McIlvaine buffer is a
buffer solution
A buffer solution (more precisely, pH buffer or hydrogen ion buffer) is an aqueous solution consisting of a mixture of a weak acid and its conjugate base, or vice versa. Its pH changes very little when a small amount of strong acid or base is ...
composed of
citric acid
Citric acid is an organic compound with the chemical formula HOC(CO2H)(CH2CO2H)2. It is a colorless weak organic acid. It occurs naturally in citrus fruits. In biochemistry, it is an intermediate in the citric acid cycle, which occurs in ...
and
disodium hydrogen phosphate
Disodium phosphate (DSP), or disodium hydrogen phosphate, or sodium phosphate dibasic, is the inorganic compound with the formula Na2HPO4. It is one of several sodium phosphates. The salt is known in anhydrous form as well as forms with 2, 7, 8 ...
, also known as citrate-phosphate buffer. It was introduced in 1921 by the
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...
agronomist Theodore Clinton McIlvaine (1875–1959) from
West Virginia University
West Virginia University (WVU) is a public land-grant research university with its main campus in Morgantown, West Virginia. Its other campuses are those of the West Virginia University Institute of Technology in Beckley, Potomac State Coll ...
, and it can be prepared in
pH 2.2 to 8 by mixing two stock solutions.
Applications
McIlvaine buffer can be used to prepare a water-soluble
mounting medium
A microscope slide is a thin flat piece of glass, typically 75 by 26 mm (3 by 1 inches) and about 1 mm thick, used to hold objects for examination under a microscope. Typically the object is mounted (secured) on the slide, and then b ...
when mixed 1:1 with glycerol.
Contents
Preparation of McIlvaine buffer requires
disodium phosphate and
citric acid
Citric acid is an organic compound with the chemical formula HOC(CO2H)(CH2CO2H)2. It is a colorless weak organic acid. It occurs naturally in citrus fruits. In biochemistry, it is an intermediate in the citric acid cycle, which occurs in ...
. One liter of 0.2M stock solution of disodium hydroxyphosphate can be prepared by dissolving 28.38g of disodium phosphate in water, and adding a quantity of water sufficient to make one liter. One liter of 0.1M stock solution of citric acid can be prepared by dissolving 19.21g of citric acid in water, and adding a quantity of water sufficient to make one liter. From these stock solutions, McIlvaine buffer can be prepared in accordance with the following table:
References
{{Reflist
Liquids
Biochemistry
Buffer solutions