A high-performance liquid chromatography method for the determination of seventeen free proteinogenic amino acids (FPAA) in soil solutions is described. Sample preparation involves obtaining soil solution and pre-column derivatization of free amino acids using phenyl isothiocyanate. Phenyl thiocarbamyl derivatives are separated on a reversed-phase column by using linear gradient elution with 140 mM sodium acetate buffer solution (pH 6.0) contained 0.05% triethylamine as mobile phase A and acetonitrile-water (60:40,v/v) as mobile phase B. The described method showed adequate linearity, recovery values, limits of detection, and suitable for the determination of FPAA in soil solutions.