Boric acid/borate react with chemical compounds containing multiple hydroxyls groups (polyols) such as mannitol, generating anionic complexes at the neutral pH of water.

The borate esters are formed and dissociated spontaneously in a variety of pH dependent equilibria. During to the release of acidic protons during complexation there is a concomitant decrease of pH which tends to reverse the reaction and thus, in order to maintain stable complexes there is a need to avoid pH decrease. The amount of acidification produced upon the addition of mannitol is proportional to the extent of borate ester formation.

The HI 38074 test kit can determine boron concentration in irrigation waters by direct titration of boric acid.