Prediction of retention indexes. IV. Chain branching in alkylbenzene isomers with C10-13 alkyl chains identified in a scintillator solvent.
Twenty solvent components in a commercial scintillator were identified by chromatography on polar and non-polar columns and by gas chromatography-mass spectrometry (GC-MS) as isomeric 1-(alkyl)m(alkyl)nbenzenes with formulae C16H26, C17H28, C18H30 and C19H32. These isomers occur in four clusters of chromatographic peaks representing ca. 6, 44, 34 and 16% of the total solvent mass. The retention indexes of the isomers are influenced by the lengths of the alkyl chains in the molecule, and their polarity and polarizability can affect the column difference, which is the difference between retention indexes on polar and non-polar columns. 1-Methylalkylbenzenes have higher retention indexes and larger column differences than the evenly distributed isomers, such as 1-butylhexyl-1-pentylhexyl, 1-pentylheptyl- and 1-pentyloctylbenzene. The results demonstrate the effect of structural symmetry on the retention indexes of the isomers. This study shows that the ability to relate GC data and column differences to structures can facilitate the interpretation of GC-MS data in the structure identification of isomers.
Peng
C T
CT
Department of Pharmaceutical Chemistry, School of Pharmacy, University of California, San Francisco 94143-0446.
Hua
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RL
Maltby
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D
D000478:Alkylation; D001554:Benzene / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D002849:Chromatography, Gas; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D007536:Isomerism; D012588:Scintillation Counting / Q000379:methods; D012997:Solvents / Q000032:analysis*
D012997:Solvents; D001554:Benzene