Fractionation
Encyclopedia
See also: Fractionated spacecraft
Fractionation is a separation process
in which a certain quantity of a mixture
(solid, liquid, solute, suspension or isotope
) is divided up in a number of smaller quantities (fraction
s) in which the composition changes according to a gradient
. Fractions are collected based on differences in a specific property of the individual components. A common trait in fractionations is the need to find an optimum between the amount of fractions collected and the desired purity in each fraction. Fractionation makes it possible to isolate more than two components in a mixture in a single run. This property sets it apart from other separation techniques.
Fractionation is widely employed in many branches of science and technology. Mixtures of liquids and gases are separated by fractional distillation
by difference in boiling point. Fractionation of components also takes place in column chromatography
by a difference in affinity between stationary phase and the mobile phase. In fractional crystallization
and fractional freezing
, chemical substance
s are fractionated based on difference in solubility at a given temperature. In cell fractionation
, cell
components are separated by difference in mass
.
Fractionation is also used for culinary purposes, as coconut oil, palm oil
,and palm kernel
oils are fractionated to produce oils of different viscosities, that may be used for different purposes. These oils typically use fractional crystallization (separation by solubility at temperatures) for the separation process instead of distillation.
. One of the very effective ways for carrying out this process is the addition of alcohol to the plasma pool while simultaneously cooling the pool. This process is sometimes called cold alcohol fractionation or ethanol fractionation. It was described by and bears the eponym of Dr Edwin J. Cohn. This procedure is carried out in a series of steps so that a single pool of plasma yields several different protein products, such as albumin and immune globulin. Human serum albumin prepared by this process is used in some vaccines, for treating burn victims, and other medical applications.
with radiation therapy
. When the total dose of radiation
is divided into several, smaller doses over a period of several days, there are fewer toxic effects on healthy cells. This maximizes the effect of radiation on cancer and minimizes the negative side effects
. Typical fractionation schemes divide the dose into 30 units delivered every weekday over 6 weeks, though current research is considering the benefits of accelerated fractionation (2 deliveries per day and/or deliveries on weekends as well).
Fractionated Spacecraft
A fractionated spacecraft is a satellite architecture where the functional capabilities of a conventional monolithic spacecraft are distributed across multiple modules which interact through wireless links...
Fractionation is a separation process
Separation process
In chemistry and chemical engineering, a separation process, or simply a separation, is any mass transfer process used to convert a mixture of substances into two or more distinct product mixtures, at least one of which is enriched in one or more of the mixture's constituents. In some cases, a...
in which a certain quantity of a mixture
Mixture
In chemistry, a mixture is a material system made up by two or more different substances which are mixed together but are not combined chemically...
(solid, liquid, solute, suspension or isotope
Isotope
Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...
) is divided up in a number of smaller quantities (fraction
Fraction (chemistry)
A fraction in chemistry is a quantity collected from a sample or batch of a substance in a fractionating separation process. In such a process, a mixture is separated into fractions, which have compositions that vary according to a gradient. A fraction can be defined as a group of chemicals that...
s) in which the composition changes according to a gradient
Gradient
In vector calculus, the gradient of a scalar field is a vector field that points in the direction of the greatest rate of increase of the scalar field, and whose magnitude is the greatest rate of change....
. Fractions are collected based on differences in a specific property of the individual components. A common trait in fractionations is the need to find an optimum between the amount of fractions collected and the desired purity in each fraction. Fractionation makes it possible to isolate more than two components in a mixture in a single run. This property sets it apart from other separation techniques.
Fractionation is widely employed in many branches of science and technology. Mixtures of liquids and gases are separated by fractional distillation
Fractional distillation
Fractional distillation is the separation of a mixture into its component parts, or fractions, such as in separating chemical compounds by their boiling point by heating them to a temperature at which several fractions of the compound will evaporate. It is a special type of distillation...
by difference in boiling point. Fractionation of components also takes place in column chromatography
Column chromatography
Column chromatography in chemistry is a method used to purify individual chemical compounds from mixtures of compounds. It is often used for preparative applications on scales from micrograms up to kilograms.The main advantage of column chromatography is the relatively low cost and disposability...
by a difference in affinity between stationary phase and the mobile phase. In fractional crystallization
Fractional crystallization (chemistry)
In chemistry, fractional crystallization is a method of refining substances based on differences in solubility. If a mixture of two or more substances in solution is allowed to crystallize, for example by allowing the temperature of the solution to decrease, the precipitate will contain more of...
and fractional freezing
Fractional freezing
Fractional freezing is a process used in process engineering and chemistry to separate two liquids with different melting points. It can be done by partial melting of a solid, for example in zone refining of silicon or metals, or by partial crystallization of a liquid, for example "freeze...
