Viscosity modifying properties of citrate compounds / Syakinah Mohd Shukri

AIM: This study reported the effects of citrate based additives on the viscosity profile of hydroxypropylmethylcellulose (HPMC) solution.
METHOD: The HPMC solution, with or without the incorporation of additives, was subjected to viscosity test using a U-tube viscometer at 30°C. Selected samples of test solutions were subjected to Fourier Transform Infrared spectroscopy (FTIR) analysis.
RESULTS: The viscosity of HPMC solutions was reduced when appropriate amounts of citric acid, triacetin, triethyl citrate and trisodium citrate were added. Using 0.5% (w/w) HPMC solution, small molecular weight additive such as citric acid demonstrated the best viscosity lowering effect when an appropriate amount of citric acid was added. Using I% (w/w) HPMC solution, trisodium citrate demonstrated the best viscosity lowering effect when an appropriate amount of trisodium citrate was added. FTIR analysis indicated that the viscosity profile of HPMC solution could be mediated through the interaction of additives with HPMC via 0-H or non 0-H functional groups of the polymer.
CONCLUSION: Citric acid, triacetin, triethyl citrate and trisodium citrate exhibited viscosity modifying properties in HPMC solution.