Is the exact mass/concentration of an oligosaccharide known?

Megazyme oligosaccharides are not certified analytical standards. 

We recommend that the end user standardise, validate and certify these products themselves if required. 

Our oligosaccharide products are packed in solution and then freeze dried. The solution concentrations are assayed using the phenol-sulfuric acid procedure prior to freeze-drying and we typically pack +5% of the stated mass on the label. 

Vials are capped as soon as the vials are removed from the freeze drier but we cannot guarantee that some moisture from the air is not absorbed, particularly for hygroscopic compounds. 

Megazyme data sheets often state a purity of >95% when in fact no impurities have been identified using our analytical procedures and in these cases we are providing a minimum purity specification.