Determination of Emodin in Giant Knotweed by Scanning Thin Layer Chromatography

Scanning thin layer chromatography (TCL) was applied to the determination of emodin in giant knotweed,using silica gel as adsorbent supported on the TLC plate,and a mixture of toluene,ethylacetate and formic acid (mixed in the ratio of 30∶4∶2) as developing solvent. Quantitative measurement was made by DW reflective linear scanning of the emodin spot at the wavelengths of λS 440 nm and λR 600 nm. Linear relationship between values of integral of peak area of the spots and mass of emodin was obtained in the range of 0.40-0.81 μg,as shown be the linear regression equation of y=1 899.985 0 x+122.946 1 (r=0.984 0). Precision of the method was performed on the same silica gel plate by spotting 4 μL portions of reference standard solution of emodin of same content,and value of RSD′s (n=7) found was 0.95%. Test of recovery was made by adding standard solutions to samples with known contents of emodin,values of recovery found were in the range of 95.7%-99.4%.