Objective: To establish a method for determination of (R

S)-epigoitrin in decoction of Isatidis Radix and optimize ceramic membrane microfiltration purification technology for decoction of Isatidis Radix. Method: The content of (R

S)-epigoitrin was determined by HPLC

chromatographic conditions were as follows:mobile phase of methanol-water-phosphoric acid-triethylamine (14.0:85.3:0.6:0.1)

detection wavelength 245 nm.Single factor tests were used to optimize ceramic membrane aperture according to indexes of transfer rate of (R

S)-epigoitrin and removal rate of impurity

then turbidity of decoction of Isatidis Radix before and after purified was determined. Result: Standard curves of (R

S)-epigoitrin was linear in the range of 0.002 5-0.248 μg with r=0.999 9

the average recovery was 98.9% with RSD of 1.9%.Optimal purification technology was as following:ceramic membrane aperture 200 nm

inlet pressure was 0.2 MPa

When liquid volume in reservoir barrel was not enough to circulate

water with equal to the amount of the least circulation volume of membrane filtration system was added to the barrel once

and when filtration volume was equivalent to the original

microfiltration was ended;Under these conditions

transfer rate of (R

S)-epigoitrin was (87.8±1.9)%

removal rate of impurity was (18.7±0.4)%.Turbidity of membrane filtrate with 200

50

10 nm were (1.4±0.3)

(1.5±0.2)

(0.5±0.2) NTU

Turbidity of retentate were (181.0±2.1)

(220.4±2.5)

(226.2±2.4) NTU. Conclusion: This determination method was rapid

accurate and stable with fine repeatability

it could be adopted to determined the content of (R

S)-epigoitrin.Ceramic membrane with 3 kinds of aperture could be well separated insoluble suspended particulate matter in aqueous extract of Isatidis Radix

but clarify effect had no difference among each aperture.