Category Archives: test

Thin Layer Chromatography used in DNA aging research

Excerpts from a paper posted on the U.S. National Library of Medicine and the National Institutes of Health web site DNA strandstitled:

TLC-based detection of methylated cytosine: application to aging epigenetics

5-Methylcytosine (m(5)C) has a plethora of functions and roles in various biological processes including human diseases and aging. A TLC-based fast and simple method for quantitative determination of total genomic levels of m(5)C in DNA is described, which can be applicable to aging research with respect to rapid and high throughput screening and comparison. Using this method, an example of the analysis of global alternations of m(5)C in serially passaged human skin fibroblasts is provided, which shows age-related global hypomethylation during cellular aging in vitro.

Click Here to access the paper.

CDC recommends Thin Layer Chromatography to test anti-malarial drugs

The U.S. Centers for Disease Control and Prevention advise that, “Counterfeit (fake) drugs are products deliberately made to resemble a brand name pharmaceutical. They may contain no active ingredients or contain ingredients inconsistent with the package description.”
Malaria treatment
For example, the CDC says, “In Cambodia in 1999, counterfeit antimalarial drugs were responsible for the deaths of at least 30 people. A recent survey in Southeast Asia showed that among 104 tablets presented as the antimalarial drug artesunate, 38% did not contain any artesunate.”

Users of pharmaceutical products (not only antimalarials) should take the following precautions:

  • Travelers should purchase in advance, in their home country, all the medicines they will need.
  • Travelers should record the drug’s generic and brand names as well as the name of the manufacturer; should they run out, they can look for the correct product.
  • Make sure that the drug is in its original packaging.
  • Inspect the packaging because many times poor quality printing indicates a counterfeited product.
  • Be suspicious of tablets that have a peculiar odor, taste or color, or that are extremely brittle.

The CDC recommends testing suspicious drugs.

“drug quality can be evaluated in the field by two simple, effective, and low-cost techniques: thin-layer chromatography (TLC) and colorimetry… The TLC technique consists of placing a spot of drug sample on a thin layer of silica attached to a plate of glass, aluminum, or plastic. The plate is then inserted into a vessel containing a solvent mixture. By capillary action, the solvent mixture creeps up the silica material and dissolves the sample. The drug sample consists of a mixture of drug and inactive ingredients. These compounds will have various affinities to the silica matrix and will migrate with the solvent at various speeds. This characteristic effectively separates out a mixture of compounds. After migration of the solvent is complete, individual components can be visualized by chemical treatment or ultraviolet (UV) absorbance. The distance that the components migrate is characteristic for each compound; therefore the active ingredient can be recognized by comparison with a known drug standard. The solvent can be modified to increase resolution between various components. This method is relatively inexpensive, specific, and sensitive. It is commonly used to assess drug quality.”

Click Here for more details from the CDC.

Click Here to find out more about Thin Layer Chromatography plates and accessories.

More details on swine flu and testing with chromatography

Following yesterday’s post about swine flu testing with chromatography, there’s been numerous articles, posts, and papers offered up about the swine flu break out.swine flu vaccine

We’ve compiled some of these here, and invite you to keep us informed of anything you come across that may be of interest – simply submit your material below.

First, for all of the latest from the Centers for Disease Control and Prevention on the swine flu, click here.

For information about how Thin Layer Chromatography is used to detect counterfeit pharmaceuticals, including Tamiflu, click here.

For an article from TheScientist.com about biotech’s response to swine flu, click here.

For an article from the Wall Street Journal about the need for rapid tests, click here.

Chromatography used for testing Swine Flu

UPDATE: Article from TheScientist.com – Can biotech tackle swine flu? – click here to read

For decades, scientists have been using Thin Layer Chromatography, HPLC, gas, and other forms of chromatography to study swine influenza.

Scientists working on swine fluHere is just one example. In October of 1985, a team from the Department of Neurology at The Medical University of South Carolina published “Lipid content of swine influenza and other vaccines” – here’s a couple of excerpts:

ABSTRACT: An analysis of the lipids in swine influenza vaccines was performed, comparing six different lots of swine influenza, other influenza and noninfluenza vaccines.
Cholesterol content and phospholipid content varied greatly, but there were no major differences between the types of vaccines. Appreciable amounts of phosphatidylethanolamine were found in only one swine influenza vaccine. The major phospholipids of influenza vaccines were phosphatidylcholine, sphingomyelin and phosphatidic acid. A detectable amount of phosphatidylserine was not found in any swine influenza vaccine, but was present in two of three nonswine influenza vaccines. Only two of six swine influenza vaccines showed trace amounts of ganglioside. However, larger quantities of galactocerebroside were found in all
influenza vaccines examined, including swine influenza vaccines.

Neutral lipids were separated on silica gel thin layer chromatography (TLC) plates developed in light petroleum ether/diethyl ether (96:4, v/v) and visualized by exposure to iodine vapors.
Phospholipids were separated by two-dimensional TLC using high performance TLC (HPTLC) plates. After application, samples were chromatographed in C/M/concentrated ammonia (65:35:5, v/v/v) to the top of the plate plus an additional 10 min. HPTLC plates were air-dried and held in vacuo overnight over P205 to reactivate the silica gel. Chromatography in the second direction was performed in chloroform/acetone/methanol/acetic acid/water (5:2:1:1:0.5, v/v/v/v/v). After being air-dried, phospholipids were visualized by exposure to iodine vapors, matched to standards and marked. After sublimation of I2, marked areas were carefully scraped from the glass backing, charred and assayed for liberated phosphate by the method of Ames {27}. Prior to TLC, aliquots were withdrawn and assayed in the same manner for total phospholipid determination.

 Click Here to Access the complete paper.

Click Here to learn more about high quality Thin Layer Chromatography plates and accessories.