A detailed MSn study for the molecular identification of a dimer formed from oxidation of pinene

作者：Beck Martin; Hoffmann Thorsten^*

来源：Atmospheric Environment, 2016, 130: 120-126.

DOI：10.1016/j.atmosenv.2015.09.012

• Natural aerosol formation
• Biogenic secondary organic aerosol (BSOA)
• Product studies
• Structure elucidation
• High molecular weight compounds
• Mass spectrometry
• Functional group derivatization
• MS/MS

Dimeric products formed in the oxidation of alpha- and beta-pinene have been frequently observed in laboratory and field studies of biogenic SOA formation. While their existence is undoubted, their exact chemical structures remain unclear. This study uses a combined two step approach aiming on the molecular identification of the most important of the various dimers that have been observed in biogenic secondary organic aerosol formation, a dimer with the molecular weight 358 g mol(-1). The first step is the application of a functional group derivatization technique (esterification) to quantify the number of carboxylic acid groups in the target molecule. Based on the detailed interpretation of the MSn spectra (up to n = 7) of the derivatized product further information about the exact structure of the compound of interest is compiled. To increase the intensity of precursor ions for the MSn-studies and especially to facilitate successive fragmentation of the target molecule, which yields structurally informative product spectra, cationization reagents (Li+, NH4+) are introduced. The results clearly point to the formation of a dimer containing three carboxylic acid groups and a structure containing a terpenylic acid building block and a pinic acid building block, strongly supporting a structure suggestion by Claeys and coworkers (Yasmeen et al., 2010).

• 出版日期2016-4