On-line system for improving detection level of analytes by liquid chromatography and analysis method using same

An on-line system for improving a detection level of analytes by a liquid chromatography (LC), the on-line system comprising:

• a first pump and a second pump for supplying a solvent;
• a liquid chromatography (LC) including a separation column (SC) connected to the first pump;
• a trapping column (TC) for collecting the analytes separated from the separation column;
• a concentration column (CC) for concentrating the analytes collected in the trapping column (TC);
• a detector;
• and
• first to third switching valves that communicate fluid with at least one of the first and second pumps, the separation column (SC), the trapping column (TC), the concentration column (CC) and the detector, and wherein each of the first to third switching valves has a plurality of ports,
• wherein the first to third switching valves are connected to each other through a flow path and configured to switch the fluid flow to an LC mode, a trapping mode or a concentration mode by changing connection states of the plurality of ports included in each of the switching valves,
• wherein a first eluting solvent in the LC mode is supplied to the separation column (SC) through the first pump to separate the analytes, and then the LC mode is sequentially switched to the trapping mode and the concentration mode, and a solvent having an elution intensity lower than that of the first eluting solvent is supplied to the trapping column (TC) and the concentration column (CC) through the second pump to trap and concentrate the analytes moving by flow of the first eluting solvent, and
• wherein after the analytes are trapped and concentrated by flow of the first eluting solvent, the first pump supplies a second eluting solvent for ionization of the analytes through solvent exchange, whereas operation of the second pump is stopped so that the analytes concentrated in the concentration column (CC) by the second eluting solvent are detected by introducing them into the detector.