Online Volatile Compound Emissions Analysis Using a Microchamber/Thermal Extractor Coupled to Proton Transfer Reaction-Mass Spectrometry

Abstract

Indoor air is a complex and dynamic mixture comprising manifold volatile organic compounds (VOCs) that may cause physiological and/or psychological discomfort, depending on the nature of exposure. This technical note presents a novel approach to analyze VOC emissions by coupling a microchamber/ thermal extractor (μ-CTE) system to a proton transfer reactionmass spectrometer (PTR-MS). This configuration provides an alternative to conventional emissions testing of small objects. The dynamic emission profiles of VOCs from a representative 3Dprinted model are presented as a proof-of-concept analysis. Emission profiles are related to the target compound volatility, whereby 2propanol and acetaldehyde exhibited the highest emissions and most rapid changes compared to the less volatile vinyl crotonate, 2hydroxymethyl methacrylate, and mesitaldehyde, which were present at lower concentrations and showed different dynamics. Comparative measurements of the emission profiles of these compounds either with or without prior static equilibration yielded stark differences in their dynamics, albeit converging to similar values after 15 min of sampling time. Further, the utility of this system to determine the time required to capture a specific proportion of volatile emissions over the sampling period was demonstrated, with a mean duration of 8.4 ± 0.3 min to sample 50% of emissions across all compounds. This novel configuration provides a means to characterize the dynamic nature of VOC emissions from small objects and is especially suited to measuring highly volatile compounds, which can present a challenge for conventional sampling and analysis approaches. Further, it represents an opportunity for rapid, targeted emissions analyses of products to screen for potentially harmful volatiles.

Volatile Compound Emissions from Stereolithography Three-Dimensional Printed Cured Resin Models for Biomedical Applications

“…Studies on exhaled breath indicated a maximum temperature of 34 °C; thus, the upper limit of 40 °C represents extreme conditions. 35,36 Sampling proceeded by flushing the closed microchamber with dry (∼33% relative humidity (RH) at 25 °C) synthetic air at a rate of 75 mL•min −1 , which was either purged directly through an adsorption tube attached to the lid of the microchamber (for GC−MS analysis) or sampled directly via a bespoke interface and heated (80 °C) transfer line (for PTR-MS analysis), as previously described; 33 sampling onto adsorption tubes was preceded by a 15 min equilibration period under static conditions. Sampling proceeded for 15 min (GC−MS; equating to 1.13 L of headspace gas purged through the tube) or 20 min (PTR-MS).…”

“…First, conventional sampling using sorbent tubes was performed, with subsequent chemical analysis using thermal desorption-comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (TD-GC × GC-TOFMS) to identify VOCs in the sample. Second, the μ-CTE was directly interfaced with a proton transfer reaction time-of-flight mass spectrometer (PTR-TOFMS), as recently reported, 33 to quantify the VOC emissions from the models directly in the gas phase. Concentrations determined via the latter approach were then used to calculate the emission rates of selected compounds as reference values for exposure assessments.…”

The optimization and comparison of two high-throughput faecal headspace sampling platforms: the microchamber/thermal extractor and hi-capacity sorptive extraction probes (HiSorb)

“…especially those who perform breath metabolomics. Moreover, HiSorb probe sampling has been automated using CENTRI, and Microchamber sampling has been extended to online real time analysis to omit imperfect trapping of (very-) volatiles [2]. Although we wish not to condemn one of the methods as right or wrong, altogether we hypothesize to use the Microchamber to capture extremely low quantity volatiles in a targeted setting, or its extension when worries exist regarding imperfect trapping of volatiles.…”

“…Its non-invasive nature, in addition to ease of collection and the mostly absent requirement for sample pre-treatment, mark its suitability for high-throughput applications, making it increasingly popular. Of crucial importance is the continuous effort towards the optimization and standardization of the various platforms used for VOC sampling and their subsequent analysis [1][2][3][4][5][6][7][8][9][10][11][12]. To study gut-health, faecal samples provide the closest proxy towards the anatomical location of the gut while considering gut-microbiome characteristics.…”

Emissions and uptake of volatiles by sampling components in breath analysis

“…Sampling of emissions under controlled conditions was carried out using a commercial microchamber/thermal extractor (µ-CTE) system (µ-CTE250, Markes International Ltd, Llantrisant, UK), which comprised four individual 114 cm 3 chambers that were heated to 40 • C and flushed with nitrogen (purity 5.0; Linde GmbH; ∼33% relative humidity at 25 • C) at a controlled rate of 60 ml min −1 , as reported previously [10,13]. Analyses via this configuration were used to provide qualitative data on VOC emissions to support the quantitative data from the simulated measurements.…”