Analytical Sciences

Determination of DNA with Cetyltrimethylammonium Bromide by the Measurement of Resonance Light Scattering

Yuan Fang LI,* Wei Qun SHU,** Ping FENG,* Cheng Zhi HUANG,*  and Ming LI*

*Institute of Environmental Chemistry, Southwest Normal University, Chongqing 400715, P. R. China
**Department of Environmental Health, The Third Military Medical University, Chongqing 400038, P. R. China

A simple assay of DNA was developed based on the measurements of enhanced signals of Resonance Light Scattering (RLS) of cetyltrimethylammonium bromide (CTMAB) by DNA. The enhanced RLS signals, measured by simultaneously scanning the excitation and emission monochromators of a common spectrofluorometer with lambda_ex = lambda_em, was optimized for the DNA assay with CTMAB. On the conditions of pH 2.21 and ionic strength 0.002, the enhanced RLS intensity at 470.0 nm, deltaI, was found to be proportional to the concentration of DNA in the range 0 - 2.5 ug/ml if 1.5 x 10^-5 M CTMAB was used. Limits of determination for calf thymus DNA and fish sperm DNA were 4.9 ng/ml and 9.2 ng/ml, respectively. Synthetic samples were determined with the recovery ratio ranging from 93.2% to 105.1%, and the RSD is lower than 2.7%.

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