Abstract: In a high-performance, high-pressure liquid chromatography system, gradient elution of solvent components from a plurality of component reservoirs can be accomplished according to a programmed temporally variable ratio by a single reciprocating pump. The pumping cycle comprises a plurality of fill strokes with intervening pumping strokes. During one of the fill strokes of the cycle, a proportioned mixture of solvent components is admitted to the pump chamber from the respective reservoirs by means of proportioning valves. During each of the other fill strokes of the cycle, only a single solvent component is admitted to the pump chamber. Consequently, a relatively low concentration of a particular component can be delivered by the pump with precision over a complete pumping cycle, although a comparatively higher and therefore more accurately measurable concentration of that component is admitted to the pump chamber during any given fill stroke.

Abstract: The present inventive fluorometer provides a rapid means for accurate sample quantitative measurements by making instrumental calibration measurements during sample equilibration time. Increased speed of equilibration and calibration and simultaneously performing these two functions increases the throughput speed with which individual measurements can be accomplished, thus increasing the number of samples which can be routinely processed. This decreases the cost per test and more importantly renders new treatment protocols possible which require the doctor and patient to be able to know within minutes the level of certain drugs in various body fluids.

Abstract: In a liquid chromatography system, the effluent from the chromatographic column is passed through a detector flow cell, which is packed with a stationary phase that is adsorptive of the sample species to be detected. Detection of the sample species adsorbed at the stationary phase is effected by measuring fluorescence emitted from such species in response to electromagnetic radiation incident thereon at the flow cell. The fluorescing species, which are in equilibrium between the stationary phase and the mobile phase in the flow cell when fluorescence is being measured, can be detected at lower concentration thresholds than when the fluorescing species are in equilibrium only with the mobile phase.

Abstract: This thermostatable flow cell for fluorescence measurements enables rapid thermal equilibration and precise temperature control. For a flow cell volume of less than 20 microliters, a selected temperature in the range up to 20.degree. C. above ambient can be attained within five seconds, and this selected temperature can be maintained stable within 0.1.degree. C. The cell comprises a cylindrical cavity whose walls include a metallic portion for heat conduction and a transparent window portion for light acceptance and fluorescence observation. The metallic portion of the cell is formed from a cell block to which a temperature sensing means is affixed. The window portion is affixed to the cell block by an inert bonding material. A thermoelectric device responsive to the temperature sensing means causing heating or cooling of the cell block as necessary to provide thermal equilibration at the selected temperature.