A reliable syringe-pump-based flow analyzer for photometric analysis and photometric titration

A robust automatic ow analyzer for laboratory routine analysis or industria l process analysis is introduced, which is based on syringe piston pumps, a rotary valve, a light emitting diode (LED) and phototransistor photometer, and a single chip microcomputer system. Both the pumps and the valve are d riven qv stepper motors with photoswitch position detection. By movement co ordination of the pumps and the valve, no separate waiting time is necessar y for the syringe to be refilled or discharged, and the leakage problem of the valve is also alleviated. The analyzer can be operated in two modes, fl ow-injection-analysis mode, in to which most current FIA methods developed with peristaltic pumps can be easily adapted, and microtitration mode, with which major components in a sample can be citrated quickly, accurately, an d in a microchemical way. To demonstrate, the analyzer was employed both fo r the determination of trace amounts of tungsten in the raffinate of ammoni um paratungstate (APT) processing with FIA mode and for the determination o f caustic hydroxide in the industrial production of aluminum oxide with mic rotitration mode. The typical sampling rates are 60 and 45 samples h(-1) fo r FIA mode and titration mode, respectively. (C) 2000 John Wiley & Sons, In c. Lab Robotics and Automation 12:108-113, 2000.