Simultaneous qualitation and quantitation of natural trans-1,4-polyisoprene from Eucommia ulmoides Oliver by gel permeation chromatography (GPC)

•First, we aimed at enabling a simultaneous gel permeation chromatography (GPC) method to analyze the content and molecular-weight distribution (MWD) of natural trans-1,4-polyisoprene (TPI) from Eucommia ulmoides Oliver.•Second, we investigated TPI from multiple plant issues of E. ulmoides, such as leaves, fruit coatings and bark, and explored the MWD relationship among them.•Results showed that because of higher yield and higher MW, fruit coating was more suitable for rubber industry use and turned out to be a promising source of natural TPI.

Natural trans-1,4-polyisoprene (TPI) as a functional biomaterial has aroused great interest for rubber industrial product use. Here, we proposed a method that enables simultaneous analysis of the content and molecular-weight distribution (MWD) of natural TPI by gel permeation chromatography (GPC). The natural TPIs were collected from leaves, fruit coatings and bark of Eucommia ulmoides Oliver (E. ulmoides) through toluene extraction followed by ethanol purification. The results of TPI contents from leaves and fruit coatings were shown ca. 3.5% and 13.8%, respectively. Accordingly, limits of detection (LODs) of TPI were 0.58 mg/mL from leaves and 0.47 mg/mL from fruit coatings. The MWDs of TPI demonstrated a bimodal distribution from leaves, a unimodal distribution from bark, and a unimodal distribution with a tiny peak shoulder from fruit coatings. In real-life E. ulmoides analysis, the results from three independent methods (GPC, gravimetric method, and infrared spectroscopy) were obtained with good consistency.