Quantitative analysis of glucosinolate of Chinese kale by HPLC-external standard method
The feasibility of glucosinolate quantitative analysis by Sinigrin as external standard and the glucosinolates in bolting stem of Chinese kale were studied. It was found that there was a positive correlation between the concentration of Sinigrin and peak area under the condition of 14.2 U sulfatase and HPLC measurement. The regression equation was y =3E -07x +0.001 and coefficient of regression is 0.9994. The standard recovery and comparison experiments indicated that Sinigrin external standard method is precise and can be used instead of the expensive internal standard Glucotropaeolin. 11 GS compounds in Chinese kale bolting stems were separated by HPLC and confirmed by electrospray mass spectrometry, including 7 kinds of aliphatic GSs and 4 kinds of indolyl GSs which accounted for 63.41% and 36.59% of total GSs content, respectively. Among them, Glucoerucin was detected in Chinese kale for the first time. The highest content GS in bolting stem of Chinese kale was Gluconapin, while the lowestcontent of GS was Glucoerucin.