Inconsiderationoftheadsorptionofsolvent,diluentandsolutemoleculesonthesurfaceofastationaryphase,anewequationforsoluteretentioninliquidchromatographyispresented.Thisequationincludesthreeparameters:thedisplacementequilibriumconstant(Ksd)betweenthesolventanddiluentmoleculesonthesurfaceofthestationaryphase,thetotalnumber(N)ofthesolventanddiluentmoleculesreleasedfromthestationaryphaseafteronesolutemoleculebeingadsorbed,andtheparameter(I)relatedtothethermodynamicequilibriumconstantforthesoluteadsorptiononthestationaryphase.Overthewholeconcentrationrangeofthesolventinthemobilephase,theexperimentalretentiondatacanbewelldescribedbythisequation,parametersKsd,NandIcanbeobtainedbytheregressionanalysisoftheexperimentalretentiondata,andconsequentlythenumberofthesolventandthediluentmoleculesdisplacedbyonesolutemoleculefromthestationaryphasecanalsobederivedatdifferentsolventconcentrationsinthemobilephase.