sodium monochloroacetate for example or which do not polymerize under the reaction conditions for example unsaturated monomers such as sodium vinyl sulfonated do not polymerize in the absence of free radicals since each sugar ring contains on average 3 hydroxy functions the ds varies between 0 and 3 ds 1 means that on average 1 reagent has been grafted per anhydro sugar ring while 2 out of the 3 initial hydroxyl groups are still intact the ds is measured using various methods depending on grafts nature and extent of grafting for example nmr is used to measure the ds of carboxymethyl guars cmgs when high ds is expected above 0 5 while titration is used for ds below 0 5 molar substitution ms this terminology is used to describe the guar modification with reagents such as po eo propylene oxide ethylene oxide which in theory might form oligomers under the reaction conditions consequently ms is theoretically not limited to 3 the ms is usually measured by nmr or other techniques depending on grafts nature and extent of grafting average molecular weights mw gel permeation chromatography gpc or size exclusion chromatography sec are sometimes used providing relative molecular weights currently absolute molecular weights are routinely measured in r amp d facilities by malls multi angle laser light scattering coupled with a gpc column viscosity measurements are still performed as part of quality control in guar gum the basic unit of the polymer consists of two mannose units with a glycosidic linkage and a galactose unit attached to a hydroxyl group of one of the mannose units on the average each of the anhydro sugar units contains three available hydroxyl sites a degree of substitution of three would mean that all of the available hydroxy sites have.