AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Method Development for Determination of Trace Concentrations of Aldehydes and Carboxylic Acids in Particulate Matter
JANA ROUSOVA, Manikyala R. Chintapalli, Anastasia Lindahl, Jana Stavova, Alena Kubatova, University of North Dakota
Abstract Number: 418 Working Group: Instrumentation and Methods
Abstract Carboxylic acids and aldehydes are present in ambient particulate matter originating from both primary and secondary organic emissions. Within secondary atmospheric reactions aldehydes readily oxidize to acids as well as participate in reactions with acids leading to formation of polymers. The activity of these reactive species in atmospheric processes demonstrates a need for their accurate determination. A common approach addressing both carbonyl and carboxylic functional groups employs O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) in sequence with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA). In this approach PFBHA is usually dissolved in water, which requires labor evaporation of particulate matter extract prior to derivatization, and labor intensive extraction of derivatized species. Therefore, in this work we have adopted a PFBHA/BSTFA protocol using PFBHA dissolved in methanol followed by gas chromatographic mass spectrometric analysis. A broad range of species with various functionalities (~35) was studied, including long chain monocarboxylic acids, dicarboxylic acids, aromatic acids, ketoacids and hydroxyacids. Unfortunately, both methyl and trimethylsilyl esters were observed upon initial derivatization with PFBHA/BSTFA rendering difficult species’ identification. We have resolved this issue by adjusting the PFBHA derivatization method, a complete methylation was achieved for majority of acids with exception of aromatic acids. The derivatization of aromatic acids and species with hydroxy groups was then completed with BSTFA. The advantage of the proposed protocol is the initial methylation of carboxylic acids (in contrast to trimethylsilylation) and thus easier MS interpretation without initial interference from numerous hydroxy groups.