Abstract: A carousel receives a plurality of removable reagent containers, a turntable receives a plurality of sample fluid containers and a rotatable cuvette assembly holds an annular array of reaction and test cuvettes. A robotic arm carrying a fluid transfer needle coupled to a pair of syringes picks up one or more reagents and sample fluid for deposit into a cuvette. As the arm moves the needle tip exterior is washed and contaminants sent to a waste collector. At the end of a test cycle, the needle core is flushed and cleaned. A colorimetry photometric test is performed on the reacted fluids in each cuvette by a system employing ten interference filters, corresponding diode detectors and amplifiers employing two identical multiplexers providing identical filtered signals for logarithmic calculation of absorbance.