Dynamic range extension

FT/ICR experiments have conventionally been carried out with pulsed or frequency-sweep excitation. Because the cyclotron experiment connects mass to frequency, one can construct ("tailor") any desired frequency-domain excitation pattern by computing its inverse Fourier transform for use as a time-domain waveform. Even better results are obtained when phase-modulation and time-domain apodization are used. Applications include dynamic range extension via multiple-ion ejection, high-resolution MS/MS, multiple-ion simultaneous monitoring, and flatter excitation power (for isotope-ratio measurements). 

Dynamic range extension in GD quadrupole/ion-trap MS based on selective ion-accumulation (e.g. by mass-selective instability, single-frequency resonance ejection, combined rf-dc and entrance end-cap dc methods) allows the selective accumulation of the analyte ions and enables the dynamic range to be increased by a factor of 105 [233]. The linearities and relative trapping efficiencies of the previous methods were assessed with respect to the injection time and the methods were used for the GD ion-trap MS determination of major and minor constituents in NIST SRM 1103 Free Cutting Brass. 

D. C. Duckworth, C. M. Barshick, D. H. Smith, and S. A. McLuckey, Dynamic range extension in glow discharge quadrupole ion trap mass spectrometry. Anal. Chem. 66, 92-98 (1994). 

An image sensor can increase the effective dynamic range beyond that of an individual pixel by utilizing multiple exposures. There are basically two methods by which this can be achieved temporal or spatial. Image sensors of both types are available in the automotive market. Here we describe the principle of dynamic range extension, and the basic operations as well as the benefits and drawbacks of each of these methods. Actual implementations usually include additional post-processing and artifact-reduction techniques available in the sensor or in a separate device. 

Sawicki (13) used solid-surface fluorescence techniques extensively in the 1960 s for air pollution research. In 1967, Roth (14) reported the RTF of several pharmaceuticals adsorbed on filter paper. Schulman and Walling (15) showed that several organic compounds gave RTF when adsorbed on filter paper. Faynter et al. (16) reported the first detailed analytical data for RTF and gave limits of detection, linear dynamic ranges, and reproducibilities for the compounds. 

Wavelength database libraries of >32000 analytical lines can be used for fast screening of the echellogram. Such databases allow the analyst to choose the best line(s) for minimum interferences, maximum sensitivity and best dynamic range. Further extension of the wavelength range (from 120 to 785 nm) is desirable for alkali metals, Cl, Br, Ga, Ge, In, B, Bi, Pb and Sn, and would allow measurement of several emission lines in a multivariate approach to spectral interpretation [185]. 

The enormous dynamic range of proteins in the sample represents an additional difficulty in proteome analysis. The best example is semm with a protein abundance ranging over eleven orders of magnitude (Anderson and Anderson, 2002). To detect the low abundant species, one has to load a sufficient amount of digest on a column to meet the limit of detection (LOD) of the MS instrument. Some reports published used up to 2.5 L of plasma with an extensive fractionation of intact proteins prior to LC-MS analysis on the peptide level (Rose et al., 2004). 

API-MS methods have been successfully applied to the quantification of M2D-C3-0-(E0)n-Me, with reliable and reproducible results obtained after online HPLC separation [29,30]. The method was used to quantify recoveries of the surfactant from the surface of plant foliage and from solid substrates under controlled laboratory conditions. Extension of the method to environmental samples has not been investigated. The entire linear dynamic range for HPLC-APCI-MS was not determined, but linearity was observed within the required... 

Most important features of atomic spectrometry are the element specific detection and the superior sensitivity. Features such as the large dynamic range, the relative freedom from matrix effects even when atomic spectrometry is coupled to chromatography can be used more extensively to save time and to earn more accurate data using coupling techniques. 

T.-C. L. Wang, T. L. Ricca, and A. G. Marshall, "Extension of Dynamic Range in Fourier Transform Ion Cyclotron Resonance Mass Spectrometry via Stored Waveform Inverse Fourier Transform Excitation," Anal. Chem., IS, 2935-2938. 

The fluorescence technique combines the advantages of the large dynamic range of emission techniques with the simplicity and high selectivity of absorption techniques. Flame sources have been extensively used, however, for elements with refractory oxides, the ICP source has been found to be more satisfactory for AFS. A system for hollow cathode lamp excited ICP-AFS, as proposed by Demers and Allemand (1981), is commercially available as a modular simultaneous multielement ICP system. Although fluorescence techniques often offer two orders of magnitude sensitivity improvement over absorption, the multielement approach for AFS has not yet been commercially successful. Also promising for the future is the laser-excited furnace AFS where the detection limits for most elements are comparable to those of ICP-AES and for some elements, for eg, As, Cd, Pb, Tl, Lu, even lower (Omenetto and Human, 1984). The future for AFS techniques has been discussed by Stockwell and Corns (1992). 

---