Plasma-based mass spectrometry for simultaneous acquisition of elemental and molecular information

Abstract

Chemical speciation studies are commonly accomplished by resorting to hyphenated analytical techniques, consisting of a powerful chromatographic separation technique coupled to a highly sensitive elemental spectrometric detector. However, in addition to this element-selective information, complementary molecular spectrometric tools are often required for a complete identification of macromolecules. Therefore, there is an increased research effort focused towards the development of integrated instruments to carry out the complete chemical speciation within a sample using a single instrument. An outline of recent developments in plasma-based mass spectrometric instrumentation for such comprehensive chemical speciation studies is here presented and their pros and cons detailed. In this context, the use of complementary techniques operating in parallel after splitting to a single chromatographic separation (dual sources) providing simultaneously elemental and molecular information is critically reviewed. Also, instrumental developments involving the use of stationary plasma sources operated in non-traditional modes (e.g. low pressure and low power) are also discussed. Moreover, the capabilities of tunable plasma-based ionization sources (allowing different ionization processes and, so, quasi-simultaneously providing elemental and molecular information with a single instrument) as a relatively simple and cheap approach are revised.

The Determination of Arsenic Compounds: A Critical Review

“…Although not a constraint for the "routine" determination of inorganic arsenic species in rice, the need to elute separated components into an organic mass spectrometer for qualitative analysis via an ionization source such as electrospray ionization (ESI) places restrictions on the components of the mobile phase. The continuing search for, and identification of, arsenic compounds in foods (and other materials such as plants with potential for phytoremediation) will be considerably helped by the simultaneous collection of data from an ICP-MS instrument and an ESI instrument [131]. Several research laboratories around the world have such HPLC detectors set up parallel; for example, the Aberdeen group have identified new arsenolipids in fish tissue with such a system [132], and there is even one research group, (Hieftje, Indiana) working on the construction of an instrument consisting of one mass spectrometer with dual ICP, ESI inlets [133,134].…”

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

“…These ionization sources can either be hard-ionization sources providing elemental information such as the inductively coupled plasma [5,6] or soft ionization sources such as electrospray ionization, chemical ionization, or matrix-assisted laser desorption ionization (MALDI) [7,8] which provide molecular weight information. There are approaches to combine these techniques within one instrument [9,10]. However, the instruments do not generate all the information from the same sample volume.…”

Atomic spectrometry update. Elemental speciation

“…This group has also surveyed the applications of plasma-based mass spectrometry for the simultaneous acquisition of elemental and molecular information. 10 The latter article covers a lot of the same material as the GD-MS review but does contain a section devoted to measurements made with parallel MS instruments and dual source instruments. Three other reviews cover the topic of elemental imaging with MS. [11][12][13] The spatial location of a compound containing an element of interest with respect to the rest of the matrix is not technically ''speciation'' according to the IUPAC definition cited above.…”