An oil-in-water propofol emulsion that contains soybean oil and egg lecithin, which provide a source of nutrition for microorganisms. Current products include additives to act as a microbial growth retardation agent, the processes described herein detail several methods for the optimization of the innate microbial retardation capability of propofol. Using this process improves the safety of a propofol emulsion solution by controlling microbial growth without the side effects associated with growth retardation additives.