AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Thermal Decomposition Characterization of Filter Inlet for Gases and AEROsols (FIGAERO) Coupled with Chemical Ionization Time-of-Flight Mass Spectrometer (ToF-CIMS)
LAURA YANG, Masayuki Takeuchi, Nga Lee Ng, Georgia Institute of Technology
Abstract Number: 381 Working Group: Instrumentation and Methods
Abstract There have been several studies on the effects of thermal decomposition on the interpretation of FIGAERO data, but no systematic study has been conducted to fully characterize the thermal decomposition behaviors nor the impact of instrument parameters on thermal decomposition. The objectives of this project are 1) to evaluate the mechanisms of thermal decomposition (i.e., decarboxylation and dehydration) in the FIGAERO using a suite of standard compounds with carboxylic acid and/or alcohol groups, and 2) to provide qualitative and quantitative means to infer the degree of thermal decomposition in the FIGAERO data by identifying patterns in measurement parameters, such as decomposition temperature and time profile. The temperature ramping rate effect is investigated as sub-objectives. Standard compounds of choice for testing include 1,2,3,4-butanetetracarboxylic acid, di-pentaerythritol, and citric acid. Each standard compound was diluted to 0.1 g/L and thermally desorbed at a temperature rate of 10 C/min, soaked for 20 minutes, and cooled for 10 minutes. Furthermore, experiments were conducted with different temperature ramping rates: < 15 min (fast), 15 minutes (normal), and > 15 minutes (slow) with citric acid while maintaining the soaking and cooling times constant. For 1,2,3,4-butanetetracarboxylic acid and citric acid, dehydration is observed to be the major thermal decomposition behavior with each dehydrated product desorption signal peak appearing sequentially (i.e., 1,2,3,4-butanetetracarboxylic acid desorption temperature: C8H10IO8: 155C, C8H8IO7: 165C, and C8H6IO6: 170C). Moreover, the thermal desorption profile of normal ramping rate exhibits a distinctive pattern from that of the other ramping rates. This could be due to chemical compound behaving differently under a varying temperature gradient. This study provides new insights into how to choose the best instrumental parameters to obtain consistent results when using FIGAERO for aerosol studies.