Couplings mass spectrometry

Plasma torches and thermal ionization sources break down the substances into atoms and ionized atoms. Both are used for measurement of accurate isotope ratios. In the breakdown process, all structural information is lost, other than an identification of elements present (e.g., as in inductively coupled mass spectrometry, ICP/MS). 

The low concentrations of lead in plasma, relative to red blood cells, has made it extremely difficult to accurately measure plasma lead concentrations in humans, particularly at low PbB concentrations (i.e., less than 20 pg/dL). However, more recent measurements have been achieved with inductively coupled mass spectrometry (ICP-MS), which has a higher analytical sensitivity than earlier atomic absorption spectrometry methods. Using this analytical technique, recent studies have shown that plasma lead concentrations may correlate more strongly with bone lead levels than do PbB concentrations (Cake et al. 1996 Hemandez-Avila et al. 1998). The above studies were conducted in adults, similar studies of children have not been reported. 

Abstract Mobile Au in soil has been postulated for many years. It has been used by the mineral exploration industry in areas of transported overburden as a vector towards buried deposits. Until now, the nature of this mobile Au has not been known or investigated. Soil samples from a colluvial area above the Bounty Deposit (Yilgarn Craton, Western Australia) investigated by analytical techniques including laser ablation inductively coupled mass spectrometry (LA-ICP-MS) and synchrotron x-ray fluorescence (SXRF) combined with X-ray absorption spectrometry (XAS) have allowed us to map the invisible Au in these soils and suggests that at least some of it occurs in an ionic form. 

Engstrom E, Rodushkin I, Baxter DC, Ohlander B (2006) Chromatographic purification for the determination of dissolved silicon isotopic compositions in natural waters by high-resolution multicollector inductively coupled mass spectrometry. Anal Chem 78 250-257 Epica community members (2004) Eight glacial cycles from an Antarctic ice core. Nature 429 623-628... 

Startin, J.R. Gilbert, J. (1984) Single ion monitoring of butadiene in plastics and foods by coupled mass-spectrometry-automatic headspace gas chromatography. J. Chromatogr.. 294, 427-430... 

Some reviews [5-7] have appeared on NCE-electrospray ionization-mass spectrometry (NCE-ESI-MS) discussing various factors responsible for detection. Recently, Zamfir [8] reviewed sheathless interfacing in NCE-ESI-MS in which the authors discussed several issues related to sheathless interfaces. Feustel et al. [9] attempted to couple mass spectrometry with microfluidic devices in 1994. Other developments in mass spectroscopy have been made by different workers. McGruer and Karger [10] successfully interfaced a microchip with an electrospray mass spectrometer and achieved detection limits lower than 6x 10-8 mole for myoglobin. Ramsey and Ramsey [11] developed electrospray from small channels etched on glass planar substrates and tested its successful application in an ion trap mass spectrometer for tetrabutylammonium iodide as model compound. Desai et al. [12] reported an electrospray microdevice with an integrated particle filter on silicon nitride. 

Carey, J.M., Vela, N.R and Caruso, J.A. (1992) Multi-element detection for supercritical fluid chromatography by inductively coupled mass spectrometry./. Anal. At. Spectrom., 7, 1173-1181. 

Michalke, B. and Schramel, P. (1996) Hyphenation of capillary electrophoresis to inductively coupled mass spectrometry as an element-specific detection method for metal speciation. J. Chromatogr. A, 750, 51-62. 

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. 

S. Munro, L. Ebdon, Application of inductively coupled mass spectrometry (ICP-MS) for trace metal determination in foods, J. Anal. Atom. Spectrom., 1 (1986), 211-221. 

Atomic absorption, flame emission, electrothermal atomization, inductively coupled mass spectrometry 66... 

Several papers utilizing 3 mm probe capabilities were also published that delved into the area of protein structures. Hepatocyte nuclear factor 4 was studied by a group lead by Williams.155 It is interesting to note that a 2.7 A X-ray study showed a fatty acid in the pocket of HNF4y. Gas chromatography coupled mass spectrometry (GC/MS) and 3 mm NMR studies of extracts from purified HNF4x led to the identification of mixtures of saturated and crs-monounsaturated Ci4 to Qg fatty acids. Bertini and co-workers156 utilized 3 mm probe capabilities in the determination of the solution structure of CopC, a cupredoxin-like protein involved in copper homeostasis. 

GC-coupled mass spectrometry with electron ionization (EI-MS) or with electron capture, negative ionization (ECNI-MS), and GC with electron capture detection (ECD) have been the major techniques for the analysis of aryl methyl sulfone fractions isolated from tissue (Sect. 5.1). GC/ECD detection and identification of MeS02-PCBs relies on a comparison of GC retention times relative to authentic standards, which is dependent on the absence of co-eluting interfe-rents. GC/MS techniques have provided important structural information for MeS02-PCBs, especially in the absence of authentic standards. 

