Liebermann–Burchard test

Liebermann–Burchard test is a chemical test used primarily to indicate the presence of cholesterol. The test is named after the chemists Carl Liebermann and Heinrich Burchard, who developed it. It is a specific application within the broader field of biochemistry and analytical chemistry, particularly in the analysis of lipids.

Principle

The Liebermann–Burchard test is based on the reaction of cholesterol with acetic anhydride and concentrated sulfuric acid. When cholesterol is treated with acetic anhydride and then sulfuric acid is added, a complex series of reactions occur. Initially, the mixture turns a green color, which gradually changes to blue and then to a deep purple or red. This color change is due to the formation of polyene complexes. The intensity of the color produced can be used to estimate the amount of cholesterol present.

Procedure

The procedure for the Liebermann–Burchard test involves dissolving a small amount of the sample suspected to contain cholesterol in chloroform. Acetic anhydride is then added, followed by careful addition of concentrated sulfuric acid down the side of the test tube, so it forms a layer beneath the chloroform solution. The test tube is observed for color changes, which indicate the presence and, to some extent, the quantity of cholesterol.

Applications

The Liebermann–Burchard test is utilized in various fields, including food industry to check for cholesterol in food products, in clinical laboratories for the analysis of blood cholesterol levels, and in pharmaceuticals for the purity assessment of cholesterol-containing products.

Limitations

While the Liebermann–Burchard test is useful for indicating the presence of cholesterol, it is not highly specific. Other sterols can also give a positive reaction, and the presence of impurities can affect the color and interpretation of results. Therefore, it is often used in conjunction with other methods for a more accurate determination of cholesterol.

See Also

• Chemical test
• Cholesterol
• Biochemistry
• Analytical chemistry