Capillary Gel Electrophoresis: Difference between revisions

From OpenWetWare
Jump to navigationJump to search
No edit summary
 
(31 intermediate revisions by 4 users not shown)
Line 1: Line 1:
{{Template:CHEM-ENG590E}}
{{Template:CHEM-ENG590E}}
=Introduction: Protein Analysis through Electrophoresis=
Gel electrophoresis is the separation of particles by their charge and mass through the application of an electric field. Briefly, when the field is applied charged particles migrate towards the cathode or anode, for negatively and positively charged particles respectively, at a speed proportional to their charge density, due to their electrophoretic mobility, and size and shape, due to gel filtration. Smaller molecules have more mobility in the gel than larger molecules, and thus molecules of a similar charge and size separate and move as a band through the gel, effectively separating the proteins.  This is usually done in an agarose or polacrylamide gel, in between two glass plates or in a capillary. There are many different advantages to carrying out gel electrophoresis in a capillary as opposed to its' larger scale, making capillary gel electrophoresis (CGE) a useful tool for specific applications. How CGE works is that a small plug of the sample that needs separating is put into one end. Then, the electric field is put on the capillary, and components separate and move through the capillary in plugs.Capillaries used in CGE usually have diameters around 20-100 µm. This narrow diameter makes it such that lateral diffusion effects are negligent, and that high voltages can be used with very little temperature differences within the capillary. These high voltages mean a quick and efficient separation of small samples of product, as opposed to electrophoresis in a gel slab. The conditions for these separations are easy to reproduce, making CGE very useful for analytical applications, before moving it up to the higher scale. CGE, due to the gel that affects the velocity of the particles based off of size, is used in many biological applications for separating protein and DNA molecules, which may have similar charges but different sizes.


[[Image:CGE_separation.png|thumb|right|400px|'''Figure 1:''' Shows inlet plug of of proteins, at t=0, and the proteins separating in the gel matrix and travelling towards the charged end, with charge and size effects determining the order. ]]
=Capillary Gel Electrophoresis (CGE)=
[[Image:Chem728_CGE_separation.png |thumb|right|600px|'''Figure 1:''' Shows inlet plug of proteins, at t=0, and the proteins separating in the gel matrix and traveling towards the charged end, with charge and size effects determining the order. (Figure courtesy of Elvan Cavac)]]


Capillary Gel Electrophoresis (CGE) is an analytical separation method where charged molecules are separated in capillaries filled with porous gel matrix. CGE is basically an adaptation of the traditional slab gel electrophoresis to the capillary electrophoresis (CE) method for its advantageous features. CGE is used to separate large biological molecules like protein, DNA, and RNA. In free solution, these molecules have similar electrophoretic migration rates due to similar charge-to-mass ratios. However, in CGE, the non-convective medium allows them to separate based only on their size. The general protocol follows four steps: 1) The start and end vials and the connecting capillaries are filled with electrolyte solution, 2) The sample to be separated is introduced in the capillary, 3) Electric field is applied and the analytes migrate in the opposite charge direction, 4) Samples and separations are detected via various modes depending on the experimental setup. The sieving matrix could be selected from a diverse array of gel materials based on the experimental requirements. 
At this scale, there is a smaller sample volume and reagent requirement, the analysis is done in a shorter time and offers higher resolution, the separation is more efficient, and the analyte concentration is quantified more reliably through UV absorbance, fluorescence, or mass spectrometry. The disadvantages come from the difficulty in building the device, and the restriction in the sample size. Figure 1 shows the migration of negatively charged macromolecules through the porous gel via an applied voltage. The smallest macromolecule migrates the fastest while the largest one migrates the slowest.


