Automatic fluorimetric procedure for the determination of aluminium in plant nutrient solution and natural water employing a multicommutated flow system

A fluorimetric flow procedure for the determination of aluminium in plant nutrient solutions and natural waters using morin (3,5,7,2',4'-(pentahydroxyflavone) as a fluorimetric reagent is described. The flow system comprised a set of three-way solenoid valves that were assembled to implement the multicommutation and monosegmented flow approaches. The calibration graph was linear in the range between 0.1 to 1.0 mg L-1 Al3+. A relative standard deviation of 1.7% (n=7) for a typical sample containing 0.5 mg L-1 Al was achieved. Comparing the results with those obtained by atomic emission spectrometry (ICP-AES), no significant difference at the 95% confidence level was observed. Other profitable features such as an analytical throughput of 60 determinations per hour; a reagent consumption of 1.6 mug of morin per determination and a detection limit of 0.04 mg L-1 were also achieved.