A distal end portion of a probe has a multi-pipe structure, in which an effluent solution from a high speed liquid chromatography passes through an innermost flow passage, a matrix solution through an outer flow passage, and the air through an outermost flow passage. A distal end of the outermost pipe extends 1.2 mm longer than the distal end of the inner duplex tube to form a liquid reservoir. When dropping a liquid droplet from the distal end of the probe, the air is blown out to expel the liquid gathered in the liquid reservoir to be dropped.