=Basis of Electrophoretic Separations=


=Current Methods=
Electrophoresis is the migration of ions in a system where an electric field is applied. Force applied by the Electric Field (FE<sub>f</sub>) is proportional to its effective charge (q) and the electric field strength (E)
=====Gel=====
For proteins, generally the method used for purification is SDS-PAGE. PAGE stands for polyacrylamide gel electrophoresis, which has a pH high enough (around 9) so that proteins generally have negative charges, and move in the same direction towards the cathode, and a set pore size so that the filtration in the gel is characteristic of size. SDS stands for sodium dodecyl sulfate, which is a detergent that denatures proteins so that the separation by size is based purely off of molecular weight, as opposed to other size factors in folded proteins. Agarose gel, which is better for larger molecules, is usually the gel used for separating DNA fragments.
=====Capillaries=====
Usually, the material used for capillaries for CGE is fused silica, which is heated and stretched to the desired dimensions to form the capillaries. However, there are challenges faced due to the silica capillaries, due to the negatively charged silanol groups that compose the inner diameter of silica capillaries. of One is electroosmotic flow (EOF). EOF occurs when liquid near a charged surface, such as in electrophoresis, causes bulk liquid flow at that surface. Due to the small inner diameter in CGE, which creates a high surface area to volume ratio, EOF can be a significant effect on fluid flow. EOF increases the velocity of the flow, which could push the protein solution out of the capillary prior to completing separation. The velocity of EOF is determined by this equation:


V=-(εζ/4πη)E
:::::::::: FE<sub>f</sub> = qE (1)


In this equation, ε is the dielectric constant, ζ is zeta potential, η is viscosity, and E is the potential applied with the electric field. Zeta potential, in terms of CGE, is the charge on the inner wall of the capillary due to the makeup of the capillary wall. Zeta potential is proportional to the charge density on the surface, and modifying the surface to reduce this zeta potential is thus a common way of reducing the effects of EOF.  
The movement of the ion is faced by a retarding frictional force (F<sub>f</sub>), which is proportional to the velocity of the charged molecule (V<sub>ep</sub>), and the friction coefficient (f). In Gel Electrophoresis, friction is correlated with the sieving matrix and its pore size.  


[[Image:EOF.png]]
:::::::::: F<sub>f</sub> = f V<sub>ep</sub> (2)
 
This means that the charged molecule reaches a steady state velocity in its movement where the accelerating force equals to the frictional force.
 
:::::::::: FE<sub>f</sub> = F<sub>f</sub> (3)
 
Therefore, we can write:
 
:::::::::: qE = f V<sub>ep</sub> (4)
 
If we rearrange:
 
:::::::::: V<sub>ep</sub> = qE / f =  µ<sub>ep</sub>E (5)
 
In this equation, µ<sub>ep</sub> (electrophoretic mobility) refers to a constant of proportionality between the velocity of the molecule and the applied electric field strength. µ<sub>ep</sub> is proportional to the charge of the ion and inversely proportional to the friction coefficient.
 
The friction coefficient f is correlated with the hydrodynamic radius of the charged molecule (r) and the viscosity of the medium (η) and can be written as:
 
:::::::::: f = 6πηr (6)
This shows that a larger radius of the ion has a lower electrophoretic mobility. In summary, larger charged molecules migrate slower whereas the smaller molecules migrate faster.
 
=Gel Types=
[[Image: Chem728_CGE_.jpg|thumb|right|250px|'''Figure 2:'''A. Linear Branched (Physical or Non-crosslinked) Polymers) B. Branched Polymers. C. Crosslinked (Chemical or Network) Polymers. <sup>[3]</sup> ]]
 
The sieving matrix in the capillaries can be selected, based on separation needs, between permanent (chemical) gels and reversible (physical) gels. The polymer network reduces the adsorption of the solute to the capillary wall and the solute diffusion rate; resulting in the suppressed electroosmotic flow of water. These features increase efficiency; a short column is sufficient to achieve efficient separation. 
 
==Physical Gels==
Physical gels are networks of molecular entanglements or secondary forces including ionic, hydrogen bonding or hydrophobic interactions. All the physical interactions that take place prevent dissolution; but are reversible and can be disrupted by changes in physical conditions. (Figure 2).
 
