Desalter, description

Desalting electrodialysis, 14 120, 121 Descaling, sodium in, 22 777 Descriptive analysis... 

Descriptions are provided for (1) desalting and dewatering (2) separation processes, of which distillation is the prime example (3) conversion processes, of which coking and catalytic cracking are prime examples and (4) finishing processes, of which hydrotreating to remove sulfur is a prime example. Descriptions of the various petroleum products (from fuel gas to asphalt and coke) sire also given. 

This method is a description of the use of gel filtration for desalting or buffer exchange, while Subheading 3.2.2 describes the use of gel filtration for purification of some classes of antibodies. Desalting and buffer exchange of protein samples are particular examples of gel filtration in which the size difference of the molecules to be separated is large (at least a factor of 10). 

To avoid the above problems we routinely use an extraction method in which DNA fragments become bound to hyroxyapatite powder (9). This is handled in the form of a centriftiged chromatography column for the purposes of washing with various buffers and final elution of pure DNA in 0.5 M potassium phosphate. This DNA is concentrated and desalted in a centrifugal ultrafiltration device (Centricon-10 from Amicon). Many commercial kits are available for the isolation of pure DNA from biological samples therefore a detailed description of the above method seems inappropriate, however, choice of the method should take into account the above considerations. 

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