Salkowski test for cholesterol – Its principle and procedure

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Salkowski’s Test: Detecting the Presence of Cholesterol


Salkowski’s test, a chemical assay, plays a crucial role in the field of biochemistry and clinical diagnostics. It is widely used to detect the presence of cholesterol, a vital lipid molecule, in various biological samples. This test is named after the Polish-born biochemist Józef Stanisław Salkowski, who developed the method in the late 19th century. Understanding Salkowski’s test is essential for researchers, clinicians, and biochemists, as it provides valuable insights into cholesterol metabolism and related disorders. In this article, we will delve into the details of Salkowski’s test, its principle, procedure, and its significance in clinical and research settings.

The Significance of Cholesterol

Cholesterol is a lipid molecule found in cell membranes and is a precursor for various important compounds such as steroid hormones and bile acids. It is transported in the bloodstream in lipoprotein particles. While cholesterol is essential for various physiological processes, abnormal levels of cholesterol in the body can lead to severe health problems, including cardiovascular diseases.

Principle of Salkowski’s Test

Salkowski’s test relies on the principle of colorimetry, which involves measuring the concentration of a substance by the intensity of the color it produces when reacting with specific reagents. In this case, the test detects the presence of cholesterol by measuring the color produced during its reaction with sulfuric acid and acetic anhydride.


  1. Sample Preparation: To perform Salkowski’s test, a biological sample containing cholesterol is required. This sample can be serum, plasma, urine, or any other appropriate body fluid or tissue extract.
  2. Reagent Preparation: Prepare a reagent mixture by combining concentrated sulfuric acid (H2SO4) and acetic anhydride (C4H6O3) in a specific ratio. The reagent mixture should typically contain one part sulfuric acid and two parts acetic anhydride. Extreme caution should be exercised while handling concentrated sulfuric acid, as it is highly corrosive.
  3. Reaction: In a test tube, add a small amount of the prepared sample containing cholesterol. Then, carefully overlay the sample with the reagent mixture. A characteristic blue-green color will develop immediately if cholesterol is present in the sample.
  4. Measurement: The intensity of the color is directly proportional to the concentration of cholesterol in the sample. To quantify the cholesterol level, a spectrophotometer can be used to measure the absorbance of the colored solution at a specific wavelength, typically 550 nm.

Interpretation of Results

The presence of the characteristic blue-green color after the addition of the reagent mixture indicates a positive result for cholesterol. The intensity of the color is used to estimate the cholesterol concentration, with a higher intensity indicating a higher cholesterol level.

Clinical Applications

Salkowski’s test is a valuable tool in clinical laboratories for diagnosing and monitoring disorders related to cholesterol metabolism. Abnormal cholesterol levels are associated with conditions like hypercholesterolemia (high cholesterol) and hypocholesterolemia (low cholesterol), both of which have significant clinical implications. Additionally, the test can aid in the assessment of lipid-lowering therapies and the management of cardiovascular diseases.


Salkowski’s test, based on the principles of colorimetry, is an essential technique for detecting cholesterol in various biological samples. Its simplicity and reliability make it a valuable tool in clinical diagnostics and research. By understanding and utilizing this test, healthcare professionals and researchers can gain insights into cholesterol metabolism and its role in health and disease.

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