==Chemical Gels==
Chemical gels are prepared by covalent crosslinking, have defined and controllable pore sizes, and produce high-resolution separations. Poly-acrylamide and PEG gels are commonly used with pore sizes that go as low as 1 nm, depending on the experimental requirements. Poly-acrylamide gels are widely used and preferred due to their electroneutrality.
 
 
 
 
=Advantages of Capillary Gel Electrophoresis=
 
Capillary Gel Electrophoresis (CGE) follows the theoretical principles of slab gel electrophoresis (SGE). In typical slab gel electrophoresis, an electric field is applied through a porous gel matrix and molecules (DNA, RNA, protein) are separated based on their size: larger molecules move slowly through the sieving matrix, while smaller molecules migrate faster. The main disadvantage of the SGE is joule heating as a result of the solution resistance to the applied current. Using capillaries instead of a slab gel provides controlled heat dissipation.
 
:::::::::: H=VIt (7)
 
The heat produced is proportional to the voltage (V), electric current (I), and time (t) it takes to run a gel.  In SGE, the heat build-up in a 10*15 cm gel cassette cannot be effectively dissipated from the system. As a result, the porous gel matrix may melt or the density gradients in the gel can alter the efficiency of separation.  Whereas in CGE, the capillaries have diameters around 20-100 µm (large ratio of surface area to volume); therefore the capillaries can dissipate heat more efficiently. When potentials go up to ~200V for a typical slab gel, current technology uses CGE to apply high potentials (up to 30 kV) for fast and efficient separations.
 
=Capillaries=
 
 
 
The inner coating of the capillaries should be selected so that electroosmosis is prevented and the analytes will not interact with the capillary wall. Naked fused capillaries have disadvantages since they show electroosmosis above a pH of 3 and conclude in the buffer migration towards the cathode. To avoid this, the inner silica surface is covalently coated for stability.  Figure 3 shows the preparation steps of a typical Si-C bond coating.  The capillary is first etched with KOH solution and rinsed with water. After, it’s flushed with hydrochloric acid to remove K+ ions to expose free silanol groups on the wall surface. After drying, a solution of  trimethoxysilne is pumped in and the unbound region is flushed away. By another reaction carried out, an epoxide group is opened with a solution of PEG and boron trifluoride. Then the capilleries are rinsed with DI water. This process will help decrease a significant amount of adsorption.
 
[[Image:Chem728_capilleries.png|thumb|center|500px|'''Figure 3:''' Scheme of the procedure for the deactivation of the silica wall. Me = methyl. <sup>[7]</sup>]]
 
=Applications=
 
[[Image:1-s2.0-S016793170200494X-gr7.jpg‎|thumb|right|300px|'''Figure 4:''' A. Top view of microchip device used for protein separation. B. To-scale view of connection channel, which has a width of 50 µm, leading into the separation channel. C. Side view of PDMS layer, with separation channels, and inlets on a glass base.<sup>[8]</sup> ]]
 
CGE is mainly used for separation of molecules with similar mass/size ratio, but different sizes. Therefore, the separation of nucleic acids and proteins has been very common through this method. Some of the groundbreaking research in molecular biology in the past decades took advantage of the capillary gel electrophoresis method.
 
CGE was used in the human genome project, employing a physical gel, after a long period of frustrations with chemical hydrogels.  The stability problems of the cross-linked polyacrylamide gels were halting the application of this separation method to DNA sequencing. If CGE were to be used in sequencing the human genome, the polymer matrix in the separation capillary had to be replenished in an automated system. In the early 90’s, it was shown that through the use of non-crosslinked polymer matrices and high pressure, the polymer could be replaced entirely. Thus, the human genome project used replaceable linear polymer matrices for automated large-scale DNA sequencing.<sup>[5]</sup>
 
For the separation of proteins, their properties must be taken into account. While different proteins vary in size; they also vary in charge. In order to separate proteins based on size in CGE, proteins are treated with a detergent SDS that allows their native charge to be masked. Since SDS molecules are highly negatively charged, the native charge of the proteins can be masked. This technique is analogous to the SDS-PAGE method.
 
