Determining an active ingredient’s solubility in various solvents and determining which solvent classes work well for it is critical in first determining the type of formulation that can be used. The solubility level of the active ingredient must also be determined for each solvent tested by determining the maximum weight percentage of active ingredient that can be solubilized. Because solubility is also dependent upon temperature and agitation, the solubility of an active ingredient must be determined at room temperature, elevated temperatures such as 40°C and refrigerated temperatures such as 4°C with vigorous mixing.
Automation can help by quickly determining the solubility of active ingredients in various solvents. Hamilton’s graphical software can be easily used to set up active concentration gradients in various solvents for preparation in tubes or wells of SBS formatted plates. The software not only allows for automated liquid transferring, but capping/decapping options and labware transports to temperature-controlled shaking devices for continuous mixing over a specified period of time.
Although quantitative methodologies can also be used for determining solubility, Hamilton’s automated solution can incorporate a CCD camera channel that captures images of each tube or well, providing the ability to quickly determine solubility with a much less costly and time-consuming qualitative approach.