Evaluation of a modified halo flowing atmospheric pressure afterglow ion source for the analysis of direct injected volatile organic compounds

A modified Flowing Atmospheric Pressure Afterglow source with concentric-tube electrodes (modified-hFAPA) is coupled to an Atmospheric Pressure Interface Time of Flight Mass Spectrometer (API-TOFMS) for the analysis of gas samples. The hFAPA is an ionization source easy to manufacture, operate and handle, and with low consumption in terms of gas flow rates and electric power. The analytical performance of this plasma-based ambient ionization sources is evaluated for the direct analysis of VOCs, using Benzene as a model compound. The influence of the different operating parameters, such ionization distance, discharge current, and gas flow rates is evaluated to optimize the detection of the benzene molecular ion. Matrix effects are evaluated using mixtures of different VOCs, and spiked synthetic air and human breath. Moreover, calibration curves for benzene are obtained using both matrices.