Ionization sources for mass

Dacheux N, Aupiais J (1997) Determination of uranium, thorium, plutonium, americium, and curium ultratraces by photon electron rejecting alpha liquid scintillation. Anal Chem 69 2275-2282 Duan YX, Chamberlin EP, Olivares JA (1997) Development of a new high-efficiency thermal ionization source for mass spectrometry. Inti JMass Spectrom IonProcessesl61 27-39 Edwards RL, Chen JH, Wasserburg GJ (1987) systematics and the precise... 

Electron ionization (El) was the primary ionization source for mass analysis until the 1980s, limiting the chemist to the analysis of small molecules well below the mass range of common bioorganic compounds. This limitation motivated the development of the techniques commonly known as ESI, 1 MALDI, 2 and fast atom bombardment (FAB) 3,4 (Table 1). These ion sources allow for rapid and easy peptide analyses that previously required laborious sample preparation or were not possible with electron ionization. The mechanism of ionization these ion sources employ, which is somewhat responsible for their ability to generate stable molecular ions, is protonation and/or deprotonation. 

Ostman P, Marttila SJ, Kotiaho T et al (2004) Microchip Atmospheric Pressure Chemical Ionization Source for Mass Spectrometry. Anal Chem 76 6659-6664... 

Vela N. P., Caruso J. A. and Satzger R. D. (1997) Potential for an atmospheric-pressure low-power microwave-induced plasma ionization source for mass spectrometry, Appl. Spectrosc. 51 1500-1503. 

Now, many elements are determined routinely at the same time by ICP-AES, as evidenced by the fact that several thousand of these instruments are in routine use throughout the world. In 1980, just when ICP-AES seemed secure in its niche as the all-around champion for elemental analysis, the ICP was shown to be an excellent ionization source for mass spectrometry (MS) (Houk et al. 1980). In just a few years, ICP-MS has already exerted a considerable impact on analytical spectroscopy, particularly for determination of rare earth elements, for which it is clearly superior to any other technique. 

Balogh, M. A High Speed Combination Multi-mode Ionization Source for Mass Spectrometars, PCT Int. Appl., WO 2003102537 A2 20031211, 2003, 38 pp. 

In 1960 Tal roze and Frankevich (39) first described a pulsed mode of operation of an internal ionization source which permits the study of ion-molecule reactions at energies approaching thermal energies. In this technique a short pulse of electrons is admitted to a field-free ion source to produce the reactant ions by electron impact. A known and variable time later, a second voltage pulse is applied to withdraw the ions from the ion source for mass analysis. In the interval between the two pulses the ions react under essentially thermal conditions, and from variation of the relevant ion currents with the reaction time the thermal rate constants can be estimated. 

Geromanos, S., Freckleton, G., and Tempst, P., Tuning of an electrospray ionization source for maximum peptide-ion transmission into a mass spectrometer, Anal. Chem., 72, 777, 2000. 

Figure 8.1 Schematic diagram of electron impact (El) source for mass spectrometry. The sample enters the evacuated chamber as a gas and is intersected by a beam of electrons released from the heated cathode and accelerated towards the positive anode at the top. The impact of the electrons atomizes and ionizes the sample, and the resulting positive ions are attracted towards the annular cathode on the right, passing through it and out of the source towards the mass selection device.

Hsieh, Y APPI a new ionization source for LC-MS/MS assays, in Using Mass Spectrometry for Drug Metabolism Studies, CRC Press, Boca Raton, 2005, pp 253-276. 

Electrospray (ESI) is an atmospheric pressure ionization source in which the sample is ionized at an ambient pressure and then transferred into the MS. It was first developed by John Fenn in the late 1980s [1] and rapidly became one of the most widely used ionization techniques in mass spectrometry due to its high sensitivity and versatility. It is a soft ionization technique for analytes present in solution therefore, it can easily be coupled with separation methods such as LC and capillary electrophoresis (CE). The development of ESI has a wide field of applications, from small polar molecules to high molecular weight compounds such as protein and nucleotides. In 2002, the Nobel Prize was awarded to John Fenn following his studies on electrospray, for the development of soft desorption ionization methods for mass spectrometric analyses of biological macromolecules. ... 

