Purified therapeutic nanoparticles are provided herein. Such nanoparticles comprise an active pharmaceutical ingredient and human serum albumin, wherein the weight ratio of human serum albumin to the active ingredient in the therapeutic nanoparticles is from 0.01:1 to 1:1, and wherein the nanoparticles are substantially free of free human serum albumin that is not incorporated in the nanoparticles. The present disclosure also provides pharmaceutical compositions that comprise the purified therapeutic nanoparticles and are also substantially free of free human serum albumin. Methods for preparing and using the purified therapeutic nanoparticles and compositions thereof are also provided.