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Method and apparatus for the formation of particles

a particle and particle technology, applied in the field of particle particle formation methods and apparatuses, can solve problems such as suffering detrimental effects, and achieve the effect of low solubility of lactos

Inactive Publication Date: 2002-01-31
BRADFORD PARTICLE DESIGN
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0140] The following examples were carried out using a method according to the present invention, and apparatus generally similar to that shown in FIGS. 1-4. They illustrate the versatility of the method of the invention, its usefulness in forming particles of materials which would otherwise be difficult to prepare by supercritical fluid techniques and the advantageous effects which can thereby be achieved.

Problems solved by technology

It may be a substance which, though soluble in an appropriate supercritical fluid-soluble solvent, would suffer detrimental effects if dissolved in that solvent prior to particle formation (for instance, a hydrophilic protein), or be otherwise incompatible with such a solvent.

Method used

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  • Method and apparatus for the formation of particles
  • Method and apparatus for the formation of particles
  • Method and apparatus for the formation of particles

Examples

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Effect test

examples 1 & 2

[0141] Formation of Lactose Particles

[0142] The following examples illustrate the successful and controlled formation of crystalline lactose, using carbon dioxide as a supercritical fluid, despite the very low solubility of lactose in conventional CO.sub.2-soluble organic solvents. According to the present invention, two vehicles were used for the lactose, water as the first and an organic solvent (methanol), which is miscible with water and soluble in supercritical carbon dioxide, as the second.

example 1

[0143] Preparation of Lactose (I)

[0144] In accordance with the invention, a solution of lactose in a relatively small amount of water and a relatively large amount of a second vehicle, methanol, was used. The solution was co-introduced, with supercritical CO.sub.2, into a particle formation vessel of the type shown in FIGS. 1 and 2, through a three-passage nozzle of the type shown in FIG. 3. The pressure and temperature inside the vessel were carefully maintained at the desired operating levels throughout particle formation. It is thought that the miscible water and methanol were extracted together into the supercritical CO.sub.2, despite the insolubility of water in the supercritical fluid.

[0145] 0.3 g of alpha-lactose monohydrate was dissolved in 2 ml de-ionised water, 98 ml of methanol was added to the aqueous solution and the mixture was introduced into the 32 ml particle formation vessel through the three-passage nozzle. The operating conditions were 270 bar and 70.degree. C. i...

example 2

[0146] Preparation of Lactose (II)

[0147] In an experiment similar to that of Example 1, a 0.5% w / v solution of alpha-lactose monohydrate in methanol:water (95:5 v / v) was prepared and delivered to a 50 ml high pressure particle formation vessel via a two-passage nozzle. The working conditions were 150 bar and 50.degree. C. inside the vessel, with a flow rate of 0.7 ml / min for the solution and 9 ml / min for the supercritical CO.sub.2. The collected product was a free flowing, fine white powder. FIGS. 7 and 8 show an SEM micrograph and XRD pattern respectively for this product.

[0148] The SEM micrographs for the products of Examples 1 and 2 reveal a marked difference in the shape of the lactose particles prepared under the different operating conditions. The XRD patterns indicate the crystalline nature of the products.

[0149] As can be seen from these examples, the present invention provides an extremely effective technique for the controlled formation of lactose particles using supercrit...

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Abstract

The invention provides a method for forming particles of a substance, by co-introducing into a particle formation vessel, in which the temperature and pressure are controlled, of a supercritical fluid; a solution or suspension of the substance in a first vehicle; and a second vehicle which is both substantially miscible with the first vehicle and substantially soluble in the supercritical fluid, in such a way that dispersion of the solution or suspension and the second vehicle, and extraction of the vehicles, occur substantially simultaneously and substantially immediately on introduction of the fluids into the vessel, by the action of the supercritical fluid. Preferably the solution / suspension of the substance is introduced separately from the second vehicle, in such a way that contact between the solution / suspension and the second vehicle occurs either substantially simultaneously with, or immediately before, their dispersion by the supercritical fluid and extraction of the vehicles by the supercritical fluid. The method allows a high degree of control over the size, shape, crystalline form and other physico-chemical properties of the particulate product. The invention also provides apparatus for carrying out such a method, using a coaxial nozzle to introduce the fluids into the particle formation vessel, and a particulate product made using the method or the apparatus.

Description

[0001] This invention relates to the controlled formation of particulate products using supercritical fluids. It provides a method and apparatus for the formation of a substance in particulate form, and the particulate product of such a method.BACKGROUND TO THE INVENTION[0002] The use of supercritical fluids (SCFs) and the properties thereof have been extensively documented; see for instance J. W. Tom and P. G. Debenedetti, "Particle Formation with Supercritical Fluids--A Review", J. Aerosol. Sci., 22 (5), pp555-584 (1991). Briefly, a supercritical fluid can he defined as a fluid at or above its critical pressure (Pc) and critical temperature (Tc) simultaneously. Such fluids have been of considerable interest, not least because of their unique properties. These characteristics include:[0003] High diffusivity, low viscosity and low surface tension compared with liquids.[0004] High compressibility compared with the ideal gas implies large changes in fluid density with only slight chan...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): A61K9/16B01J2/04B01J3/00
CPCA61K9/1688B01D11/0411B01J2/04B01J3/008B01D11/0403B01D11/0488B01J3/02B01D11/0407Y02P20/54
Inventor HANNA, MAZANYORK, PETER
Owner BRADFORD PARTICLE DESIGN
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