A tandem time-of-flight mass spectrometer incorporating a fast atom bombardment source has been designed and constructed for the purpose of studying collision-induced decomposition spectra. A deflection of the secondary ion beam is used to form the ion packets for time-of-flight analysis. A floating collision cell that represents a potential barrier to ions transversing the time-of-flight tube enables ionic and neutral fragments from collision-induced decomposition reactions to be separated in time from the parent ion. The instrument operating in the tandem mode is capable of performing charge exchange and collision-induced decomposition studies of both positive and negative incident ions.

A battery powered portable monitor based on Row injection potentiomctry 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 clectrode, 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 lo-' and 1 x

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