The biotechnology industry uses CGE method for separation analysis of biomaterials on a routine basis with microchips. As other processes must be run prior to CGE for protein and nucleic acid analysis, microchips provide the opportunity to run these assays concomitantly on the same platform. This allows the cost of the experiment to be low during the analytical trials. In addition, CGE provides an alternative to liquid chromatography with higher resolution quality and ability to be incorporated into a microchip. Figure 4 shows a classic PDMS microchip that incorporates two parts: a PCR chamber to amplify the DNA, and a separation chamber to separate the DNA strands.


Another problem with the capillary surface is that the proteins that need separating can end up interacting with the negatively charged silica wall, because of its' small diameter. Controlling this is very important, which is why the inner surface of silica capillaries is often coated or treated with base to reduce the effects of EOF and protein interactions with the wall. Treatment of base, as shown in the figure below, leads to hydrolysis of the silanol groups on the surface of the wall, which negates the negative charge of the surface and reduces the effects of EOF in the capillary. Materials that capillaries are generally coated with are polyacrylamide, polyvinyl alcohol, polyethylene glycol, and polyvinylpyrolidone, which all have high pH values. The way coating reduces EOF and protein interaction effects is that they alter the pH of the wall, or shield the negative charges of the wall, for the same reasons of reducing surface interactions.
=Microchip Devices for CGE=
CGE is done on a miniaturized microchip platform, making benefits from CGE being in a smaller system increase, for a simple and efficient method for analyzing proteins, and other biomedical materials. Column length in microchips is small, so this process can be done quite fast, this experiments can be reproduced quickly with many trials without much variation, with low cost. This miniaturization is important, because many biomedical analyses that use electrophoretic separation are used by the biotechnology industry. Biotechnology, pharmaceutical companies especially,can be pricey, and thus lowering costs of analysis for these uses would be beneficial for that purpose. Generally, PDMS chips on glass have been used for these purposes. This has already become a tool used for pharmaceutical analysis. It can be used to determine drug concentrations in fluids, which is important in knowing the kinetics and toxicity of the drug such that appropriate doses can be determined. PDMS based microfluidic devices are useful because they can be designed such that different channels can be running multiple analytical processes on a single chip. For example, as shown in the figure below, when separating DNA microchips can have a chamber for PCR to amplify the DNA, which can then flow into the separation chamber to separate the DNA strands. However, due to the incompatibilities in the different parts of the process,  it has been difficult to get all parts of protein purification and analysis onto a single chip. Once progress is made on this, it could become a very important tool for drug development purposes.
[[Image:1-s2.0-S016793170200494X-gr7.jpg‎]]
=References=
=References=
1. Nuchtavorn, Nantana, Suntornsuk, W., Lunte, S., Suntornsuk, L. (2015) Recent applications of microchip electrophoresis to biomedical analysis. Journal of Pharmaceutical and Biomedical Analysis. 113, 72-96. http://dx.doi.org/10.1016/j.jpba.2015.03.002
1. Xu, Y. Tutorial: Capillary Electrophoresis. ''Chem. Educator'' '''1996''', ''1'', 1-14. http://dx.doi.org/10.1007/s00897960023a
 
2. Camilleri, P. ''Capillary Electrophoresis: Theory and Practice''. CRC Press: Boca Raton, 1993.
 
3. Landers, J. P. ''Handbook of Capillary Electrophoresis''. CRC Press: Boca Raton, 1994.
 
4. Ewing, A. G.; Wallingford, R. A.; Olefirowicz, T. M. Capillary Electrophoresis. ''Anal. Chem.'' '''1989''', 61(4), 292A–303A. https://doi.org/10.1021/ac00179a722


