Fully Automated Online Dynamic In-Tube Extractionfor Continuous Sampling of Volatile Organic Compounds in Air

摘要

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 stabilityand suitability of the developed system was validated with a consecutive19 day atmospheric air campaign under automation. By using an electrospunpolyacrylonitrile nanofibers packed ITEX, selective extraction ofsome VOCs and durability of over 1500 extraction and desorption cycleswere achieved. Especially, the latter step is critically importantfor on-site long-term application at remote regions. This ITEX methodprovided 2–3 magnitudes lower quantitation limits than theheadspace dynamic ITEX method and other needle trap methods. Our resultsproved the excellence of the fully automated online dynamic ITEX–GC/MSsystem for tracking VOCs in the atmospheric air.