Variable temperature computerized dual-beam, rapid scanning stopped-flow apparatus for the study of air-sensitive systems and transients in enzyme reactions

A double-beam, vacuum tight, thermostated stopped-flow apparatus has been constructed and computer interfaced. A specially designed all-quartz mixing and observation cell equipped with a double mixer and two optical path lengths has been used. The syringes were made out of heavy-walled precision bore Pyrex tubing. Steel plungers with adjustable Teflon tips were machined to fit them. The entire apparatus was constructed such that the solutions contact only Pyrex, quartz, and Teflon, while the flow system is surrounded by a thermostat bath. Quartz fiber optics were utilized to transmit the dispersed light from a Perkin--Elmer Model 108 rapid-scan monochromator to the flow and reference cells and then to a pair of photomultipliers. The performance of the system has been tested by studying a number of well characterized chemical reactions. (auth)