Consideration of a millisecond pulsed glow discharge time-of-flight mass spectrometer for concurrent elemental and molecular analysis

Abstract

The glow discharge ionization source operated in the trace levels is becoming the major area of interest in analytical pulsed (or modulated ) power mode offers unique characchemistry. Therefore, any new analytical technique that is teristics not available from its steady state counterpart. It applied to these problems must be extremely sensitive. Other has been well established that higher instantaneous power applications that require molecular mass and elemental comdensities are obtainable without compromising the sample position characterization include clinical analysis, materials integrity when pulsed plasmas are implemented. This chemistry and pharmaceuticals. It is well known that the operating parameter affords higher sputter yields and oxidation state and the chemical form of hazardous materials lower limits of detection relative to the steady state play a vital role in their actual toxic effects on biological plasmas. Of special interest are the discrete temporal systems and the environment in general.7,11,12 In the near regions associated with the modulated plasma. The presfuture, these criteria will play an increasingly important role ence of these time regimes offers temporal selectivity, in measuring and classifying hazardous sites. Subsequently, it allowing the collection of analytical data in a region where is becoming paramount to identify the molecular forms of the contribution from background and contaminant these elements and their corresponding concentrations in species is minimized. These regions are characterized by environmental samples. strikingly different ionization mechanisms. Acquisition of At present, the acquisition of both elemental and molecular data during each of these temporal regimes provides both molecular and elemental information. In this work the information requires mutually exclusive techniques.13 potential use of the pulsed glow discharge for collecting Although this manner of analysis is possible and indeed works concurrent molecular and elemental information was fairly well, it suffers from a number of disadvantages. The explored. This task was accomplished using time-of-flight most apparent shortcomings of using two independent techmass spectrometry ( TOFMS). TOFMS has a significantly niques involve the time needed to complete an analysis and high throughput and duty cycle, making it ideally suited the amount of sample required. Unfortunately, time and for rapid acquisition of spectra. This characteristic allows sample size are two very important factors when considering data acquisition during each of these temporal regions for a potential new technique. Hence, it is apparent that a technique each discharge pulse power cycle, affording concurrent that could limit analysis time and sample size requirements elemental and molecular detection. p-Xylene was used as could fill a niche that has so far eluded us. a test molecule for these studies.Currently, there are many mass and optical spectrometry based systems that are well suited for each particular type of analysis. T...

A comparison of non-pulsed radiofrequency and pulsed radiofrequency glow discharge orthogonal time-of-flight mass spectrometry for analytical purposes

“…In our pulsed RF system it is also possible to use the GD source time resolution to further separate analyte ions from polyatomic and discharge gas species because they are formed at different temporal and spatial locations. 20,21 For instance, Fig. 5a shows the mass spectrum interval between 27.…”

Peer Reviewed: Pulsed Glow Discharge: Temporal Resolution in Analytical Spectroscopy

“…For example, Steiner et al took advantage of these temporal phenomena by sampling a pulsed millisecond GD at different points in time to produce complementary mass spectra without TOF (18). In the initial discharge breakdown period, the primary active ionization agents are electrons, which can be accelerated in the GD field to high energies.…”

Tunable fragmentation of organic molecules in laser ablation glow discharge time-of-flight mass spectrometry

“…By using a pulsed GD, it is possible to achieve a high instantaneous pulse power, avoiding over heating of the cathode [12][13][14] and generating different temporal regimes [15,16]. These regimes, prepeak, plateau, and afterglow, provide different information about the composition of a sample [17]. Ionization during the prepeak is dominated by electron ionization (EI), whereas the plateau regime consists of a mixture of EI, Penning ionization (PI) and charge exchange processes.…”

“…For instance, Steiner et al [17] used a pulsed DC GD TOFMS for sequential elemental and molecular analysis of volatile samples. In these studies, a small amount of p-xylene was introduced into a GD plasma.…”