922 
Assay  of  Aconite  Preparations. 
( Am.  Jour.  Pharm. 
(     December,  1920. 
AN  IMPROVED  METHOD  FOR  THE  ASSAY  OF  ACONITE 
PREPARATIONS.* 
By  E.  J.  Chappbiv,  a. I.e.,  and  Noei.  I^.  Ai.i.port. 
The  standardization  of  tincture  and  liniment  of  aconite  was  made 
official  for  the  first  time  in  the  19 14  edition  of  the  British  Pharma- 
copoeia. In  the  method  to  be  adopted  for  their  assay  the  analyst  is 
left  to  base  his  process  upon  that  described  for  the  root.  According 
to  this  method,  the  liquid  preparation  is  evaporated  to  dryness  at  a 
temperature  not  exceeding  60°,  and  the  solid  residue  is  then  dis- 
solved in  A^/50  sulphuric  acid.  The  resulting  solution  is  next  filtered 
but  this  operation  is  often  so  slow  and  tedious  that  a  more  expeditious 
method  is  needed.  It  is  claimed  that  this  disadvantage  is  overcome 
in  the  modified  process  here  described. 
It  has  been  proposed  by  others  to  extract  the  acid  liquid  with 
ether,  without  previous  filtration,  but  this  gives  troublesome 
emulsions,  and  we  have  found  the  use  of  petroleum  ether  to  be  much 
better,  as  there  is  no  such  tendency  with  this  solvent.  Other  sol- 
vents were  tried,  but  none  was  found  to  give  such  easy  manipulation 
as  petroleum  ether.  As  the  result  of  many  experiments  the  following 
method  is  recommended: 
15  Cc.  of  the  liniment  or  100  Cc.  of  the  tincture  are  evaporated 
at  a  low  temperature  to  remove  the  bulk  of  the  alcohol.  5  Cc.  of  10 
per  cent,  sulphuric  acid  diluted  with  20  Cc.  of  water  are  added,  and  the 
whole  transferred  to  a  separating  funnel,  with  the  assistance  of  a 
glass  rod  to  break  up  the  separated  resin;  the  dish  is  then  rinsed 
carefully  with  a  little  water. 
About  20  Cc.  of  petroleum  ether  (B.  P.  4o°-6o°)  are  added, 
and  the  mixture  shaken.  Separation  is  rapid,  the  aqueous  liquor  is 
drawn  off  and  again  shaken  with  petroleum  ether.  The  two  petroleum 
liquors  are  mixed,  rinsed  twice  with  water,  and  the  washings  added 
to  the  acid  liquid,  which  is  then  rendered  alkaline  with  ammonia  and 
extracted  four  times  with  either.  The  ethereal  extracts  are  washed 
successively  with  the  same  portion  of  water,  after  which  they  are 
run  into  a  flask  and  evaporated  to  dryness.  The  alkaloidal  residue 
is  dried  at  a  low  temperature  to  ensure  removal  of  ammonia,  and 
then  titrated  in  the  usual  manner. 
The  great  advantage  is  the  saving  of  time  in  avoiding  trouble- 
some filtration,  which  may  take  several  hours.    The  process  may  be 
*Reprinted  from  The  Pharmaceutical  Journal  and  Pharmacist,  July  24,  1920. 
