SOLID-SURFACE ROOM-TEMPERATURE PHOSPHORESCENCE OPTOSENSING IN CONTINUOUS-FLOW SYSTEMS - AN APPROACH FOR ULTRATRACE METAL-ION DETERMINATION

Solid-surface room-temperature phosphorescence (SSRTP) optosensing in an aqueous flow is reported here for the first time, and it has been applied to aluminum control in samples of clinical interest. This technique makes use of flow injection analysis (FIA) and is based on the transient immobilization (on a strongly basic anion-exchanger resin packed in a flow cell) of the complex formed by the phosphorogenic reagent 8-hydroxy-7-iodo-5-quinolinesulfonic acid (ferron) with aluminum in a continuous flow carrier at pH 5.5. The analytical performance characteristics of the proposed method for semiautomated analysis and control of very low levels of Al were as follows: 2-mu-g/L detection limit, +/- 3.2% precision analyzing 40-mu-g/L of the metal and most of the common ions in biological samples did not interfere. Only Fe(III) caused serious interference, but it can be masked by 1,10-phenanthroline. The recommended method has been successfully tested for Al determinations at mu-g/L levels in samples of particular importance today (dialysis fluids and concentrates). Basic experiments on the characteristics of the RTP observed for different media used to secure the necessary rigidity (micelles, vesicles, filter paper, strong anionic resins, etc.) have demonstrated that Dowex 1x2-100 resin seems to provide the best sheltering to the excited triplet state. Possible interaction mechanisms between phosphor and supports are suggested.