, chemical substance
Chemical substance
In chemistry, a chemical substance is a form of matter that has constant chemical composition and characteristic properties. It cannot be separated into components by physical separation methods, i.e. without breaking chemical bonds. They can be solids, liquids or gases.Chemical substances are...
s are fractionated based on difference in solubility at a given temperature. In cell fractionation
Cell fractionation
Cell fractionation is the separation of homogeneous sets, usually organelles, from a heterogeneous population of cells.-Steps:There are three principal steps involved:#Disruption of cells and liberation of organelles.#Macro Filtration...
, cell
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....
components are separated by difference in mass
Mass
Mass can be defined as a quantitive measure of the resistance an object has to change in its velocity.In physics, mass commonly refers to any of the following three properties of matter, which have been shown experimentally to be equivalent:...
.
Fractionation is also used for culinary purposes, as coconut oil, palm oil
Palm oil
Palm oil, coconut oil and palm kernel oil are edible plant oils derived from the fruits of palm trees. Palm oil is extracted from the pulp of the fruit of the oil palm Elaeis guineensis; palm kernel oil is derived from the kernel of the oil palm and coconut oil is derived from the kernel of the...
,and palm kernel
Palm kernel
Many plants and trees like olive, soybean, canola, sunflower and coconut palm produce one type of oil. The fruits of the oil palm tree, however, yields two distinct oils - palm oil and palm kernel oil....
oils are fractionated to produce oils of different viscosities, that may be used for different purposes. These oils typically use fractional crystallization (separation by solubility at temperatures) for the separation process instead of distillation.
Plasma protein fractionation
Plasma proteins are separated by using the inherent differences of each protein. Fractionation involves changing the conditions of the pooled plasma (e.g., the temperature or the acidity) so that proteins that are normally dissolved in the plasma fluid become insoluble, forming large clumps, called precipitate. The insoluble protein can be collected by centrifugationCentrifugation
Centrifugation is a process that involves the use of the centrifugal force for the sedimentation of mixtures with a centrifuge, used in industry and in laboratory settings. More-dense components of the mixture migrate away from the axis of the centrifuge, while less-dense components of the mixture...
. One of the very effective ways for carrying out this process is the addition of alcohol to the plasma pool while simultaneously cooling the pool. This process is sometimes called cold alcohol fractionation or ethanol fractionation. It was described by and bears the eponym of Dr Edwin J. Cohn. This procedure is carried out in a series of steps so that a single pool of plasma yields several different protein products, such as albumin and immune globulin. Human serum albumin prepared by this process is used in some vaccines, for treating burn victims, and other medical applications.
Fractionation as cancer treatment
Fractionation also refers to a method of treating cancerCancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
with radiation therapy
Radiation therapy
Radiation therapy , radiation oncology, or radiotherapy , sometimes abbreviated to XRT or DXT, is the medical use of ionizing radiation, generally as part of cancer treatment to control malignant cells.Radiation therapy is commonly applied to the cancerous tumor because of its ability to control...
. When the total dose of radiation
Radiation
In physics, radiation is a process in which energetic particles or energetic waves travel through a medium or space. There are two distinct types of radiation; ionizing and non-ionizing...
is divided into several, smaller doses over a period of several days, there are fewer toxic effects on healthy cells. This maximizes the effect of radiation on cancer and minimizes the negative side effects
Side Effects
Side Effects is an anthology of 17 comical short stories written by Woody Allen between 1975 and 1980, all but one of which were previously published in, variously, The New Republic, The New York Times, The New Yorker, and The Kenyon Review. It includes Allen's 1978 O...
. Typical fractionation schemes divide the dose into 30 units delivered every weekday over 6 weeks, though current research is considering the benefits of accelerated fractionation (2 deliveries per day and/or deliveries on weekends as well).