Zeta potential suspension stability

Duro R, Alverez C, Martinez-Pachecon R, Gomez-Amoza JE, Concheiro A, Souto C. The adsorption of cellulose ethers in aqueous suspensions of pyrantel pamoate effects of zeta potential and stability. Eur J Pharm Biopharm 1998 45 181-188. 

Response to Electric and Acoustic Fields. If the stabilization of a suspension is primarily due to electrostatic repulsion, measurement of the zeta potential, can detect whether there is adequate electrostatic repulsion to overcome polarizabiUty attraction. A common guideline is that the dispersion should be stable if > 30 mV. In electrophoresis the appHed electric field is held constant and particle velocity is monitored using a microscope and video camera. In the electrosonic ampHtude technique the electric field is pulsed, and the sudden motion of the charged particles relative to their counterion atmospheres generates an acoustic pulse which can be related to the charge on the particles and the concentration of ions in solution (18). 

The determination of the zeta potential of particles in a disperse system provides useful information concerning the sign and magnitude of the charge and its effect on the stability of the system (see Sec. II.B) [56, 206 208], It can be of value in the development of pharmaceutical suspensions, particularly if the... 

JB Kayes. Pharmaceutical suspensions relation between zeta potential, sedimentation volume and suspension stability. J Pharm Pharmacol 29 199-204, 1977. 

In another application, the magnitude of the zeta potential is measured as a function of added counterions. The variation in zeta potential is found to be related to the stability of the colloidal suspension. The results of a gold colloidal suspension (gold solute) are reported as follows ... 

Recent advances made in measuring particle charge and mobility in nonaqueous suspensions are reviewed. Microelectrophoretic techniques have been used to determine zeta potential and the measurements related to particle stability. 

All povidone types can be used as hydrophilic polymers to physically stabilize suspensions [39,119]. Their most important and primary function in all suspensions is as protective colloids, which hydrophilize the individual solid particles and sterically separate them. This increases the volume of any sediment and makes it easier to redisperse by shaking. Povidone also prevents the dissolved portion of the active substance from crystallizing out by forming soluble complexes with it [389] (see also Sections 2.2.7 and 2.4.5). The Zeta potential of many substances, e. g. iron oxide pigments, can also be reduced with povidone [421]. 

Biro EJ, Racz I. The role of zeta potential in the stability of albendazole suspensions. S T P Pharma Sci 1998 8 311-315. 

These forces and hence the stability of the dispersions can be altered/controlled by the adsorption of ions, surfactants, or polymers at the solid-liquid interface. Adsorption of surfactants and polymers at the solid-liquid interface depends on the nature of the surfactant or polymer, the solvent, and the substrate. Ionic surfactants adsorbing on oppositely charged surfaces exhibit a typical four-region isotherm. Such adsorption can alter the dispersion stability mainly by changing the double layer interaction, which depends on the extent of adsorption. Thus, it is seen that alumina suspensions are destabilized by the adsorption of SDS when the zeta potential is reduced to zero. At higher concentrations, bilayered surfactant adsorption can occur with changes in wettability and flocculation of the particles by altering the hydrophobic interactions. 

Stability of Suspensions with Relation to Zeta Potential... 

If the suspension is for parenteral administration, it will need to be sterilized. Terminal heat sterilization can affect both its chemical and physical stability, the latter usually observed as crystal growth or aggregation of the particles (Na et al. 1999). Another measure of suspension stability is the zeta potential, which is a measure of the surface charge. However, various... 

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