Physicochemical fundamentals of two new chromatographic methods—the liquid-gas (LGC) and the liquid-gas-solid chromatography (LGSC) are stated. The mechanism of the stationary gas phase retention in the pores of hydrophobic supports is explained and practical results of the effect obtained are considered. Examples of the LGC and LGSC application for preconcentration of gases and volatile organic compounds dissolved in water are discussed. These methods have substantial advantages in comparison with the common head-space analysis.