Abstract: A pressure control apparatus for a supercritical fluid according to the present invention includes: a valve comprising; a valve chamber provided in a midway of a channel through which a supercritical fluid passes; and an electrically-operated valve element located in the valve chamber; a pressure detection member for detecting the pressure of the supercritical fluid in the channel on an upstream or downstream side of the valve chamber; an open/close control member for controlling the pressure detected by the pressure detection member to be a target pressure; and a valve-opening rate adjustment member for adjusting the valve-opening rate when the valve is opened based on the state of the supercritical fluid.

Abstract: An object of the present invention is to provide a pressure control apparatus for a supercritical fluid in which variation in pressure is small even in measurement in which analysis conditions are changed with time to improve separation and other performance.

Abstract: A microcell used in analysis of very small amounts of liquid samples, the microcell comprising: a plate spacer having a plurality of small holes with notches widening toward sample injection openings in a side wall; and window plates made of a material passing measuring light, disposed to face each other on either side of the spacer to cover the plurality of small holes from the front and the back; wherein spaces formed by the plurality of small holes of the spacer and the window plates serve as a plurality of cell chambers for containing the liquid samples; and a dimension of the plurality of small holes and the thickness of the spacer are determined in accordance with the amounts of the liquid samples, and a dimension of parts joining the notches and the plurality of small holes is smaller than the dimension of the plurality of small holes.