Stability of Avermyctin Emulsion in Water

The preparation of avermyctin emulsions in water was achieved by mixing the surfactants polyoxyethylene (10) octylphenyl ether (OP10), polyoxyethylene styrenated phenol ether (602), and polyoxyethylene (40) castor oil ether (EL-40) with polyoxyethylene (20) castor oil ether (EL-20), separatively, Emulsion stability was investigated by analyzing the hydrophile-lipophile balance (HLB), critical micelle concentration (cmc), and surface tension. Then, the surfactants of polyoxyethylene polyoxypropylene styrenated phenol ether (1601), block copolymer (L64). and octyl phenyl polyoxyethylene phosphonatc (A) were added to the emulsion made by blending EL-40 and EL-20. separatively. The stability of the emulsions was investigated further and discussed in terms of droplet size, surface tension, and zeta potential. Results showed that the blend of EL-40 and EL-20 resulted in a relatively stable emulsion because of its lower surface tension. The addition of 1601 and L64 improved the stability of the emulsion to some extent, while A greatly enhanced the stability because it markedly decreased the droplet size and the surface tension while increased the zeta potential.