A nonaqueous reversed phase liquid chromatography mass spectrometry (LC-MS) method has been developed for extremely hydrophobic MPCs (monolayer-protected dusters), and has been applied to the efficient separation of gold-dodecanethiolate (ddt) assemblies, leading to the identification of three dodecanethiolate-protected gold dusters, Au-130(ddt)(50), Au-137(ddt)56, and Au-144,(ddt)(60), as prominent components of a commercial product of nominally 2 nm (core-diameter) protected gold nanopartides obtained from nano-Composix, Inc. Various components were separated, according to hydrophobic character, using a linear gradient of methanol dichloromethane mobile phases, on a C-18 HPLC column. Varying concentrations of mobile-phase modifier (triethylammonium acetate) were compared for effect on chromatographic peak shape and duster retention. Positive electrospray ionization (ESI) was used to ionize all components in the sample. LC separation prior to inline + ESI-MS detection facilitated sample analysis via production of simplified mass spectra for each eluting duster species and provided insight into the relative polarity of the dusters shown here. UV vis detection facilitated method development and allowed determination of nonionizing, and/or polydisperse components.