Liquid‐sheath‐flow electrospray ionization feasibility study of direct water analysis with the use of high‐resolution ion‐mobility spectrometry

Ion‐mobility spectrometry (IMS) in conjunction with radioactive ionization sources has been employed for field‐portable applications for the past two decades. Recently, electrospray ionization (ESI) sources have been shown as a viable ionization source with IMS instruments, enabling the analysis of many nonvolatile compounds. Introduction of a liquid‐sheath‐flow ESI source enabled the direct analysis of water samples. The ESI source was built with relatively simple lightweight components, making it feasible for use in field applications. A comparison between traditional ESI solvent conditions (water plus organic solvent) and the liquid‐sheath‐flow concept shows the new source to be able to spray water samples directly without prior sample preparation. The novel electrospray ionization source was evaluated with two nonfiltered water samples, one from a snow sample and the other obtained from a local stream. In both cases, 1 ppm of Terbutryn (a widely used herbicide) was easily detected.