The development and general applications of capillary electrophoresis (CE) in the field of clinical chemistry are discussed. It is shown how the early development of electrophoresis was closely linked to clinical testing. The rise of gel electrophoresis in clinical chemistry is described, as well as the eventual developments that lead to the creation and the use of modern CE. The general principles of CE are reviewed and the potential advantages of this method in clinical testing are examined. Finally, an overview is presented of several areas in which CE has been developed and is currently being explored for use with clinical samples

Hage, David S

English

DigitalCommons@University of Nebraska

University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln David Hage Publications Published Research - Department of Chemistry 2019 An Overview of Capillary Electrophoresis (CE) in Clinical Analysis David S. Hage Follow this and additional works at: https://digitalcommons.unl.edu/chemistryhage  Part of the Medicinal-Pharmaceutical Chemistry Commons This Article is brought to you for free and open access by the Published Research - Department of Chemistry at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in David Hage Publications by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln.   An Overview of Capillary Electrophoresis (CE) in Clinical Analysis    David S. Hage  University of Nebraska-Lincoln  Abstract  The development and general applications of capillary electrophoresis (CE) in the field of clinical chemistry are discussed. It is shown how the early development of electrophoresis was closely linked to clinical test-ing. The rise of gel electrophoresis in clinical chemistry is described, as well as the eventual developments that lead to the creation and the use of modern CE. The general principles of CE are reviewed and the poten-tial advantages of this method in clinical testing are examined. Finally, an overview is presented of several areas in which CE has been developed and is currently being explored for use with clinical samples.   Keywords Capillary electrophoresis, Clinical chemistry, Clinical applica-tions, History of capillary electrophoresis    1 Introduction   Electrophoresis has been an important tool in clinical analysis for decades [1–3]. The primary mode of separation in this method is based on the different rates of migration of analytes in an electric field. However, there are many formats for this type of separation and 1digitalcommons.unl.eduPublished as Chapter 1 in Terry M. Phillips (ed.), Clinical Applications of Capillary Electrophoresis: Methods and Protocols, Methods in Molecular Biology, vol. 1972DOI: https://doi.org/10.1007/978-1-4939-9213-3_1 Copyright © 2019 Springer Science+Business Media, LLC, part of Springer Nature. Used by permission.D.  Hage in Clinical  Appl icat ions of Capillary Electrophores is  (2019)       2a variety of schemes by which the migration rates of chemicals in a sample can be modified [4–9]. These features, plus the fact that many biological agents hold some charge, have made electrophoresis a key method in clinical analysis for the examination of amino acids, pep-tides, proteins, and nucleic acids, as well as many small charged sol-utes [1–3].  One way of using electrophoresis is to apply small amounts of a sample to a support (usually a gel or paper) and allow the compo-nents in this sample to travel in a running buffer through the support in the presence of an electric field. These approaches are known as “gel electrophoresis” or “paper electrophoresis” and they have histor-ically been the most common types of electrophoresis found in clin-ical laboratories [3, 4]. It is also possible to separate the components of a sample by using a narrow capillary that is filled with a running buffer, followed by placement of this buffer and its contents into an electric field. This second method, known as “capillary electrophoresis” or “CE” [5–8], is the focus of this text. This chapter provides an over-view of CE as related to the historical development of this technique and its use in clinical analysis. A summary of the clinical applications of CE, as discussed in more detail in later chapters, is also presented.   