344 
The  Stability  of  Iodine  Ointments.     { Am-  /our-  Pharm- 
-y      J  Aug.  1917. 
pared  from  each  according  to  the  U.  S.  P.  process.  Another  spec- 
imen was  made  from  benzoinated  lard  and  iodine  only*  without  the 
addition  of  either  glycerin  or  potassium  iodide.  This  was  made  to 
contain  4  per  cent,  of  iodine. 
Immediately  after  preparation  each  of  these  iodine  ointments 
was  assayed  for  free  iodine,  and  each  was  reassayed  at  intervals 
later.  The  method  for  the  determination  of  iodine  in  the  ointment 
was  that  employed  in  this  laboratory  for  the  determination  of  iodine 
in  Iocamfen  Ointment.10  It  is  essentially  the  same  as  was  employed 
by  Pullen  for  the  determination  of  uncombined  iodine  in  iodine  oint- 
ment.11 As  carried  out  in  this  laboratory  for  iodine  ointment  it  is 
as  follows : 
From  5  to  8  Gm.  of  the  ointment  were  weighed  in  a  small  porcelain  cap- 
sule, the  capsule  and  contents  placed  in  a  16  oz.  salt  mouth  bottle  together 
with  20  Cc.  of  chloroform,  10  Cc.  of  potassium  iodide  solution  and  40  Cc.  of 
water.  Tenth-normal  sodium  thiosulphate  was  slowly  added  with  agitation 
until  the  pink  color  of  the  chloroform  layer  had  nearly  disappeared.  A  little 
soluble  starch  was  then  added  and  the  titration  continued  until  a  blue  color 
in  the  aqueous  layer  could  no  longer  be  obtained  by  repeated  shaking. 
The  findings  for  the  several  assays  are  tabulated  herewith : 
Table  I. 
Iodine  Content  of  Iodine  Ointments. 
Age  at  time  of  assay. 
Freshly  made.. 
After  3  days . .  . 
After  7  days. .  . 
After  3  weeks. . 
After  7  weeks. . 
After  3  months 
U.  S.  P.  oint- 
ment from 
laboratory 
rendered  lard 
(%  I)- 
U.  S.  P.  oint- 
ment from 
commercial  lard 
Grade  I 
(%T). 
U.  S.  P.  oint- 
ment from 
commercial  lard 
Grade  II 
(%D- 
Ointment  from 
lard  and  iodine 
only  (laboratory 
rendered  lard) 
3-32 
3-26 
3-30 
0.32 
3-25 
0.23 
2.99 
3-17 
3.15 
3-OI 
3-19 
3-07 
3.12*  * 
3.10 
3.02 
2.98 
2.88 
2.88  ' 
*  This  slight  rise  in  iodine  content  followed  by  a  fall  could  not  be  ac- 
counted for.  The  specimen  was  believed  to  have  been  very  thoroughly  mixed 
at  the  time  of  manufacture.  • 
That  the  fatty  constituents  of  the  ointment  contained  iodine 
after  the  preparation  had  been  made  for  some  time  was  demon- 
strated.   Some  of  the  material  was  examined  as  follows : 
*  In  order  to  facilitate  the  incorporation  of  the  iodine  with  the  fatty  base 
the  iodine  was  first  powdered  by  trituration  with  alcohol  and  drying  the 
powder  in  the  air. 
10  Rep.  Lab.  A.  M.  A.,  0,  118  (1916). 
11  Pharm.  Jour.,  89,  610  (1912). 
