Comparison of Two Methods for Detecting Vitamin C in Apple

In order to determine vitamin C in apple,2,4-dinitrophenylhydrazine method and UV spectrophotometry were compared.In the 2,4-dinitrophenylhydrazine method,the maximum absorbance wavelength was 500 nm,the reaction was carried out in 37 ℃ water bath for 3h.Its correlation coefficient(R2) for standard curve was 0.999 5,linear regression equation was y=0.232 1x-0.001 2.In UV spectrophotometry,the maximum absorbance wavelength was 243 nm,its correlation coefficient(R2) for standard curve was 0.998 4,linear regression equation was y=0.007 5x-0.014 0.The contents of vitamin C detected with these two methods were 7.36 mg/100 g and 7.32 mg/100 g,respectively.