2 Origins of Electrophoresis in Clinical Testing   It has been known for over a century that substances like proteins and enzymes will travel in an electric field [10–12]. However, the use of this phenomenon for routine chemical separations did not occur until the late 1930s, when Arne Tiselius demonstrated that electrophoresis could be utilized for the separation of serum proteins [13]. The ap-proach used by Tiselius, as later recognized by the 1948 Nobel Prize in Chemistry, was the first practical example in which electrophoresis was used for clinical analysis. The apparatus that was used by Tise-lius in these experiments consisted of a U-shaped tube into which he placed his sample and a running buffer (see Fig. 1). When an electric field was applied across this tube, the proteins in the sample began to separate based on their charge and size as they migrated toward the electrode of opposite charge. The result was a series of broad and only partially resolved bands that were then used to study the pro-tein content in the sample [8, 9]. The method that was employed by D.  Hage in Clinical  Appl icat ions of Capillary Electrophores is  (2019)       3Tiselius is now known as “moving boundary electrophoresis” because it produced a series of moving boundaries between regions that con-tained different mixtures of proteins [3, 9]. In modern laboratories, it is more common to use more efficient separation devices and to instead use a small amount of sample that will allow analytes to be separated into narrow bands or zones. These conditions result in a general ap-proach that is now known as “zone electrophoresis” [5–9].  It is interesting that even though Tiselius employed an open tube system, the use of gels or other supports instead of open tubes be-came the main format for electrophoresis that was employed in clin-ical laboratories for over 50 years [1–4]. The emphasis on gel or pa-per electrophoresis during this time was due to the smaller sample requirements, greater ease, and better reproducibility of conduct-ing separations by this approach as opposed to using large open tubes filled with a running buffer. The popularity of gel electropho-resis in particular was further enhanced through the development of improved supports for these separations, such as polyacrylamide gels, and the introduction of new methods based on gel electropho-resis. Two examples of these methods that are still common in clin-ical and biomedical laboratories are sodium dodecyl sulfate poly-acrylamide gel electrophoresis (SDS-PAGE) and isoelectric focusing (IEF) [3–5, 9, 14].  Fig. 1 General design of the apparatus that was used by Arne Tiselius in his early work with electrophoresis and the separation of serum proteins   D.  Hage in Clinical  Appl icat ions of Capillary Electrophores is  (2019)       4Interest did continue in further pursuing the use of open tube sys-tems for electrophoresis [14–19]. For instance, Hjerten developed a system in 1967 that utilized 1–3 mm I.D. quartz capillaries to carry out electrophoretic separations in free solution [15]. This system was used for the separation of proteins, nucleic acids, and microorgan-isms, among other analytes, and included an online detector. Unfor-tunately, the relatively large diameters of the capillaries in this system required the continuous rotation of these capillaries to minimize the effects of Joule heating and convection [14]. It was demonstrated in 1974 by Virtanen that narrower 0.2 mm I.D. capillaries could be used to eliminate the need for rotation to minimize the effects of heating convection [14, 16]. However, it was not until the commercial devel-opment of small diameter silica capillaries in the late 1970s, and the subsequent work by Jorgenson and Lukacs with 75–100 μm I.D. silica capillaries in the early 1980s, that CE became a viable alternative to gel electrophoresis for the separation of clinical and biological sam-ples [17–19].    3 Basic Principles and Advantages of Capillary Electrophoresis   Figure 2 shows a typical system for CE, as might be found in a clin-ical laboratory [3, 6–8]. This system includes a power supply, which can often provide an applied potential up to 25–30 kV, and a computer for control of the system and for the collection of data. There are also two electrodes for applying an electric field across the capillary and buffer containers that supply a contact between these electrodes and the solution within the capillary. Modern CE systems include an on-line detector, which may be based on the use of UV-vis absorbance, laser-induced fluorescence, electrochemical detection, or mass spec-trometry [3, 8]. In addition, the system has some means for injecting samples onto the capillary. Typical volumes for the injected samples are in the pL-nL range and can be applied by using methods such as electrokinetic injection or hydrodynamic injection [6–8].  The capillaries in most modern CE systems have inner diameters of 20–100 μm and lengths of 20–100 cm [6–8]. The use of these nar-row bore tubes allows the heat that is generated in the presence of an electric field to be quickly dissipated to the surrounding environ-ment. The removal of this heat helps to provide much more efficient D.  