Application of magdala red as a fluorescence probe in the determination ofnucleic acids

A fluorescence quenching method was developed for the rapid determination o f DNA and RNA using magdala red as fluorescence probe. In weakly acidic med ium, the fluorescence of magdala red (lambda ex\lambda em = 540\555 nm) can be largely quenched by DNA or RNA. The calibration graphs are linear over the range 0.01-1.2 mu g/mL for both calf thymus DNA (CT DNA) and salmon DNA (SM DNA), and 0.015-1.0 mu g/mL for yeast RNA, respectively. The correspon ding detection limits are 6.0 ng/mL for CT DNA, 7.0 ng/mL for SM DNA and 15 .0 ng/mL for yeast RNA, respectively. CT DNA could be determined in the pre sence of 20% (w/w) yeast RNA, and the relative standard deviation of six re plicate measurements is 3.18% for 400 ng/mL of CT DNA. Interference from co existing substances in the determination of DNA was also examined. Real sam ples were determined with satisfactory results.