Evolution and revolution in instrumentation for plasma-source mass spectrometry

Abstract

Plasma-source mass spectrometry, usually in the form of inductively coupled plasma mass spectrometry (ICP-MS), has matured into a widely accepted method for ultra-trace multielemental analysis. However, the method exhibits shortcomings. For example, it does not provide adequate precision for isotope ratio measurements if many isotopes are to be determined. Moreover, isobaric overlaps (spectral interferences) can be very troublesome in some situations. Similarly, matrix interferences can adversely affect many determinations. Yet, it is in the area of high-speed transient measurements that ICP-MS perhaps suffers its greatest weakness. When sampling devices such as flow injection, laser ablation, electrothermal vaporization, or chromatography are employed, the user must choose between broad elemental or isotopic coverage and signal-to-noise ratio (S/N). In turn, compromised S/N means lower precision or poorer detection limits. Here, new instrumentation aimed at overcoming these limitations will be described. One system, based on a time-of-flight mass spectrometer, provides excellent detection limits, resolving power better than commercial quadrupole mass filters, precision of at least 0.02% rsd in a ratioing mode, and extraordinarily high speed for use with transient sampling devices. The second instrument is based on a sector-field mass spectrometer but, unlike other such units, is equipped with a focal-plane array detector. So equipped, the system can detect a broad mass range at once.

An Overview of Analytical Applications of Time of Flight-Mass Spectrometric (TOF-MS) Analyzers and an Inductively Coupled Plasma-TOF-MS Technique

“…[137][138][139][140][141] Detailed reviews of the development and analytical performance of TOF-MS combined with ICP ion source have been presented. [142][143][144][145] Attempts to couple TOF-MS to a microwave induced plasma (MIP) for elemental analysis have also been described.…”

“…For being familiar with a range of technical arrangements in ICP-TOF-MS the reader is referred to some excellent review papers discussing the subject in detail. [143][144][145][148][149][150][151][152][153] Two concepts of ion gating: an-axial (linear) and orthogonal, are characteristic for the ICP-TOF-MS instruments developed. In an-axial configuration the drift tube of the TOF-MS is in line with the supersonic beam extracted from the plasma.…”

“…The performance of both arrangements was considered by Myers and Hiefje in their first report on the ICP-TOF-MS device, and was discussed in later publications. 16,[143][144][145][148][149][150][151][152][153] Commercially available ICP-TOF-MS instruments (the LECO Renaissance, USA, and the GBC Optimass8000, Australia) use different settings of plasma source and TOF-MS analyzers: anaxial (LECO) and an orthogonal (GBC). A detailed summary of those instruments is available.…”

Elemental Bioimaging by Means of Fast Scanning Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry

“…Thus, it would be superior to acquire signals of all elements, or at least all elements that could be of further interest, in one single run and to have a full mass spectrum available for each acquired pixel [11]. In the field of Borganic^mass spectrometric imaging, with matrix assisted laser desorption ionization (MALDI) as its common ionization technique, this is achieved for example by utilization of Orbitrap [12] or time of flight (ToF) [13] mass analyzers.…”

“…However, these techniques suffer from a lack of simple quantitation capabilities compared with ICP-based approaches. Nevertheless, Binorganic^mass spectrometry struggles to cope with short transient signals, and different dedicated approaches have been proposed to overcome this issue in LA-ICP-MS [11,[14][15][16].…”