Metabolomic Applications of Inductively Coupled Plasma-Mass Spectrometry (ICP-MS)
Inductively coupled plasma-mass spectrometry is a versatile technique for rapid multielement analysis of metabolomic samples. It allows analysis of elements in solution or solids at the major, minor, or trace component levels in a very wide range of sample matrices. Laser Ablation, Gas Chromatography, Liquid Chromatography, and Capillary Electrophoresis have been successfully interfaced to extend the analytical capability of the technique for the speciation of organometallic metabolites. The principles of the technique are described, with practical details, followed by illustrative examples in the metabolomics field.
Key wordsLaser Ablation Inductively coupled plasma Mass spectrometry Elemental analysis
(IP) of each element is the number of electron volts (eV) required to release an electron from the outermost orbit of an atomic state to generate a singly charged ion (M+). This largely determines the ICP-MS sensitivity.
A confined plasma (qv) is maintained by energy input from a radiofrequency (rf) field. The plasma ionizes materials at the atomic level, which can then be analyzed by various detection modalities, including mass spectrometry.
Laser is an acronym for “light amplification by the stimulated emission of radiation.” A laser produces a narrow, pulsed or continuous beam of monochromatic, coherent light in the visible, infrared (IR) or ultraviolet (UV) regions of the electromagnetic spectrum that delivers energy to where it is focused at the surface of the sample. For laser ablation the sample is contained in a sample chamber which has a window transparent to laser light. Argon or helium carrier gas is used to transport the sample particles produced by the ablation process to the argon plasma of the ICP-MS instrument.
The fourth state of matter in which atoms are ionized to created a gas comprising free electrons and cations that interact over a substantial range. Plasmas are found in deep space, the sun, plasma screen monitors, as well as in laboratory conditions including ICP and in tokamaks. Such plasmas are created at very high temperature to maintain an ionized state.
- 8.Willard H, Merritt L, Dean J, Settle F (1981) Instrumental methods of analysis, 6th edn. Wadsworth, BelmontGoogle Scholar
- 16.Larsen EH, Lobinski R, Burger-Meyer K, Hansen M, Ruzik R, Mazurowska L, Rasmussen PH, Sloth JJ, Scholten O, Kik C (2006) Uptake and speciation of selenium in garlic cultivated in soil amended with symbiotic fungi (mycorrhiza) and selenate. Anal Bioanal Chem 385(6):1098–108PubMedCrossRefGoogle Scholar
- 19.Afton S, Kubachka K, Catron B, Caruso JA (2008) Simultaneous characterization of selenium and arsenic analytes via ion-pairing reversed phase chromatography with inductively coupled plasma and electrospray ionization ion trap mass spectrometry for detection applications to river water, plant extract and urine matrices. J Chromatogr A 1208(1–2):156–63PubMedCrossRefGoogle Scholar
- 21.Sloth JJ, Larsen EH, Julshamn K (2005) Report on three aliphatic dimethylarsinoyl compounds as common minor constituents in marine samples. An investigation using high-performance liquid chromatography inductively coupled plasma mass spectrometry and electrospray ionisation tandem mass spectrometry. Rapid Commun Mass Spectrom 19(2):227–35PubMedCrossRefGoogle Scholar
- 30.Easter RN, Chan Q, Lai B, Ritman EL, Caruso JA, Qin Z (2010) Vascular metallomics: copper in the vasculature. Vasc Med 15(1):61–69Google Scholar