LAUSR

Typical ionization techniques used for mass spectrometry (MS) analysis face challenges when trying to analyze organic species in a high salt environment. Here, we present results using a recently developed ionization source, liquid sampling-atmospheric pressure glow discharge (LS-APGD), for marine-relevant salt-containing organic samples. Using two representative sample types, a triglyceride mixture and dissolved organic matter, this method is compared to traditional electrospray ionization (ESI) under saline and neat conditions. LS-APGD produced equal or higher (15%+) ion intensities than ESI for both salt-containing and neat samples, although important differences linked with adduct formation in high salt conditions explain the molecular species observed. For all sample types, LS-APGD observed a higher diversity of molecules under optimized settings (0.25 mm electrode spacing at 20 mA) compared to traditional ESI. Furthermore, because the LS-APGD source ionizes molecular species in a ~1 mm3 volume plasma using a low-power source, there is the potential for this method to be applied in field studies, eliminating de-salting procedures which can be time-consuming and not ideal for low concentration species.