PRODUCTION OF ANTIPNEUMOCOCCIC SERUM 589 



mice affords a rapid and convenient means of detecting the pres- 

 ence of toxic amounts of some of the chemical preservatives used in 

 serum. 



Final Processing of Serums 

 After a lot of antipneumococcic serum has been selected and, as 

 is the case in many laboratories, has been concentrated, there are 

 routine procedures to be followed before the product is ready for 

 distribution. A brief discussion of a convenient and approved sys- 

 tem covering this phase of processing follows. 



TOTAL SOLIDS 



It is necessary to determine the total amount of solids present 

 in concentrated preparations intended for human use, because the 

 solids content may be too high to permit of ready filtration and 

 ease of administration. The determination is made by drying to 

 constant weight an accurately measured amount — at least ten 

 cubic centimeters — of serum and calculating the percentage of 

 dried matter in terms of the original weight of serum. Experience 

 has shown that concentrated serum with a total solids content be- 

 tween 10 and 15 per cent is usually of satisfactory viscosity to 

 meet the requirements in processing and administration to pa- 

 tients. Lots with a solids content above this level are diluted with 

 an appropriate volume of salt solution. 



FILTRATION 



All antipneumococcic serum intended for therapeutic use must 

 be passed through a Berkefeld or some similar filter to ensure the 

 absence of contaminating microorganisms. Filtration of concen- 

 trated products is facilitated by first passing the serum through a 

 high-speed centrifuge. Warming the serum to slightly above room 

 temperature also facilitates filtration. In order to minimize subse- 

 quent testing, it is desirable to filter as large quantities of serum 

 as possible into single containers. The usual aseptic precautions 

 must be observed throughout the process. 



