By shirish patel on Monday, February 4, 2002 - 04:55 am:
I AM TYRING TO DEVELOP METHOD OF ANALYSIS FOR THE NUTRACEITICAL COMPUNDS , GLUCOSAMINE SULPHATE HCL AND CHONDROITIN SULPHATE NA SALT THIS BOTH THE COMPOUNDS ARE SOULBLE IN WATER FREELY
I HAVE SATARTED WITH 97 WATER AND 3 ACN BUT GETTING A PEAK WITHIN t0 values and not successful and both peaks are merged , so i decided to use a ion pair
mobile phase 0.2%octane sulphonic acid, 0.1%TRIETYLAMINE AND PH OF BUFFER IS 2.5WITH PHOSPHORIC ACID .(BUFFER/ACN) (97:3)
COLUMN USED LUNA C18(2) 25cm
FLOWRATE IS - 0.8ML/MIN
WAVELENGH IS 200 NM
STELL FINDING DFIFFICULTY IN SEPERATION IAM GETTING RESOLUTION= 2.0 AND DIFFICULTIES IN DOING QUANTITAION I ALSO TRIED WITH XTERRA C18 RP 3.5um 15cm column but here also same thing happened 2.00is my resolution.
I WANT TOGET RESOLUTIN AROUND 5. TO 6.0 IS IT POSSIBLE IN FOLLOWING WAY OR BY SOME OTHER WAYS
i have partisil scx column which is benzene sulphonic acid chemically bonded to silica
can this column work for this application , wheather i can use methanol or acetonirile along with the buffer in this column.as i am thinking that as both this comound having a NH2 GORUPS THEY WILL MAKE PAIR WITH THE STATIONARY PHASE AND WILL REMAIN STROGLY ADSORBED
REPLY TO ME AT
shi_ri@yahoo.com
By ravi on Monday, February 4, 2002 - 05:34 am:
Try columns with Extended Polar Selectivity, like PRONTOSIL EPS C18 (Mac-Mod), or Discovery RP amide C16 (from Supelco), or Symmetry Shiled C18 (Waters). These columns are supposed to give better separation for polar compounds by retaining them longer in the column.
By ravi on Monday, February 4, 2002 - 05:36 am:
I forgot to tell you. Try not to use any ion pair reagent while using EPS columns, just go with Buffer/CH3CN.
By Chris Pohl on Monday, February 4, 2002 - 02:03 pm:
Shirish,
It seems that these compounds might be better separated using an ion pairing reagent for anionic solutes such as tetrabutylammonium ion. The Merck Index lists chondroitin sulfate as a high molecular weight polymer with one sulfate group as well as a glucuronic acid group for every disaccharide unit (there is no mention of any free amino groups). Do you have any idea what the molecular weight of your chondroitin sulfate is?
By SHIRISH on Tuesday, February 5, 2002 - 04:39 am:
CHRIS POHL
CHONDROITIN IS HAVING A NITROGEN WITH A LOAN PAIR AND GLUCOSAMINE IS HAVING A NH2 GROUP . I DO NOT HAVE ANY IDEA ABOUT THE MOLECULAR WT OF CHONDROITIN AS ITS A POLYMET IT MUST BE HIGH
By Anonymous on Tuesday, February 5, 2002 - 03:43 pm:
What happens if you decrease the ACN to 0%?
By shirish on Wednesday, February 6, 2002 - 04:43 am:
i have not tired to decrease the acn to 0% as its harmful to the c18 column but i can if i will use symeetyshied column. i trying to get that column.
By A. Ganza on Thursday, February 7, 2002 - 04:16 am:
We have found good retention and selectivity for polar compounds with new Discovery HSF5 columns even with high percentages of acetonitrile.
By Michele on Thursday, February 7, 2002 - 09:59 am:
I have had good retention of polar molecules with the Phenomenex Ultracarb (30) C18 columns, particullarly if I adjust the pH of the mobile phase, although the columns have not been very rugged.
By Anonymous on Tuesday, February 12, 2002 - 08:29 am:
if that difficult why don't think about Normal Phase? you can test on TLC first if you are in a phar. lab.
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