The moment analysis of cyclic adenosine monophosphate (cAMP) was performed using chromatograms that were obtained with the pulse input method from an octadecyl silica (ODS) high-performance liquid chromatography (HPLC) column. The general rate (GR) model was employed to calculate the first absolute moment and the second central moment. Three important coefficients for moment analysis, which are molecular diffusivity (Dm), external mass transfer coefficient (kf), and intra-particle diffusivity (De), were estimated by the Wilke-Chang equation, Wilson-Geankoplis equation, and comparing van Deemter equation to theoretical plate number equation, respectively. Experiments were conducted by various conditions of flow rates, methanol volume ratio of the mobile phase, and solute concentration. After the moment analysis, results were organized by van Deemter plots. Also van Deemter coefficients were compared each other to effect Hax, Hf, and Hd on height equivalent to a theoretical plate (HETP, Htotal). The value of intraparticle diffusion (Hd) was the primary factor which makes for HETP whereas external mass transfer (Hf) was disregardable factor.