Electropherogram, Evaluation

Table 1 also contains some peak measurement/analysis parameters that might be investigated in a robustness test (see Section III.C). ° However, except from the detection wavelength, these parameters are hardly ever evaluated in a robustness test, even though they can have a large influence on the electropherogram. 

Equation 5.5 enabled evaluating an entire electropherogram on a dimensionless scale from 0 (poor) to 1 (desirable) corresponding to poor separation and/or long total analysis time to good resolution with short analysis time, respectively. 

The study of comigrations is fundamental in order to be aware of the limitations of electrophoretic separation. Resolution deficiencies can be checked in a very simple way from the inspection of overlaid electropherograms of pure analytes and blanks. Besides, the appearance of partially resolved peaks, shoulders, tails, etc. is another sign of poor separation. In the case of minor components imbibed in a large peak as well as in the case of high overlapping, however, the detection of contamination may result in a more complex issue, and a mathematical evaluation of data may be required to ascertain the occurrence of comigration (16). 

Two electrically dependent phenomena contribute to the net mobility of an analyte, i.e., the intrinsic electrophoretic mobility and the electro-osmotic flow (EOF) [154], The mobility can be evaluated from the electropherogram using the migration time, t, of the analyte migrating a distance from the injection point to... 

Figure 4 (A) CZE-ESI-MS (negative ionization modus) intensity piot of Suwannee River NOW (ammonium carbonate, pH 10) (B) TIC in timescale (C) CZE-UV (254nm) electropherogram in effective mobility scale of Suwannee River NOM and superimposed electropherograms of selected FFE fractions (measured in CE immediately after FFE separation). (D) FFE-TOC of Suwannee river NOM in effective mobility scale with superimposed weighted (m/z) values as obtained from offline ESI-MS (positive ionization modus) of selected FFE fractions. (Adapted with permission from Schmitt-Kopplin P and Kettrup A (2003) Capillary electrophoresis-elect-rospray ionization-mass spectrometry for the characterization of natural organic matter an evaluation with free flow electrophoresis-off-line flow injection electrospray ionization-mass spectrometry. Electrophoresis 24 3057-3066 Wiley-VCH.)...

Fig. 5 Electropherogram of a mixed anion standard. Hydrodynamic injection (15 cm, 120 sec, 39.1 nl) with sodium borate buffer at pH 8. Peak 1 3.2 ppm selenate peak 2 3.6 ppm selenite peak 3 1.9 ppm arenate peak 4 4.4 ppm DMA peak 5 4.7 ppm arsenite. Source From An evaluation of ultrasonic nebulizers as interfaces for capillary electrophoresis of inorganic anions and cations with inductively coupled plasma mass spectrometric detection, in Spectrochim. Acta Part with permission of Elsevier Science.

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