Abstract: An automated kinetic solubility assay apparatus that uses turbidimetric means to assess the kinetic solubility of a succession of testable mixtures is disclosed. A large number of sample containers (one test compound per container), each having a pierceable septum, may be arranged for sequential testing, and the apparatus automatically (i.e., without operator intervention) tests the compounds one at a time to determine the kinetic solubility of each compound (e.g., a drug candidate being preliminarily screened) in a test fluid of interest (e.g., a liquid that mimics gastric juices). A cuvette in which the test mixture is exposed to the testing light and having a pierceable septum, a septum-piercing needle that is used to transfer the compound from its container to the cuvette, and a cleaning solution that may be used to clean the cuvette, all of which can be used in the automated apparatus, are also disclosed.