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

The determination of DNA using the coupling between a photochemical reactio n and a chemiluminescent reaction in a flow injection (FI) system is descri bed. The method is based on intercalating 9,10-anthraquinone-2,6-disulphoni c acid (AQ) (disodium salt) within the helix of double-stranded calf thymus (CT) DNA. The anthraquinone molecules that are thus intercalated cannot se nsitize the photooxidation of ethanol to yield hydrogen peroxide, which is monitored through the chemiluminescent reaction with luminol catalysed by h ematin. There is a linear relationship between the decrease in the chemilum inescent response and the DNA concentration at a constant concentration of anthraquinone. Under the optimal conditions, the calibration graph is linea r in the range 0.04-5.5 mu g ml(-1) with a throughput of 45 samples per hou r and relative standard deviations between 0.17% and 1.3%. The 3 sigma limi t of detection is 17 ng ml(-1). The method was used for the determination o f DNA extracted from rabbit tissues and leaves of the orange tree and the f lame tree. (C)1999 Elsevier Science B.V. All rights reserved.