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CE on the Web Steve Miller
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ne website describes capillary electrophoresis (CE) as “something of an orphan technique in mainstream analysis, despite some clear advantages over the chromatographic techniques familiar to the analytical chemist.” So, is your lab ready to adopt an orphan? Granted, adding yet another technique for looking at mixtures might be a big commitment, especially if you already have your hands full with the rest of the family—GC, LC, TLC, and the spectroscopies. But it might be worth a look. Published applications for CE range from the largest to the smallest organic molecules, and from DNA sequencing to acetic acid process stream monitoring. Or, how about inorganic ions in media ranging from clean water to blood serum? There are plenty of places on the Internet to check out the possibilities. What have you got to lose? You might even find that all those stories about how hard CE is to use date back to the days when it was an experimental technique—and a rather cranky one at that.
What is CE? Unless your lab works near the biological end of the science spectrum, your last experience with electrophoresis may have been in an undergraduate lab— and CE may be one of those terms that you should be familiar with, but aren’t. Which brings up the first questions: What is CE and where does it fit into the analytical family? For an answer, check out the CE page of the Natural Toxins Research Institute at Texas A&M University–Kingsville. The site presents the basic theory, applications, and procedures for CE in an outline
form, punctuated with clear simple drawings and occasional animations. (If you decide CE is not for you, you can browse the institute’s serpent page for some great photos of snakes.) For a “snake-free” site with an extensive overview of CE and a wealth of references, move on to the Biotechnology and Applied Biochemistry CE Review page. Originally published in print in
1998, the site provides a good review of CE techniques and their application to biochemicals and pharmaceuticals. It also discusses the limitations and possible future directions of CE. Now that you are interested, a comprehensive overview of CE is waiting at the CE and Capillary Electrochromatography page. Self-described as a “one-stop” webpage covering all aspects of these two
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techniques, the site—developed by Kevin Altria, the editor of LCGC’s CE Currents Section—does a good job of living up to its billing. After discussing theory and application—with a lot of links—it addresses a range of topics, including CE/MS, nonaqueous CE, conferences, and societies. The site even provides book reviews.
are unfamiliar with HPCE and wish to learn a little about it.” Despite the description, the primer is also worthwhile for the advanced user. After clearly and thoroughly explaining CE theory, it pursues a range of practical topics, including sample preparation, injection techniques, buffer and mobile-phase selection, and system troubleshooting. Practical advice CE Resources will introduce you to If you are hooked and ready to buy, it’s five capillary electroseparation methtime to check out the manufacturer ods—capillary zone electrophoresis, websites, which offer information rangcapillary gel electrophoresis, micellar ing from the basics to detailed applicaelectrokinetic capillary chromatography, tion notes. Microsolv Technologies has capillary isotachophoresis, and capillary put together a good reference site with isoelectric focusing—with a wide array a general introduction, helpful hints, of application notes. The applications background information, and lots of discussed include many inorganic ions practical tips. The site offers a “primer and small organic molecules in water provided to students and scientists [who] and bodily fluids. Okay, you bought a CE instrument, but it is sitWhat is CE? ting on the bench pouting Texas A&M University–Kingsville because it’s doing nothing. http://ntri.tamuk.edu/ce/ce.html You’ll need the CE “Quick http://ntri.tamuk.edu/serp/index.html Start Guide to Maintenance Biotechnology and Applied Biochemistry CE Review and Troubleshooting”. You http://bab.portlandpress.co.uk/bab/027/0009/bab0270009.htm can find it by going to AgiCE and Capillary Electrochromatography Page lent’s literature search page www.CEandCEC.com and entering the publication number, G1600-90010, or “quick start maintenance Practical advice and troubleshooting” in Microsolv Technologies the keyword box. You will www.microsolvtech.com/ce.htm find an extensive collection CE Resources of operating tips, prevenwww.ce-resources.com tive maintenance checklists, Agilent Technologies troubleshooting steps, and www.chem.agilent.com/scripts/LiteratureSearch.asp information on basic CE method development and optimization in an easyDNA sequencing to-follow flowchart. Lawrence Berkeley National Lab http://hgighub.lbl.gov/esd/bio/cap.htm University of Texas–Austin www.icmb.utexas.edu/core/SequencingProtocol.pdf University of Alberta http://hobbes.chem.ualberta.ca/~karl/titlepg.html
Digging deeper Electrophoresis Society www.aesociety.org EuTech’s CE Knowledge Base www.eutechsci.com/ce/cesearch.asp Buffer Calculator www.bi.umist.ac.uk/users/mjfrbn/buffers/makebuf.asp
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DNA sequencing One CE application that has received substantial recent interest is DNA sequencing. According to the Lawrence Berkeley National Lab’s CE website, “Recent rapid progress in [CE] technology suggests that it soon will have the capability of replacing the slab gel sequencer in production work.” The lab
provides details of the development of a 96-capillary sequencing system, operating procedures, and a number of references. More DNA sequencing information, including detailed protocols, is available from the Institute for Cellular and Molecular Biology at the University of Texas–Austin and the chemistry department at the University of Alberta (Canada).
Digging deeper Once you begin using CE or any other form of electrophoresis, keep an eye on the Electrophoresis Society, an international organization that promotes technologies for biomolecular separation and detection. There are links to electrophoresis organizations worldwide, along with quite a few specialized pages. Although the CE section was still under construction at the time of publication, the overall tone of the site indicates that it will be an asset to CE users. Are you wondering if CE has achieved the pesky separation that has eluded your every attempt by GC and LC? Check out the CE literature using a search engine provided by EuTech Scientific Services, a contract research company focused on the development of new analytical methods. Their CE Knowledge Base links to CE literature from 1980 to the present and contains more than 5000 references that can be accessed by keyword or author. If you have read all of the information cited so far, you know that one of the key factors to success in CE is choosing the right buffer. For help with this step, check out the really useful Webbased Buffer Calculator at the University of Manchester Institute of Science and Technology (United Kingdom). Although the site doesn’t specifically address CE, you can plug in values for pH, ionic strength, concentration, and operating temperature, and the calculator will provide a detailed recipe for the appropriate buffer solution. The site claims to have recipes for over 70,000 buffers. Even if you decide not to use CE, you can probably still use this page. Steve Miller is a freelance writer based in State College, Pa.