James, M.R., Wayman, T., Stellmacher, K. and Hall, R.J.B., The determination of plutonium in urine by electro-thermal vaporisation inductively coupled mass spectrometry (ETV-ICP-MS), presented at 3rd Surrey Conference on Plasma Source Mass Spectrometry, Manchester, England, July 1989. 

Metals. Although metals analysis has traditionally been carried out using atomic absorption spectrophotometry and more recently inductively coupled mass spectrometry, HPLC can be used in certain circumstances by chelation of the appropriate metal. It would be unlikely that HPLC would be a first choice technique unless it helped to determine... 

Coupling mass spectrometry (MS) to capillary electrophoresis provides detection and identihcation of amino acids, peptides, and proteins based on the accurate determination of their molecular masses [15]. The most critical part of coupling MS to CE is the interface technique employed to transfer the sample components from the CE capillary column into the vacuum of the MS. Electrospray ionization (ESI) is the dominant interface which allows a direct coupling under atmospheric pressure conditions. Another distinguishing features of this soft ionization technique when applied to the analysis of peptides and proteins is the generation of a series of multiple charged, intact ions. 

Electron ionization usually gives some molecular ions and sometimes these are abundant. Often it is difficult to be certain which ion, if any, is the molecular ion. For this rea.son, it is advantageous to obtain both El and Cl spectra, the first giving good structural information and the second good molecular mass information. g Plasma torches and thermal ionization sources break down the substances into atoms and ionized atoms. Both are used for measurement of accurate isotope ratios. In the breakdown process, all structural information is lost, other than an identification of elements present (e.g., as in inductively coupled mass spectrometry, ICP/MS),... 

Feng, R., Machado, N. Ludden, J. (1993) Lead chronology of zircon by laser probe-inductively coupled mass spectrometry (LP-ICP-MS). Geochimica et Cosmochimica Acta 57, 3479-3486. 

AUain P, Berre S, Mauras Y, Le Bouil A. Evaluation of inductively coupled mass spectrometry for the determination of platinum in plasma. Biol Mass Spectrom 1992 21 141-3. 

Chinese gold with femtosecond laser ablation-inductively coupled mass spectrometry. Journal of Archaeological Science 36(2) 461-466. 

For library analysis of compound mixtures, reliable results are obtained by coupling mass spectrometry with HPLC or capillary electrophoresis (CE). In this arrangement, mixtures of several hundred compounds can be analyzed. A comparison of MS, CE, and NMR for library characterization has been made in [93]. It was concluded that existing analytical techniques can provide sufficient information about prepared libraries. 

Automated discrete sampling flame AAS was applied for sequential determination of Ca, Fe, and Mn in moss samples as an alternative to ICP-MS (Inductively Coupled Mass Spectrometry) and in comparison with this method (Kmetov et al. 2003). 

Peobst T Zeh P and Kim J-I (1995) Multielement determinations in ground water ultrafiltrates using inductively coupled mass spectrometry and monostandard neutron activation analysis. Fresenius J Anal Chem 351 745-751. 

Inductively coupled mass spectrometry (ICP-MS) has been undoubtedly a hot analytical technique in the last few years. Since the commercial introduction of ICP-MS instruments (VG Elemental Ltd.).in 1983, approximately 150 of them were installed worldwide during the first five years. A number of conferences have been dedicated to ICP-MS, and many analytical and spectroscopic meetings have included an ICP-MS session or symposium. Now two commercial systems (VG PlasmaQuad and Perkin Elmer Sciex ELAN ICP-MS systems) are available. 

Food residues containing cocoa were also found in vessels dating from the preclassical Maya period (900 BC-250 AD). The vessels were burial artefacts, which were found in the city of Colha (52 km north of Belize City). Cocoa (Theobroma cacao) is the only Central American plant which contains theobromine. Therefore, It Is the indicator substance to prove the prior existence of cocoa at those archaeological sites its detection Involves HPLC coupled mass spectrometry. [135]... 

The ability of the Fe state as a catalyst was also demonstrated in the reduction of nitromethane, CH3N02 . Voltammetry of Mb/DDAB under solutions of nitromethane at pH 5.5, obtained a catalytic current at the formal Fe / couple, without an observable shift at the Fe 4/ couple. Mass spectrometry analysis of aqueous products from bulk electrolysis confirmed production of methylhy-droxylamine, CH3NHOH. The catalytic efficiency, Ic/h current ratio, decreased significantly with increased pH or scan rate, indicative of a strongly proton dependant process. The slope of the catalytic potential was ca. 30mV/pH unit, in agreement with the proposed le /2 H+ limiting step, Eqs. (4.49)-(4.51). 

---