Hage in Clinical  Appl icat ions of Capillary Electrophores is  (2019)       5and faster separations than gel or paper electrophoresis. The absence of a gel or support in most types of CE also eliminates eddy diffusion and minimizes secondary interactions that may occur with the sup-port. These conditions create a situation in which longitudinal diffu-sion is often the main source of band-broadening and in which more efficient separations are obtained as the voltage is increased and an-alytes spend less time in the capillary. The result is a fast separation with high efficiency and narrow peaks [6–8, 17–19].  There are many features of CE that make this method attractive as an alternative to gel or paper electrophoresis for clinical analysis. For instance, CE is faster and more efficient than these traditional meth-ods. CE is also easier to perform as part of an automated system. The small sample size requirements of CE and its ability to be used with various detectors and detection formats are additional features that make this method appealing for clinical analysis [3, 20–25].    Fig. 2 General design of a modern capillary electrophoresis system. This particular configuration is based on the “normal polarity” mode, in which the sample is ap-plied to a silica capillary at the side of the positive electrode   D.  Hage in Clinical  Appl icat ions of Capillary Electrophores is  (2019)       64 Applications of CE in Clinical Analysis   Following the introduction of the first commercial CE instruments in the late 1980s, there has been a steady increase in the use of CE for various samples of clinical interest. Some early reviews of clinical ap-plications for CE can be found in references [4, 20–23].  Figures 3 and 4 illustrate how the interest in CE for clinical analysis has grown during the last three decades. This interest is indicated by both the number of publications that have appeared on this topic (Fig. 3) and citations that have been made to these papers (Fig. 4). Most of these applications have involved the use of urine, serum, plasma, or blood. In 1990, there were only two publications that dealt with such samples and that included “capillary electrophoresis” within their ti-tles. However, between 1990 and 2017 there were over 1380 publica-tions dealing with these samples and that included “capillary electro-phoresis” in their titles. There were also over 27,000 citations to these articles over the same period of time. In addition, work appeared on more exotic specimens such as saliva, cerebrospinal fluid, and tears, with over 80 publications and almost 1760 citations to these papers appearing between 1990 and 2017.  Many applications for CE in clinical chemistry have been explored and developed, as is illustrated in Fig. 5 [1, 3, 23–25]. One set of these applications has involved the use of CE in the analysis of clini-cal biomarkers. These biomarkers may be serum proteins, enzymes, peptides, carbohydrates, lipids, and small organic or inorganic com-pounds [21, 24]. For instance, some chapters in this text will examine the use of CE to analyze glucose and lactose or serum transthyretin in clinical samples [1, 2]. The use of CE for metabolomics will also be considered in this text. In this latter field, a group of analytes that are involved in one or more metabolic pathways are monitored to deter-mine how their composition changes in the presence or absence of a given clinical condition [24].  Several additional applications for CE in clinical chemistry will be examined in this text [20–29]. One area in which CE has been em-ployed is hematology, or the study of diseases that are related to blood and blood-forming components [1, 27–29]. Other uses that have reported for CE are in the areas of bacteriology and virology, for the detection or characterization of bacteria or viruses, and in the field of endocrinology, for the analysis and study of hormones within the D.  Hage in Clinical  Appl icat ions of Capillary Electrophores is  (2019)       7Fig. 3 Number of publications appearing between 1990 and 2017 that included the term “capillary electrophoresis” in their titles and that involved typical clinical samples. The results in (a) are for papers that contained “urine,” “serum,” “plasma,” or “blood” in the title of the paper. The results in (b) are for papers that contained “tear(s),” “saliva,” or “cerebrospinal fluid” (CSF) in the title. The results were gener-ated on March 23, 2018, using the Web of Science. The phrases “inductively cou-pled plasma” and “inductively-coupled plasma” were excluded during the search for papers that included the term “plasma” in their titles   D.  