A solution containing a target compound is passed through a trap column (14) to capture the target compound in the column (14). Thereafter, wash water is introduced in the trap column (14). Then, the setting of a six-port valve (7) is changed and an on/off valve (6) is opened to introduce nitrogen gas through a supply-side passage (8) in the trap column (14). In this stage, the nitrogen gas is warmed by means of a heat-exchange block (10), and the trap column (14) is warmed via a column rack (15). Any water remaining in the trap column (14) is initially thrust upwards by the nitrogen gas, to be extruded from an exit edge (14b) and discharged through a discharge-side passage (20). Furthermore, any water adhering to adsorbent or the inner wall surface of the trap column (14) is quickly vaporized and carried away by the nitrogen gas. In this manner, any water remaining in the trap column (14) can be rapidly removed, so that no water will be included in an eluate in the subsequent stage where a solvent with a strong elution power is introduced into the trap column (14) to collect the eluate. Thus, the eluate is rapidly vaporized and dried, so that the target compound in solid forms can be efficiently collected.