Flow-injection chemiluminescence determination of DNA based on a photochemical reaction Original Research Article

The determination of DNA using the coupling between a photochemical reaction and a chemiluminescent reaction in a flow injection (FI) system is described. The method is based on intercalating 9,10-anthraquinone-2,6-disulphonic acid (AQ) (disodium salt) within the helix of double-stranded calf thymus (CT) DNA. The anthraquinone molecules that are thus intercalated cannot sensitize the photooxidation of ethanol to yield hydrogen peroxide, which is monitored through the chemiluminescent reaction with luminol catalysed by hematin. There is a linear relationship between the decrease in the chemiluminescent response and the DNA concentration at a constant concentration of anthraquinone. Under the optimal conditions, the calibration graph is linear in the range 0.04–5.5 μg ml−1 with a throughput of 45 samples per hour and relative standard deviations between 0.17% and 1.3%. The 3σ limit of detection is 17 ng ml−1. The method was used for the determination of DNA extracted from rabbit tissues and leaves of the orange tree and the flame tree.