Automatic sampler for liquid chromatograph

An automatic sampler for a liquid chromatograph and for injecting a taken-in sample into an analytical flow path of the liquid chromatograph, the automatic sampler comprising:

• a first plunger pump for taking in the sample;
• a second plunger pump for taking in the sample and having a larger cylinder capacity than the first plunger pump;
• a sample loop for temporarily retaining the sample taken in by the first or second plunger pump;
• a flow path switching mechanism including a switching valve and for switching, by switching of the switching valve, between a flow path for taking the sample into the sample loop with the first or second plunger pump and a flow path for supplying the sample taken into and retained by the sample loop to an analytical flow path of the liquid chromatograph with a mobile phase;
• a pump selecting mechanism disposed between intake ports and discharge ports of both the plunger pumps and the flow path switching mechanism, and for switching connection with the flow path switching mechanism so as to selectively connect one of the plunger pumps to the flow path switching mechanism, and
• a pump selecting means for switching the pump selecting mechanism so that the pump selecting mechanism selects the first plunger pump when an amount of the sample to be injected into the analytical flow path of the liquid chromatograph is a predetermined amount or smaller and selects the second plunger pump when the injected amount of the sample is larger than the predetermined amount.