Methyl Ether-Derivatized Sterols and Coprostanol Produced via Thermochemolysis Using Tetramethylammonium Hydroxide (TMAH)

• Published in: Molecules (Basel, Switzerland) Vol. 24; no. 22; p. 4040
• Main Authors: Nakakuni, Masatoshi, Yamasaki, Yoshimi, Yoshitake, Nonoka, Takehara, Keiko, Yamamoto, Shuichi
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 07.11.2019; MDPI
• Subjects: Cholestanol - analysis; Cholestenes - analysis; Cholesterol; coprostanol; Ethers; Fecal coliforms; Gas chromatography; Gas Chromatography-Mass Spectrometry; Geologic Sediments - chemistry; Lipids; Mass spectra; Mass spectrometry; Mass spectroscopy; Methylation; Microorganisms; Quaternary Ammonium Compounds - chemistry; Sediment samplers; Sediments; Solvents; Sterols; tetramethylammonium hydroxide (tmah); thermochemolysis; United States > US; thermochemolysis; sterols; coprostanol; tetramethylammonium hydroxide (TMAH)
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules24224040

Sterols are widely distributed in nature from lipids in organisms to sediments. As a conventional method, extraction and derivatization with TMS have been applied for sterol analysis, requiring a long preparation time for gas chromatography-mass spectrometry analysis. In this study, for sterol analysis, thermochemolysis using tetramethylammonium hydroxide (TMAH) was applied. This method performs hydrolysis and methylation simultaneously; thus, free and ether-bonding sterols can be analyzed as sterol methyl ethers in a relatively short time period. A sediment sample from a tideland (the Yatsu tideland, Japan) was analyzed using the TMAH method, and we detected more than 10 sterols, which include cholest-5-en-3 -ol (cholesterol), 24-ethylcholest-5-en-3 -ol (sitosterol), 24-methylcholesta-5,22 -3 -ol (brassicasterol), 24-ethylcholesta-5,24(28) -dien-3 -ol (isofucosterol), 4 ,23,24-trimethyl-5 (H)-cholest-22 -en-3 - ol (dinosterol), and 5 (H)-cholestan-3 -ol (coprostanol). The detection of the various sterols can be attributed to multiple natural and artificial sources around the Yatsu tideland. In this paper, the mass spectra of these sterols are provided together with an interpretation of their fragmentation patterns. Additionally, the fecal pollution in the Yatsu tideland is discussed in the context of the detection of coprostanol.