DERIVATIZATION OF GUAR TO SODIUM CARBOXY METHYL HYDROXY PROPYL DERIVATIVE; CHARACTERIZATION AND EVALUATION

Guar gum is derived from the seeds of Cyamopsis tetragonolobus (Linn, Family Leguminosae). Guar has extensive pharmaceutical applications; however; it has certain draw- backs like uncontrolled rate of hydration, fall in viscosity on storage, susceptibility to microbial degradation and turbidity in aqueous dispersion. Many of these drawbacks can be over come by effecting chemical derivatization of guar gum molecule to Sodiumcarboxymethyl hydroxypropyl guar; the derivatization was ascertained by spectral characterization. In aqueous dispersion, the derivative was subjected to the effect of electrolytes, varied pH conditions and storage at elevated temperatures. The sodium carboxymethyl hydroxypropyl guar derivative revealed superior viscosity retaining qualities when compared to guar gum. The derivative was subjected for detailed rheological investigation and rate of hydration studies. In 1% w/v dispersion the derivative revealed pronounced pseudoplastic behavior and in 2 % w/v dispersion, a distinct pseudoplastic behavior with slight thixotropic effect is seen. In contrast to guar gum, the derivative revealed a more controlled rate of hydration. The derivative revealed sodium content of 10.4% w/w and Degree of substitution of 1.5.