Abstract: The invention provides a flow cell system for high throughput solubility testing of compounds that is particularly useful for screening large compound collections, such as combinatorial chemical libraries or other such synthetic chemical libraries. The system includes a flow cell to channel a fluid sheath which itself channels a continuous or intermittent sample liquid stream containing a compound for testing. Where the concentration of compound in the sample exceeds the solubility limit, particles of the test compound precipitate. These particles scatter the light from an interrogating light beam directed at the sample liquid stream. Individual flashes of scattered light are detected as electronic pulse signals from the detector and their intensity analyzed according to intensity and number of events. System software analyzes the stored pulse signal data in real-time to determine whether there is a significant increase in scattering over the highly variable background scattering.

Abstract: A particle detection system exhibits an increased ability to detect the presence of submicron diameter particles and to distinguish between noise and pulse output signals generated by small diameter particles on which a light beam is incident. This increased ability results from the incorporation of a light reflector, a pair of detector elements that detect correlated portions of the light beam that have been scattered in multiple directions, and a coincidence circuit that determines whether each detector element in the pair concurrently generates a pulse output signal exceeding a predetermined threshold. Sample particles are counted only when both detector elements concurrently detect scattered light components.