LIQUID CHROMATOGRAPH

• US 20120024048A1
• Filed: 04/07/2010
• Published: 02/02/2012
• Est. Priority Date: 04/16/2009
• Status: Active Grant

• Current Assignee: Shimadzu Corporation
• Original Assignee: Shimadzu Corporation
• Inventors: Maeda, Yoshiaki
• Granted Patent: US 8,794,052 B2
• Time in Patent Office: Days
• US Class Current: 73/61.55
• CPC Class Codes: G01N 30/20 using a sampling valve
• CPC Class Codes: G01N 30/24 Automatic injection systems
• CPC Class Codes: G01N 30/32 of pressure or speed G01N30/36 takes precedence

Abstract

In injecting a sample sucked into a sample loop in an autosampler from an injection needle into an analytical flow path via an injection port by a mobile phase, a sending flow rate of the mobile phase is reduced from a certain flow rate determined in an analysis condition to reduce pressure applied on a joint section between the needle and the injection port to thereby reduce the sample remaining in the injection port.

Claims

1. A liquid chromatograph comprising:

an analytical flow path including a column disposed on a flow path for a mobile phase to separate an introduced sample into components and a detector for detecting sample components separated by the column;

a mobile phase sending section for supplying the mobile phase with a solvent delivery pump;

an autosampler including an injection needle, a sample loop having one end connected to the injection needle, an injection port, a metering pump, and a flow path switching valve, and being configured to be switched between a sample sucking mode and a sample introducing mode, the sample sucking mode being a mode in which the flow path switching valve connects the other end of the sample loop to the metering pump to suck the sample into the sample loop from the injection needle, and the sample introducing mode being a mode in which the flow path switching valve connects the other end of the sample loop to the mobile phase sending section and connects the injection needle from the injection port to the analytical flow path to introduce a whole quantity of the sample sucked in the sample sucking mode into the analytical flow path by the mobile phase; and

a flow rate control section for controlling operation of the solvent delivery pump in synchronization with operation of the autosampler,

wherein the flow rate control section has a first flow rate for separating the sample components in the analytical flow path and a second flow rate being lower than the first flow rate as flow rate set values of the solvent delivery pump, and

wherein the flow rate control section controls the solvent delivery pump so that the flow rate is the first flow rate at a time for which the sample components are eluted in the analytical flow path and that the flow rate is the second flow rate at a time for which the whole quantity of the sample sucked in the sample sucking mode passes through the injection port in the sample introducing mode of the autosampler.

2. The liquid chromatograph according to claim 1, wherein the flow rate control section automatically calculates a time for which the solvent delivery pump operates at the second flow rate after the flow path switching valve is switched to the sample introducing mode from a sample sucking quantity into the sample loop and the set second flow rate.

3. The liquid chromatograph according to claim 1, wherein the flow rate control section switches the flow rate of the mobile phase by the solvent delivery pump from the first flow rate to the second flow rate before switching the autosampler to the sample sucking mode for the next sample when analysis of one sample is finished.

4. The liquid chromatograph according to claim 1, wherein the flow rate control section switches the flow rate of the mobile phase by the solvent delivery pump from the first flow rate to the second flow rate before switching the autosampler to the sample sucking mode for the next sample when peak elution of one sample is finished.

5. The liquid chromatograph according to claim 1, wherein the injection port is directly incorporated in the flow path switching valve in the autosampler.