Analyte, solution mass spectra measured

Figure 6.6 Mass spectrum of rare earth elements tREEs) measured by CE-ICP-MS with on line separation of analytes (50 nl solution volume) a) natural isotopic pattern, concentration of each REE - 800ngg b) in an irradiated tantalum target (). S. Becker and H. ]. Dietze, Int. /. Mass Spectrom. Ion Proc. 197, 1-35 (2000). Reproduced by permission of the Royal Society of Chemistry.)...

A single measurement of a calibration sample can give the concentration of the test solution by a simple ratio. This is often done in techniques where a calibration internal standard can be measured simultaneously (within one spectrum or chromatogram) with the analyte and the system is sufficiently well behaved for the proportionality to be maintained. Examples are in quantitative nuclear magnetic resonance with an internal proton standard added to the test solution, or in isotope dilution mass spectrometry where an isotope standard gives the reference signal. For instrument responses As and /sample for internal standard and sample, respectively, and if the concentration of the internal standard is Cjs, then... 

The Evans NMR method requires a coaxial NMR tube where two solutions can be physically separated. One chamber in the tube contains a solution of a reference solute and the other contains a solution of the paramagnetic analyte and the reference solute. The reference solute must be inert toward the analyte. Because the chemical shift(s) for the resonances of the reference solute in the resulting NMR spectrum will be different for that in the solution with the paramagnetic analyte than in the solution without the analyte, resonances are observed for each chamber. The frequency shift of the selected reference resonance (measured in Hz) is proportional to the mass susceptibility of the analyte. Application of high-field NMR spectrometers is ideal for these studies because rather small chemical shift differences can be resolved. 

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