354 
Laudanum  Assay. 
•'Am.  Jour.  Pharm. 
\       July,  ld»2. 
LAUDANUM  ASSAY. 
By  Frank  X.  Moerk,  Ph.G. 
Contribution  from  the  Chemical  Laboratory  of  the  Philadelphia  College  of  Pharmacy. 
No.  ui. 
Objection  has  repeatedly  been  made  to  the  U.  S.  Pharmacopoeia 
process  for  the  assay  of  opium  that  it  is  not  applicable  to  the  assay 
of  opium  preparations.  In  the  following  the  writer  gives  a  method 
that  has  been  very  satisfactory  in  his  hands  in  the  assay  of  laudanum 
and  it  can  no  doubt  be  used  for  other  preparations.  While  70 
grams  of  the  laudanum  sample  in  a  tared  capsule  are  being  slowly 
evaporated  to  a  syrupy  consistence  on  a  water-bath  (the  water  being 
kept  below  the  boiling  point),  2  to  3  grams  of  the  sample  are  evapo- 
rated on  a  watch-crystal  or  in  a  small  beaker,  so  as  to  ascertain  the 
amount  of  total  solids  (this  figure  should  be  close  to  60  per  cent.) ; 
it  is  important  to  make  the  syrupy  liquid  spread  over  as  much  sur- 
face as  possible  to  facilitate  the  drying  which  is  completed  at  a  tem- 
perature of  from  100-1050  C.  Calculation  is  then  made  to  find  the 
total  solids  in  the  70  grams  taken  for  the  assay  ;  the  syrupy  liquid 
from  the  70  grams  is  then  made  up  by  adding  water  to  a  weight 
obtained  by  adding  the  total  solids  to  10  gms  (10  cc.  water).  (It  has 
been  found  easier  in  the  U.  S.  P.  process  to  thoroughly  incorporate 
the  opium  and  lime  with  10  cc.  water  than  with  20  cc,  hence  the 
above  change).  3  grams  slaked  lime  are  then  added  to  the  contents 
of  the  capsule  and  thoroughly  stirred  with  a  pestle  until  a  uniform 
mixture  results ;  by  the  gradual  addition  of  the  remaining  60  cc. 
water  this  mixture  is  rinsed  into  a  flask  or  beaker  and  then  frequently 
shaken  or  stirred  during  one-half  hour.  After  filtering  50  cc.  of 
the  filtrate  are  mixed  with  5  cc.  alcohol  and  25  cc.  stronger  ether, 
and  after  thorough  agitation  3  grams  ammonium  chloride  are  added 
and  the  U.  S.  P.  directions  further  followed.  In  pouring  the  mixture 
from  the  capsule  into  another  vessel  a  little  petrolatum  applied  to 
the  lip  of  the  capsule  will  prevent  the  liquid  from  running  down 
the  outside.  Another  point  in  the  assay  of  opium  that  has  been 
found  to  help  in  obtaining  uniform  results  was  the  drying  of  the 
slaked  lime  at  a  temperature  not  above  ioo°  C.  to  free  the  slaked 
lime  from  excess  of  moisture;  to  do  this  the  lime  was  slaked  in  a 
beaker  and  covered  with  a  watch-crystal,  it  was  then  dried  until 
moisture  no  longer  showed  itself  on  the  lower  side  of  the  watch- 
crystal. 
