The second-order scattering study of the Tb(III)-RNA and determination of RNA

The second-order scattering technique (SOS), using a common spectrofluorometer, was first developed as a sensitive instrumental analysis method for determination of the ribonucleic acid (RNA). The results indicate that RNA had a weak SOS peak and the Tb(III) ion can greatly enhance the SOS intensity of RNA with the maximum peak located at 612.0 nm. Mechanism study shows that the peak results from the long-range assembly of Tb(III) ion on the molecular surface of RNA. At the pH 7.50 and with cetyltrimethylammonium bromide (CTMAB) (6.0 × 10−5 M), the enhanced SOS intensity was in proportion to the concentration of RNA in the range of 2.0 × 10−8 to 2.0 × 10−5 g/ml. The detection limit was 1.96 ng/ml. The relative standard deviation (five replicates) was within ±5% in the linear range. This method has been used satisfactorily for the determination of both synthetic and real samples. In comparison with most other methods for the determination of ribonucleic acids, this method is more sensitive.