RE: ORGLIST: help HPLC & Purification

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From: Ilya Avrutov (iavrutov$##$dalton.com)
Date: Mon Mar 28 2005 - 14:49:18 EST




Dear Dr. Tushar,

They could be tens different reasons why. First of all you didn't give
enough data. For example, what solvent system was used for HPLC. Let's
imagine the system contained acid. So may be this peak at 3.56 min is
not peak of the original impurity, but peak of its salt with the acid.
Which could be much more polar, than the original impurity.
Because you see polar treatment doesn't reduce your imprutity I would
try just opposite: trituration with less polar solvent: EtOAc, CH2CL2,
chloroform, toluene.

Good luck,
Dalton Chemical Laboratories Inc.
Ilya Avrutov
Process Development Group Leader
iavrutov$##$dalton.com
349 Wildcat Rd. Toronto ON M3J 2S3
tel: 416-661-2102 (320)
fax: 416-661-2108
mobile: 416-726-2556
------------------------------------

-----Original Message-----
From: everybody-bounces$##$orglist.net
[mailto:everybody-bounces$##$orglist.net] On Behalf Of Dr. Tushar Mehta
Sent: Monday, March 28, 2005 12:55 PM
To: everybody$##$orglist.net
Subject: ORGLIST: help HPLC & Purification

Dear All

 I have one Query about HPLC results

  I have a compound which i got analysed out side give
results as follows
 
  Impurity RT area %
   1 3.56 0.237
   2 5.07 0.535
   3 15.09 0.890
   4 23.00 97.6
 and other small impurities peak
 I m Doing purification as follows
    1. Ethyl acetate + Metanol
    2. Methanol ( carbon treat ment)
    3. Methanol slurry
    4. Methanol Slurry

 After these four purification one by one still i m
getting impurity at RT 3.56 around 0.20 by area % and
purity incerase to 99.67 % at RT 23.00

 Now My question is is this HPLC results is look
authentic.
  Why the impurity at 3.56 is not getting removed even
after 4 purification in polar system
  while the impuritie at other RT getting less to
almost less than 0.05(less polar compare to impurity
at 3.56

  I welcome all comment
 if u need aditional info i will provide u to analyse
theproblem

  Thanks

  Dr.Tushar Mehta
R & d
  
 


                
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