Study on the Small Molecular Composition of Cutinite from Luquan Cutinitic Liptobiolith by Ultrasonic-Assisted Sequential Extraction

Abstract

The cutinite content in a typical cutinitic liptobiolith from the Luquan area of Yunnan Province, China, of middle Devonian, can be up to 85%. The equal density gradient method was used to separate the cutinite with the density gradient of cutinite being primarily 1.07–1.21 g/cm3. Then, the cutinite was sequentially extracted with methanol, acetone, isometric N-methyl-2-pyrrolidone/carbon disulfide mixture (NMP/CS2), and cyclohexanone with ultrasonic irradiation to afford soluble portions (E1–E4) and residues (R1–R4). In total, about 48.60% of the organic matter in cutinite became soluble. According to the analysis of soluble portions by gas chromatography/mass spectrometry and 1H NMR, E1 was rich in nitrogen-containing organic compounds and esters, amounting to 50.72 and 30.32%. Esters were found in E1, E2, and E4. The content of esters in E2 was 43.54%. In addition, alkanes also were found in E2 and E3, attaining 21.10 and 19.88%, respectively. The main products of cyclohexanone extraction were ketones,...