STUDIES ON TLC-SCANNING DETERMINATION OF ALKALOIDS IN THE CHINESE DRUG QINJIAO(GENTIANA MACROPHYLLA)

Quantitative determination of the alkaloids in the Chinese drug Qinjiao (G. macrophylla) with a Sbimadzu TLC-scanner is described.Powdered crude drug was extracted with mixed solvent. The extract was directly spotted on a silliea gel GF₂₅₄ plate alongside with the standard substances. Using Et₂O—Me₂CO (5:1) as developing Solvent, the plate was saturated for 30 min and then developed for 16 cm, the alkaloids in the extract were well separated. The spots were detected with fluorescence quenching and fluorometry and scanned by a dual wavelength TLC-seanner Shimadzu model CS-930. The program parameters are: reflectance mode; Zig-Zag scanning; λ_S 255 nm, λ_R 280 nm for gentianine and λ_S 300 nm, λ_R 330 nm for gentianal respectively; SX=7; slit=2×2 mm; △y=0.2; ID Ext=1; two straight lines (gentianine in the range of 4～24μg, gentianal in the range of 0.2～1.2μg) passing through the origin were obtained. The stability of spots was 0.5～6h. The average recoveries of the two alkaloids were 102.75% and 100.42%, the variation coefficients were 2.48% and 0.22%, respectively.This method is simple, rapid, sensitive, accurate and reproducible. It was applied to the determination of gentianine and gentianal in Qinjiao from the same and different habitats. The alkaloid contents were compared in different organs of the same species. Both cultivated and wild Qinjiao were studied. These results showed that the alkaloids contents in Gansu Qinjiao were higher than those in other provinces.