Low-Temperature Plasma Ionization Ion Mobility Spectrometry

• Published in: Analytical chemistry (Washington) Vol. 83; no. 3; pp. 797 - 803
• Main Author: Jafari, Mohammad T
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.02.2011
• Subjects: Analytical chemistry; Chemistry; Desorption; Effects; Evaporation; Exact sciences and technology; Ions; Plasma; Protons; Spectrometric and optical methods; Temperature; Plasma; Positioning; Chemical analysis; Time; Direct method; Paracetamol; Signal; Amine; Ion spectrometry; Peak; Corona effect; Solvent; Low temperature; Tool; Drug; Ion source; Sample; Use; Desorption; Positive ion; Vaporization; Ion mobility; Ionization; Reagents; Parameter; Ionization potential; Portable equipment; Explosives; Negative ion; Application; Figure of merit
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac1022937

In this research work, the capability of low-temperature plasma (LTP) as an ionization source for ion mobility spectrometry (IMS) has been investigated for the first time. This new ionization source enhances the potential of IMS as a portable analytical tool and allows direct analysis of various chemical compounds without having to evaporate the analyte or seek a solvent or reagent whatsoever. The effects of parameters such as the flow rate of the discharge gas, plasma voltage, and positioning of the LTP on the IMS signal were investigated. The positive reactant ions generated by the LTP ionization source were similar to those created in a corona discharge ionization source, where the proton clusters ((H2O) n H+) are the most abundant reactant ion, and in the negative mode, in addition to a saturated electron peak, several negative reactant ions (e.g., NO x −) were observed too. These reactant ions subsequently ionized the gaseous samples directly and liquids or solids after evaporation by plasma desorption. The ion mobility spectra of a few selected compounds, including explosives, drugs, and amines, were obtained to evaluate the new ionization source in positive and negative modes, and the reduced mobility values (K 0) of the originated ions were calculated. Furthermore, the method has also been applied to obtain the figures of merit for acetaminophen as a test compound. The results obtained are promising enough to ensure the use of LTP as a desorption/ionization source in IMS for analytical applications.