Electrochemiluminescent metallopolymer coatings: Combined light and current detection in flow injection analysis

The application of thin films of the metallopolymer [Ru(bpy)(2)PVP10](2+) f or the electrochemiluminescent (ECL) detection of oxalate in a flow injecti on analysis system is reported, where bpy is 2,2'-bipyridyl and PVP is poly (4-vinylpyridine). Immobilization of the ECL reagent means that it Can Be r egenerated in situ, eliminating the need to constantly: deliver it to the r eaction zone. Electrochemically:generated Ru3+ reacts with the analyte to f orm the excited-state [Ru2+]*, which luminesces at 610 nm. The reaction is optimal at low pH, where the layer is swollen and homogeneous charge transp ort through the layer is more facile.: Unlike traditional approaches, we si multaneously monitor both the amperometric and luminescent response of the modified electrode. The precision of both signals is:similar at similar to2 % (n = 10). However, the ECL response has a larger dynamic range extending from the low-micromolar to higmillimolar range and a lower limit of detecti on, similar to0.2 muM or 4 pmol of oxalate injected. The ECL approach displ ays excellent selectivity for oxalate over:a wide range of potential interf erences including oxygen, amines, iron sulfate, ammonium nitrate, urea, and glucose. Ascorbic acid represents the most significant ECL interference. H owever, the signal observed for a 1 mM solution of ascorbic acid is still. only 2.6% of the response Observed for the injection of a similar concentra tion of oxalate.