The contact angle of a solution is related to the adsorbed masses at contact points of three different interfaces through Lucassen-Reynders's relation. The direct use of this relation is restricted by the difficulty of measurement of adsorbed mass at the solid-vapor and vapor-liquid interfaces. We have extended the Lucassen-Reynders's relation to show that adsorbed masses are related linearly with the wetting effect, which is defined as the difference of wetting tensions of solution and solvent. The wetting effects are determined from the measured contact angle of aqueous solution of poly(oxyethylene), poly[1-(2-oxopyrrolidin-1-yl)ethylene], poly(sodium 4-styrene sulfonate), poly(acrylic acid), albumin, and fibrinogen on various self-assembled surfaces and surface tension of solutions. The extended Lucassen-Reynders's relation is verified using the experimentally determined wetting effect and adsorbed mass of polymers and proteins determined using a quartz crystal microbalance (QCM). The reasonable value of the determined adsorbed mass on liquid-vapor and solid-vapor interfaces indicates the applicability of our methodology.