Coupling Flowing Atmospheric Pressure Afterglow (FAPA) with Differential Mobility Spectrometry-Mass Spectrometry (DMS-MS) for rapid analysis of solid metal complexes

Abstract Metal-ligand complexes are important analytical targets across environmental, industrial, security, and biological investigations. The various complex forms of these species calls for analytical techniques that can selectively detect them in their native ( in-situ ) environment. Fieldable screening technologies based on portable mass spectrometry (MS) require simplified sample-preparation and ionization methods. Therefore, various direct ambient desorption/ionization sampling methods, such as the flowing atmospheric-pressure afterglow (FAPA), are of high interest as portable tools and possess the capability to desorb/ionize complexed elemental species. With such sample introduction, matrix from ambient chemicals may interfere with the analyte of interest leading to false-positive detection. Differential mobility spectrometry (DMS) can provide additional post-ionization separation and reduction of interferences. Herein, we explore coupling a FAPA desorption/ionization source with DMS for the first time for metal-ion speciation. The FAPA-DMS hybrid was used for separation and detection of individual ionic species from cobalt and nickel complexes with acetylacetonate in standard mixtures. We observe a concentration dependence of the DMS separation in mixtures. Altered DMS dispersion behavior is attributed to high concentrations of desorbed neutral complexes acting as a gas-phase modifier. For the case of Ni(AcAc) 2 , solutions deposited from 100 to 1000 μg/mL exhibit good linearity when the DMS is employed. The results described herein suggest a method which may be used in in situ applications for inorganic complex analyses.