2.  Zhu, Zaifang, Lu, J., Liu, S. (2011) Protein Separation by Capillary Electrophoresis: A Review, doi:  10.1016/j.aca.2011.10.022
6.  Whatley H. ''Basic Principles and Modes of Capillary Electrophoresis''. In: Petersen J.R., Mohammad A.A. (eds) Clinical and Forensic Applications of Capillary Electrophoresis. Pathology and Laboratory Medicine. Humana Press: Totowa, NJ, 2001. https://doi.org/10.1007/978-1-59259-120-6_2


3. Whatley, Harry, (2001), Basic Principles and Modes of Capillary Electrophoresis, Pathology and Laboratory Medicine Part 1, 21-58, DOI
7. S. F. Y. Li. ''Capillary Electrophoresis—Principles, Practice and Application''. Elsevier: Amsterdam, 1992. https://doi.org/10.1002/bmc.1130070215
10.1007/978-1-59259-120-6_2


4. Morbioli, Giogio, Mazzu-Nascimento, T., Aquino, A., Cervantes, C., Carrilho, E.,(2016) Recombinant drugs-on-a-chip: The usage of capillary electrophoresis and trends in miniaturized systems- A review. Analytica Chimica Acta. 935, 44-57. http://dx.doi.org/10.1016/j.aca.2016.06.019
8. Karger B. L.; Guttman A. DNA sequencing by CE. ''Electrophoresis'' '''2009''', 30(S1), S196–S202. http://dx.doi.org/10.1002/elps.200900218.


5. Fuji, Teruo (2002) PDMS-based microfludic devices for biomedical  applications.  Microelectric Engineering, 61-62, 907-914. http://dx.doi.org/10.1016/S0167-9317(02)00494-X
9. Hebenbrock K.; Schügerl K.; Freitag R. Analysis of plasmid-DNA and cell protein of recombinant Escherichia coli using capillary gel electrophoresis. ''Electrophoresis'' '''1993''', 14(8), 753-8. doi: 10.1002/elps.11501401118.

Latest revision as of 10:34, 27 March 2023

CHEM-ENG 535: Microfluidics and Microscale Analysis in Materials and Biology

Home        People        Wiki Textbook       

Capillary Gel Electrophoresis (CGE)

Figure 1: Shows inlet plug of proteins, at t=0, and the proteins separating in the gel matrix and traveling towards the charged end, with charge and size effects determining the order. (Figure courtesy of Elvan Cavac)

Capillary Gel Electrophoresis (CGE) is an analytical separation method where charged molecules are separated in capillaries filled with porous gel matrix. CGE is basically an adaptation of the traditional slab gel electrophoresis to the capillary electrophoresis (CE) method for its advantageous features. CGE is used to separate large biological molecules like protein, DNA, and RNA. In free solution, these molecules have similar electrophoretic migration rates due to similar charge-to-mass ratios. However, in CGE, the non-convective medium allows them to separate based only on their size. The general protocol follows four steps: 1) The start and end vials and the connecting capillaries are filled with electrolyte solution, 2) The sample to be separated is introduced in the capillary, 3) Electric field is applied and the analytes migrate in the opposite charge direction, 4) Samples and separations are detected via various modes depending on the experimental setup. The sieving matrix could be selected from a diverse array of gel materials based on the experimental requirements. At this scale, there is a smaller sample volume and reagent requirement, the analysis is done in a shorter time and offers higher resolution, the separation is more efficient, and the analyte concentration is quantified more reliably through UV absorbance, fluorescence, or mass spectrometry. The disadvantages come from the difficulty in building the device, and the restriction in the sample size. Figure 1 shows the migration of negatively charged macromolecules through the porous gel via an applied voltage. The smallest macromolecule migrates the fastest while the largest one migrates the slowest.

