Patent ID: 7555937

Claim:
A sample injection device, comprising: a sample injection port connected to a column; a mobile phase supplying unit configured to supply a mobile phase; a first sample injection needle attachable to the sample injection port; a second sample injection needle attachable to the sample injection port; a sample-suctioning unit connectable to the first sample injection needle and configured to draw a sample into the first sample injection needle when connected thereto; and a switching valve configured to selectively connect the first sample injection needle to the mobile phase supplying unit or the sample-suctioning unit and to connect the second sample injection needle to the mobile phase supplying unit; wherein the switching valve is configured to connect the first sample injection needle to the mobile phase supplying unit when the first sample injection needle is attached to the sample injection port, and configured to connect the first sample injection needle to the sample-suctioning unit and to connect the second sample injection needle to the mobile phase supplying unit when the second sample injection needle is attached to the sample injection port.