Enhancement of photoacoustic spectroscopy with sorption enrichment for ppt-level benzene detection

TL;DR

This paper presents a real-time benzene detection system using sorption enrichment and photoacoustic spectroscopy, achieving ppt-level sensitivity with a 90-second sampling cycle and evaluating interference effects.

Contribution

The study introduces a combined sorption enrichment and cantilever-enhanced photoacoustic spectroscopy method for ultra-sensitive benzene detection at ppt levels.

Findings

Detection limit of 150 ppt benzene within 90 seconds

Effective enrichment using Tenax TA sorbent for 30 seconds

Interference effects from humidity and petrochemicals are characterized

Abstract

A real time trace gas detector for benzene is demonstrated. The measurement system takes an advantage of modest enrichment through short adsorption periods to reach a ppt-level detection limit with a sampling cycle of 90 s, which includes sample adsorption, desorption and a spectroscopic measurement. Benzene is collected on Tenax TA sorbent for 30 s and then detected from the enriched samples with photoacoustic spectroscopy. A high sensitivity is achieved using cantilever-enhanced photoacoustic spectroscopy and a continuous-wave quantum cascade laser emitting at the wavelength 14.8 $\mu$m, which corresponds to the absorption wavelength of the strongest benzene infrared band. We reach a detection limit of 150 ppt of benzene, over one sampling cycle. Interference from humidity and other common petrochemicals is evaluated.