Basis of Electrophoretic Separations

Electrophoresis is the migration of ions in a system where an electric field is applied. Force applied by the Electric Field (FEf) is proportional to its effective charge (q) and the electric field strength (E)

FEf = qE (1)

The movement of the ion is faced by a retarding frictional force (Ff), which is proportional to the velocity of the charged molecule (Vep), and the friction coefficient (f). In Gel Electrophoresis, friction is correlated with the sieving matrix and its pore size.

Ff = f Vep (2)

This means that the charged molecule reaches a steady state velocity in its movement where the accelerating force equals to the frictional force.

FEf = Ff (3)

Therefore, we can write:

qE = f Vep (4)

If we rearrange:

Vep = qE / f = µepE (5)

In this equation, µep (electrophoretic mobility) refers to a constant of proportionality between the velocity of the molecule and the applied electric field strength. µep is proportional to the charge of the ion and inversely proportional to the friction coefficient.

The friction coefficient f is correlated with the hydrodynamic radius of the charged molecule (r) and the viscosity of the medium (η) and can be written as:

f = 6πηr (6)

This shows that a larger radius of the ion has a lower electrophoretic mobility. In summary, larger charged molecules migrate slower whereas the smaller molecules migrate faster.

Gel Types

Figure 2:A. Linear Branched (Physical or Non-crosslinked) Polymers) B. Branched Polymers. C. Crosslinked (Chemical or Network) Polymers. [3]

The sieving matrix in the capillaries can be selected, based on separation needs, between permanent (chemical) gels and reversible (physical) gels. The polymer network reduces the adsorption of the solute to the capillary wall and the solute diffusion rate; resulting in the suppressed electroosmotic flow of water. These features increase efficiency; a short column is sufficient to achieve efficient separation.

Physical Gels

Physical gels are networks of molecular entanglements or secondary forces including ionic, hydrogen bonding or hydrophobic interactions. All the physical interactions that take place prevent dissolution; but are reversible and can be disrupted by changes in physical conditions. (Figure 2).

Chemical Gels

Chemical gels are prepared by covalent crosslinking, have defined and controllable pore sizes, and produce high-resolution separations. Poly-acrylamide and PEG gels are commonly used with pore sizes that go as low as 1 nm, depending on the experimental requirements. Poly-acrylamide gels are widely used and preferred due to their electroneutrality.



Advantages of Capillary Gel Electrophoresis

Capillary Gel Electrophoresis (CGE) follows the theoretical principles of slab gel electrophoresis (SGE). In typical slab gel electrophoresis, an electric field is applied through a porous gel matrix and molecules (DNA, RNA, protein) are separated based on their size: larger molecules move slowly through the sieving matrix, while smaller molecules migrate faster. The main disadvantage of the SGE is joule heating as a result of the solution resistance to the applied current. Using capillaries instead of a slab gel provides controlled heat dissipation.

H=VIt (7)

The heat produced is proportional to the voltage (V), electric current (I), and time (t) it takes to run a gel. In SGE, the heat build-up in a 10*15 cm gel cassette cannot be effectively dissipated from the system. As a result, the porous gel matrix may melt or the density gradients in the gel can alter the efficiency of separation. Whereas in CGE, the capillaries have diameters around 20-100 µm (large ratio of surface area to volume); therefore the capillaries can dissipate heat more efficiently. When potentials go up to ~200V for a typical slab gel, current technology uses CGE to apply high potentials (up to 30 kV) for fast and efficient separations.

Capillaries

The inner coating of the capillaries should be selected so that electroosmosis is prevented and the analytes will not interact with the capillary wall. Naked fused capillaries have disadvantages since they show electroosmosis above a pH of 3 and conclude in the buffer migration towards the cathode. To avoid this, the inner silica surface is covalently coated for stability. Figure 3 shows the preparation steps of a typical Si-C bond coating. The capillary is first etched with KOH solution and rinsed with water. After, it’s flushed with hydrochloric acid to remove K+ ions to expose free silanol groups on the wall surface. After drying, a solution of trimethoxysilne is pumped in and the unbound region is flushed away. By another reaction carried out, an epoxide group is opened with a solution of PEG and boron trifluoride. Then the capilleries are rinsed with DI water. This process will help decrease a significant amount of adsorption.

