Collision octopole

Figure 4.8 Product-ion spectrum of catalytic ion at m/z 649, and collision with ethyl vinyl ether in the collision octopole at low energy (nominal leV).

As with most methods for studying ion-molecule kinetics and dynamics, numerous variations exist. For low-energy processes, the collision cell can be replaced with a molecular beam perpendicular to the ion beam [106]. This greatly reduces the thennal energy spread of the reactant neutral. Another approach for low energies is to use a merged beam [103]. In this system the supersonic expansion is aimed at the tluoat of the octopole, and the ions are passed tluough... 

Note The initial kinetic energy of slow ions can be lost upon several collisions, thereby stopping their motion along the cell. [119,120] Under such conditions, the continuous ion current into the cell is the only impetus to push the ions through as a result of space-charge effects. The resulting dwell time of about 10 ms allows up to about 5000 (reactive) collisions to take place at some 5 Pa collision gas (or reagent gas) pressure in an octopole collision cell. [123]... 

Figure 3.13 Combination of an ion trap with octopole collision cell in an ICP mass spectrometer. (D. Koppenaal, C. J. Barinaga and M. R. Smith, J. Anal. At. spectrom. 9, 1053 (1994). Reproduced by permission of The Royal Society of Chemistry.)...

Collision/reaction cell Agilent ceVcs2 octopole cell (ORS) Elan DRC II quadrupole dynamic reaction cell XSeries11 hexapole cell ( XS-Minus modus) Varian-820-MS using collision reaction interface... 

Miniaturization of HPLC-ICP-MS is an important issue in bioanalytical chemistry when small amounts of sample (e.g., single cells) need to be investigated.33 ICP-MS (with an octopole collision cell) in combination with nano-HPLC (75 pun column) was optimized for the detection of selenopeptides in a selenium-yeast protein digest after 100-fold preconcentration on a C18 capillary precolumn (300 (im column for salt removal and cleanup).34 Under identical separation and preconcentration conditions, electrospray MS/MS (using Nanospray qQqToF-MS - QSTAR from Applied... 

An accurate determination of copper and zinc traces in human serum samples from the International Measurement Evaluation Programme-17 launched by IRMM (Geel) has been made by isotope dilution TIMS.38 An analytical method for the multi-element determination of metals (Ti, V, Cr, Co, Ni and Mo) potentially released from dental implants and prostheses into human body fluids (in blood and urine) by ICP-MS (double-focusing sector field instrument and quadrupole instrument with octopole collision cell) for medical studies was developed in Sanz-Medel s group.39 The Cr and Co concentrations found in blood samples of patients with chromium-cobalt based alloy varied in the sub-p,gl 1 range and were not significantly higher than the basal levels found by other authors.40... 

Accurate determination of the biological important element, selenium, in blood serum by isotope dilution analysis using ICP-QMS with octopole collision cell (Agilent 7500ce, Tokio, Japan) is described by Schaumloffel and coworkers.55 A recovery of selenium from human serum reference material was only 78 % when hydrogen was applied as collision gas but 96.7 % using xenon as a non-reactive collision gas to eliminate isobaric interferences. A detection limit of 3.3p,gl-1 was achieved.55... 

Size exclusion chromatography coupled to an ICP-QMS with an octopole collision cell was employed for the multi-elemental speciation of essential elements (P, S, Cr, Mn, Fe, Co, Cu, Zn, Br, Se and I) and Al as a toxic element in premature human milk.28 Comparison of speciation results demonstrates that premature human mothers milk differs significantly from formula milks in terms of the element binding pattern to the biomolecules. It was found that premature human milk is very rich in high molecular weight species associated with metals. The authors concluded that more attention must be paid to the chemical form in which essential elements are added to the formulas, particularly those used for the nutrition of premature babies.28... 

H2-X where X is a molecule. If a molecule other than H2 is chosen as the collision al partner X, new absorption bands appear at the rotovi-brational bands of that molecule. As an example, Fig. 3.17 shows the rototranslational enhancement spectra [46] of H2-CH4 for the temperature of 195 K. At the higher frequencies (v > 250 cm-1), these look much like the H2-Ar spectrum of Fig. 3.10 the H2 So(J) lines at 354, 587, and 815 cm-1 are clearly discernible. Besides these H2 rotational lines, a strong low-frequency spectrum is apparent which corresponds to the (unresolved) induced rotational transitions of the CH4 molecule these in turn look like the envelope of the rotational spectra seen in pure methane, Fig. 3.22. This is evident in the decomposition of the spectrum, Fig. 3.17, into its main components [46] the CH4 octopole (dashed curve) and hex-adecapole (dot-dashed curve) components that resemble the CH4-CH4 spectrum of Fig. 3.22, and the H2 quadrupole-induced component (dotted curve) which resembles the H2-Ar spectrum, Fig. 3.14. The superposition (heavy curve) models the measurement (big dots) closely. Similar spectra are known for systems like H2-N2 [58]. 

Both photon-assisted collisions and collision-induced absorption deal with transitions which occur because a dipole moment is induced in a collisional pair. The induction proceeds, for example, via the polarization of B in the electric multipole field of A. A variety of photon-assisted collisions exist for example, the above mentioned LICET or pair absorption process, or the induction of a transition which is forbidden in the isolated atom [427], All of these photon-assisted collision processes are characterized by long-range transition dipoles which vary with separation, R, as R n with n — 3 or 4, depending on the symmetry of the states involved. Collision-induced spectra, on the other hand, frequently arise from quadrupole (n = 4), octopole (n = 5) and hexadecapole (n = 6) induction, as we have seen. At near range, a modification of the inverse power law due to electron exchange is often quite noticeable. The importance of such overlap terms has been demonstrated for the forbidden oxygen —> lD emission induced by collision with rare gases [206] and... 

Chen, Z., N.I. Khan, G. Owens, et al. 2007. Elimination of chloride interference on arsenic speciation in ion chromatography inductively coupled mass spectrometry using an octopole collision/reaction system. Microchem. J. 87 87-90. 

Other gas-phase ion chemical reactions were explored by using oxygen introduced into the octopole collision cell product ions were injected into and analyzed by the quadrupole ion trap [55]. Reaction of oxygen with Y+, Zr+, and Xe+ was found to proceed rapidly, forming YO+, ZrO+, and Xe neutrals, effectively eliminating interferences by the atomic ions. These ions are particularly difficult... 

When 1 -butene was used as reaction partner and thermalization gas in the first octopole, a new signal with the mass corresponding to the propylidene complex 17 appeared in the spectrum, indicating that an olefin metathesis reaction had occurred. This reactivity was confirmed by mass-selecting either 15 or 16 in the first quadrupole and reaction with 1-butene in the collision cell. The... 

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