Determination of the content of Eucommia ulmoides gum by Variable Temperature Fourier Transform Infrared Spectrum

摘要

AbstractConsidering the rapidity and lesser sample amount required, the Fourier Transform Infrared Spectra (FTIR) was often used to quantitatively determine the rubber content of Russian dandelion, guayule, etc. This is because their chemical structure arecis-1,4-polyisoprene (CPI) which has a unique and isolate skeleton stretching vibration peak at 835?cm?1band, and is convenient for determining the rubber content. However, this method is not suitable forEucommia Ulmoides (EU)gum which will crystallize easily at room temperature due to the regular chemical structure oftrans-1,4-polyisoprene (TPI), that will restrict the skeleton stretching vibration of TPI greatly. As a result, its FTIR spectrum only shows a very small peak at 845?cm?1band hiding among a number of crystalline peaks around nearby, thus it cannot be used to determine the rubber content ofEucommia ulmoidesoliv (E.?ulmoids) directly. Actually, these crystalline peaks could be eliminated easily by elevating the temperature over 60?°C, and a unique and isolate skeleton stretching vibration characteristic band at 845?cm?1was left alone in the TPI's FTIR spectrum which can be used expediently to determine the content ofEUgum. At the present paper, the Variable Temperature Fourier Transform Infrared Spectroscopy (VTFTIR) was used to determine the rubber content ofE.?ulmoides. The results indicate that the rubber content ofE.?ulmoidessamples (1–40, 5–35, 22–11) provided by Northwest Agriculture and Forestry University (NAFU) are 4.66%, 4.04%, 4.32% respectively, and the errors of average value were less than 5% compared with Soxhlet Extraction.Graphical abstractThe traditional determining methods of rubber content for NR are not suitable forEucommia ulmoidesgum due to the difference of chemical structure. So the Variable Temperature Fourier Transform Infrared Spectroscopy was used to determine the rubber content ofEucommia ulmoidesoliver, and the results indicate that the rubber content of three samples are 4.66%, 4.04%, 4.32% respectively, and the errors to average value were less than 5% compared with Soxhlet Extraction.Display Omitted]]>