492 
Studies  on  Licorice  Root. 
5  Am.  Jour.  Pharm. 
I      July,  1921. 
The  most  obvious  explanation  is  not  the  true  one.  One  might 
think  that : 
1.  Either  the  preliminary  solvent  removed  glycyrrhizin. 
2.  Or  the  glycyrrhizin  was  more  or  less  contaminated  with  bitter 
substances  according  as  they  were  less  or  more  removed  by  the  pre- 
liminary treatment. 
The  first  possibility  is  easily  disproved  by  examining  the  ether  or 
alcohol  extracts  for  glycyrrhizin.  Never  more  than  a  trace  is 
present. 
The  second  possibility  may  account  for  a  small  part  of  the  dif- 
ferences.in  the  values,  but  judging  by  taste  and  color  there  can  be  no 
large  amount  of  impurity  in  the  glycyrrhizin  obtained.  The  main 
cause  of  the  differences,  as  already  explained  in  detail,  is  that,  the 
more  non-glycyrrhizin  removed  in  the  preliminary  treatment,  the 
more  subject  to  loss  by  washing  is  the  glycyrrhizin,  on  account  of 
being  then  left  in  a  granular  form  rather  than  in  a  compact  form 
which  can  be  kneaded  with  the  ice-cold  wash-water. 
In  summarizing,  it  must  be  remembered  that  no  known  method 
weighs  pure  glycyrrhizin.  We  have  to  choose  the  method  weighing  as 
pure  a  glycyrrhizin  as  possible,  and  in  which  the  loss  in  manipulation 
is  as  low  as  possible. 
With  the  preliminary  alcoholic  extraction  I  feel  that  serious 
manipulative  losses  are  difficult  to  avoid,  and  in  some  cases  inevitable. 
On  the  other  hand  I  feel  that  a  direct  treatment  of  the  root  with 
75  per  cen,t.  alcohol  yields  a  glycyrrhizin  which  is  contaminated  a  lit- 
tle more  than  necessary  with  impurities. 
As  the  best  available  compromise  I  therefore  choose  an  ether  ex- 
traction to  remove  resins,  followed  by  extraction  with  75  per  cent, 
alcohol  to  obtain  glycyrrhizin. 
The  details  of  the  method  are  here  set  forth : 
DETERMINATION  OF  GLYCYRRHIZIN  IN  LICORICE  ROOT. 
The  sample  of  ground  root  (it  is  not  necessary  to  specify  any 
particular  degree  of  fineness,  but  it  should  be  not  coarser  than  20 
mesh)  is  dried  to  a  moisture  content  of  not  more  than  2  per  cent. 
This  is  easily  accomplished  by  allowing  to  stand  in  an  oven  for  an 
hour  or  two  at  about  500  C,  or  by  spreading  out  £  thin  layer  for  a 
day  in  a  sulphuric  acid  desiccator. 
