High sensitive fluorophotometric determination of nucleic acids with Pyronine G sensitized by N,N-dimethylformamide.

In Tris-HCl buffer (pH 8.0), the fluorescence of Pyronine G emitted at 552 nm was quenched by nucleic acids when excited at 525 nm. Adding N, N-dimethylformamide (DMF) as a sensitive media can enhance the sensitivity greatly. Based on the fluorescence reactions sensitive fluorimetric methods for nucleic acids at nanogram levels were proposed. Under the optimum conditions, the calibration curves were linear in the range of 0.0032 ∼ 2.5 μg mL -1 for ct DNA and 0.0024 ∼ 2.5 μg mL -1 for hs DNA. The limits of determination were 3.2 ng mL -1 and 2.4 ng mL -1 respectively. This method has good selectivity and high sensitivity. It has been applied to the determination of DNA in the synthetic samples and real samples with satisfactory results.