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

A robust automatic flow analyzer for laboratory routine analysis or industrial 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 driven by stepper motors with photoswitch position detection. By movement coordination of the pumps and the valve, no separate waiting time is necessary 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, flow-injection-analysis mode, into 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 titrated quickly, accurately, and in a microchemical way. To demonstrate, the analyzer was employed both for the determination of trace amounts of tungsten in the raffinate of ammonium paratungstate (APT) processing with FIA mode and for the determination of caustic hydroxide in the industrial production of aluminum oxide with microtitration mode. The typical sampling rates are 60 and 45 samples h⁻¹ for FIA mode and titration mode, respectively. © 2000 John Wiley & Sons, Inc. Lab Robotics and Automation 12:108–113, 2000