“…The main shaft was replaced by a more precisely machined lead screw to reduce flow rate variations. Upstream of the injector, the sample carrier stream flows through a cation exchange resin bed to remove possible trace levels of NH 4 ϩ within the degassed DI water, and then through a 2 m filter. The instrument operates under computer (386SX PC) control using an Access I/O Products (San Diego) A/D 12-8 analog to digital converter board with digital I/O capability mounted in the computer and an AIM-16 multiplexer mounted on the analyzer housing.…”