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The application of direct analysis in real-time mass spectrometry (DART-MS), which is finding increasing use in atmospheric chemistry, to two different laboratory model systems for airborne particles is investigated: (1) submicron C3–C7 dicarboxylic acid (diacid) particles reacted with gas-phase trimethylamine (TMA) or butylamine (BA) and (2) secondary organic aerosol (SOA) particles from the ozonolysis of α-cedrene. The diacid particles exhibit a clear odd–even pattern in their chemical reactivity toward TMA and BA, with the odd-carbon diacid particles being substantially more reactive than even ones. The ratio of base to diacid in reacted particles, determined using known diacid–base mixtures, was compared to that measured by high-resolution time-of-flight aerosol mass spectrometry (HR-ToF-AMS), which vaporizes the whole particle. Results show that DART-MS probes ∼ 30 nm of the surface layer, consistent with other studies on different systems. For α-cedrene SOA particles, it is shown that varying the temperature of the particle stream as it enters the DART-MS ionization region can distinguish between specific components with the same molecular mass but different vapor pressures. These results demonstrate the utility of DART-MS for (1) examining reactivity of heterogeneous model systems for atmospheric particles and (2) probing components of SOA particles based on volatility.
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In situ lipid profiling of insect pheromone glands by direct analysis in real time mass spectrometry
Lipid pheromones play a significant role in the behavior and ecology of many insects. The characterization of pheromone structures is a significant challenge due to their low abundance and ephemeral nature. Here we present a method for the analysis of lipid molecules from single pheromone glands of Drosophila melanogaster (fruit fly) using Direct Analysis in Real Time mass spectrometry (DART MS). Our results reveal that DART MS analysis of single tissues generates reproducible, species-specific lipid profiles comprised of fatty acids, wax esters, diacylglycerides and triacylglycerides. In addition, the ion source temperature and application of a solvent wash can cause significant qualitative and quantitative changes in the mass spectral profile. Lastly, we show that untargeted chemical fingerprinting of the gland can be used to accurately categorize species according to phylogenetic subgroup or genotype. Collectively, our findings indicate that DART MS is a rapid and powerful method for characterizing a broad range of lipids in tissues with minimal preparation. The application of direct tissue DART MS will expand the “secretome” of molecules produced by pheromone glands. In addition to its direct relevance to chemical ecology, the method could potentially be used in pharmaceutical studies for the screening and detection of tissue-specific drug metabolites.
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- Award ID(s):
- 2025669
- PAR ID:
- 10359096
- Date Published:
- Journal Name:
- The Analyst
- Volume:
- 147
- Issue:
- 14
- ISSN:
- 0003-2654
- Page Range / eLocation ID:
- 3276 to 3284
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/d2an00840h
