Analytical techniques Flashcards
How can be determined the molecular weight distribution of polymers ?
With high performance size exclusion chromatography (HPSEC) were larger molecules are less retained by the column compared with small molecules. –>effect of the enzymatic modification.
Why is the signal of polymer signal as measured by HPSEC after enzyme treatment not a reliable measure for the amount of the non-degraded glucan?
Removing starch from the mixture by amylase may leave other polysaccharides intact and those are giving a nice polymer peak. However, you cannot be sure that no other types of polymers are
present, next to beta-glucan.
How can you check whether you have an acidic polysaccharide present as sample?
Methylene blue colour test. Neutral polysaccharides will not bind any methylene blue.
What could be an easy assay to illustrate the presence of sulfate as substituent. Which polymer would be present in case of a positive test? Assuming that the polymer under investigation is quite pure, what can you say about the polymer when judging the amount of sulfate measured?
Rhidozinate color assay after acid hydrolysis to release the bound sulfate. The most common class of sulphated hydrocolloides are carrageenans and agar. The amount of sulfate will distinguish between kappa (1 sulfate per dimer of gal/anhydrogal), iota (2 sulfate per dimer) and lambda (3 sulfate per dimer).
Assuming the presence of a neutral or slightly acidic polymer, how can be checked whether we have galactomannans present?
By using a pure mannase and monitoring the digest either by HPSEC or by reducing sugar assay.
Upon hydrolysis of a polymer, every bond split will result in an additional reducing end.
How can you measure the monosaccharide composition ?
Hydrolyzing the polymer to its monomeric building blocks. Analysis of these mono-sugars by either high performance liquid chromatography or gas chromatography.
Neutral acids–> GC, HPLC
Neutral and uronic acids–> High performance ion exchange chromatography
