Intra-liquid particle classification apparatus using light scattering

Abstract

A liquid sample is sucked from a staining vessel by a first sampling nozzle and the liquid sample is discharged into a flow cell unit, the liquid sample being supplied to the staining vessel by a second sampling nozzle so as to be stained in the staining vessel in advance. When the liquid sample is being discharged through the first sampling nozzle, a sheath liquid is supplied to a flow cell so that the sheath liquid flows with the liquid sample included therein. In this condition, passage of particles in the flow cell is detected by an optical system for detection at a still frame image pick-up position, and after a predetermined delay time based on the detection, strobe light is radiated so as to pick up a still frame image due to the scattered light to thereby perform classification and counting of the particles. Foreign matter in the liquid sample discharged from the sampling nozzle is caught by a filter and exhausted by the sheath liquid which overflows to the upper portion of the filter after completion of discharge of the liquid sample from the sampling nozzle. Bubbles in the flow cell are removed through an air vent and bubbles in the sheath liquid are removed after once reserved in an air vent chamber. Thus, foreign matter/bubbles in the liquid sample/sheath liquid can be prevented from entering the flow cell unit to make it possible to perform testing with high accuracy without lowering testing efficiency.