Determination of nucleic acids with tetra-( N-hexadecylpyridiniumyl) porphyrin sensitized by cetyltrimethylammonium bromide (CTMAB) using a Rayleigh light-scattering technique

Abstract

Using a common spectrofluorometer to measure the intensity of Rayleigh light-scattering (RLS), a method for determination of nucleic acids has been developed. At pH 10.24 and ionic strength 0.01 mol l −1 (NaCl), the Rayleigh light-scattering of the tetra-( N-hexadecylpyridiniumyl) porphyrin (TC 16PyP) is greatly enhanced by nucleic acids in the presence of cetyltrimethylammonium bromide (CTMAB), with the scattering peak located at 311.8 nm. The enhanced RLS intensity is in proportion to the concentration of calf thymus DNA (ctDNA) in the range 0.2–6.0 μg ml −1 and to that of fish sperm DNA (fsDNA) in the range 0.05–3.0 μg ml −1. The limits of detection are 0.016 μg ml −1 for calf thymus DNA and 0.023 μg ml −1 for fish sperm DNA when the concentration of TPP was chosen 2.0×10 −6 mol l −1. Four synthetic samples were determined satisfactorily.