The disclosure relates to a reversed-phase chromatography method for the determination of at least one of glyphosate or AMPA in a sample. The method includes obtaining the sample comprising the at least one of glyphosate or AMPA in a sample matrix and introducing the sample to a reversed-phase chromatography system. The reversed-phase chromatography system includes a reversed-phase column having a stationary phase material contained inside the column. The stationary phase material includes a phenyl functional group. The method also includes flowing the sample with a mobile phase eluent through the reversed-phase column, wherein the at least one of glyphosate or AMPA is substantially resolved and retained. The mobile phase eluent has a pH between about 1.5 to about 2.5. The at least one of glyphosate or AMPA are detected using a detector.