Equipment and method for feeding liquid gradient in nano/micro liquid chromatography

A gradient liquid transfer method for a nano/micro liquid chromatograph provided with:

• a primary-solvent liquid transfer section having a metering pump for transferring a primary solvent and a primary-solvent passage subsequent to the metering pump;
• at least one liquid transfer section having a metering pump for transferring one other solvent and a solvent passage subsequent to the metering pump;
• and a solvent mixing section connected to the passages and to a mixed-solvent passage for passing a mixed solvent made by mixing the solvents supplied through the passages at a predetermined mixing ratio and for leading to a subsequent separation system, the nano/micro liquid chromatograph gradually changing the mixing ratio of the mixed solvent and transferring the mixed solvent to the subsequent separation system for gradient elution, and comprising, in the vicinity of the solvent mixing section, opening and closing means capable of opening and closing the solvent passage for transferring the one other solvent, and the gradient liquid transfer method comprising:
• a first step of closing the opening and closing means, of filling, in advance, a passage from the metering pump of the at least one liquid transfer section to the opening and closing means with the one other solvent, and of applying an appropriate pressure to the one other solvent;
• a second step of transferring the primary solvent to the subsequent separation system from the primary-solvent liquid transfer section through the solvent mixing section;
• and a third step of opening the opening and closing means, of transferring the one other solvent to the solvent mixing section at a predetermined flow rate, and of transferring the mixed solvent having the predetermined mixing ratio of the primary solvent and the one other solvent to the subsequent separation system.