Abstract: System for analyzing a protein sample, comprising a reactor vessel, a chromatographic column, a mass spectrometer, and a computer system. The reactor vessel comprises an enzyme activity capable of digesting the protein sample in order to provide a plurality of peptide digests, an inlet port for receiving the protein to be digested, and an exit port for discharging the peptide digests. The chromatographic column comprises a chromatographic medium capable of chromatographically fractionating the peptide digests as the peptide digests are eluted through the column, wherein the chromatographic column comprises an inlet port for receiving the peptide digests, said inlet port being in flow communication with the exit port of the reactor vessel, and wherein the chromatographic column comprises an exit port for discharging an effluent comprising the chromatographically fractionated peptide digests.