Insulin crystals

Recrystallization is an essentially physical process that has meanings in chemistry, metallurgy and geology. Commons:Image:Insulincrystals. ... Commons:Image:Insulincrystals. ... It has been suggested that Oral insulin be merged into this article or section. ... Chemistry (from Greek χημεία khemeia[1] meaning alchemy) is the science of matter at the atomic to molecular scale, dealing primarily with collections of atoms, such as molecules, crystals, and metals. ... Metallurgy is a domain of materials science and of materials engineering that studies the physical and chemical behavior of metallic elements, their intermetallic compounds, and their mixtures, which are called alloys. ... This article does not cite its references or sources. ...

Chemistry

In chemistry, recrystallization is a procedure for purifying compounds. The most typical situation is that a desired "compound A" is contaminated by a small amount of "impurity B". There are various methods of purification that maybe attempted, which includes recrystallization. There are also different recrystallization techniques that can be used such as: Chemistry (from Greek χημεία khemeia[1] meaning alchemy) is the science of matter at the atomic to molecular scale, dealing primarily with collections of atoms, such as molecules, crystals, and metals. ... A chemical compound is a chemical substance consisting of two or more different chemically bonded chemical elements, with a fixed ratio determining the composition. ...

Single-solvent recrystallization

Typically the mixture of "compound A" and "impurity B" are dissolved in the minimum amount of solvent to fully dissolve the mixture i.e. a saturated solution. The solution is then allowed to cool. As the solution cools the solubility of compounds in solution drops. This results in the desired compound dropping (recrystallizing) from solution. The slower the rate of cooling the bigger the crystals formed will be. In chemistry, saturation has four different meanings: In physical chemistry, saturation is the point at which a solution of a substance can dissolve no more of that substance and additional amounts of that substance will appear as a precipitate. ... Dissolving table salt in water In chemistry, a solution is a homogeneous mixture composed of one or more substances, known as solutes, dissolved in another substance, known as a solvent. ...

The crystallization process requires an initiation step. Once a small crystal has formed, more crystals can grow from that crystal. Since "Compound A" is in excess this will usually result in these crystals forming first and thus leaves a greater ratio of impurity in solution. Thus the resulting solid is more pure than the original mixture.

The level of purity can then be checked by taking a melting point range of the solid and comparing it to an accepted melting point range if one exists. Compounds have higher melting points when pure, so the melting point will rise when the compound is more pure. Obviously other analytical techniques can be used to asses compound purity such as NMR spectroscopy. Nuclear Magnetic Resonance Spectroscopy most commonly known as NMR Spectroscopy is the name given to the technique which exploits the magnetic properties of nuclei. ...

This purification technique results in the inevitable loss of the part of "compound A" that remains in solution. A yield of 80% would be considered quite good. However the impure solution can be concentrated and the procedure repeated to gather a "second crop" of crystals. Yield in chemistry, also known as chemical yield and reaction yield, is the amount of product obtained in a chemical reaction. ...

Successful recrystallization depends on finding the right solvent. This is usually a combination of prediction/experience and trial/error. The mixture must be soluble at higher temperatures, and must be insoluble (or have low solubility) at lower temperatures.

Multi-solvent recrystallization

This method is the same as the above but where two (or more) solvents are used. This relies on both "compound A" and "impurity B" being soluble in a first solvent. A second solvent is slowly added. Either "compound A" or "impurity B" with be insoluble in this solvent and precipitate, whilst the other of "compound A"/"impurity B" will remain in solution. The thus the proportion of first and second solvents are critical. Typically the second solvent is added slowly until one of the compounds begins to crystallize from solution and then the solution is cooled. Heating is not required for this technique but can be used.

The reverse of this method can be used where a mixture of solvent dissolves both A and B. One of the solvents is then removed by distillation or by an applied vacuum. This results in the a change in the proportions of solvent causing either "compound A" or "impurity B" to precipitate.

Hot filtration

Hot filtration can be used to separate "compound A" from both "impurity B" and some "insoluble matter C". This technique normally uses a single solvent system as described above. When both "compound A" and "impurity B" are dissolved in the minimum amount of hot solvent, the solution is filtered to remove "insoluble matter C". This matter maybe anything from a third impurity compound, to bits of broken glass. For a successful procedure one needs to ensure that the filtration apparatus is piping hot to stop the dissolved compounds precipitating from solution. Often it is simpler to do the filtration and recrystallization as two independent and separate steps. That is dissolve "compound A" and "impurity B" in a suitable solvent at room temperature, filter, remove solvent and then recrystallize.

