Patent ID: 7363801

Claim:
A sample injector for injecting a liquid sample into a sample-vaporizing chamber located at an inlet of a column of a gas chromatograph, which is used to analyze a sample that needs to undergo a derivation process before an analysis, the sample injector comprising: a) a liquid-holding device having a syringe with a needle attached to its tip and a plunger slidably inserted into the syringe; b) an actuator for activating the plunger; and c) a controller for controlling the actuator to push or pull the plunger so that: a derivation reagent is suctioned into the syringe, whereafter a sample to be analyzed is suctioned so that the sample is held closer to the needle and the derivation reagent farther from the needle; the needle is inserted into the sample-vaporizing chamber; and the plunger is pushed into the syringe in a manner so that the sample held in the syringe is first injected into the sample-vaporizing chamber, and then the derivation reagent held in the syringe is injected into the sample-vaporizing chamber when a predetermined period of time has elapsed after the injection of the sample into the sample-vaporizing chamber.