Fluorescence resonance energy transfer between acridine orange and rhodamine 6G and its analytical application for vitamin B12 with flow-injection laser-induced fluorescence detection

By coupling flow-injection with laser-induced fluorescence detection, a setup was developed and a novel method combining fluorescence resonance energy transfer (FRET) and flow-injection analysis (FIA) was proposed for the determination of vitamin B12 (VB12) based on its fluorescence quenching on the system of acridine orange (AO)/rhodamine 6G (R6G). The effective energy transfer could occur between AO and R6G in the dodecyl benzene sodium sulfonate (DBS) while 454 nm argon laser was used as the excitation source, and as a result, the fluorescence emission of R6G has been increased significantly. It was found that the fluorescence of the above system could be sharply diminished by VB12. By using the mixed solution AO–R6G–DBS and the same solution containing VB12 as the carrier and sample, respectively, a series of negative peaks which could be applied for the quantification of VB12 were obtained. The detection limit for VB12 was 1.65 × 10−6 mol/L. The linear range for determining VB12 was 4 × 10−4 to 2 × 10−6 mol/L (correlation coefficient, r = 0.9923). The method was applied to measure VB12 injections with satisfactory results.