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Differentiation of isomeric cresols by silylation in combination with gas chromatography/mass spectrometry analysis
Author(s) -
Xu Jiaxiang,
Zhu Guohua,
Zhang Huarong,
Liu Jinsong,
Jiang Kezhi
Publication year - 2020
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.8576
Subject(s) - chemistry , silylation , trimethylsilyl , mass spectrometry , electron ionization , silanes , mass spectrum , dissociation (chemistry) , gas chromatography , phenol , chromatography , gas chromatography–mass spectrometry , silane , analytical chemistry (journal) , ion , organic chemistry , ionization , catalysis
Rationale m ‐Cresol is listed as a priority controlled contaminant in many countries, but it is very difficult to accurately determine isomeric cresols due to their incomplete chromatographic separation on commercially available chromatographic columns and their nearly identical mass spectra. Methods Silylation of isomeric cresols was carried out by treatment with N ‐methyl‐ N ‐(trimethylsilyl)trifluoroacetamide. The formed trimethyl(tolyloxy)silanes were analyzed by gas chromatography/mass spectrometry (GC/MS). Theoretical calculations were carried out with the Gaussian 03 program using the density functional theory (DFT) method at the B3LYP/6‐311 + G(2d,p) level. Results The derivatives of three isomeric cresols and six isomeric xylenols have been completely separated on an HP‐5MS capillary column within a GC run of only 10 minutes. In addition, the derivative o ‐cresol can be very easily differentiated from its isomers due to its characteristic base peak ion at m / z 91 in electron ionization (EI)‐MS. DFT calculation results indicated that the formation of the abundant fragment ion at m / z 91 is attributed to a facile dissociation pathway involving the shift of a neighboring phenylmethyl hydrogen atom in EI‐MS of trimethyl( o ‐tolyloxy)silane. Conclusions Silylation provides a promising solution for simultaneous determination of isomeric cresols and isomeric xylenols.