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The structure of the fuchsin dye. The Schiff test is an early organic chemistry named reaction developed by Hugo Schiff, [1] and is a relatively general chemical test for detection of many organic aldehydes that has also found use in the staining of biological tissues. [2]
Hugo (Ugo) Schiff (26 April 1834 – 8 September 1915) was an Italian naturalized chemist. [ 1 ] [ 2 ] The son of a Jewish businessman and brother of the physiologist Moritz Schiff , Hugo Schiff was German by nationality.
Schiff bases are common enzymatic intermediates where an amine, such as the terminal group of a lysine residue, reversibly reacts with an aldehyde or ketone of a cofactor or substrate. The common enzyme cofactor pyridoxal phosphate (PLP) forms a Schiff base with a lysine residue and is transaldiminated to the substrate(s). [7]
The Schiff test detects aldehydes; Tollens' reagent tests for aldehydes (known as the silver mirror test) The Zeisel determination tests for the presence of esters or ethers; Lucas' reagent is used to distinguish between primary, secondary and tertiary alcohols. The bromine test is used to test for the presence of unsaturation and phenols.
These aldehydes then react with the Schiff reagent to give a purple-magenta color. A suitable basic stain is often used as a counterstain. • PAS diastase stain (PAS-D) is PAS stain used in combination with diastase, an enzyme that breaks down glycogen. • Alcian blue/periodic acid–Schiff (AB/PAS or AB-PAS) uses alcian blue before the PAS step.
This solution is used to detect ketones and aldehydes. A positive test is signalled by the formation of a yellow, orange or red precipitate of the dinitrophenylhydrazone. Aromatic carbonyls give red precipitates whereas aliphatic carbonyls give more yellow color. [2] The reaction between DNPH and a generic ketone to form a hydrazone is shown below:
It is used to dye polyacrylonitrile fibers.; It is used to detect sulfur dioxide. [5]Pararosaniline is used as a colorimetric test for aldehydes, in the Schiff test.It is the only basic fuchsine component suitable for making the aldehyde-fuchsine stain for pancreatic islet beta cells.
Tollens' test for aldehyde: left side positive (silver mirror), right side negative Ball-and-stick model of the diamminesilver(I) complex. Tollens' reagent (chemical formula ()) is a chemical reagent used to distinguish between aldehydes and ketones along with some alpha-hydroxy ketones which can tautomerize into aldehydes.