Isotachophoresis instrumentation

The separation unit of the capillary isotachophoresis instrument used is shown in Fig. 13.1. A 0.85mm id capillary tube made of fluorinated ethylene propylene copolymer was used in the pre-separation (first) stage and a capillary tube of 0.30mm id made of the same material served for the separation in the second stage. Both tubes were provided with conductivity detection cells [18] and an ac conductivity mode of detection [15] was used for making the separations visible. 

Fig. 4 Examples of portable microfluidic instruments, (a) The system integrates fluidics, microseparation chips, lasers, optics, high-voltage power supplies, electronic controls, data algorithms, and a user interface into a hand-portable instrument (Reprinted from [55] with permission of The American Chemistry Society), (b) A miniature LED-induced fluorescence microdevice (Reprinted from [56] with permission of The Royal Society of Chemistry), (c) Hand-held isotachophoresis instrument (dimensions 7.6 x 5.7 x 3.8 cm) (Reprinted from [57] with permission of The Royal Society of Chemistry)...

One of the major advantages of CE as a separation technique is the wide variety of separation modes available. Analytes can be separated on the basis of charge, molecular size or shape, pi, or hydrophobicity. The same CE instrument can be used for zone electrophoresis, IEF, sieving separations, isotachophoresis, and chromatographic techniques such as MEKC and capillary electrokinetic chromatography. This section provides a brief description of each separation mode. Zone electrophoresis, IEF, and sieving are the primary modes used for protein separations, and these will be discussed in detail in the following sections. 

The length of the analyte zone in cITP is a quantitative parameter and is related to the concentration of the analyte in that zone. The height of the step is a quantitative parameter that is characteristic of the analyte, and it is directly proportional to analyte mobility. Conductivity detection is the detection system generally used for isotachophoresis, although UV detection is employed occasionally in commercial instrumentation. Figure 5.19 shows a typical electropherogram obtained using cITP with conductivity detection. 

Everaerts, D.M., Beckers, J.L. and Verheggen Th. P.E.M. In Isotachophoresis—Theory Instrumentation and Applications. Elsevier, Amsterdam, Oxford, New York (1976). 

Volume 6 Isotachophoresis. Theory, Instrumentation and Applications by F.M. Everaerts, J.L. Beckers and Th.P.E.M. Verheggen... 

Everaerts FM, Beckers JL, Verheggen T. P. E. M. Isotachophoresis. Theory, Instrumentation and Applications. Amsterdam, The Netherlands Elsevier, 1976. 

Everaerts FM, Beckers JL, Verheggen TP (1976) Isotachophoresis Theory, instrumentation and applications. Journal of Chromatography Library, Vol. 6, Elsevier, Amsterdam. 

A. M. Wolters, D. A. Jayawickrama, C. K. Larive, and J. V. Sweedler, Capihary isotachophoresis/NMR Extension to trace impurity analysis and improve instrumental coupling, Anal. Chem. 74 (2002), 2306 2313. 

Sloan, J. E. Thorman, W. Twitty, G. E. Bier, M. "Automated recycling freeflow isotachophoresis Principle, instrumentation and first results" /. Chromatography. 1988, 457, pp 137-148. 

Capillary electrophoresis is the generic name for a family of related techniques which have their origin in capillary zone electrophoresis (CZE) and are capillary gel electrophoresis (CGE), capillary isoelectric focusing (CIEF), miscellar electrokinetic capillary chromatography (MECC) and capillary isotachophoresis (CITE). Though the techniques differ significantly in principle of operation they can be carried out largely on the same basic instrumentation. 

Isotachophoresis is an electrophoretic technique. It is used in the field of inogenic compounds in solutions. With the use of adequate instrumentation the separations can be performed at a considerable speed (3-5 min). For both qualitative and quantitative analysis easily measurable parameters of the record (height and length of the step) are available. 

The study is aimed at making the readers acquainted with the basic theory, instrumentation and application possibilities of analytical isotachophoresis. The article also incluedes advanced knowledge of the method itself and simultaneously outlines problems of the present basic research and prospects for further development. 

A basic feature which differentiates isotachophoresis from the other electrophoretical techniques is that zones migrate at the same velocity from the moment the equilibrium has established. By this the name iso-tachos is explained. Its simplest version is the moving boundary technique applied to the measurement of transference numbers (known since Nemst ° Whetham and Kohlrausch ). Theoretical, experimental and instrumental elaboration of this technique was described in detail by Macinnes and Longsworth Based on the example of this simple method, basic features and characteristics of isotachophoretical migration and its terminology can be described and explained. 

The development of the instrumentation for analytical isotachophoresis has played a leading role in the extension of the knowledge of the technique itself and in its applications. Although a detailed historical review has been reported, it is expedient to note, at least briefly in chronological sequence, some of the contributions to instrumentation and applications and to mention the previous terms for the present analytical isotachophoresis. 

A more extensive study on the displacement electrophoresis was reported by Martin and Everaerts in 1970. In this study they covered substantial parts of the theory, the instrumentation and the application of this technique. The year 1970 is a certain milestone in the nomenclature since the name isotachophoresis was then introduced and adopted (cf. ). 

The present state of the instrumentation used for analytical isotachophoresis can be characterized by the fact that both commercial devices " and fairly advanced home-made devices are being used for analytical and preparative purposes. (For a description see 2.53,61.69) ... 

The basic instrumental parts of isotachophoresis are as follows a high-voltage stabilized d.c. current supply, an isotachophoretic column and a detection equipment with a recorder. 

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