Cross Platform Analysis of Volatile Organic Compounds Using Selected Ion Flow Tube and Proton-Transfer-Reaction Mass Spectrometry

Abstract

Volatile breath metabolites serve as potential disease biomarkers. Online mass spectrometry (MS) presents real-time quantification of breath volatile organic compounds (VOCs). The study aims to assess the relationship between two online analytical mass spectrometry techniques in the quantification of target breath metabolites: selected ion flow tube mass spectrometry (SIFT-MS) and proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF-MS). The two following techniques were employed: (i) direct injection with bag sampling using SIFT-MS and PTR-ToF-MS and (ii) direct injection and thermal desorption (TD) tube comparison using PTR-ToF-MS. The concentration of abundant breath metabolites, acetone and isoprene, demonstrated a strong positive linear correlation between both mass spectrometry techniques (r = 0.97, r = 0.89, respectively; p < 0.001) and between direct injection and TD tube (r = 0.97, r = 0.92, respectively; p < 0.001) breath sampling techniques. This was reflected for the majority of short chain fatty acids and alcohols tested (r > 0.80, p < 0.001). Analyte concentrations were notably higher with the direct injection of a sampling bag compared to the TD method. All metabolites produced a high degree of agreement in the detection range of VOCs between SIFT-MS and PTR-ToF-MS, with the majority of compounds falling within 95% of the limits of agreement with Bland–Altman analysis. The cross platform analysis of exhaled breath demonstrates strong positive correlation coefficients, linear regression, and agreement in target metabolite detection rates between both breath sampling techniques. The study demonstrates the transferability of using data outputs between SIFT-MS and PTR-ToF-MS. It supports the implementation of a TD platform in multi-site studies for breath biomarker research in order to facilitate sample transport between clinics and the laboratory.

Plant‐Wearable Sensors for Intelligent Forestry Monitoring

“…[78][79][80][81][82][83][84][85][86][87][88][89][90][91][92][93][94][95][96] The amount of VOCs released depends on the degree of damage, and the local concentrations can be as high as 10 parts per million (ppm) when multiple parts of the leaf are damaged. [97] Therefore, the detection and monitoring of VOCs is an effective means to counteract pest attacks. Advanced photoionization detector-based VOC sensors can achieve effective monitoring; however, they are expensive and not suitable for deployment in forestry owing to high power consumption.…”

Non‐invasive exhaled breath diagnostic and monitoring technologies

“…With the developments of technology, especially the introduction of proton-transfer-reaction time-of-flight mass spectrometry (PTR-TOF-MS), and the improvements of sensitivity and detection limit, the boundaries of real-time breath analysis are being broadened. 44…”

“…The experiments show that PTR‐MS has great potential to capture the continuous kinetics of non‐polar, low‐solubility volatile organic compounds over a wide measurement range, while assessing the determinant physiological factors that affect exhalation kinetics. With the developments of technology, especially the introduction of proton‐transfer‐reaction time‐of‐flight mass spectrometry (PTR‐TOF‐MS), and the improvements of sensitivity and detection limit, the boundaries of real‐time breath analysis are being broadened 44 …”