Phase separation temperatures of mixtures of Triton X-114 and Triton X-45: application to protein separation

Triton X-114 solutions separate above 22 degrees C into two immiscible aqueous phases. The more dense phase is enriched in detergent, and the less dense phase is depleted of detergent, relative to the original single phase. This phenomenon has been used to partition proteins according to hydrophobicity. The phase separation temperature is sensitive to the length of the polyoxyethylene headgroup. When Triton X-45, with a shorter headgroup, is mixed with Triton X-114 in various proportions, the phase transition temperature can be adjusted anywhere between 0 and 22 degrees C. Partitioning properties of the resulting mixtures are similar to those of Triton X-114 alone.