Hage in Clinical  Appl icat ions of Capillary Electrophores is  (2019)       8Fig. 4 Number of citations to publications that involved the use of capillary electro-phoresis and typical clinical samples. The search parameters and procedures were the same as used in Fig. 3. The results in (a) are for papers that contained “urine,” “serum,” “plasma,” or “blood” in the title of the paper. The results in (b) are for papers with titles that contained the terms “tear(s),” “saliva,” or “cerebrospinal fluid” (CSF)    D.  Hage in Clinical  Appl icat ions of Capillary Electrophores is  (2019)       9body [1, 2, 24]. Another important set of applications for CE is in the field of immunology, which deals with diseases of the immune sys-tem [1, 2, 24]. A closely related topic is that of CE-based immunoas-says, in which CE is combined with the use of antibodies or antibody-related agents for the selective binding and recognition of particular analytes in a sample [26]. CE has also been utilized for the analysis of drugs in clinical samples [21, 24, 25], as might be used for therapeu-tic drug monitoring or for the detection of drugs of abuse [1, 2]. Fi-nally, CE can be used as a tool for genetic analysis and the identifica-tion of inherited disorders [24]. Many of these areas will be explored in more detail in the following chapters.     References   1. Rifai N, Horvath AR, Wittwer CT (eds) (2018) Tietz textbook of clinical chemistry and molecular diagnostics, 6th edn. Amsterdam, Elsevier  2. Gornall AG (1986) Applied biochemistry of clinical disorders. Lippincott, New York  3. Hage DS (2016) Chromatography and electrophoresis. In: Clarke W (ed) Contemporary practice in clinical chemistry, 3rd edn. AACC Press, Washington, DC  4. Allen RC, Griffiths JC (1991) Electrophoresis. Anal Chem 63:209R–213R  Fig. 5 Applications for CE in the field of clinical chemistryD.  Hage in Clinical  Appl icat ions of Capillary Electrophores is  (2019)       105. Jorgenson JW (1986) Electrophoresis. Anal Chem 58:743A–760A  6. Skoog DA, Holler FJ, Crouch SR (2017) Principles of instrumental analysis, 7th edn. Cengage Learning, Boston  7. Hage DS, Carr JD (2011) Analytical chemistry and quantitative analysis. Prentice Hall, Boston  8. Cazes J (ed) (2005) Ewing’s analytical instrumentation handbook, 3rd edn. CRC Press, Boca Raton  9. Karger BL, Snyder LR, Hovath C (1973) An introduction to separation science. Wiley, New York  10. Hardy WB (1899) On the coagulation of proteid by electricity. J Physiol 26:288–304  11. Hardy WB (1905) Colloidal solution. The globulins. J Physiol 33:251–337  12. Michaelis L (1909) Elektrische uberfuhrung von fermenten. Biochem Z 16:81–86  13. Tiselius AWK (1937) A new apparatus for electrophoretic analysis of colloidal mixtures. Trans Faraday Soc 33:524–531  14. Wehr T, Zhu M (1994) Capillary electrophoresis: historical perspectives. In: Landers JP (ed) Handbook of capillary electrophoresis. CRC Press, Boca Raton  15. Hjerten S (1967) Free zone electrophoresis. Chromatogr Rev 9:122–219  16. Virtanen R (1974) Zone electrophoresis in a narrow-bore tube employing potentiometric detection. Acta Polytech Scand Chem 123:1–67  17. Jorgenson JW, Lukacs KD (1981) Zone electrophoresis in open-tubular glass capillaries. Anal Chem 53:1298–1302  18. Jorgenson JW, Lukacs KD (1981) High resolution separations based on electrophoresis and electroosmosis. J Chromatogr 218:209–216  19. Jorgenson JW, Lukacs KD (1983) Capillary zone electrophoresis. Science 222:266–272  20. Xu Y (1995) Capillary electrophoresis. Anal Chem 65:425R–433R  21. Xu Y (1995) Capillary electrophoresis. Anal Chem 67:463R–473R  22. Landers JP (1995) Clinical capillary electrophoresis. Clin Chem 41:495–509  23. Petersen JR, Okorodudu AO, Mohammad A, Payne DA (2003) Capillary electrophoresis and its application in the clinical laboratory. Clin Chim Acta 330:1–30  24. Phillips TM, Kalish H (eds) (2013) Clinical applications of capillary electrophoresis. Human Press, Totowa, NJ  25. Bojarski J, Szymura-Oleksiak J (2003) Applications of capillary electrophoresis in clinical analysis of drugs. In: Aboul-Enein HY (ed) Separation techniques in clinical chemistry. Marcel Dekker, New York  26. Moser AC, Willicott CW, Hage DS (2014) Clinical applications of capillary electrophoresis-based immunoassays. Electrophoresis 35:937–955  27. Şahin A, Laleli YR, Ortancil R (1995) Haemoglobin analysis by capillary zone electrophoresis. J Chromatogr A 709:121–125  D.  Hage in Clinical  Appl icat ions of Capillary Electrophores is  (2019)       1128. Mario N, Baudin B, Bruneel A, Janssens J, Vaubourdolle M (1999) Capillary zone electrophoresis for the diagnosis of congenital hemoglobinopathies. Clin Chem 45:285–288  29. Greene DN, Vaughn CP, Crews BO, Agarwal AM (2015) Advances in detection of hemoglobinopathies. Clin Chim Acta 439:50–57    

