Localization of Double Bonds in Wax Esters by High-Performance Liquid Chromatography/Atmospheric Pressure Chemical Ionization Mass Spectrometry Utilizing the Fragmentation of Acetonitrile-Related Addu

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• 作者：Vladimi虂r Vrkoslav ; Martina Ha虂kova虂 ; Karolina Peckova虂 ; Kla虂ra Urbanova虂 ; Josef Cvac虒ka
• 刊名：Analytical Chemistry
• 出版年：2011
• 出版时间：April 15, 2011
• 年：2011
• 卷：83
• 期：8
• 页码：2978-2986
• 全文大小：1038K
• 年卷期：v.83,no.8(April 15, 2011)
• ISSN：1520-6882

文摘

Unsaturated wax esters (WEs) provided molecular adducts with C₃H₅N ([M + 55]^{+鈥?/sup>) in APCI sources in the presence of acetonitrile. CID MS/MS of [M + 55]+鈥?/sup> yielded fragments allowing the localization of double bond(s) in the hydrocarbon chains of the WEs. These fragments were formed by a cleavage on each side of the double bond. In methylene-interrupted polyunsaturated WEs, diagnostic fragments related to each double bond were detected; the most abundant were those corresponding to the cleavage of the C鈭扖 bond next to the first and the last double bond. To differentiate between those fragments differing in their structure or origin, a simple nomenclature based on 伪 and 蠅 ions has been introduced. Fragmentation of the 伪-type ions (fragments containing an ester bond) provided information on the occurrence of a double bond in the acid or alcohol part of the WEs. While no significant differences between the spectra of the WEs differing by cis/trans isomerism were found, the isomers were separated chromatographically. A data-dependent HPLC/APCI-MS2 method for the comprehensive characterization of WEs in their complex mixtures has been developed and applied to natural mixtures of WEs isolated from jojoba oil and beeswax. More than 50 WE molecular species were completely identified, including the information on the acid and alcohol chain length and the position of the double bonds.}