摘要:
To accommodate microscale chromatographs, a flow cell has an inlet port, inlet path, light path, outlet path and outlet port, with the inlet and outlet paths being formed continuously around wires of the proper diameters during molding. The wires pass through the mold and against a metal light-path insert during molding and are removed from the plastic after molding to form portions of the inlet and outlet paths. The insert for the light path is formed in two parts, each having a groove in the form of a half cylinder along its center for the light path and having channels on each side. The paths are machined prior to lapping, and after lapping, the light path is coated with a bright metal such as rhodium and then it is burnished for a mirror image with a roughness of less than sixteen RMS micro inches.
摘要:
To reduce tailing, the frit at the outlet to the liquid chromatographic column has a diameter substantially equal to that of the inside diameter of the outlet end of the column and less than 2 millimeters. It is held directly against the packing of the column within a cylindrical member having a shoulder with a central aperture at least the size of the diameter of the frit and cylindrical walls which are fastened to resist force in the direction of the axis of the column from its inlet to its outlet. A gasket seals the cylindrical holder against the column wall.
摘要:
To measure the nuclear radiation of a sequence of radioactive samples, magazines that hold sample containers are removably positioned in shuttles, some of which are driven step-by-step by a toothed belt that engages racks on the sides of the shuttles from one compartment to another through a measuring station, with the shuttles that are being driven by the belt driving other shuttles not in engagement with the belt at that time. In the measuring station, the sample containers are released from the magazines one at a time through openings in their bottoms and lowered by a reciprocable support to a position adjacent to a radiation detector for the measurement, after which they are raised by the support to the magazine and the shuttle is driven one more step to the next position.
摘要:
To reduce the sensitivity of a heat of adsorption detector to changes in the flow rate of the carrier solvent upon a reference thermistor and a measuring thermistor, the flow of heat is adjusted to balance the flow-rate-dependent temperature increases against the flow-rate-dependent temperature decreases that occur with the same change in flow rate. Some of the techniques for adjusting the flow of heat are: (1) controlling the temperature of the solvent at the inlet of the heat of adsorption detector with one heat exchanger and the temperature of the body of the heat of adsorption detector with another heat exchanger; (2) controlling the temperature of the walls of the heat of adsorption detector with a heating coil; and (3) controlling the heat emitted by the thermistors.