Direct Mass Spectrometry Analysis Using In-Capillary Dicationic Ionic Liquid-Based in Situ Dispersive Liquid–Liquid Microextraction and Sonic-Spray Ionization

The current study reports on a direct mass spectrometry (MS) analysis method using in-capillary dicationic ionic liquid (DIL)-based in situ dispersive liquid–liquid microextraction (DLLME) and sonic-spray ionization (SSI). The developed method merged extraction, enrichment, ionization, and detection...

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Bibliographic Details
Published in:Analytical chemistry (Washington) 2019-05, Vol.91 (10), p.6661-6668
Main Authors: Lv, Yueguang, Bai, Hua, Yang, Jingkui, He, Yujian, Ma, Qiang
Format: Article
Language:English
Subjects:
Analytical chemistry
Capillary flow
Capillary pressure
Chemistry
Dispersion
Gas flow
Ionic liquids
Ionization
Ions
Mass spectrometry
Mass spectroscopy
Mass transfer
Metathesis
Negative ions
Perfluoro compounds
Positive ions
Reagents
Scientific imaging
Sensitivity
Sensitivity analysis
Sensitivity enhancement
Spectroscopy
Water analysis
Water sampling
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Summary:The current study reports on a direct mass spectrometry (MS) analysis method using in-capillary dicationic ionic liquid (DIL)-based in situ dispersive liquid–liquid microextraction (DLLME) and sonic-spray ionization (SSI). The developed method merged extraction, enrichment, ionization, and detection of perfluorinated compounds (PFCs) in environmental water into a single step. A microliter-scale ternary fluidic system was designed and integrated into a disposable pulled capillary, in which an imidazolium-based germinal DIL reagent activated an in situ metathesis reaction. A penetrating slug-flow microextraction (SFME) process was subsequently initiated with significantly enhanced interfacial areas and mass transfer rates for the analytes of interest, the mechanism of which was revealed by simulations. An SSI assembly was in-house built, and it enabled a Venturi self-pumping using a stream of nitrogen gas flow coaxial to the capillary under atmospheric pressure to automatically spray at the tip of the capillary. The in situ formed DIL could bind with anionic PFC analytes to generate a positively charged complex, which benefits a signal increase of 1 to 2 orders in magnitude in the positive ion mode than in the negative ion mode for most analytes. The high sensitivity allowed the measure of sub-ppb (parts per billion) levels of PFCs in the environmental water samples. The developed method is a promising protocol for MS analysis because of unprecedented ease, significantly enhanced sensitivity, and potentially high sample throughput.
ISSN:0003-2700
1520-6882
DOI:10.1021/acs.analchem.9b00597