QEPAS spectrophones: design, optimization, and performance

Laser absorption spectroscopy (LAS) in the mid-infrared region offers a promising new effective technique for the quantitative analysis of trace gases in human breath. LAS enables sensitive, selective detection, quantification and monitoring in real time, of gases present in breath. This review summarizes some of the recent advances in LAS based on semiconductor lasers and optical detection techniques for clinically relevant exhaled gas analysis in breath, specifically such molecular biomarkers as nitric oxide, ammonia, carbon monoxide, ethane, carbonyl sulfide, formaldehyde and acetone.