The scope of the mass spectrometry approach of this study was to detect the presence or absence of bL19, bL 19-EGFP, bS20 and bS20-mCherry protein in 70S ribosome preparation from E. coli MC4100 or E. coli reporter strain (RN31). Therefore, in-gel digestion and nanoUPLC-ESI-Orbitrap-MS/MS were used.