Why is the most common LC technque called Reversed-phase?
It’s a matter of historical accident. The original “chromatography” described by Tswett at the beginning of the 20th century used powdered chalk (calcium carbonate; a polar adsorbent) as the stationary phase and ligroin (“petroleum ether; a non-polar hydrocarbon solvent) as the mobile phase. The relative polarities of the phases (stationary phase = polar; mobile phase = non-polar) was considered an integral part of the technique. Later, stationary phases composed of diatomaceous earth impregnated with mineral oil were combined with mobile phases consisting of mixtures of water and alcohols were tried with some success. Because the relative polarities of the two phases had been reversed (stationary phase = non-polar; mobile phase = polar), this variation was dubbed — you guessed it — “reversed phase” chromatography. The original approach then came to be called “normal-phase” chromatography With the advent of HPLC in the late 1960’s, reversed-phase was found to be the more versatile of
