Am.  Jour.  Pharm.  ) 
March,  1909.  } 
U.  S.  P.  Assay  Methods. 
121 
In  the  assay  of  nux  vomica  the  most  difficult  part  of  the  opera- 
tion is  the  oxidation  of  the  brucine.  We  find,  when  making  dupli- 
cate assays,  that  both  solutions  often  do  not  act  uniformly,  as  one  is 
usually  completed  before  the  other ;  at  times  the  oxidation  is  incom- 
plete at  the  expiration  of  the  ten  minutes  allowed  for  it.  The 
trouble  seems  to  be  in  the  temperature  of  the  solution,  as  it  has  been 
shown  that  if  it  is  slightly  warm  an  immediate  oxidation  occurs, 
producing  a  bright  red  solution.  In  view  of  this  fact  it  would  be 
of  great  benefit  if  the  temperature,  at  which  the  oxidation  is  to  be 
conducted,  should  be  stated. 
No  matter  at  what  temperature  it  is  conducted,  decrepitation 
usually  occurs  in  evaporating  off  the  solvent,  which  is  likely  to  cause 
some  of  the  alkaloid  to  be  ejected  from  the  flask.  If  the  flask  is 
rotated  while  evaporating  the  last  portion  of  the  solvent,  this  danger 
is  minimized. 
A  condition  similar  to  the  one  in  the  assay  of  colchicum  corm  and 
colchicum  seed  is  found  in  the  assay  of  conium,  in  which  an  excess 
of  about  6  c.c.  of  menstruum  is  required  to  be  prepared.  While 
there  is  not  as  much  waste  in  this  case,  nevertheless  it  must  be  con- 
sidered as  such,  because  there  is  more  menstruum  than  is  necessary 
for  the -operation. 
The  assay  of  pepsin  is  facilitated  if  the  egg  albumin  be  passed 
while  hot  through  the  sieve.  This  part  of  the  method  should  contain 
the  instructions  to  sieve  the  albumin  as  soon  as  it  has  been  boiled. 
A  source  of  error  is  introduced  into  the  method  for  the  assay 
of  physostigma,  when  it  neglects  to  require  the  cylinder,  in  which 
the  ethereal  solution  containing  the  alkaloid  has  been  measured,  to 
be  rinsed  with  some  of  the  solvent.  It  is  true  that  the  error  would 
be  slight,  but  an  accumulation  of  errors,  such  as  this,  would  cause  a 
serious  discrepancy  in  the  final  result. 
If  these  suggestions  were  adopted,  they  would  increase  the 
volume  of  the  Pharmacopoeia  to  but  a  very  small  extent,  but  they 
would  contribute  much  to  greater  accuracy  in  work,  which  is  the 
main  factor  in  alkaloidal  assaying. 
Analytical  Laboratory, 
Smith,.  Kline  &  French  Co. 
