A Doped Surface Ionization Method for Ion Mobility Spectrometry.

Rationale: Exhaled breath can be used for early warning of disease, with organic nitrogen compounds, including triethylamine (TEA), being linked to various medical conditions. Surface ionization ion mobility spectrometry (SI-IMS) facilitates the direct detection of TEA in exhaled breath. However, the presence of multiple ionization products of TEA poses challenges for both quantitative and qualitative analyses.

Methods: A doped surface ionization (DSI) method consisting of surface ionization of dopants and gas-phase reaction of samples was proposed, and TEA was detected when combined with an ion mobility spectrometer. TEA at different concentrations and spiked by human breath was detected to evaluate the method's properties.

Results: TEA with concentrations from 5.99 to 30.50 ppb and a relative humidity of 80% was detected. The peak intensity of the protonated TEA ions demonstrated a linear correlation with concentration, yielding a fitted correlation coefficient of R = 0.94. A standard deviation less than 0.066% was obtained with 10 replicate analyses of 29.92 ppb TEA, and the recovery rate of the sample was 93.57%.

Conclusions: The SI-IMS based on the DSI method has the advantages of excellent selective ionization, high accuracy and sensitivity, and remarkable repeatability for detecting TEA. It is a promising method for detecting specific organic nitrogen compounds in exhaled breath.