Sample injector, sample injecting method, and liquid chromatograph

A sample injecting method for injecting a sample into a column using a sample injector including a sample injection part connected to the column to inject the sample into a column;

• a sample injection needle attachable to the sample injection part;
• a sample suction part connectable to the sample injection needle and configured to cause a predetermined amount of the sample to be drawn by suction into the sample injection needle upon connecting to the sample connection needle;
• a mobile phase supply part configured to supply the column with a mobile phase;
• a first switching valve for selectively connecting the sample injection needle to one of the sample suction part and the mobile phase supply part;
• and a second switching valve, including the sample injection part, for supplying the sample and the mobile phase to the column via the sample injection needle in a case of having the sample injection needle attached to the sample injection part and for supplying the mobile phase to the column via the first switching valve in a case of having the sample injection needle removed from the sample injection part, the sample injecting method comprising:
• a first mobile phase supplying step of connecting the sample injection needle and the mobile phase supply part through path switching performed by the first switching valve and supplying the mobile phase from the sample injection needle to the column in the case of having the sample injection needle attached to the sample injection part;
• a sample suction step of connecting the sample injection needle and the sample suction part through the path switching performed by the first switching valve and causing the sample to be drawn by suction into the sample injection needle;
• and
• a second mobile phase supplying step of supplying the column with the mobile phase from the mobile phase supply part through path switching performed by the first switching valve and the second switching valve while causing the sample to be drawn by suction into the sample injection needle by the sample suction step,
• wherein the second switching valve includes a first path for supplying the sample and the mobile phase to the column and a second path for supplying the mobile phase to the first path in the case of having the sample injection needle removed from the sample injection part, and
• the second path is closed by the sample injection needle inserted through the sample injection part into the first path in the case of having the sample injection needle attached to the sample injection part.

A liquid chromatograph, comprising:

• a sample injector,
• the sample injector including a sample injection part connected to a column to inject a sample into the column;
• a sample injection needle attachable to the sample injection part;
• a sample suction part connectable to the sample injection needle and configured to cause a predetermined amount of the sample to be drawn by suction into the sample injection needle upon connecting to the sample connection needle;
• a mobile phase supply part configured to supply the column with a mobile phase;
• a first switching valve for selectively connecting the sample injection needle to one of the sample suction part and the mobile phase supply part;
• and a second switching valve, including the sample injection part, for supplying the sample and the mobile phase to the column via the sample injection needle in a case of having the sample injection needle attached to the sample injection part and for supplying the mobile phase to the column via the first switching valve in a case of having the sample injection needle removed from the sample injection part,
• the second switching valve including
• a first path for supplying the sample and the mobile phase to the column;
• and
• a second path for supplying the mobile phase to the first path in the case of having the sample injection needle removed from the sample injection part,
• wherein the second path is configured to be closed by the sample injection needle inserted through the sample injection part into the first path in the case of having the sample injection needle attached to the sample injection part.