An Overview of Capillary Electrophoresis (CE) in Clinical Analysis

UNL | Libraries

University of Nebraska - Lincoln 
DigitalCommons@University of Nebraska - Lincoln 
David Hage Publications Published Research - Department of Chemistry 
2019 
An Overview of Capillary Electrophoresis (CE) in Clinical Analysis 
David S. Hage 
Follow this and additional works at: https://digitalcommons.unl.edu/chemistryhage 
 Part of the Medicinal-Pharmaceutical Chemistry Commons 
This Article is brought to you for free and open access by the Published Research - Department of Chemistry at 
DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in David Hage Publications 
by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. 
 
 
An Overview of Capillary Electrophoresis 
(CE) in Clinical Analysis  
 
 
David S. Hage  
University of Nebraska-Lincoln
 
 
Abstract  
The development and general applications of capillary electrophoresis 
(CE) in the field of clinical chemistry are discussed. It is shown how the 
early development of electrophoresis was closely linked to clinical test-
ing. The rise of gel electrophoresis in clinical chemistry is described, as 
well as the eventual developments that lead to the creation and the use 
of modern CE. The general principles of CE are reviewed and the poten-
tial advantages of this method in clinical testing are examined. Finally, an 
overview is presented of several areas in which CE has been developed 
and is currently being explored for use with clinical samples.  
 
Keywords Capillary electrophoresis, Clinical chemistry, Clinical applica-
tions, History of capillary electrophoresis  
 
 
1 Introduction  
 
Electrophoresis has been an important tool in clinical analysis for 
decades [1–3]. The primary mode of separation in this method is 
based on the different rates of migration of analytes in an electric 
field. However, there are many formats for this type of separation and 
1
digitalcommons.unl.edu
Published as Chapter 1 in Terry M. Phillips (ed.), Clinical Applications of Capillary 
Electrophoresis: Methods and Protocols, Methods in Molecular Biology, vol. 1972
DOI: https://doi.org/10.1007/978-1-4939-9213-3_1 
Copyright © 2019 Springer Science+Business Media, LLC, part of Springer Nature. 
Used by permission.
D.  Hage in Clinical  Appl icat ions of Capillary Electrophores is  (2019)       2
a variety of schemes by which the migration rates of chemicals in a 
sample can be modified [4–9]. These features, plus the fact that many 
biological agents hold some charge, have made electrophoresis a key 
method in clinical analysis for the examination of amino acids, pep-
tides, proteins, and nucleic acids, as well as many small charged sol-
utes [1–3].  
One way of using electrophoresis is to apply small amounts of a 
sample to a support (usually a gel or paper) and allow the compo-
nents in this sample to travel in a running buffer through the support 
in the presence of an electric field. These approaches are known as 
“gel electrophoresis” or “paper electrophoresis” and they have histor-
ically been the most common types of electrophoresis found in clin-
ical laboratories [3, 4]. It is also possible to separate the components 
of a sample by using a narrow capillary that is filled with a running 
buffer, followed by placement of this buffer and its contents into an 
electric field. This second method, known as “capillary electrophoresis” 
or “CE” [5–8], is the focus of this text. This chapter provides an over-
view of CE as related to the historical development of this technique 
and its use in clinical analysis. A summary of the clinical applications 
of CE, as discussed in more detail in later chapters, is also presented. 
 
