PURPOSE: To remove a solvent completely and thereby to improve the precision of analysis and to prolong the lifetime of the device by a method wherein the outlet of a column of gas chromatograph (GC) is connected with an He separator provided at the inlet of an ion source of a mass spectrometer (MS) by a specific sleeve having a throttle.

CONSTITUTION: Between the outlet (joint part) 4 of the column of GC and the He separator 6 provided at the inlet of the ion source of MS is provided a solvent removing part 5 formed by putting the sleeve 10 made of hard glass and having the throttle 12 (at two places of 12a and 12b) and three communication holes 13a communicating with pipes 16a, 16b and 16c into a body 11 which is a pipe made of stainless steel. The end part of the column 3 and the end part of the separator 6 are connected with the sleeve 10 airtightly inside the body 11 by box nuts 15 and packings 14. The solvent from the column 3 is removed by a valve system 8 and a rotary pump 9b. By this device, corrosion of the solvent removing part 5, leakage of pressure and the like are eliminated and massive entrance of unnecessary components into MS is prevented. Therefore, the precision of analysis and the durability of the device are improved.