Extending the Dynamic Range

Although most discrete dynode detectors are very similar in the way they work, there are subtle differences in the way the measurement circuitry handles low and high ion count rates. When ICP-MS was first commercialized, it could only handle up to five orders of dynamic range. However, when attempts were made to extend the dynamic range, certain problems were encountered. Before we discuss how modem detectors deal with this issue, let us first look at how it was addressed in earlier instrumentation. 

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Second, and more important for extending the dynamic range, is the availability of different binding sites with multiple binding constants K, K,2... Kn), for the species X. In that case, the response will include a contribution from all of the binding events. Ignoring for the moment the interferants, according to (1.11) the activity of the bound species is... 

How would you achieve reversibility and at the same time extend the dynamic range of such designer biosensors ... 

I. L. Garcia, P. Vinas, N. Campillo, M. H. Cordoba, Extending the dynamic range of flame atomic absorption spectrometry a comparison of procedures for the determination of several elements in milk and mineral waters using online dilution, Fresenius J. Anal. Chem., 355 (1996), 57-64. 

The potential of AMT in FT-ICR-MS was already discnssed [31-33], If an AMT can be isotope-coded, the same strategy can be applied to quantitative proteomics. One of the problems of FT-ICR-MS in quantitative proteomics is the space charging constraint of the FT-ICR cell. Data-dependent selective ejection of highly abundant ions and prolonged accumulation of low-abundant ions in the external quadrapole, prior to ion transfer to the FT-ICR cell, helps in extending the dynamic range of the method [108],... 

I. Lopez Garcia, P. Vifias, N. Campillo, M. Hernandez Cordoba, Use of submicroliter-volume samples for extending the dynamic range of flow injection flame atomic absorption spectrometry, Anal. Chim. Acta 308 (1995) 85. 

Widmann, J. R, Presser, C., and Leigh, S. D. "Extending the Dynamic Range of Phase Doppler Interferometry Measurements." Atomization and Sprays 12, no. 4 (2002) 513-37. 

Khayamian, T., Ensafi, A.A., Benvidi, A. Extending the dynamic range of copper determination in differential pulse adsorption cathodic stripping voltammetry using wavelet neural network. Talanta 69, 1176-1181 (2006)... 

For example, in electron spin echo (ESE) [78-81] spectroscopy, pulse experiments are performed which are similar to those discussed in the previous section. Again, different relaxation times can be used to extend the dynamical range, accessible by conventional CW techniques. There is, however, one major drawteck of dynamic ESE, namely the spectrometer dead time, which prevents the study of fast motions. 

The more modem approach is to use just one detector to extend the dynamic range. This has typically been done by using the detector both in pulse and analog mode, so... 

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