The fractional preparation of antitoxic serum / by Edwin J. Banzhaf and Robert Banks Gibson.

  • Banzhaf, Edwin J.
Date:
1907
Catalogue details

Licence: In copyright

Credit: The fractional preparation of antitoxic serum / by Edwin J. Banzhaf and Robert Banks Gibson. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    of antitoxin.' This consisted in precipitating the diluted plasma with an equal volume of saturated ammonium sulphate and sep- arating the antitoxic proteids by extracting the precipitate with saturated sodium chloride solution. We now have employed the method of salt fractionation to study further the concen- tration of antitoxin. There exists at the present time considerable confusion in comprehend- ing the methods and basic principles of ammonium sulphate fractional precipitation of proteids. The nomenclature which we have employed and which designates the number of cc. of saturated ammonium sulphate solution in lo cc. of the precipitated mixture has been used by some author- ities; it avoids the confusion developed by the use of such terms as “per cent (NHJ2SO4solution” and “per cent saturation (NHJjSO^” “per cent of saturated (NH4)jS04 solution” and “per cent saturation (NH4)jS04 solution” and it seems the simplest and hest practical expression of de- grees of saturation yet suggested. We advise that this method be em- ployed in future papers on fractional precipitation. Mann, in his version of Cohnheim’s “ Chemie der Eiweisskorper,” states (p. 292): “As the solubility of ammonium sulphate is 76.8° (percent ?) at room temperature, it is easy to calculate what percentage of ammonium sulphate is required for bringing about incipient and complete precipita- tion of any one albumin, as soon as we know what amounts of saturated ammonium sulphate have to be added for any given quantity of fluid.” The simplicity of the above method of calculating vanishes when atten- tion is drawn to the fact that while 100 parts of water dissolve 76.8 gms. of dry ammonium sulphate, the volume resulting is increased to 141 cc. so that 100 cc. of the saturated solution actually contain approximately 54 gms. of the salt, and the degree of saturation as indicated by the con- tend of dry ammonium sulphate must be calculated with reference to the latter figure. An example will make clearer the above statement; To obtain a concentration of “half saturation” ammonium sulphate, equal volumes of the proteid solution and of saturated ammonium sulphate solution are mixed; according to the apparent meaning of Mann’s obscure statement, 100 cc. of the resulting “ half saturated” solution would con- tain 38.4 gms. of the dry salt; it actually does contain 27 gms. of ammo- nium sulphate.^ ' The literature on the purification and chemical characters of anti- bodies has been briefly reviewed in a paper on “The Practical Concentra- tion of Diphtheria Antitoxin for Therapeutic Use, ” this Journal, i, p. 161, 1906, and more recently by Ledingham: Journ. of Hyg., vii, p. 65, 1907. * Because of the change in the volume of the solvent on adding the salt, it is similarly not possible to add 38.4 gms. of ammonium sulphate to 100 cc. of water and have a solution at “half saturation.” In this case the volume would be increased to 120.7 cc. and 100 cc. would contain 31.7 gms. of the salt.
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