In all the protocols I could find on that topic it was mentioned that absorbance at 230 nm is related to polysaccharide or polyphenol contaminations. However, none of these protocols are citing bibliographic sources. What in polysaccharides could provoke the absorbance at 230 nm, or what kind of polysaccharides can be detected at this wavelength?
Plant cell wall polysaccharides may bear phenolic esters on their side chains such as feruloyl, p-coumaroyl and p-hydroxybenzoyl esters. Xylans in grasses and pectins in the Chenopodiaceae are well-known examples. Carbohydrates without phenolics only absorb at very low wavelengths (below 200nm).
The absorbance spectrum of a phenolic compound has a maximum at 250 - 280nm (for simple phenols such as tyrosine or p-hydroxybenzoyl ester) or 308 - 340nm (for those with a conjugated side chain, such as ferulic acid). This is due to the n-π* transition. The π-π* transition produces another maximum at shorter wavelengths (somewhere around 220nm). It should be remembered that the molar absorption coefficient will fall to a minimum somewhere between the first and second maximum, but it will never go down to zero. So the answer to your question is that any polysaccharide carrying phenolic ester groups is likely to absorb at 230nm.
Plant cell wall polysaccharides may bear phenolic esters on their side chains such as feruloyl, p-coumaroyl and p-hydroxybenzoyl esters. Xylans in grasses and pectins in the Chenopodiaceae are well-known examples. Carbohydrates without phenolics only absorb at very low wavelengths (below 200nm).
The absorbance spectrum of a phenolic compound has a maximum at 250 - 280nm (for simple phenols such as tyrosine or p-hydroxybenzoyl ester) or 308 - 340nm (for those with a conjugated side chain, such as ferulic acid). This is due to the n-π* transition. The π-π* transition produces another maximum at shorter wavelengths (somewhere around 220nm). It should be remembered that the molar absorption coefficient will fall to a minimum somewhere between the first and second maximum, but it will never go down to zero. So the answer to your question is that any polysaccharide carrying phenolic ester groups is likely to absorb at 230nm.
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