SELECTIVE DETERMINATION OF DNA BY ITS ENHANCEMENT EFFECT ON THE FLUORESCENCE EU3+-TETRACYCLINE COMPLEX

fluorescence enhancement of the Eu3+-tetracycline complex by DNA or RNA was studied. Studies involving natural and denatured fish sperm DNA, calf thymus DNA, and yeast RNA revealed that double-stranded and single-stranded DNA is capable of enhancing the fluorescence of the Eu3+ -tetracycline complex, while RNA showed very little enhancement effect, which founded a basis for selective determination of DNA in the presence of RNA. Maximum fluorescence was produced in the pH range 8.0-9.7, with maximum excitation and emission wavelengths at 398 and 615 nm, respectively. Under optimal conditions, the calibration graphs were linear between 0.02 and 1.0 mu g mL(-1) for both double-stranded calf thymus and fish sperm DNA. The corresponding detection limits were 0.01 mu g mL(-1). The relative standard deviation (seven replicates) was within 3.0% in the linear range, DNA could be determined in the presence of yeast RNA. If the time-resolved mode was used, the low end of the linear range could be extended to 0.005 mu g mL(-1), with a detection limit of 0.003 mu g mL(-1), The mechanism for the fluorescence enhancement was also studied.