Most elements are almost completely singly ionized in the argon ICP (a fact which also makes it an ideal ion source for mass spectrometry), hence the majority of the most sensitive emission lines result from atomic transition of ionised species, so-called ion lines, with fewer sensitive atom lines. Ion lines are usually quoted as, e.g., Mn II 257.610 nm and atom lines as, e.g., Cu 1324.754 nm, with the roman numerals II and I denoting ionic and atomic species, respectively. 

Inductively Coupled and Microwave Induced Plasma Sources for Mass Spectrometry 4 Industrial Analysis with Vibrational Spectroscopy 5 Ionization Methods in Organic Mass Spectrometry 6 Quantitative Millimetre Wavelength Spectrometry 7 Glow Discharge Optical Emission Spectroscopy A Practical Guide 8 Chemometrics in Analytical Spectroscopy, 2nd Edition 9 Raman Spectroscopy in Archaeology and Art History 10 Basic Chemometric Techniques in Atomic Spectroscopy... 

Intense laser sources have been used to induce ionization or fluorescence of products in several kinds of photolytic experiments. Welge and his colleagues have used these sources to detect NO by multiphoton ionization (MPI) of the product. They have also used lasers that have been extended to the VUV region by various nonlinear mixing schemes as photoionization sources for mass spectrometric detection of reaction products. 

The application of molecular SIMS as a sensitive ionization source for nonvolatile and thermally labile molecules compares favorably with other new ionization methods in mass spectrometry such as field desorption (FD), Californium-252 plasma desorption (PD), fast heavy ion induced desorption (FHIID), laser desorp-... 

Analytical research applications of mass spectrometers fitted with electro-optical ion detectors are carried out at the present time at JPL and the FOM Institute. These involve" (1) at JPL a 1" EOID on sector type mass spectrometer (CEC type 21-490) in conjunction with an API (armospheric pressure ionization) source for the development of an automated assay procedure for amino acid derivatives produced by a novel Edman type sequenator (23), and (2) at the FOM Institute a 1" EOID on a sector mass spectrometer,fitted with magnetic and electrostatic quadruple "Zoom" lenses, permitting variation of dispersion for focusing a greater number of masses on the 1" detector (24,25). 

APCI has become a popular ionization source for applications of coupled HPLC-MS. Figure 1.33 shows an example of an application of HPLC-APCI coupling [79]. It shows the analysis obtained from extracts of maize plants. Six compounds are identified by mass spectrometry. These compounds have been identified as glucoconjugated DIMBOA (2,4-dihydroxy-7-methoxy-l,4-benzoxazin-3-one) and similar molecules that differ by the number of methoxy groups in the benzene ring and/or by the N-O methylation of the hydroxamate function. This example clearly shows the influence of the analyte on the type of observed molecular species. Indeed, the presence of an acidic group in the compound from peak 1 allows mainly the detection of deprotonated molecular ions, whereas the compound from peak 4 does not contain an acid group and thus leads only to the formation of adduct ions. 

Mass spectrometry is now widely used for inorganic characterization and microsurface analysis. El is the preferred ionization source for volatile inorganic compounds, whereas the others which are non-volatile may be analysed using ionization sources already described such as SIMS, FD, FAB, LD or ESI [92-94], The example in Figure 1.40 shows the analysis of orthorhombic sulfur (Sg ring) and Cr(CO)2(dpe)2, respectively obtained with an El source and an ESI source. 

The studies of calcium metabolism in normal children are underway with 15-20 children to be studied in the near future The data generated from these studies will be used as the basis for studies of diseases of calcium metabolism in children We anticipate being able to study a number of children with FOP and possibly contribute to innovative therapies for these children by monitoring changes in calcium kinetics Improvements in the thermal ionization source for the quadrupole mass spectrometer are underway a substantial improvement in sesitivity is expected from this effort The model used for data analysis is under continuing investigation in order to improve its predictive and experimental design capabilities ... 

The development of the electrospray ionization (ESI) source for mass spectrometry provided an ideal means of detection for capillary electrophoretic (CE) separations. The ESI source is currently the preferred interface for CE-MS, due to the fact that it can produce ions directly from liquids at atmospheric pressure and with high sensitivity and selectivity for a wide range of analytes. 

---