Electromembrane Extraction and Dual-Channel Nanoelectrospray Ionization Coupled with a Miniature Mass Spectrometer: Incorporation of a Dicationic Ionic Liquid-Induced Charge Inversion Strategy

Abstract

Green analytical chemistry aims at developing analytical methods with minimum use and generation of hazardous substances for the protection of human health and the environment. To address this need, a green analytical protocol has been developed for the analysis of anionic compounds integrating electromembrane extraction (EME), dual-channel nanoelectrospray ionization (nanoESI), and a miniature mass spectrometer. Haloacetic acids (HAAs) have attracted considerable public concern due to their adverse effects on human health and were selected as model analytes for method development. A flat membrane EME device was developed and assembled in-house. Optimization of fundamental operational parameters was performed using single-factor test and response surface methodology. Both the EME acceptor phase and an imidazolium-based dicationic ionic liquid (DIL), 1,1-bis­(3-methylimidazolium-1-yl) butylene difluoride (C4(MIM)2F2), were subjected to dual-channel nanoESI and miniature mass spectrometry analysis based on a charge inversion strategy, where positively charged complexes were formed. Enhancement in signal intensity by as much as 2 magnitudes was achieved in the positive-ion mode compared to the negative-ion mode in the absence of the dicationic ion-pairing agent. The developed protocol was validated, obtaining good recoveries ranging from 82.7 to 109.9% and satisfactory sensitivity with limits of detection (LODs) and quantitation (LOQs) in the ranges of 1–5 and 2–10 μg/L, respectively. The greenness of the analytical procedure was assessed with a calculated score of 0.71, indicating a high degree of greenness. The developed method was applied to the analysis of real environmental or municipal water samples (n = 16), exhibiting appealing potential for outside-the-laboratory applications.

Physico‐Chemical Properties of Magnetic Dicationic Ionic Liquids with Tetrahaloferrate Anions

“…For example, their melting points and other physicochemical properties can also be manipulated greatly by forming either symmetric [21] or asymmetric cations. [22] Imidazolium-based DcILs, due to many applicable structural variations and improved physicochemical properties, [23] have gained significant importance in the field of organic synthesis, [24] electro-membrane extraction, [25] catalysis, [26] and lithium ion batteries [27] while the DcILs with transition-metalcontaining anions exhibit strong magnetic response, [28] offer new supramolecular architecture and potential applications arising from their magnetic properties (magnetic fluids, [29] transport and separation of magnetic materials [30] ), and absorbent liquids to lubrication [31] and catalysis. [32] Here, we describe magnetic dicationic ionic liquids, consisting of a high-spin d 5 iron(III) system in the form of [FeCl 3 Br] À as paramagnetic counter anion which is also responsible for lowering the melting point while still permitting the tunability of many physicochemical properties with the retention of magnetic responsivity.…”

Online hyphenation of in-capillary aptamer-functionalized solid-phase microextraction and extraction nanoelectrospray ionization for miniature mass spectrometry analysis

“…Thus, the need for timeconsuming and labor-intensive sample preparation and chromatographic separation procedures can be eliminated. [13][14][15] The methodologies coupling ambient ionization with miniature MS have demonstrated outstanding performance across a broad range of in-field applications, such as food safety, [16][17][18][19] consumer product safety, 18,[20][21][22] environmental monitoring, [23][24][25][26][27] life sciences, [28][29][30] clinical diagnosis, [31][32][33] public security, [34][35][36][37][38] and forensic investigation. [39][40][41] Despite the ever-growing applications in various fields, the direct analysis of trace amounts of analytes in raw samples with complex matrices remains challenging for the following reasons:…”

“…Thus, the need for time-consuming and labor-intensive sample preparation and chromatographic separation procedures can be eliminated. 13–15 The methodologies coupling ambient ionization with miniature MS have demonstrated outstanding performance across a broad range of in-field applications, such as food safety, 16–19 consumer product safety, 18,20–22 environmental monitoring, 23–27 life sciences, 28–30 clinical diagnosis, 31–33 public security, 34–38 and forensic investigation. 39–41…”

Ultra‐low current electrospray ionization of chloroform solution for the analysis of perfluorinated sulfonic acids

“…One example is perfluorooctanoate sulfonate (PFOS), which has been on the Stockholm Convention's list of persistent organic pollutants since 2009. As a result, most ESI methods for ppt‐level PFOS involve extraction and preconcentration, such as solid‐phase microextraction (SPME), 12,13 aerosol enrichment, 14 and electromembrane extraction 15 …”