Seeding

Crystallization requires a initiation step. This can be spontaneous or can be done by adding a small amount of the pure compound to the saturated solution, or can be done by simply scratching the glass surface to generate a seeding surface for crystals to grow. It is thought that even dust particles can act as simple seeds.

Single perfect crystals (for X-ray analysis)

Growing crystals for X-ray crystallography can be quite difficult. For X-ray analysis, single perfect crystals are required. Typically a small amount (5-100 mg) of pure compound is used, and crystals are allowed to grow very slowly. Several techniques can be used to grow these perfect crystals: X-ray crystallography is a technique in crystallography in which the pattern produced by the diffraction of X-rays through the closely spaced lattice of atoms in a crystal is recorded and then analyzed to reveal the nature of that lattice. ...

• Slow evaporation of a single solvent - typically the compound is dissolved in a suitable solvent and the solvent is allowed to slowly evaporate. Once the solution is saturated crystals can form.
• Slow evaporation of a multi-solvent system - the same as above, however as the solvent composition changes due to evaporation of the more volatile solvent. The compound is more soluble in the volatile solvent, and so the compound becomes increasingly insoluble in solution and crystallizes.
• Slow diffusion - similar to the above. However, a second solvent is allowed to evaporates from one container into a container holding the compound solution (gas-diffusion). As the solvent composition changes due to an increase in solvent that is has gas-diffused into solution, the compound become increasingly insoluble in solution and crystallizes.
• Interface/slow mixing (often performed in an NMR tube). Similar to the above, but instead of one solvent gas-diffusing into another, the two solvents mix (diffuse) by liquid-liquid diffusion. Typically a second solvent is "layered" carefully on top of the solution containing the compound. Overtime the two solution mix. As the solvent composition changes due to diffusion, the compound becomes increasingly insoluble in solution and crystallizes, usually at the interface.
• Specialized equipment can be used in the shape of a "H" to perform the above.

An NMR tube filled with a colorless sample, sealed with a green polyethylene cap and Parafilm Left to right: Flame, septum and polyethylene cap sealed NMR tubes Aqua regia has been added to these NMR tubes to remove all traces of organic material. ...

Geology

In geology, solid-state recrystallization is a metamorphic process that occurs under situations of intense temperature and pressure where grains, atoms or molecules of a rock or mineral are packed closer together, creating a new crystal structure. The basic composition remains the same. This process can be illustrated by observing how snow recrystallizes to ice without melting. As opposed to metasomatism, which is a chemical change caused by metamorphism, recrystallization is a physical process. However, recrystallization can occur when a local migration of chemicals results in the chemical change of the rock or mineral with no external addition of materials. This article does not cite its references or sources. ... Metamorphism can be defined as the mineralogical, chemical and crystallographic changes in a solid-state rock, i. ... Metasomatism is a geologic process where metamorphism causes an alteration in a mineral or rock mass that involves a chemical change of the substance with the addition of material, as when chrysolite (olivine) is converted to serpentine basically by the addition of water. ...

Limestone is a sedimentary rock that undergoes metamorphic recrystallization to form marble, and clays can recrystallize to muscovite mica. Limey shale overlaid by limestone. ... Two types of sedimentary rock: limey shale overlaid by limestone. ... Venus de Milo, front. ... The Gay Head cliffs in Marthas Vineyard are made almost entirely of clay. ... rock with mica Mica sheet mica flakes The mica group of minerals includes several closely related materials having highly perfect basal cleavage. ...

Metallurgy

In metallurgy, recrystallization is the nucleation and growth of new undeformed grains in a deformed metal. Metallurgy is a domain of materials science and of materials engineering that studies the physical and chemical behavior of metallic elements, their intermetallic compounds, and their mixtures, which are called alloys. ... Recrystallization is a process by which deformed grains are replaced by a new set of undeformed grains that nucleate and grow until the original grains have been entirely consumed. ...

Ice

For ice, recrystallization refers to the growth of larger crystals at the expense of smaller ones. Some biological antifreeze proteins have been shown to inhibit this process, and the effect may be relevant in freezing-tolerant organisms. To meet Wikipedias quality standards, this article or section may require cleanup. ... Antifreeze proteins AFPs or ice structuring proteins ISPs refer to a class of polypeptides produced by certain fish, vertebrates, plants, fungi and bacteria that permit their survival in subzero environments. ...