By ves on Thursday, January 22, 2004 - 08:56 am:
I amt trying to get bile acids and sterols out of faeces so I can do HPLC and probably ELSD or RI or maybe even PDA. I've seen a paper of SFE of faeces followed by concentration with a SPE c18 cartridge. WOndering if anyone had a non-SFE cocktail for extracting the acides and sterols?
By Anonymous on Thursday, January 22, 2004 - 03:29 pm:
Sterols and bile acids should be fairly straightforwards by liquid extraction with a non-polar solvent such as carbon tetrachloride or methylene chloride.
By ves on Wednesday, January 28, 2004 - 02:33 am:
extraction is not a big problem - hplc is. I've tried C-18 with
a. water (0.1% h3po4) to meoh (0.1%h3po4).
b. water (0.1%h3po4) to meoh.
c. water (0.1%h3po4) to meoh(0.1%h3po4) to meoh.
a & b were publshed in lit.
By Anonymous on Wednesday, January 28, 2004 - 04:30 am:
I thought the analysis of these sterols (at least) was generally performed by GC. Then you do not have any problems detecting the non-UV absorbing sterols (maybe the sensitive of your ELSD detector is good enough if you're using faeces and this is not an environmental application). You won't get much response from coprostanol from you PDA detector though!
David
By ves on Tuesday, February 17, 2004 - 05:48 am:
The student is having trouble with the derivitization and his standards are not so pure. I was in hopes of picking out a lower-limit absorber to help identify the sterols on hplc. One "standard" has five peaks - each separated by several minutes.