Multi-ion counting

K. P. Jochum, Trace element analysis of geological samples by modern spark source mass spectrometry using multi-ion counting, Spectrosc. Eur. 9, 22-27 (1997). 

Bouman, C., Cocherie, A., Robert, M., Schwieters, J.B., Wiser, M. (2003) In situ U-Pb zircon dating using laser ablation multi ion counting ICP-MS (LA-MIC-ICPMS). Thirteenth Annual Goldschmidt Conference, September 7-12,2003, Kurashiki, Japan. 

Cocherie, A., Robert, M. (2007) Direct measurement of lead isotope ratios in low concentration environmental samples by MC-ICPMS and multi-ion counting. Chemical Geology, 243, 90-104. 

Cocherie,A.,Fanning, CM., Jezequel, R, Robert, M. (2009) LA-MC-ICPMS and multi-ion counting system, and SHRIMP U-Pb dating of complex zircons from quaternary tephras from the French Massif Central magma residence time and geochemical implications. Geochimica et Cosmochimica Acta, 73,1095-1108. 

Jochum, K.P., Laue, H., Seufert, H.M., Dienemann, C., Stoll, B., Pfander, I, Flanz, M., Achtermann, H., Hofmann, A.W. (1997) Multi-ion counting-spark source mass spectrometry (MIC-SSMS) a new multielement technique in geo- and cosmochercastvy. Fresenius Journal of Analytical Chemistry, 359,385-389. 

Fig. 15.7. Spark source mass spectrometer of Mattauch-Herzog design offering alternative detection on photoplate or by channeltron array for multi-ion counting. Reproduced from Ref. [42] with permission. Addison Wesley Longman, 1997.

Jochum, K.P. Stoll, B. Pfander, J.A Seufert, M. Flanz, M. Maissenbacher, P. Hofmarm, M. Hofmarm, A.W. Progress in Multi-Ion Counting Spark-Source Mass Spectrometry (MIC-SSMS) for the Tlnalysis of Geological Samples. Fresenius J. Anal. Chem. 2001, 370, 647-653. 

Multiple-collection techniques. Uranium. Table 1 shows a typical protocol used by multi-collector instruments (equipped with one ion counting channel) both in MC-TIMS, MC-ICPMS and LA-MC-ICPMS (e.g., Cohen et al. 1992 Stirling et al. 1995 Luo et al. 1997 Stirling et al. 2000 Pietruszka et al. 2002). A first sequence monitors the atomic ratios between and by aligning Faraday collectors for masses (10 ... 

Taylor, R.N., Wameke, T., Milton, J.A., Croudace, I.W., Warwick, P.E., and Nesbitt, R.W. (2003) Multiple ion counting determination of plutonium isotope ratios using multi-collector ICPMS, J. Anal. At. Spectrom., 18, 480-484. 

Representative spectra from a lanthanide and an actinide are shown in figs. 21 and 22. The most abundant analyte peaks are from monatomic ions (M" ), and these are observed at sensitivities of 10 -10 count s per mg in solution. Ion count rates as low as 2counts s can be distinguished from the background, so the detection limits for most elements are of the order of 10-100 ng/ . At present, these powers of detection are superior to those obtainable with any other common multi-element technique. Atomic absorption spectrometry with electrothermal vaporization does provide detection limits in a similar range but is generally used only for single-element determinations. 

With no stable isotope pair within the U system or a suitable AME, a standard-sample bracketing protocol is usually employed to correct for mass bias. Human urine generally contains very low concentrations of U (generally 1-5 ng/L), so an isotope dilution strategy is required, together with ion-counting detection (ideally a Daly photomultiplier or discrete dynode secondary electron multiplier) and a multi-static (rather than multi-dynamic) peak-jumping routine, for precise measurement of the total U concentration and the minor isotopes of and even... 

One part of the formula may be a multi-atom ion which remains intact after the reaction [e.g. the reaction shown below of sodium chloride with silver nitrate to give sodium nitrate and silver chloride, the nitrate ion (NO ) remains unchanged]. It is not necessary to count the individual atoms of the multiple atom ion separately, you can just count groups . 

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