With the rapid increase of water contamination

membrane separation technology and their corresponding molecular weight cut-off (MWCO) evaluation method become more necessary. In this study

Panax notoginseng

saponins was used as a new standard marker to determinate ultrafiltration (UF) membrane MWCOs

series of Millipore membranes were selected as control group to analyze and calculate the relationship between retention rate and MWCOs with exponential or logarithmic equation. A new and convenient method was provided for determining the membrane MWCO by modeling analysis retention rate with MWCOs

and the regression coefficients ≥0.990. The feasibility and practicability of established method was verified by different manufactures' membrane and dextrans. In the detection progress

as the main ingredient of

Panax notoginseng saponins

Notoginsenoside R

1

Ginsenoside Rg

1

Ginsenoside Rb

1

and

Ginsenoside Rd

with different surface activity

the MWCO range of UF membranes can be divided into two zones mainly due to the retention rate difference among

Notoginsenoside R

1

Ginsenoside Rg

1

Ginsenoside Rb

1

and

Ginsenoside Rd

. Zone I

1000-10000; and Zone II

10000-100000. Thus

the new method would be helpful to improve the applicability of UF membrane in separation technology.