Solvation dynamics of 2,6-p-toluidinonaphthalene sulfonate (TNS) is studied in an aggregate containing human serum albumin (HSA) and sodium dodecyl sulfate (SDS). Solvation dynamics of TNS bound to HSA displays two components, 90 and 4000 ps. When SDS binds to HSA the solvation dynamics becomes faster and a significant portion is missed in a picosecond setup. This is attributed to the displacement of the bound water molecules by SDS in the immediate vicinity of TNS in the HSA-SDS aggregate. (C) 2003 Elsevier B.V. All rights reserved.