The MS dataset was acquired to demonstrate that our new approach to measuring condensate composition is not limited to systems containing at most two chemically distinct solutes. We determined the composition of condensates containing poly(A)-RNA together with several protein species, quantifying the absolute (molar) amounts of these species with mass spectrometry. The dataset includes raw LC-MS/MS spectra in .raw format (ThermoFisherScientific). The details of sample preparation, mass spectrometric analysis and absolute quantification procedure using chimeric protein standard are described in the Materials&Methods and SI of the manuscript (doi.org/10.1038/s41557-025-01928-3). Structure of the file names: each file name "pAB-C_D" comprises the code of the related experiment pAB (gel lanes 2-9), analyzed gel lane region C (1-3) (see Extended Data Fig. 7 for details), and the sample replicate number D.