Interaction of cetylpyridine bromide with nucleic acids and determination of nucleic acids at nanogram levels based on the enhancement of resonance Rayleigh light scattering

Resonance Rayleigh light scattering (RRLS) spectra of cetylpyridine bromide (CPB)-nucleic acid system and their analytical application have been first studied. The effective factors and optimum conditions of the reaction have been investigated. After CPB and nucleic acid are mixed together, a new absorption peak located at 300 nm appeared, which is due to the formation of new ion associate of CPB-nucleic acid. The new associate can result in two apparent RRLS peaks at 310-400 and 460-480 nm. The RRLS peak of the corrected spectra located at 290-350 nm, which indicate that the RRLS is originated from the absorption of CPB-nucleic acid associate. The peak at 460-480 nm disappears in the corrected RRLS spectra, which indicated that this peak is originated from the strong line emission of the Xe lamp. Under the optimum conditions, the enhanced intensity of RRLS is proportional to the concentration of nucleic acid in the range of 5.0 x 10(-9)-5.0 x 10(-5) g ml(-1) for calf thymus DNA (etDNA), 1.0 x 10(-8)-4.0 x 10(-5) g ml(-1) for fish sperm DNA (fsDNA) and 1.0 x 10(-8)-5.0 x 10(-5) g ml(-1) for yeast RNA (gammaRNA). The detection limits (S/N= 3) are 4.3, 8.7 and 7.4 ng ml(-1), respectively. Synthetic samples were determined satisfactorily. (C) 2002 Elsevier Science B.V. All rights reserved.