 
2 Origins of Electrophoresis in Clinical Testing  
 
It has been known for over a century that substances like proteins 
and enzymes will travel in an electric field [10–12]. However, the use of 
this phenomenon for routine chemical separations did not occur until 
the late 1930s, when Arne Tiselius demonstrated that electrophoresis 
could be utilized for the separation of serum proteins [13]. The ap-
proach used by Tiselius, as later recognized by the 1948 Nobel Prize 
in Chemistry, was the first practical example in which electrophoresis 
was used for clinical analysis. The apparatus that was used by Tise-
lius in these experiments consisted of a U-shaped tube into which he 
placed his sample and a running buffer (see Fig. 1). When an electric 
field was applied across this tube, the proteins in the sample began 
to separate based on their charge and size as they migrated toward 
the electrode of opposite charge. The result was a series of broad and 
only partially resolved bands that were then used to study the pro-
tein content in the sample [8, 9]. The method that was employed by 
D.  Hage in Clinical  Appl icat ions of Capillary Electrophores is  (2019)       3
Tiselius is now known as “moving boundary electrophoresis” because 
it produced a series of moving boundaries between regions that con-
tained different mixtures of proteins [3, 9]. In modern laboratories, it is 
more common to use more efficient separation devices and to instead 
use a small amount of sample that will allow analytes to be separated 
into narrow bands or zones. These conditions result in a general ap-
proach that is now known as “zone electrophoresis” [5–9].  
It is interesting that even though Tiselius employed an open tube 
system, the use of gels or other supports instead of open tubes be-
came the main format for electrophoresis that was employed in clin-
ical laboratories for over 50 years [1–4]. The emphasis on gel or pa-
per electrophoresis during this time was due to the smaller sample 
requirements, greater ease, and better reproducibility of conduct-
ing separations by this approach as opposed to using large open 
tubes filled with a running buffer. The popularity of gel electropho-
resis in particular was further enhanced through the development 
of improved supports for these separations, such as polyacrylamide 
gels, and the introduction of new methods based on gel electropho-
resis. Two examples of these methods that are still common in clin-
ical and biomedical laboratories are sodium dodecyl sulfate poly-
acrylamide gel electrophoresis (SDS-PAGE) and isoelectric focusing 
(IEF) [3–5, 9, 14].  
Fig. 1 General design of the apparatus that was used by Arne Tiselius in his early 
work with electrophoresis and the separation of serum proteins   
D.  Hage in Clinical  Appl icat ions of Capillary Electrophores is  (2019)       4
Interest did continue in further pursuing the use of open tube sys-
tems for electrophoresis [14–19]. For instance, Hjerten developed a 
system in 1967 that utilized 1–3 mm I.D. quartz capillaries to carry 
out electrophoretic separations in free solution [15]. This system was 
used for the separation of proteins, nucleic acids, and microorgan-
isms, among other analytes, and included an online detector. Unfor-
tunately, the relatively large diameters of the capillaries in this system 
required the continuous rotation of these capillaries to minimize the 
effects of Joule heating and convection [14]. It was demonstrated in 
1974 by Virtanen that narrower 0.2 mm I.D. capillaries could be used 
to eliminate the need for rotation to minimize the effects of heating 
convection [14, 16]. However, it was not until the commercial devel-
opment of small diameter silica capillaries in the late 1970s, and the 
subsequent work by Jorgenson and Lukacs with 75–100 μm I.D. silica 
capillaries in the early 1980s, that CE became a viable alternative to 
gel electrophoresis for the separation of clinical and biological sam-
ples [17–19].  
 
 
3 Basic Principles and Advantages of Capillary Electrophoresis  
 
Figure 2 shows a typical system for CE, as might be found in a clin-
ical laboratory [3, 6–8]. This system includes a power supply, which can 
often provide an applied potential up to 25–30 kV, and a computer 
for control of the system and for the collection of data. There are also 
two electrodes for applying an electric field across the capillary and 
buffer containers that supply a contact between these electrodes and 
the solution within the capillary. Modern CE systems include an on-
line detector, which may be based on the use of UV-vis absorbance, 
laser-induced fluorescence, electrochemical detection, or mass spec-
trometry [3, 8]. In addition, the system has some means for injecting 
samples onto the capillary. Typical volumes for the injected samples 
are in the pL-nL range and can be applied by using methods such as 
electrokinetic injection or hydrodynamic injection [6–8].  
The capillaries in most modern CE systems have inner diameters 
of 20–100 μm and lengths of 20–100 cm [6–8]. The use of these nar-
row bore tubes allows the heat that is generated in the presence of 
an electric field to be quickly dissipated to the surrounding environ-
ment. The removal of this heat helps to provide much more efficient 
D.  Hage in Clinical  Appl icat ions of Capillary Electrophores is  (2019)       5
and faster separations than gel or paper electrophoresis. The absence 
of a gel or support in most types of CE also eliminates eddy diffusion 
and minimizes secondary interactions that may occur with the sup-
port. These conditions create a situation in which longitudinal diffu-
sion is often the main source of band-broadening and in which more 
efficient separations are obtained as the voltage is increased and an-
alytes spend less time in the capillary. The result is a fast separation 
with high efficiency and narrow peaks [6–8, 17–19].  
There are many features of CE that make this method attractive as 
an alternative to gel or paper electrophoresis for clinical analysis. For 
instance, CE is faster and more efficient than these traditional meth-
ods. CE is also easier to perform as part of an automated system. The 
small sample size requirements of CE and its ability to be used with 
various detectors and detection formats are additional features that 
make this method appealing for clinical analysis [3, 20–25].  
 
