Sensing Of NO Based On Yttrium Methyl Salicylate Complex

The chemistry of nitric oxide (NO) plays a critical role in many physiological processes. So, studies on the biochemical properties and the detection methods of NO are the frontier topics in the world present. A mass of experimental and theoretical studies on NO chemistry as well as the methods of NO sensing have been reported in literature. However, more attention should be paid on finding out more simply and effectively way to trapping and sensing NO because of its exsilient and oxidation properties. In this study, we proposed and established a simply way for NO sensing based on the selective color reaction of NO with methyl salicylate complexes of rare earths. And then we discussed the relating mechanism on this chemical reaction.We found that bubbling NO into ethyl acetate solution containing methyl salicylate complexes and rare earth perchlorates at a given temperature resulted in the formation of stable cyan product. However, this reaction does not occure for salicylate ester and their complexes with transition metals such as iron. These facts indicate that this characteristic reaction only occurs between NO and the complexes of salicylate ester with rare earths. The optimum reaction ratio of rare earth, methyl salicylate and NO of the color reaction was found to be 2:2:1 by means of equimolar series method. We suggest that the color compounds are the adducts of NO and phenol ring of salicylates coordinated to rare earths. The maximum peak at 640nm in UV spectrum is attributed to the charge transfer between NO and phenol ring. Further, it is also probablely involves the formation of nitrosation adducts.Based on this selective reaction and the linear relationship between the absorbance of reaction solution and the concentration of NO, we proposed and established an simply way for NO sensing. And the optimum coloration conditions and concrete steps were determined thereafter:ethyl acetate is selected for absorbing NO, and ethyl acetate solution of yttrium perchlorate and methyl salicylate with mole ratio of 1:1 is employed as chromogenic reagent. After absorbing NO, a certain volume of sample solution should be taken into a colorimetric tube within 10 min, and then excess chromogenic reagent is added. The mixture solution is placed in a thermostatic water bath for reacting 20-30mins at 90℃; The resulting solution is coolled to room temperature and then diluted to scale. The absorbance is determined at 640nm using reagent as blank, and then content of NO can be calculated according to the standard curve. This method was demonstrated to be of good reproducibility and high sensitivity. The detection limit is achieved to be 4×10-8 mol.