Abstract
Comprehensive and time-dependent information (e.g., chemical composition, concentration) of volatile organic compounds (VOCs) in atmospheric, indoor, and breath air is essential to understand the fundamental science of the atmosphere, air quality, and diseases diagnostic. Here, we introduced a fully automated online dynamic in-tube extraction (ITEX)–gas chromatography/mass spectrometry (GC/MS) method for continuous and quantitative monitoring of VOCs in air. In this approach, modified Cycle Composer software and a PAL autosampler controlled and operated the ITEX preconditioning, internal standard (ISTD) addition, air sampling, and ITEX desorption sequentially to enable full automation. Air flow passed through the ITEX with the help of an external pump, instead of plunger up–down strokes, to allow larger sampling volumes, exhaustive extraction, and consequently lower detection limits. Further, in order to evaluate the ITEX system stability and to develop the corresponding quantitative ITEX method, two laboratory-made permeation systems (for standard VOCs and ISTD) were constructed. The stability and suitability of the developed system was validated with a consecutive 19 day atmospheric air campaign under automation. By using an electrospun polyacrylonitrile nanofibers packed ITEX, selective extraction of some VOCs and durability of over 1500 extraction and desorption cycles were achieved. Especially, the latter step is critically important for on-site long-term application at remote regions. This ITEX method provided 2–3 magnitudes lower quantitation limits than the headspace dynamic ITEX method and other needle trap methods. Our results proved the excellence of the fully automated online dynamic ITEX–GC/MS system for tracking VOCs in the atmospheric air.
Highlights
I dentification and quantitation of volatile organic compounds (VOCs) in air is essential to understand the fundamental science of the atmosphere, air quality, and disease diagnostics
Our results proved the excellence of the fully automated online dynamic in-tube extraction (ITEX)−gas chromatography/mass spectrometry (GC/MS) system for tracking VOCs in the atmospheric air
Present VOCs in atmospheric air are reactive with atmospheric oxidants (e.g., ·OH, ·NO3, or O3) and form water-soluble organic compounds which can further promote the formation of secondary organic aerosols (SOAs) or are eliminated by wet deposition.[1,2]
Summary
I dentification and quantitation of volatile organic compounds (VOCs) in air is essential to understand the fundamental science of the atmosphere, air quality, and disease diagnostics. Sanchez et al designed and utilized several multilayer sorbent-packed tubes and laboratory-made configurations for online sampling and analysis of breath and environmental air.[24−28] manual operations were still needed and the applicability of the systems for nonstop long-term measurements was not demonstrated. Another similar configuration, including a dualadsorbent preconcentrator,[29,30] has experienced the same challenge. The suitability of particulate and fibrous adsorbent as the packing materials of needle-shaped devices has been well-evaluated and demonstrated.[19,34] Nanofibers with appropriate permeability and porosity are promising alternative packing sorbents for ITEX,[35] and recently organic and inorganic nanofibers have been available as directly electrospun or indirectly calcined electrospun nanofibers with additional inorganic precursors.[35,36]
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