Though SA production in bacteria can be quantified using a UV-visible spec, I don't think there is a reliable protocol for measuring endogenous SA using spectrometer. The reason as I understand maybe due to the interference by other compounds at 527nm (used for bacterial SA). So, the least you will need is HPLC for reliable and publishable results. All the best!

Hi,

This protocol is a common technical exam for students in France. It is carried on at 300 nm, so you wouldn't be bothered by chlorophylls (absorbance between 470 and 700 nm). If you want, you can eliminate pigments using a Sep-pak column on aqueous or methanolic leaf extract. If you have an access, try :

http://onlinelibrary.wiley.com/doi/10.1002/jps.2600550411/abstract

You can also try :

http://old.iupac.org/publications/cd/medicinal_chemistry/Practica-I-11.pdf

I hope it helped. I wish you luck in your resarches.

Best regards.