120 
U.S.  P.  Assay  Methods. 
J  Am.  Jour.  Pharm. 
]     March,  1909. 
give  accurate  results,  on  account  of  the  small  amount  of  alkaloid 
present,  as  the  same  quantity  (100  c.c.)  is  required  to  be  used, 
whether  the  standard  for  the  alkaloid  in  100  c.c.  is  0.014  Gm.  or 
0.1  Gm. 
For  an  illustration,  we  will  take  the  assay  methods  for  tincture  . 
of  nux  vomica  and  for  tincture  of  physostigma.  The  standard  for 
alkaloid  in  100  c.c.  of  tincture  of  nux  vomica  is  over  seven  times  as 
high  as  that  for  tincture  of  physostigma,  but  the  same  amount  of 
tincture  is  required  in  both  cases.  When  it  is  taken  into  account 
that  the  alkaloid  which  is  titrated  from  the  nux  vomica  represents 
the  full  100  c.c,  and  the  alkaloid  from  the  physostigma  only  50  c.c, 
the  difference  is  even  greater. 
A  more  forcible  illustration  of  this  difference  is  found  between 
tincture  of  hyoscyamus,  which  has  a  standard  for  100  c.c.  of  0.007 
Gm.  and  tincture  of  hydrastis,  which  has  a  standard  of  0.4  Gm.  in 
100  c.c.  There  is  no  reason  why  it  would  not  be  as  well  to  use 
25  c.c.  in  the  case  of  both  tincture  of  nux  vomica  and  tincture  of 
hydrastis,  as  it  would  be  a  saving  of  both  time  and  material.  There 
are  several  other  cases  which  might  be  mentioned. 
In  a  work  of  the  standing  of  the  Pharmacopoeia,  it  should  be 
the  aim  to  eliminate  all  waste  and  to  make  all  methods  as  short  as 
possible.  A  sample  of  needless  waste  is  found  in  the  assays  for 
colchicum  corm  and  colchicum  seed,  in  which  we  are  instructed  to 
take  100  c.c.  of  a  mixture  of  ether  77  c.c,  chloroform  25  c.c,  and 
alcohol  8  c.c,  amounting  to  a  little  over  109  c.c,  allowing  for  con- 
traction. Here  we  have  an  excess  of  9  c.c,  and  if  a  duplicate  is 
made,  an  excess  of  18  c.c,  which  is  wasted.  It  should  be  calculated 
so  that  it  would  only  be  necessary  to  make  100  c.c,  as  is  done  in  most 
other  instances. 
The  present  methods  for  the  assay  of  alkaloidal  drugs  and  their 
preparations  are,  on  the  whole,  very  satisfactory,  but  we  come  across 
details,  here  and  there,  which  require  slight  changes  and  which 
would  give  more  accurate  results.  The  first  of  these,  which  might 
be  mentioned,  is  in  the  assay  of  opium.  After  drying  the  crystals 
of  morphine  obtained,  we  are  told  to  weigh  them  on  a  tared  watch- 
glass,  after  which  they  are  transferred  to  an  Erlenmeyer  flask. 
It  is  not  an  easy  matter  to-  transfer  a  powder  to  a  flask,  as  there  is 
danger  of  loss  by  a  portion  dropping  on  the  outside.  A  better 
method  is  to  weigh  the  crystals  on  tared  oiled  paper  which  is  con- 
siderably easier  to  handle. 
