Capillary electrochromatography
Related Terms
Amino acid, antibiotic, capillary electrophoresis, CEC, charge separation, chemical composition, chimerism, drug development, high-performance liquid chromatography, HPLC, ibuprofen, laboratory testing, peptide, protein, pharmaceutical testing, herb analysis.
Background
Capillary electrochromatography (CEC) is a method of separating small particles based on their size and electrical charge. It can be used to determine the amount of proteins, drugs, hormones, toxins, and other substances in a liquid sample, such as blood or urine.
This relatively new method is capable of separating molecules that differ by just one very small change in their structure, which may affect how the molecule functions within the body. It is also capable of testing very small samples and can be performed more rapidly than older methods.
Medical laboratories use CEC to measure levels of substances in blood and urine testing. For instance, CEC can be used to detect the levels of prescription or illegal drugs in the body.
Pharmaceutical companies use CEC to perform chiral separation. Chiral molecules are two molecules created from the same building blocks but are mirror images of each other. Many drugs are initially developed as a mixture of two chiral molecules, but often one of the molecules is more useful in the human body than the other. The reason for this probably has to do with how the shape of the molecule affects its interactions with cells in the human body. CEC can be used to separate chiral molecules so that only the most beneficial form is packaged into a drug. Examples of drugs that can be separated by CEC include escitalopram (Lexapro?) and citalopram (Celexa?), two antidepressant medications that are chiral molecules.
CEC is useful in the study of herbal products because it can separate and identify the individual molecules within an herb. It is important to identify the molecules contained in an herb in order to determine possible side effects or drug interactions.
Methods
Capillary electrochromatography (CEC) is used to separate small molecules based on differences in their size and electrical charge. The components of a CEC device include a long, thin tube (called a capillary), a device to apply an electrical charge, tiny beads that fill the capillary, and the solution to be tested.
First, an electrical charge is applied to the capillary tube. This charge results in one end of the capillary having a positive charge and the opposite end having a negative charge. The test solution is then added to one end of the capillary. Small molecules within the solution will travel more quickly than large molecules. Additionally, molecules that have a negative or positive charge will be attracted to the end of the capillary that has the opposite charge. For instance, a very small protein with a strong negative charge will travel quickly toward the positive end of the capillary tube. The beads filling the capillary tube help separate molecules based on size.
Molecules are separated based on how long it takes them to travel through the capillary tube. The molecules can then be identified as certain drugs, proteins, carbohydrates, hormones, or toxins, and their level in the solution can be determined by observing how much of the solution has traveled through the capillary tube.
Research
Capillary electrochromatography (CEC) is used to analyze complex compounds, such as herbal extracts, drugs, and toxic material, to determine exactly what they are made of. CEC can be used to determine which compounds are contained in a specific herb or in an herbal mixture. This may allow pharmacologists to determine whether the herb is safe and has the potential to interact with medications or to cause side effects. For example, CEC has been used to study the compounds in olive oil and the Chinese herb Epimidium.
CEC may be used in medical testing to determine whether a patient is being prescribed a toxic (too high) or subtherapeutic (too low) dosage of a prescription medication or to assess the levels of an illegal drug in a person's blood or urine. It can be used in clinical research to determine the level of new drugs in a patient's blood or urine and to determine the correct dosage for healthy patients. It can also be used to determine the appropriate dosages for patients with liver or kidney disease, in whom some drugs build up to toxic levels in the body over time.
Implications
Capillary electrochromatography (CEC) is capable of testing a very small amount of solution to determine which compounds it contains, so that smaller samples are required from patients. It is also able to detect very small differences between molecules. This means that laboratory tests for levels of hormones, such as steroids, and other molecules will be more accurate.
CEC allows for the rapid determination of molecules within a test solution, such as a new drug or herbal extract. This will allow for further research into the drug or herb to determine how it may act in the human body and whether it is safe.
Limitations
Capillary electrochromatography (CEC) is a relatively new technique and is not available in all hospital laboratories. Because it is a new technique, research will have to be performed to determine its usefulness in laboratory testing before it becomes widely available.
Future research
Research is being conducted to determine the usefulness of capillary electrochromatography (CEC) in routine laboratory testing. Scientists must determine whether CEC can accurately detect a specific molecule before it can be used to examine blood samples. For instance, in order to detect a specific hormone in a patient's blood sample, such as thyroid hormone, scientists must first determine the pattern that thyroid hormone has with CEC, which depends on the size and charge of the thyroid hormone molecule.
CEC may be used to further evaluate medications, illicit drugs, toxic materials, and nutritional supplements to determine what they contain. Once the compounds within a solution are known, more research can be performed to determine whether the solution is useful or harmful.
Author information
This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).
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