Patent ID: 8656754

Claim:
A gas chromatograph apparatus having at least two switchable operation modes, one mode being an analysis mode in which an analysis of a sample can be performed and another mode being a waiting mode in which no analysis is performed, where the gas chromatograph apparatus includes: a column placed in a column oven; a sample vaporization chamber provided at an inlet of the column; a carrier gas passage for feeding a carrier gas to the sample vaporization chamber; a purge passage for ejecting an impurity gas from the sample vaporization chamber; a split passage for ejecting a portion of the carrier gas from the sample vaporization chamber; a flow controller for interlockingly controlling flow rates of gases flowing through the carrier gas passage, the purge gas passage and the split passage as well as a gas pressure in the sample vaporization chamber, the flow controller having a constant linear velocity control mode, a constant column flow rate control mode, and a constant pressure control mode, as a gas control mode; and a detector for detecting a sample component in a gas which has passed through the column, wherein the gas chromatograph apparatus further includes: a) a memory for memorizing control parameters for the waiting mode, the control parameters including a minimum value of a gas flow rate required for each of the carrier gas passage and the purge passage in the waiting mode; and b) a controller for setting, in a transition from the analysis mode to the waiting mode, the gas control mode to the constant pressure control mode regardless of the gas control mode in the analysis mode, for setting a column inlet pressure at that point in time as a target pressure, and for controlling the flow controller using the control parameters memorized in the memory, and the controller includes: a flow rate determiner for estimating, in advance of the transition to the waiting mode, a column flow rate corresponding to a lowest predicted value of a temperature in the column after the transition to the waiting mode by using the control parameters memorized in the memory, and for comparing the estimated value with a preset threshold value; and a pressure changer for providing a warning to a user that the column inlet pressure at that point in time should be decreased or automatically decreasing the column inlet pressure in a case where the estimated value of the flow rate exceeds the threshold value.