Using liquid chromatography (LC; often high-resolution liquid chromatography, HPLC) for sample clean-up and pre-separation seems an obvious way to improve analyses through greatly enhanced selectivity, lower detection limits, automation, reduced solvent consumption and improved quantitative results. The basic technology was developed between 1980 and 2000, but has been more widely applied in a routine manner only since about 2010, triggered by mineral oil analysis in food. Pre-separation liquid chromatography and the use of detectors for accurately determining the relevant fraction are well-established technologies, fast and more efficient than alternative methods. It was the transfer of large volumes of liquid to gas chromatography (GC), usually based on solvent effects and the retention gap technique, that challenged analysts. Particularly in the 1990s, numerous ideas, techniques and methods have been described, highlighting the potential, but so far little has become routine. This review deals with mainstream online LC-GC, but also with ideas considered interesting and perhaps worthwhile to follow up in further developments.