Sudan stain
Encyclopedia
Sudan staining is the use of Sudan dyes to stain sudanophilic substances, usually lipid
s. Sudan lysochrome
s (Sudan II
, Sudan III
, Sudan IV
, Oil Red O
, and Sudan Black B
) are used.
Sudan dyes have high affinity to fats, therefore they are used to demonstrate triglyceride
s, lipid
s, and lipoprotein
s.
Alcoholic solutions of Sudan dyes are usually used, however pyridine
solutions can be used in some situations as well.
Sudan stain test is often used to determine the level of fecal fat
to diagnose steatorrhea
. A small sample is dissolved in water or saline, glacial acetic acid is added to hydrolyze the insoluble salts of fatty acid
s, a few drops of alcoholic solution of Sudan III are added, the sample is spread on a microscopic slide, and heated twice to boil. Normally a stool sample should show only a few drops of red-orange stained fat under the microscope. The method is only semiquantitative, however due to its simplicity it is used for screening
.
Lipid
Lipids constitute a broad group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins , monoglycerides, diglycerides, triglycerides, phospholipids, and others...
s. Sudan lysochrome
Lysochrome
A lysochrome is a soluble dye used for biochemical staining of triglycerides, fatty acids, and lipoproteins. Lysochromes such as Sudan IV bind to the lipid in a substrate and show up as colored regions. The dye does not stick to any other substrates, so a quantification or qualification of lipid...
s (Sudan II
Sudan II
Sudan II is a lysochrome azo dye used for staining of triglycerides in frozen sections, and some protein bound lipids and lipoproteins on paraffin sections. It has the appearance of red powder with melting point 156-158 °C and maximum absorption at 493 nm.-Other names:Its other names are Solvent...
, Sudan III
Sudan III
Sudan III is a lysochrome diazo dye used for staining of triglycerides in frozen sections, and some protein bound lipids and lipoproteins on paraffin sections. It has the appearance of reddish brown crystals and a maximum absorption at 507 nm.Sudan III is a dye used for Sudan staining...
, Sudan IV
Sudan IV
Sudan IV is a lysochrome diazo dye used for the staining of lipids, triglycerides and lipoproteins on frozen paraffin sections. It has the appearance of reddish brown crystals with melting point 199 °C and maximum absorption at 520 nm.Sudan IV is one of the dyes used for Sudan staining. Similar...
, Oil Red O
Oil Red O
Oil Red O is a lysochrome diazo dye used for staining of neutral triglycerides and lipids on frozen sections and some lipoproteins on paraffin sections...
, and Sudan Black B
Sudan Black B
Sudan Black B is a lysochrome diazo dye used for staining of neutral triglycerides and lipids on frozen sections and some lipoproteins on paraffin sections. It has the appearance of a dark brown to black powder with maximum absorption at 596-605 nm and melting point 120-124 °C...
) are used.
Sudan dyes have high affinity to fats, therefore they are used to demonstrate triglyceride
Triglyceride
A triglyceride is an ester derived from glycerol and three fatty acids. There are many triglycerides, depending on the oil source, some are highly unsaturated, some less so....
s, lipid
Lipid
Lipids constitute a broad group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins , monoglycerides, diglycerides, triglycerides, phospholipids, and others...
s, and lipoprotein
Lipoprotein
A lipoprotein is a biochemical assembly that contains both proteins and lipids water-bound to the proteins. Many enzymes, transporters, structural proteins, antigens, adhesins, and toxins are lipoproteins...
s.
Alcoholic solutions of Sudan dyes are usually used, however pyridine
Pyridine
Pyridine is a basic heterocyclic organic compound with the chemical formula C5H5N. It is structurally related to benzene, with one C-H group replaced by a nitrogen atom...
solutions can be used in some situations as well.
Sudan stain test is often used to determine the level of fecal fat
Fecal fat
In medicine, the fecal fat test is a diagnostic test for fat malabsorption conditions, which lead to excess fat in the feces .-Background:...
to diagnose steatorrhea
Steatorrhea
Steatorrhea is the presence of excess fat in feces. Stools may also float due to excess lipid, have an oily appearance and be especially foul-smelling. An oily anal leakage or some level of fecal incontinence may occur. There is increased fat excretion, which can be measured by determining the...
. A small sample is dissolved in water or saline, glacial acetic acid is added to hydrolyze the insoluble salts of fatty acid
Fatty acid
In chemistry, especially biochemistry, a fatty acid is a carboxylic acid with a long unbranched aliphatic tail , which is either saturated or unsaturated. Most naturally occurring fatty acids have a chain of an even number of carbon atoms, from 4 to 28. Fatty acids are usually derived from...
s, a few drops of alcoholic solution of Sudan III are added, the sample is spread on a microscopic slide, and heated twice to boil. Normally a stool sample should show only a few drops of red-orange stained fat under the microscope. The method is only semiquantitative, however due to its simplicity it is used for screening
Screening (medicine)
Screening, in medicine, is a strategy used in a population to detect a disease in individuals without signs or symptoms of that disease. Unlike what generally happens in medicine, screening tests are performed on persons without any clinical sign of disease....
.