122  Laboratory  Notes  on  Assay  Work.  {Kmi£^^rm- 
SOME  LABORATORY  NOTES  ON  ASSAY  WORK.* 
By  L.  Henry  Bernegau. 
It  is  not  my  purpose  this  evening  to  give  any  new  processes  for 
the  assay  of  drugs  or  preparations  made  from  them.  What  I  wish  to 
give  is  only  a  few  points  in  carrying  out  some  assay  methods,  which 
would  perhaps  be  of  benefit  to  those  in  the  pharmaceutical  profession 
who  wish  to  or  have  to  assay  their  own  drugs  or  preparations,  that 
should  be  assayed. 
In  the  assay  of  aconite  root  and  preparations  made  therefrom  we 
find  it  preferable  to  use  for  extracting  the  alkaloid  an  ether-chloro- 
form mixture  (100  c.c.  ether,  21  c.c.  chloroform)  to  which  has  been 
added  about  15  c.c.  of  saturated  sodium  bicarbonate  solution,  instead 
of  a  proper  amount  of  ammonia  water.  In  carrying  out  the  titration 
we  find  iodeosin  to  be  of  no  value  as  an  indicator,  and  now  use  only 
cochineal  T.  S.  as  indicator,  as  directed  by  the  U.  S.  P.,  which  gives 
very  good  results.  Aconitine  seems  to  be  most  stable,  or  to  remain 
as  such  in  those  preparations  having  the  form  of  a  tincture  or  fluid- 
extract,  that  is  to  say,  in  presence  of  a  high  percentage  of  alcohol. 
Our  records  during  1908  show  plainly  that  the  powdered  and  solid 
extracts  deteriorate  much  more  quickly  than  preparations  containing 
alcohol.  On  shaking  out  aconite  and  its  preparations,  very  often  a 
thick  emulsion  results.  As  quick  work  in  my  opinion  is  a  great 
factor  in  getting  good  results,  I  carry  out  the  assay  as  follows : 
After  shaking  the  drug  (say  12  Gm.)  with  100  c.c.  ether,  21  c.c. 
chloroform  and  12  to  15  c.c.  saturated  sodium  bicarbonate  solution 
for  about  four  hours,  I  filter  off  an  aliquot  part  of  the  ethereal 
liquid,  say  60  c.c.  equivalent  to  6  Gm.  of  drug. 
The  clear  filtrate,  removed  to  a  separatory  funnel,  is  shaken  out 
at  least  three  to  four  times  with  1  per  cent,  sulphuric  acid,  50,  40 
and  30  c.c.  respectively.  On  shaking  vigorously  an  emulsion  results 
in  most  cases,  which  is  very  difficult  to  separate.  Now,  I  personally 
do  not  wait  until  a  complete  separation  takes  place,  but  let  the  partly 
separated  lower  layer  run  into  a  second  separator.  I  repeat  this 
same  manipulation  three  or  four  times,  which  procedure  does  away 
with  the  emulsion  in  the  upper  part  of  the  separator.  Now  shake 
the  combined  acid  solutions  (containing  also  froth,  some  ether  and 
*  Read  before  the  Philadelphia  Branch  of  the  American  Pharmaceutical 
Association,  January  5,  1909. 
