An Investigation of Micro-Hollow Cathode Glow Discharge Generated Optical Emission Spectroscopy for Hydrocarbon Detection and Differentiation

Abstract

The analytical utility of a micro-hollow cathode glow discharge plasma for detection of varied hydrocarbons was tested using acetone, ethanol, heptane, nitrobenzene, and toluene. Differences in fragmentation pathways, reflecting parent compound molecular structure, led to differences in optical emission patterns that can then potentially serve as signatures for the species of interest. Spectral simulations were performed emphasizing the CH (A(2)Δ-X(2)Π), CH (C(2)Σ-X(2)Π), and OH (A(2)Σ(+)-X(2)Π) electronic systems. The analytical utility of selected emission lines is demonstrated by a linear relationship between optical emission spectroscopy and parent compound concentration over a wide range, with detection limits extending down to parts per billion (ppb) levels.

Atomic spectrometry update: review of advances in atomic spectrometry and related techniques

“…58 The same authors applied pulsed mode to analyse? 58 The same authors applied pulsed mode to analyse?…”

Direct microplasma analysis of coals and sorbents for C, H, N, S and mineral element concentrations

“…The micro-hollow glow discharge, exists typically in the discharge gap between parallel electrodes. Due to the elevated temperature and high current density, the traditional glow discharge characteristic of lowpressure systems is difficult to achieve and maintain at atmospheric pressure [60]. This high pressure restricts the current to a filamentary arc while temperature instabilities facilitate this transition [55].…”

“…Rather than laser or micro-drilling through refractory metal foils [59], or using a screenprinting process [60][61][62], a capillary metal tube functioned as the anode. It was fixed in place while the planar cathode could be axially translated to vary the inter-electrode spacing.…”

“…This pattern is unique to the particular coal tested. Such patterns could independently serve as a fingerprint of the particular coal and can provide a quick assessment of the type of coal [54,60].…”

Recent Developments in Spectroscopic Techniques for the Detection of Explosives

“…Due to the importance of rapid, automatic, and non-contact detection of explosives for homeland security and environmental safety [8], a variety of spectroscopic technologies have been employed to detect trace quantities of explosives; for example, terahertz (THz) spectroscopy [9,10], laser induced breakdown spectroscopy (LIBS) [11,12,13,14,15,16], Raman spectroscopy [17,18,19,20,21,22], ion mobility spectrometry (IMS) [23,24,25,26], nuclear magnetic resonance (NMR) [27,28,29,30], nuclear quadrupole resonance (NQR) [31,32,33], laser-induced thermal emissions (LITE) [34,35], infrared (IR) spectroscopy [36,37,38], mass spectrometry [39,40,41,42,43,44,45,46], optical emission spectroscopy (OES) [47,48], photo-thermal infrared imaging spectroscopy (PT-IRIS) [49,50,51], photoacoustic techniques [52,53,54], FT-FIR spectroscopy [55], microwave [56], and millimeter-wave [57], etc. Various electromagnetic radiations such as X-ray [58] and γ rays [59] have also been employed in explosive detection.…”