THE  AMERICAN 
JOURNAL  OF  PHARMACY 
— —  hM%  €\ 
APRIL,  igoi. 
JO 
CONTRIBUTIONS  FROM  H.  M.  GORD1N 
I.  THE  ASSAY  OF  CRUDE  DRUGS. 
The  first  step  in  the  alkaloidal  assay  of  drugs  and  galenical  prep- 
arations consists  in  the  extraction  of  the  alkaloids  from  these 
sources.  The  exactness  of  such  an  assay  will  depend  in  the  first 
place  upon  the  completeness  of  exhaustion  of  the  respective 
sources,  and  in  the  second  place  upon  the  exactness  of  the  method 
which  is  employed  for  the  estimation  of  the  isolated  alkaloids. 
With  regard  to  this  estimation,  the  method  which  I  proposed  some 
time  ago 1  seems  to  work  very  well  with  all  alkaloids  except  those 
which  are  not  precipitated  by  Mayer's  or  Wagner's  reagents  in  very 
dilute  solutions  (coniine),  or  those  that  are  only  precipitated  by 
these  reagents  in  presence  of  a  very  large  excess  of  acid  (colchi- 
cine).2 In  applying  this  method  to  the  assay  of  drugs,  it  is  often 
found  that  upon  addition  of  the  above-mentioned  reagents  the  preci- 
pitate obstinately  refuses  to  separate  out  even  upon  prolonged  shak- 
ing. In  such  cases  the  addition  of  a  little  talcum  powder,  which  of 
course  must  be  perfectly  neutral,  and  a  little  shaking  will  speedily 
throw  down  all  the  precipitate,  leaving  a  perfectly  transparent 
supernatant  liquid.  The  error  in  titration  which  is  liable  to  arise 
from  the  addition  of  the  talcum  is  probably  so  small  that  it  can 
safely  be  neglected.  Should  very  exact  results  be  desired,  this 
error  can  be  entirely  eliminated  by  standardizing  the  acid  and  alkali 
with  the  same  alkaloid  under  the  same  conditions,  i.  e.f  with  the  use 
1  Ber.  d.  Deutsch.  Chem.  Ges.,  1899,  2872  ;  Pharm.  Arch.,  Vol.  II,  No.  10. 
2  Ibid. 
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