A versatile method for quantification of DNA and PCR products based on time-resolved EuIII luminescence

A versatile and robust method for the determination of DNA and PCR products ( $0.1 ng \, \mu L^{-1}$ (dsDNA, ssDNA or circular DNA), the quenched luminescence is reinstated, AO and EB intercalating into DNA, which removes the interaction with the $Eu^{III}$ complexes. The best results are obtained with $[Eu_2(L^{C2})_3]/AO$ with detections limits in the range $0.18\mbox{\--}0.66 ng \, \mu L^{-1}$; detection limits for the $[Eu(L^{kel})]/AO$ system are slightly larger; simpler monometallic $Eu^{III}$ complexes with dipicolinate derivatives do not follow suit in that they decompose in the presence of DNA. The $Eu^{III}/AO$ method is shown to be pH insensitive in the range 3–10; furthermore it is essentially insensitive to 1000-fold excesses of potential interfering substances, e.g. BSA, glucose, chelating agents and anions, alkaline earth and transition metal cations, variations in luminescence intensity being < 5%, (10 analytes) or 5–10% (4 analytes); only $Co^{II}$ and $Cu^{II}$ interfere substantially.