Figure 3: Scheme of the procedure for the deactivation of the silica wall. Me = methyl. [7]

Applications

Figure 4: A. Top view of microchip device used for protein separation. B. To-scale view of connection channel, which has a width of 50 µm, leading into the separation channel. C. Side view of PDMS layer, with separation channels, and inlets on a glass base.[8]

CGE is mainly used for separation of molecules with similar mass/size ratio, but different sizes. Therefore, the separation of nucleic acids and proteins has been very common through this method. Some of the groundbreaking research in molecular biology in the past decades took advantage of the capillary gel electrophoresis method.

CGE was used in the human genome project, employing a physical gel, after a long period of frustrations with chemical hydrogels. The stability problems of the cross-linked polyacrylamide gels were halting the application of this separation method to DNA sequencing. If CGE were to be used in sequencing the human genome, the polymer matrix in the separation capillary had to be replenished in an automated system. In the early 90’s, it was shown that through the use of non-crosslinked polymer matrices and high pressure, the polymer could be replaced entirely. Thus, the human genome project used replaceable linear polymer matrices for automated large-scale DNA sequencing.[5]

For the separation of proteins, their properties must be taken into account. While different proteins vary in size; they also vary in charge. In order to separate proteins based on size in CGE, proteins are treated with a detergent SDS that allows their native charge to be masked. Since SDS molecules are highly negatively charged, the native charge of the proteins can be masked. This technique is analogous to the SDS-PAGE method.

The biotechnology industry uses CGE method for separation analysis of biomaterials on a routine basis with microchips. As other processes must be run prior to CGE for protein and nucleic acid analysis, microchips provide the opportunity to run these assays concomitantly on the same platform. This allows the cost of the experiment to be low during the analytical trials. In addition, CGE provides an alternative to liquid chromatography with higher resolution quality and ability to be incorporated into a microchip. Figure 4 shows a classic PDMS microchip that incorporates two parts: a PCR chamber to amplify the DNA, and a separation chamber to separate the DNA strands.

References

1. Xu, Y. Tutorial: Capillary Electrophoresis. Chem. Educator 1996, 1, 1-14. http://dx.doi.org/10.1007/s00897960023a

2. Camilleri, P. Capillary Electrophoresis: Theory and Practice. CRC Press: Boca Raton, 1993.

3. Landers, J. P. Handbook of Capillary Electrophoresis. CRC Press: Boca Raton, 1994.

4. Ewing, A. G.; Wallingford, R. A.; Olefirowicz, T. M. Capillary Electrophoresis. Anal. Chem. 1989, 61(4), 292A–303A. https://doi.org/10.1021/ac00179a722

6. Whatley H. Basic Principles and Modes of Capillary Electrophoresis. In: Petersen J.R., Mohammad A.A. (eds) Clinical and Forensic Applications of Capillary Electrophoresis. Pathology and Laboratory Medicine. Humana Press: Totowa, NJ, 2001. https://doi.org/10.1007/978-1-59259-120-6_2

7. S. F. Y. Li. Capillary Electrophoresis—Principles, Practice and Application. Elsevier: Amsterdam, 1992. https://doi.org/10.1002/bmc.1130070215

8. Karger B. L.; Guttman A. DNA sequencing by CE. Electrophoresis 2009, 30(S1), S196–S202. http://dx.doi.org/10.1002/elps.200900218.

9. Hebenbrock K.; Schügerl K.; Freitag R. Analysis of plasmid-DNA and cell protein of recombinant Escherichia coli using capillary gel electrophoresis. Electrophoresis 1993, 14(8), 753-8. doi: 10.1002/elps.11501401118.

Retrieved from "https://openwetware.org/mediawiki/index.php?title=Capillary_Gel_Electrophoresis&oldid=1109376"