Processing of Rhubarb and Determination of Five Free Anthraquinones in Raw Rhubarb and Stewed Rhubarb

[Objectives]To determine the content of five kinds of free anthraquinones in raw rhubarb and stewed rhubarb by HPLC,and compare their content difference,so as to reveal the change rule of material basis before and after processing of traditional Chinese medicine.[Methods]The content was determined by HPLC with Thermo BDS HYPERSII C18 column(4.6 mm×250 mm,5μm)as chromatographic column and methanol-0.1%phosphoric acid(85∶15)aqueous solution as mobile phase;the detection wavelength was 256 nm,the flow rate was 1.0 mL/min,the column temperature was 30℃,and the injection volume was 10μL.[Results]Aloe-emodin,rhein,emodin,chrysophanol and emodin methyl ether showed a good linear relationship in the linear range of 0.0207-0.414(R2=0.9999),0.1721-3.442(R2=0.9996),0.0203-0.406(R2=0.9999),0.148-2.96(R2=0.9998)and 0.164-3.28(R2=0.9993),respectively;the content of aloe-emodin decreased by about 8.26%,and rhein decreased by about 9.21%;the content of emodin increased by about 16.44%,chrysophanol increased by about 16.12%,and emodin methyl ether increased by about 20.01%,indicating that the processing technology had different effects on the components of rhubarb.[Conclusions]The content of five free anthraquinones in rhubarb was affected to different degrees after processing,and this method could be used as a quality control method for rhubarb and its different processed products.