A Xinjiang subbituminous coal was directly oxidized in aqueous sodium hypochlorite and sequentially extracted with diethyl ether and ethyl acetate. The extracts were esterified with diazomethane and the esterified products were analyzed using a high performance liquid chromatography/mass spectrometry (HPLC/MS) equipped with atmospheric pressure photoionization (APPI) or electrospray ionization (ESI) ion source. Toluene and a toluene/anisole mixture (vol/vol = 95:5) were used as dopant for APPI-MS. The relative content of organic species over 500 Da detected by ESI-MS was much higher than those identified by APPI-MS with and without dopant. Most of the species were associated molecules containing heteroatoms. The addition of dopant greatly enhanced the ionization efficiency and toluene induced better ionization effects compared to the mixture in both ion signal intensity and number of detected species. However, according to the ionization mechanism of APPI, analyte molecules with ionization energy value over that of dopant and less than the energy of photon were well ionized under direct APPI mode.

Molecular characteristics of a Chinese subbituminous coal using HPLC/MS

249th National Meeting (2015)

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