particle-size distribution - a measure of the distribution of the particles used to pack the LC column. In HPLC, a narrow particle-size distribution is desirable. A particle-size distribution of dp + 10% would mean that 90% of the particles fall between 9 and 11 Ám for an average 10-Ám dp packing.

See also particle size distribution.

partition - distribution phenomena of the sample between two immiscable liquid phases.

partition chromatography - separation process in which one of the liquid phases is held stationary on a solid support while the other is allowed to flow freely down the column. Solutes partition themselves between the two phases based on their individual partition coefficients. Liquid-liquid chromatography is an example.

partition coeficient (K) - quantitative expression of the partition equilibrium; usually expressed as the ratio of concentration of the sample in the stationary liquid phase and the mobile phase in liquid-liquid chromatography.