Category Archives: Thin Layer Chromatography

Thin Layer Chromatography and Ophthalmology

This bit of insight comes from our friends at Medical Blog.

corneaA variety of genetic, metabolic, developmental, and idiopathic causes can result in congenital clouding of the cornea. A common reason for congenital clouding of the cornea is congenital glaucoma. Other major causes of corneal clouding include the following: Birth trauma Peters anomaly Dermoid tumors (limbal dermoids) Sclerocornea Congenital hereditary endothelial dystrophy (CHED) Mucopolysaccharidoses Infectious/inflammatory processes The following is a mnemonic for the causes of congenital clouding of the cornea: S – Sclerocornea T – Tears in the Descemet membrane secondary to birth trauma or congenital glaucoma U – Ulcers M – Metabolic P – Peters anomaly E – Edema (CHED) D – Dermoid Other rarer causes of congenital clouding of the cornea include the following: cornea plana, corneal keloids, oculoauriculovertebral (OAV) dysplasia (Goldenhar-Gorlin syndrome), congenital corneal ectasia, congenital hereditary stromal dystrophy, posterior polymorphous dystrophy, and Fryns syndrome.

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A 4-month-old male infant had severe corneal opacity since birth. Examination revealed buphthalmos, increased IOP, and corneal opacity with neovascularization but not a dysmorphic face or hirsutism. The liver and spleen were impalpable. Hypotonia, poor head control, and absence of Moro and grasping reflexes were noted. He had no evidence of congenital infection (toxoplasmosis, other infections, rubella, cytomegalovirus infection, and herpes simplex [TORCH] study). Urine and plasma amino acid levels were normal. However, thin-layer chromatography showed excessive urinary excretion of heparan sulfate. Corneal transplantation was performed at 6 months of age. Histopathology of the corneal button showed homogeneous thickening of the Bowman layer and pinkish intracytoplasmic substances in the corneal stroma. The Alcian blue stain was positive, consistent with MPS of the cornea.

Click Here to read the full report.

Information Directory on Thin Layer Chromatography

Adiwebs.com is an online information directory. It provides useful information on a variety of topics.Thin Layer Chromatography

The site has a great write up on Thin Layer Chromatography – here’s some excerpts:

Thin layer chromatography is adsorption chromatography performed on open layers of adsorbent materials supported bon glass plates. This technique combines many of the advantages of paper chromatography with those of column chromatography.

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Superiority of TLC:

The superiority of TLC over paper chromatography lies in the following facts:

  • Because of the inorganic nature of the adsorbent (supporting medium), concentrated sulfuric acid spray followed by heating may be used to develop (or locate substances on) the chromatogram by charring and rendering visible any spots of organic nature.
  • Moreover, amino acid mixtures, which require 18 hours for separation on paper, require as little as 3 hours using cellulose TLC.
  • The advantage of this technique also lies in the choice of the adsorbents which allow separation not possible on paper.

Click Here to read more from Adiwebs.com

Monty Python and Thin Layer Chromatography – the “I’m Not Dead Yet” chemical

Chemical & Engineering News just published a fascinating Antspiece about how ants let other ants know whether they are dead or not.

Of course, the whole piece starts off with a reference to Monty Python’s great “I’m not dead yet” scene from the Holy Grail. It’s good to see yet another connection between Monty Python and Chromatography!

Here’s an excerpt from the article:

By using thin-layer chromatography and gas chromatography to compare live, just-killed, and dead ants, the team showed that a subset of chemicals disappeared from the ants’ outer covering within one hour of death. From those extracts they identified two rapidly dissipating “do not discard” signaling chemicals—specific isomers of the natural products dolichodial and iridomyrmecin.

Click Here to read more and view the video.

Thin Layer Chromatography used in identifying Sixth Nucleotide

From our friends at GenomeWeb.com:

Two researchers from Rockefeller University have identified a new nucleotide…Synthesis of IMP

While evaluating 5-methylcytosine levels in two types of mouse brain cells, the team detected a nucleotide that they could not identify. When they looked more closely at this nucleotide using thin layer chromatography, high pressure liquid chromatography, mass spectrometry, and other approaches, the researchers discovered that they were dealing with 5-hydroxymethylcytosine, a form of methylated cytosine found stably in bacterial viruses.

Their subsequent experiments suggest the nucleotide is enriched in brain cells but apparently absent from several other cell types. Based on these findings, the researchers speculated that 5-hydroxymethylcytosine may contribute to epigenetic regulation, particularly in neurons. 

Click Here to read more from GenomeWeb.com

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.

Separation of Lipids via Thin Layer Chromatography

This post comes to us from “Biochem write up”

Intro:
The aim of this practical is to carry out TLC in which the substances we wish to separate are absorbed onto the thin layer. Lipids are determined by isolation and the ability to purify the substance. Due to the way the substances interact with the matrix in different ways we are able to seperate them. Substances which interact strongly with the matrix but not with the solvent will move very slowly and those soluble in the solvent will dissolve easily and be carried along the solvent.
thin layer chromatography phospholipids
Egg yolk contains trioleine, cholesterol palmitate and phosphatidylethonolamine, The most polar of the three elements is the second element. It hardly moves up the TLC because of the presence of several polar groups; phosphate groups, amine groups and several oxygens , and cholesterol palmitate being the most non polar.

 

Free Book: “Interfacial Phenomena in Chromatography”

Our friends at “Scientist-At-Work” are offering the book “Interfacial Phenomena in Chromatography” as a free download!

“Interfacial Phenomena in Chromatography Interfacial Phenomena in Chromatography presents a combination of chromatographic theory, numerical simulation and experimental data. The text covers the interaction and size exclusion methods of separation, identification and characterization of substances in solution. It provides practical information and analysis on the most effective mechanisms of interfacial chromatography, along with its expanding possibilities for biomedical, industrial and environmental applications.

Click Here to visit Scientist-At-Work and get the free download.

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