Allantoin Allantoin is 2,5-dioxo-4-imidazolidinyl-urea that occurs naturally in plants and animals. A high-performance liquid chromatography (HPLC) method for the quantitative analysis of allantoin has been developed. Separation of allantoin from crude extract of leaves, stem and roots of Pisonia grandis was achieved using C18 column as a stationary phase and acetonitrile: phosphate buffer solution as mobile phase at a flow rate of 1 ml/min. Photo diode array detector (PDA) response was maximum at 200 nm. The calibration curve was linear in the range of 0.25 to 1.25 mg/ml. Limit of detection and limit of quantification values of allantoin were 0.435 and 1.65 mg respectively. Quantitation of allantoin in the plant extracts could be easily achieved by the proposed method with satisfactory results.