蔬菜中叶酸的催化氧化荧光法测定

建立了催化氧化荧光法间接测定叶酸的新方法。在pH5.0的HAc-NaAc缓冲溶液中,Co2+催化KIO4氧化叶酸产生强荧光,以262 nm为激发波长,在445 nm处测定叶酸的氧化产物蝶呤-6-羧酸的荧光强度,研究了反应的适宜条件及动力学参数,并探讨了反应机理。在优化实验条件下,叶酸浓度在1.0×10-8~1.0×10-5mol/L范围内与荧光强度呈良好线性关系,回归方程为ΔIF=10.82c(μmol/L)+2.867,相关系数r=0.998 5,方法的检出限为5×10-9mol/L。对5×10-7mol/L叶酸标准溶液进行11次平行测定,相对标准偏差(RSD)为0.1%。该法使用Co2+为催化剂,大大提高了方法的灵敏度。方法用于蔬菜中叶酸的测定,加标回收率为93%~104%,6次测定的相对标准偏差为0.98%~2.1%,结果令人满意。

Catalytic Oxidation Fluorometry for Determination of Folic Acid in Vegetable

Based on the catalytic effect of cobalt(Ⅱ) on the oxidation of folic acid by high potassium iodate in pH 5.0 HAc-NaAc buffer solution.A new catalytic oxidation fluorometric method for indirectly determination of folic acid was proposed.The amount of folic acid was obtained by determining the fluorescence intensity of pterin-6-carboxylic acid,the oxidation product of folic acid,at exciting wavelength of 262 nm and measuring wavelength of 445 nm.The optimum reaction conditions and kinetic parameters of this reaction were investigated,and the reaction mechanism was studied.Under the optimal conditions,the folic acid concentration within a range of 1.0×10~(-8)-1.0×10~(-5) mol/L had a good linear relation,the regression equation was ΔI_F =10.82c(μmol/L)+2.867 with a correlation coefficient of 0.998 5.The detection limit of method was 5×10~(-9) mol/L,and the relative standard deviation(RSD,n=11) for 5×10~(-7) mol/L folic acid was 0.1%.The developed method with cobalt(Ⅱ) as catalyst,showed high sensitivity,and was applied for the detection of folic acid in vegetable with spiked recoveries of 93%-104%,and RSDs of 0.98%-2.1%.