The flowing atmospheric pressure afterglow (FAPA) source was first described in its original version by Andrade et al. in 2008 as a direct-current glow discharge based helium plasma for the soft ionization of organic compounds. [1] Here, the analyte for ionization is not introduced directly into the discharge, but into the so-called afterglow region. This is the part of the plasma that is pushed out of the discharge region by the continuous flow of discharge gas. In 2013, the latest variant of the FAPA was introduced by Pfeuffer et al. [2] It differs from previous versions in terms of the arrangement of the electrodes between which the discharge takes place. The design of the halo-FAPA makes it possible to introduce the sample not only directly into the afterglow region, but also directly into the discharge zone, which opens up the possibility of using the halo-FAPA as an excitation source in emission spectrometry.

In previous studies, the general suitability of the halo-FAPA as a universal detector for organic substances in gas chromatography was already demonstrated on the basis of the emission of the C₂ radical. The presented study focuses on the suitability of halo-FAPA-OES for the determination of heteroatomic compounds, based on the emission of corresponding heteroatomic molecular fragments, employing exponential dilution for calibration and simplification of the developed method. [3] In this presentation considerations for the design of the halo-FAPA-OES system will be given and analytical figures of merit for acetonitrile, acetone and chloroform based on the detection of the emission bands of biatomic molecules such as CN, CO⁺ and CCl will be documented and critically discussed. Suggestions for future design modifications will also be given.

[1] F. J. Andrade, J. T. Shelley, W. C. Wetzel, M. R. Webb, G. Gamez, S. J. Ray, G. M. Hieftje, Anal. Chem. 2008, 80, 2646-2653.

[2] K. P. Pfeuffer, J. N. Schaper, J. T. Shelley, S. J. Ray, G. C.-Y. Chan, N. H. Bings, G. M. Hieftje, Anal. Chem. 2013, 85, 7512-7518.

[3] T. R. Booher, R. C. Elser, J. D. Winefordner, Appl. Spectrosc., 1982, 36, 99-102.