A portable flow injection analyzer for use with ion-selective electrodes

A battery powered portable monitor based on flow injection potentiometry has been developed weighing 1.8 kg, constructed in a carry-case and applicable for remote site monitoring. Portability has been achieved using a light weight rechargeable Ni-Cd battery-pack (7.2 V). The flow injection manifold incorporates a low powered peristaltic pump, a wall-jet type flow cell containing a commercial iodide ion-selective electrode and a Ag/AgCl reference electrode connected to an analog-to-digital converter, also powered by the battery pack, and a RS232-serial output to a notebook computer for real-time data display and storage. The system performance has been evaluated using the iodide ion-selective electrode, including the effects of various carrier solutions on sample peak heights, peak widths and the calibration slopes and working ranges. Fast response with peak widths as low as approximately 10 s. was observed with near Nernstian response of -53.8 mV change per activity decade and a log-linear range between 5 x 10(-6) and 1 x 10(-2) M in a 0.1 M sodium acetate carrier stream.