576 
PharmacopGcial  Standard  for 
[Am.  Jour.  Pharm. 
<-    December,  191 7. 
PHARMACOPGEIAL  STANDARD  FOR  SODIUM 
BENZOATE. 
By  Carl  E.  Smith. 
Inquiries  of  manufacturers  and  others,  in  doubt  about  a  correct 
interpretation  of  the  standards  of  purity  and  strength  for  sodium 
benzoate,  as  laid  down  in  the  United  States  Pharmacopoeia,  9th  re- 
vision, have  drawn  my  attention  to  several  instances  of  vagueness 
and  deficiencies  in  the  specifications  of  this  important  drug.  These 
deficiencies  have  caused  honest  doubt  in  the  minds  of  some  and 
have  presented  a  plausible  excuse  for  others  to  foist  an  inferior 
product  on  an  unsuspecting  public. 
One  of  the  defects,  which  are  doubtless  due  to  oversight,  is  the 
failure  to  state  explicitly  that  the  benzoic  acid  forming  part  of  the 
salt  must  conform  to  the  same  standard  of  purity  as  that  required 
for  benzoic  acid  itself  under  its  own  separate  heading.  Another  is 
the  failure  to  adequately  restrict  the  water  content.  Still  another  is 
the  inadequacy  of  the  assay  method  prescribed. 
It  seems  self-evident  that  the  Revision  Committee  did  not  intend 
to  permit  an  indefinitely  lower  standard  for  the  sodium  salt  than  for 
the  acid  from  which  it  is  made.  That  would  have  been  grossly  in- 
consistent. In  the  8th  revision  of  the  U.  S.  P.  it  was  distinctly 
stated  that  the  acid  separated  from  the  salt  must  "  conform  to  the 
tests  of  purity  given  under  Acidum  Benzoicum." 
Much  benzoic  acid  contaminated  with  excessive  quantities  of 
chlorobenzoic  acid  and  other  impurities  is  circulating  in  this  market. 
As  this  cannot  be  sold  as  benzoic  acid  U.  S.  P.,  much  of  it  is  likely 
to  be  made  into  the  sodium  salt,  with  the  impurities  remaining  in 
the  product,  and  disposed  of  under  a  lax  interpretation  of  the  U.  S. 
P.  requirements. 
In  their  own  and  that  of  the  consuming  public,  purchasers 
should  therefore  demand  that  the  sodium  benzoate  sold  as  con- 
forming to  the  U.  S.  P.  standard  should  not  contain  any  benzoic 
acid  that  is  below  the  U.  S.  P.  standard  for  that  acid. 
It  is  a  fact  apparently  little  known  outside  of  the  factories  mak- 
ing this  salt  that  it  can  hold  a  considerable  quantity  of  water  with- 
out showing  it,  as  much  as  1 1  per  cent.  The  texts  of  the  8th  and  9th 
revisions  of  the  U.  S.  P.  make  no  explicit  provisions  concerning 
permissible  water  content  and  ignore  the  fact  that  a  hydrated  salt 
