Ion Mobility Spectrometry Towards Environmental Volatile Organic Compounds Identification and Quantification: a Comparative Overview over Infrared Spectroscopy

Abstract

Volatile organic compounds (VOCs) can be extremely toxic and hazardous to expose humans in both indoor and outdoor environments; thus, their detection, correct identification, and accurate quantification are relevant and demanding tasks that need to be addressed. Fortunately, several known analytical techniques allow the qualitative and quantitative assessment of these compounds. This review paper stresses on two independent spectroscopic techniques, infrared spectroscopy and ion mobility spectrometry, both suitable for the detection of very small concentration levels of VOCs in gaseous samples. Infrared spectroscopy is a well-known technique that has been largely applied per se or combined with additional methodologies, to study VOCs at both high and low concentration levels. On the other hand, ion mobility spectrometry gained relevance in this field, due to its capability to measure trace concentration levels, namely ppbv and even pptv. For this review paper, several scientific papers were analyzed, and the most relevant were addressed throughout the text. The working principles of both techniques are carefully addressed, and updated data is provided for highlighting the advantages and disadvantages of both techniques for the environmental VOCs assessment in air quality control.

Detecting the Unseen: Understanding the Mechanisms and Working Principles of Earthquake Sensors

“…These sensors are inexpensive and can be used to construct ultra-dense arrays. Additionally, MEMS sensors are known for their high accuracy, low power consumption, and robustness, which makes them ideal for use in harsh environments [44,45].…”

Using Gas Chromatography‐Ion Mobility Spectrometry to Investigate Volatile Compound Profiles in Human Sweat during COVID‐19 Vaccination

“…These could offer the remarkable capacity in qualitative and quantitative analysis of VOCs in the concentration ranges down to parts-per-billion or parts-per-trillion. [22][23][24][25][26][27][28][29][30][31][32][33][34] Statistical analysis could then be applied to analyze GC-IMS results, classify samples into different groups and propose possible volatile markers for several tasks such as disease screening. Breath has been used for COVID-19 screening test based on analysis of the volatile markers, e. g. aldehyde such as methylpent-2-enal, [35][36][37] ethanal and octanal, [38] leading to development of breath-test electronic nose sensors for the screening.…”

Long-term in situ air quality assessment in closed environments: A gas chromatography–ion mobility spectrometry applicability study

“…26,27 Nonetheless, all the mentioned techniques and procedures lack some features that are important in the field of VOCs assessment in the indoor air of closed environments, namely, the lack of portability, which hinders in situ analyses; the necessity of additional preparation of the sample, which increases the complexity of the analyses; the lower resolution power, sensitivity and selectivity, that inhibit the detection of VOCs at trace levels of concentration; the incapacity for real-time measurement, which delays the entire analysis; the necessity of trained personal due to the instrumental complexity, and several other limitations. 24,28,29 An analytical technique that has gained significant recognition in the detection, identification and quantification of VOCs is ion mobility spectrometry (IMS). IMS has been extensively investigated in various applications owing to its high sensitivity (typically the detection limits are in the low ppb v or even ppt v ranges of concentration), analytical flexibility and simplicity.…”

“…The ratio between these two values leads to the ion mobility constant, which is also an ion-specific value (equation ( 1)). 24,30 Since the velocity corresponds to the quotient between the length of the drift tube, L, and the drift time, D t , required to cross that distance, then, a new formulation for K can be expressed as:…”

“…While the retention and drift times are used for identification purposes, the intensity can be used for quantification purposes. 24,35 The present study intends to assess the suitability of GC-IMS for in situ long-term measurements of VOCs and consequent control of indoor air quality in closed spaces. For this purpose, a year-long study was developed aiming to obtain the GC-IMS spectra of volatile organic compounds, identify the detected analytes and perform the evaluation of the daily variation of the total VOCs (tVOCs) intensity across the period of measurements.…”