Homogenization

This may find application in several areas. The first example is the homogenization of animal tissues in a high-speed blender, which enables a homogeneous sample to be obtained for subsequent analysis. This is used, for example, in the analysis of arsenic or copper in liver (Ross, 1990). A second area is the extraction of volatile fatty acids from silage. Typically, 10 g fresh silage is homogenized for between 1 and 10 min with 100 ml water in a blender before filtration (Lessard et al., 1961). The last area is the dry homogenization of linseed seeds prior to oil determination. These resist crushing and so about 4 g of seeds are homogenized at 11,500-13,000 rpm for 2 min.

There are several types of blender. One of the most popular is the Waring blender, operating on a similar principle to domestic jug-type food blenders. Containers are available in glass, stainless steel and polycarbonate. It should be noted that the working capacities of the containers are a maximum of 70%, and a minimum of 10% nominal capacity. Accessory containers enable volumes as low as 12 ml to be handled. Silage is homogenized in a Waring type blender.

There are also the dispersing shaft type homogenizers, which may be hand held or stand mounted. The shaft has a tip with teeth rotating within a fixed crenated stator, which imparts impact, shock, shearing and cavitation effects. Working volumes as low as 0.03 ml (PR020 Homogenizer) can be handled. The materials, however, should be free-flowing, and usually suspended in a liquid. For solid materials, like seeds, a blade rather than a dispersing tool is required. PROtm market a Safety-Seal® Chamber Assembly with a 25.4-mm blade which can handle a minimum of 10 ml (supplied by Radleys). Status homogenizers can be equipped with their AX60 Analytical Mill attachment (supplied by Philip Harris Scientific). This has a cooling jacket that can be used with liquid nitrogen for temperature sensitive samples.

Manufacturers' websites:

Buchi Labortechnik AG: http://www.buchi.com/ Fisherbrand: http://www.fisher.co.uk/ IKA®: http://www.ika.net/

http://www.labworld-online.com/ika/index1.html

Kinematica (Polytron®): Kinematica AG at http://www.kinematica.ch/

Tel.: +41 41 2501257 Fax: +41 41 2501460

Supplied by Philip Harris (RossLab plc)

http://www.phscientific.co.uk/html/

PRO Scientific Inc: http://www.proscientific.com/

Radleys (R.B. Radley & Co. Ltd): http://www.radleys.co.uk/

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