You can make a standard solution for calculation of coefficient
I mean wich derivatization protocol is more effective and convenient in terms of simplicity?
Dear Eugenio
I used mstfa http://www.sigmaaldrich.com/life-science/biochemicals/biochemical-products.html?TablePage=104029375 for derivatization and this gave me the possibility to identify about 15 - 20 main sugars and sugar alcohols. But, I think it is also dependent on the column and method of running. Some of them can be overlapped if the resolution will not be enough.
Hello,
are you analyzing monomeric or polymeric carbohydrates? Neutral sugars or uronic acids (e.g., Glucuronic acid or galacturonic acid) as well?
we use HMDS (or BSTFA) + TMCS + pyridine (dried with KOH pellets) for carbohydrate analysis. HMDS will give precipitation, but it's much cheaper than BSTFA.
Leave the samples (e.g., in test tubes) overnight for sufficient derivatization and run your analysis the following day. If you need to do quantification I would really recommend to use GC-FID instead of GC-MS. You could use GC-MS for identification if the same temperature program and column as in GC is used, though.
For GC-FID we use internal standard(s) and a calibration sample containing sugars of known concentration.
regards,
JR
Thank you all for your valuable answers.
I would like to quantify main sugars in fruits (sucrose, glucose, fructose) by GC-MS and looking for a simple but robust method.
I am working on that now. I like the aldonitrile acetate method. Dried sample dissolved in 2% hydroxylamine in pyridine followed by addition of acetic anhydride but it doesn't do ketoses (fructose). I does do all the aldoses and disaccarides. The solution is to divide the reaction in half after the hydroxylamine treatment and the other half add a silylating reagent such as trimethylsilylimmidizaole or BSTFA and use that half to do the ketoses.
Check out J. Agric. Food Chem. 2013, 61, 4011−4018. They have a new method of making sugar acetates using aqueous 1-methylimidazole,DMSO, and acetic anhydride. The monosaccarides are locked into ring formation.
Paam (aldonitrile) deriviatives for aldose, alcohols and disaccharides and if you need ketoses take some of the reaction mix after the first hydroxylamine in pyridine reaction and add a silylating reagent to get TMS Oximes.
Fructose seems unreliable for paan derivitives which in the case of ketoses which create a cis and trans oxime peracetate.
I've more or less completed my method. I take 0.5 ml of sample and 0.2ml ribitiol ITSD and blow it down to dryness at 45 deg C with nitrogen
add 200ul of 2% hydroxylamine pyridine incubate 1 hour at 90 deg C
cool
add 200 ul of acetic anhydride and incubate 1 hour at 90 deg C
cool and add 1ml water and 500 ul of methylene chloride.
Inject the methlene chloride layer. I use a db-5 column. monosaccharides and sugar alcohols come off ~ 200-260 deg C and disacchardies 315 deg C. I am planning to eventually get a high temp DB5 to do maltotriose. I am also eventually looking to replace the methylene chloride with either toluene or ethyl acetate.
Fructose seems to work well enough to quantitative. I get linearity of .996 vs .999-.9999 for the rest. The LOD is higher for it as it is split into two smaller peaks for the cis and trans oxime peracetate.
did u find the solution? if so pl. send me the protocol. i am interested to to the same using GCMS
dears i need to identify exopolysaccharides produced from bacteria using GC Ms
so i want to know how i can prepare the sample for GC injection ?
- Badges
- Science topic
- Similar topics
- Geoscience
- Asia
- India