Abstract: A high-pressure control valve (2) used in chromatography serves as a counter pressure control valve which, in a separating column, is intended to maintain a specific predeterminable pressure. The valve has a valve seat (12) with an outlet channel opening (18) located in its center and a valve body (13) that cooperates with the valve seat. The valve body (13) can be moved with the aid of a piezo transducer, actively in the opening direction and, while being monitored, actively in the closing direction. The opposed faces of the valve seat (12) and the valve body (13) are so shaped that an annular gap (16) that widens radially towards the outside starting from the opening (18) of the outlet channel is produced. When the valve is in the closed position, this results in the formation of a narrow sealing zone directly at the edge of the opening of the outlet channel.

Abstract: Optical high-pressure transmission cells of the type used, for example, for SFC-FTIR, comprise a pressure-resistant housing part with two intersecting bores, one of them forming a fluid passage and the other one forming a light transmission path. The bore forming the light transmission path is provided with inserted windows. There is a demand in infrared spectroscopy, for supercritical fluid chromatography, for particularly pressure-resistant cells of simple design, which demand has not been satisfied heretofore. In the case of the proposed measuring cell, the windows are designed as stepped windows having central cylindrical neck portions engaging the bore serving as a light transmission path so that the chamber is delimited by end faces of the neck portions. Sealing is effected by O-rings.

Abstract: A micro-flow cell for chromatographic, spectrometric or scintillation measurements comprises a capillary tube, preferably made of glass or silica glass, through which flows the medium to be examined, and a holding device for said capillary tube. The holding device is separably composed of at least two parts which can be separated in their longitudinal direction. The capillary tube is fixed in the holding device by suitably formed connectors so as to be stress-free and tension-free to the greatest possible extent.