Guar Gum
»Guar Gum is a gum obtained from the ground endosperms of Cyamopsis tetragonolobus(Linné)Taub.(Fam.Leguminosae).It consists chiefly of a high molecular weight hydrocolloidal polysaccharide,composed of galactan and mannan units combined through glycosidic linkages,which may be described chemically as a galactomannan.
Packaging and storage—
Preserve in well-closed containers.
Identification—
A:
Place about 2g in a 400-mLbeaker,moisten it with about 4mLof isopropyl alcohol,add 200mLof cold water with vigorous stirring,and continue stirring until the gum is completely and uniformly dispersed:an opalescent,viscous solution results.
B:
Place about 100mLof the solution prepared in Identificationtest Ain a 400-mLbeaker,heat in a boiling water bath for about 10minutes,and cool:no appreciable increase in viscosity is produced(distinction from locust bean gum—see Reagentsin the section Reagents,Indicators,and Solutions).
Loss on drying á731ñ—
Dry it at 105
for 5hours:it loses not more than 15.0%of its weight.
for 5hours:it loses not more than 15.0%of its weight.
Total ash á561ñ:
not more than 1.5%of ash.
Acid-insoluble matter—
Transfer about 1.5g of Guar Gum,accurately weighed,to a 250-mLbeaker containing 150mLof water and 1.5mLof sulfuric acid.Cover the beaker with a watch glass,and heat the mixture on a steam bath for 6hours,rubbing down the wall of the beaker frequently with a rubber-tipped stirring rod,and replacing any water lost by evaporation.At the end of the 6-hour heating period add about 500mg of a suitable filter aid,accurately weighed,and filter through a suitable tared,ashless filter.Wash the residue several times with hot water,dry the filter and its contents at 105for 3hours,cool in a desiccator,and weigh:the amount of acid-insoluble matter,determined by subtracting the weight of filter aid from that of the residue,is not more than 7.0%of the Guar Gum taken.
for 3hours,cool in a desiccator,and weigh:the amount of acid-insoluble matter,determined by subtracting the weight of filter aid from that of the residue,is not more than 7.0%of the Guar Gum taken.
Arsenic,Method IIá211ñ:
3ppm.
Lead á251ñ—
Prepare a Test Preparationas directed in the chapter,and use 10mLof Diluted Standard Lead Solution(10µg of Pb)for the test:the limit is 0.001%.
Heavy metals,Method IIá231ñ:
0.002%.
Protein—
Transfer about 1.0g of Guar Gum,accurately weighed,to a 500-mL Kjeldahl flask,and proceed as directed for Method Iunder Nitrogen Determination á461ñ:the amount of protein,obtained by multiplying by 6.25the percentage of nitrogen determined,is not more than 10.0%of the Guar Gum taken.
Starch—
To a 1in 10solution of Guar Gum add a few drops of iodine TS:no blue color is produced.
Organic volatile impurities,Method IVá467ñ:
meets the requirements.
Content of galactomannans—
Subtract from 100.0the total percentages of Loss on drying,Total ash,Acid-insoluble matter,and Protein:the content of galactomannans is not less than 66.0%.
Auxiliary Information—
Staff Liaison:Catherine Sheehan,B.Sc.,Scientist
Expert Committee:(EMC)Excipients:Monograph Content
USP28–NF23Page 3016
Pharmacopeial Forum:Volume No.29(6)Page 2017
Phone Number:1-301-816-8262