 
Fig. 2 General design of a modern capillary electrophoresis system. This particular 
configuration is based on the “normal polarity” mode, in which the sample is ap-
plied to a silica capillary at the side of the positive electrode   
D.  Hage in Clinical  Appl icat ions of Capillary Electrophores is  (2019)       6
4 Applications of CE in Clinical Analysis  
 
Following the introduction of the first commercial CE instruments 
in the late 1980s, there has been a steady increase in the use of CE for 
various samples of clinical interest. Some early reviews of clinical ap-
plications for CE can be found in references [4, 20–23].  
Figures 3 and 4 illustrate how the interest in CE for clinical analysis 
has grown during the last three decades. This interest is indicated by 
both the number of publications that have appeared on this topic (Fig. 
3) and citations that have been made to these papers (Fig. 4). Most of 
these applications have involved the use of urine, serum, plasma, or 
blood. In 1990, there were only two publications that dealt with such 
samples and that included “capillary electrophoresis” within their ti-
tles. However, between 1990 and 2017 there were over 1380 publica-
tions dealing with these samples and that included “capillary electro-
phoresis” in their titles. There were also over 27,000 citations to these 
articles over the same period of time. In addition, work appeared on 
more exotic specimens such as saliva, cerebrospinal fluid, and tears, 
with over 80 publications and almost 1760 citations to these papers 
appearing between 1990 and 2017.  
Many applications for CE in clinical chemistry have been explored 
and developed, as is illustrated in Fig. 5 [1, 3, 23–25]. One set of 
these applications has involved the use of CE in the analysis of clini-
cal biomarkers. These biomarkers may be serum proteins, enzymes, 
peptides, carbohydrates, lipids, and small organic or inorganic com-
pounds [21, 24]. For instance, some chapters in this text will examine 
the use of CE to analyze glucose and lactose or serum transthyretin 
in clinical samples [1, 2]. The use of CE for metabolomics will also be 
considered in this text. In this latter field, a group of analytes that are 
involved in one or more metabolic pathways are monitored to deter-
mine how their composition changes in the presence or absence of a 
given clinical condition [24].  
Several additional applications for CE in clinical chemistry will be 
examined in this text [20–29]. One area in which CE has been em-
ployed is hematology, or the study of diseases that are related to 
blood and blood-forming components [1, 27–29]. Other uses that 
have reported for CE are in the areas of bacteriology and virology, for 
the detection or characterization of bacteria or viruses, and in the field 
of endocrinology, for the analysis and study of hormones within the 
D.  Hage in Clinical  Appl icat ions of Capillary Electrophores is  (2019)       7
Fig. 3 Number of publications appearing between 1990 and 2017 that included 
the term “capillary electrophoresis” in their titles and that involved typical clinical 
samples. The results in (a) are for papers that contained “urine,” “serum,” “plasma,” 
or “blood” in the title of the paper. The results in (b) are for papers that contained 
“tear(s),” “saliva,” or “cerebrospinal fluid” (CSF) in the title. The results were gener-
ated on March 23, 2018, using the Web of Science. The phrases “inductively cou-
pled plasma” and “inductively-coupled plasma” were excluded during the search 
for papers that included the term “plasma” in their titles   
D.  Hage in Clinical  Appl icat ions of Capillary Electrophores is  (2019)       8
Fig. 4 Number of citations to publications that involved the use of capillary electro-
phoresis and typical clinical samples. The search parameters and procedures were 
the same as used in Fig. 3. The results in (a) are for papers that contained “urine,” 
“serum,” “plasma,” or “blood” in the title of the paper. The results in (b) are for papers 
with titles that contained the terms “tear(s),” “saliva,” or “cerebrospinal fluid” (CSF)   
 
D.  Hage in Clinical  Appl icat ions of Capillary Electrophores is  (2019)       9
body [1, 2, 24]. Another important set of applications for CE is in the 
field of immunology, which deals with diseases of the immune sys-
tem [1, 2, 24]. A closely related topic is that of CE-based immunoas-
says, in which CE is combined with the use of antibodies or antibody-
related agents for the selective binding and recognition of particular 
analytes in a sample [26]. CE has also been utilized for the analysis of 
drugs in clinical samples [21, 24, 25], as might be used for therapeu-
tic drug monitoring or for the detection of drugs of abuse [1, 2]. Fi-
nally, CE can be used as a tool for genetic analysis and the identifica-
tion of inherited disorders [24]. Many of these areas will be explored 
in more detail in the following chapters.   
 
 
References  
 
1. Rifai N, Horvath AR, Wittwer CT (eds) (2018) Tietz textbook of clinical chemistry 
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An Overview of Capillary Electrophoresis (CE) in Clinical Analysis

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