The first research papers on gas-liquid chromatography were published in 1950. Chemists used different detectors to see that compounds were flowing out of the end of the chromatograph. Most of the detectors destroyed the compounds, because they burned them or ioned them. These detectors left chemists guessing the exact identity of each compound in the sample. In the 1950s, Roland Gohlke and Fred McLafferty developed a new combined machine. They used a mass spectrometer as the detector in gas chromatography. These early devices were big, fragile, and originally limited to laboratory settings.