Dear Mamoun A. Homaida,

You can try various UPLC method (used for determination of polyphenols in other plant extracts and beverages) for the determination of polyphenol in sugarcane. Try the following methods, these methods may help you in your method development.

With Regards

Ajay Sharma 

Any C18 column, with an (acidified) water : methanol or acetonitrile gradient should work; Remember to decide whether you want the intracellular phenolics (just extract using (acidified) water : methanol, ethanol or aceton mixture) or also the cell wall phenolics (ferulic acid linked to arabinoxylans or pectins), in the later case you'll need to carry out also a saponification under intert atmosphere (argon for example, or N2).