Automatic sampler
In a direct injection type automatic sampler, a sampling needle having a liquid sample collected from a sample vessel by using suction force of a pump is inserted into an injection port. Then, a flow path-switching valve is rotated to switch a flow path to make a flow of mobile phase liquid pass through a loop to thereby introduce the collected sample into a column. The injection port is directly incorporated in the flow path-switching valve.
1. An automatic sampler comprising:
a sampling needle for drawing in and collecting a liquid sample;
an injection port having a needle seal with a through-hole in its center and into which said liquid sample is injected by said sampling needle;
a flow path-switching valve for performing switching of a flow path;
a first pump for communicating a suction force to said sampling needle when said flow path-switching valve is in a first position so as to draw in and collect the liquid sample with the sampling needle;
a second pump for pressurizing the collected liquid sample so as to inject the liquid sample from said needle into said sample port when said flow path-switching valve is in a second position, wherein, when said flow path-switching valve is in said second position said second pump is connected to both said sampling needle and said injection port by a flow path through said flow path-switching valve,
wherein said injection port is incorporated in said flow path-switching valve, and a front end of the sampling needle and the needle seal are fitted to one another.
2. The automatic sampler according to claim 1 , wherein said injection port also has a nut for pressing the needle seat.
3. The automatic sampler according to claim 1 , wherein said automatic sampler is used for a liquid chromatograph for analyzing said injected liquid sample, the liquid chromatograph being connected to a liquid feed pump by a mobile phase liquid feed flow path through said flow path-switching valve and to an inlet side of a column by a column upstream side flow path through said flow path-switching valve.
4. The automatic sampler according to claim 1 , wherein the flow path-switching valve comprises a valve body, a stator, a rotor, and a shaft, the stator and rotor being received in the valve body, said stator being fixed to an inner surface of the valve body, and wherein the rotor is fixed to the shaft and received in the valve body and frictionally rotates relative to the stator.
5. The automatic sampler according to claim 4 , wherein the valve further comprises a spring that urges the rotor against the stator.
6. The automatic sampler according to claim 5 , wherein the flow paths are provided by grooves formed in a face of the rotor, and wherein communication with each of the respective flow paths is selected by rotation of the shaft.
7. The automatic sampler according to claim 6 , wherein said injection port also has a nut for pressing the needle seal.
8. The automatic sampler according to claim 7 , wherein said automatic sampler is used for a liquid chromatograph for analyzing said injected liquid sample, the liquid chromatograph being connected to a liquid feed pump by a mobile phase liquid feed flow path through said flow path-switching valve and to an inlet side of a column by a column upstream side flow path through said flow path-switching valve.