Fluorimetric determination of nucleic acid using the enhancement of terbium-gadolinium-nucleic acid-cetylpyridine bromide system.

It is found that the fluorescence intensity of Tb-cetylpyridine bromide (CPB)-nucleic acid system can be enhanced by La(3+), Gd(3+), Lu(3+), Sc(3+) and Y(3+), of which Gd(3+) has the greatest enhancement. The experiments indicate that under the optimum condition, the fluorescence intensity of the system is in proportion to the concentration of nucleic acids in the range from 9x10(-8) to 1x10(-5) g ml(-1) for yeast RNA, from 1x10(-7) to 1x10(-5) g ml(-1) for fish sperm DNA. The detection limits are 3.2 and 4.1 ng ml(-1), respectively. This method has been used satisfactorily for the determination of both synthetic and actual samples. In comparison with most fluorescence method for the determination of nucleic acids, this method has higher sensitivity and stability.