Am.  Jour.  Pharm.  ) 
August,  1921.  5 
Caffeine  in  Tea  and  Coffee. 
56i 
was  also  evolved4,  based  upon  the  two  methods  just  mentioned  and 
the  Deker5  method,  which  has  thus  far  been  found  to  give  satisfac- 
tory results  and  which  is  rapid  and  simple  to  manipulate.  The  two 
a  view  to  the  adoption  of  one  or  the  other  as  an  optional  official 
method. 
The  proposed  new  method  is  as  follows : 
Preparation  of  sample:  Grind  the  tea  to  pass  a  1/25  inch  sieve. 
Assay :  To  5  grams  of  material  in  a  500  cc.  graduated  flask  add 
10  grams  of  heavy  magnesium  oxide  and  200  cc.  of  distilled  water." 
Boil  gently  over  a  low  flame  for  two  hours  using  a  small  bore  glass 
tube  30  inches  long  as  a  condenser.  Cool,  dilute  to  volume  and  filter 
through  a  dry  paper.  Take  an  aliquot  of  300  cc,  equivalent  to  3 
grams  of  original  material  in  an  Erlenmeyer  flask  of  1,000  cc.  ca- 
pacity, add  10  cc.  of  a  10  per  cent,  solution  of  sulphuric  acid  and 
evaporate  by  gentle  boiling  until  the  volume  is  reduced  to  about  100 
cc.  Filter  into  a  separatory  funnel  washing  the  flask  with  small 
portions  of  1  per  cent,  sulphuric  acid  and  shake  out  six  times  with 
chloroform  using  25,  20,  15,  10,  10,  10  cc.  portions.  Treat  the  com- 
bined extracts  with  5  cc.  of  a  1  per  cent,  solution  of  potassium  hy- 
droxide. When  the  liquids  have  completely  separated  draw  off  the 
chloroform  layer  into  a  suitable  flask  or  beaker.  Wash  the  alkaline 
solution  in  the  separatory  with  two  portions  of  chloroform  of  10 
cc.  each  and  unite  the  washings  with  the  main  bulk  of  extract.  Evap- 
orate or  distill  off  the  chloroform  to  small  bulk,  transfer  to  a  tared 
flask,  evaporate  to  dryness,  and  further  dry  in  a  water  oven  at 
ioo°  C.  to  constant  weight. 
If  desired,  transfer  the  residue  thus  obtained  to  a  digestion 
flask  with  successive  small  portions  of  sulphuric  acid  and  determine 
nitrogen  by  the  Kjeldahl  method,  calculating  caffeine  from  nitrogen 
by  the  factor  3.464. 
The  results  obtained  by  the  several  methods  are  given  in  Table 
XIII. 
4  By  R.  E.  Andrew  and  the  writer. 
5  Chem.  Zentr.  1,  1,  62,  1903. 
