Improved method to detect nitric oxide in biological systems

In this work an improved method is described for using organic solvent extracting to detect nitric oxide. The partition coefficients of the diethylthiocarbamate (DETC)-Fe2+ complex between different organic solvents and water, the signal intensity of the: same NO trapping complex concentration in different organic solvents, and the extracting abilities of the organic solvents were determined. It was found that ethyl acetate was the optimal organic solvent. With ethyl acetate as extracting solvent, the (DETC)(2)-Fe2+-NO complex was extracted from water phase to organic phase, and low concentration of nitric oxide in large volume could be detected by electron spin resonance (ESR) at room temperature. The ESR signal intensity had a good linear relationship with the concentration of nitric oxide, at a signal-to-noise ratio of 2. The detection threshold of this method was improved to lower than 50 nM, which was more sensitive than the usually used method. The (DETC)(2)-Fe2+-NO complex was stable in the dark at 0-4 degreesC, and there was little change after days. Nitric oxide produced by cardiomyocytes cultured in media and other biological systems was firstly detected with this method.