Volatile Organic Compounds (VOCs) exhibit a wide range of toxicity, depending on the molecular nature of specific VOCs and their associated concentrations. Existing sensing technologies are unable to determine the molecular nature of VOCs in real time, rendering the determination of a sample containing a complex VOC mixture as toxicologically safe or hazardous impossible. Herein, we demonstrate the molecular specific, real-time detection of VOCs derived from benzene, toluene, ethylbenzene, and ortho and para xylene isomers — jointly referred to as BTEX gases — within a gas mixture using a technique coined as Sample Ionisation Potential Spectroscopy (SIPS). Our solution is based on photoionization detection, utilizing tuneable, quasi-monochromatic vacuum ultraviolet (VUV) light generated by third-harmonic generation (THG) in suspended dielectric nanomembranes. The results demonstrate the potential of SIPS to identify individual BTEX compounds based on their ionisation potentials within a background matrix of five BTEX compounds in nitrogen, with a sensitivity limit down to concentration levels corresponding to occupational exposure limits. • Molecular specific detection of BTEX in real-time at atmospheric pressure within a background VOC matrix • Real-time molecular specific BTEX detection at or below the Occupational Exposure Limits set by the European Union
Vilarinho et al. (Sun,) studied this question.