omega 3 fatty acid estimation by GCMS: method availability

[jbshan]

Dear All,
I need to analyse omega 3 fatty acids (EPA& DHA) in human plasma using LCMS or GCMS. I hope GCMS will be more suitable for this analysis. Can anyone helpme out in finding the method, please

Urgent

[jdlh199]

This can be done by GC by a relatively standard method with methylation to fatty acid methyl esters (FAME's). Google 'FAME analysis by GC' for more info. You'll have to think about what exactly you are trying to measure in plasma. Do you want total plasma concentrations, free fatty acid levels, fatty acids bound to lipids etc etc.

This analysis is usually performed by FID rather than MS. You won't see molecular ions at M+.

See here for FAMEWAX application note:
http://www.restek.com/restek/images/ext ... F00499.pdf
EPA is 20:5, DHA is 22:6

See here for a GCMS application:
http://www3.interscience.wiley.com/jour ... 1&SRETRY=0

[jbshan]

Thank you very much for your inputs.Since free fatty acid levels are too low to be measured, the uptake of EPA and DHA in serum phospholipids will be used as a marker of absorbtion.The absorption of EPA and DHA wiill be evaluated as percentage in total serum phospholipids.

shan

[jbshan]

Hi, Can you please tell me what reference standards to be procured for EPA and DHA analyis. Is there any pure compoundavailable.. Please help

thanks
shan

[jdlh199]

Of course there are reference standards available for DHA and EPA, Sigma has them as should any standard chemical supplier. However, you may want to sit down and think about your approach.

If you are using GCMS and calculating "percentage of total phospholipid fatty acids" then you will have to identify and quantify every single fatty acid peak detected in your samples.

If you are using MS detection you might want to consider quantitative determination (in ug/mL) instead of percentage of total.

Or consider a more suitable detector, i.e. FID, where you can just use peak area ratios.

[Biocheckup]

Hi, Can you please tell me what reference standards to be procured for EPA and DHA analyis. Is there any pure compoundavailable.. Please help

thanks
shan

Dear Shan,

if you go for FAME I suggest you use a FAME-mix (see Supelco or Restek).
Use an internal standard: Larodan produces phospholipids with specific FAs.

Regards