to be within said portion of the analysis path so that the metering device is at least temporarily in fluid communication with the mobile phase drive and so that the metering device is flushed by the mobile phase being delivered by the mobile phase drive; or a separation mode (500; 1200) in which the metering device is switched out of said portion of the analysis path, so that the sample fluid is driven between the mobile phase drive and the separation unit for separating the compounds. at least a portion of an analysis path between the mobile phase drive and the separation unit, said portion of an analysis path being suitable for transporting fluids at high pressure; a metering device being operable for intaking a metered amount of the sample fluid into the sample injector; an injection needle drivable for immersing into the sample fluid; and a sample loop in fluid communication with the injection needle for accommodating the sample fluid upon being intaken by the metering device via the injection needle; a fluidic valve being switchable for operating the sample injector selectively in: a flushing mode (600; 1300, 1500) in which the metering device is switched at least temporarily to be within said portion of the analysis path so that the metering device is at least temporarily in fluid communication with the mobile phase drive and so that the metering device is flushed by the mobile phase being delivered by the mobile phase drive; or a separation mode (500; 1200) in which the metering device is switched out of said portion of the analysis path, so that the sample fluid is driven between the mobile phase drive and the separation unit for separating the compounds. a flushing mode (600; 1300, 1500) in which the metering device is switched at least temporarily to be within said portion of the analysis path so that the metering device is at least temporarily in fluid communication with the mobile phase drive and so that the metering device is flushed by the mobile phase being delivered by the mobile phase drive; or a separation mode (500; 1200) in which the metering device is switched out of said portion of the analysis path, so that the sample fluid is driven between the mobile phase drive and the separation unit for separating the compounds.