Abstract: A system for performing vertical spectrophotometric determinations uses a vessel which has an upper transparent surface and a lower transparent surface which are spaced apart to define a known fixed pathlength through which a light beam is transmitted. The vessel also includes a portion disposed above the upper surface which may be a spout having an opening for allowing the introduction of substances into the containment portion.

Abstract: A universal washing apparatus for use in washing wells provided in reaction containers such as wells of microtiter plates and the like. The washing apparatus has separate dispense and aspirate manifolds positioned one on top of the other which may be independently lowered or raised with respect to a microtiter plate for performing various wash operations. The washing apparatus uses an indexing mechanism for indexing the well plate relative to the manifolds in the horizontal plane so that the washing apparatus is compatible for washing different well plate configurations.