Glyphosate and glufosinate are active ingredients in widely used foliar herbisides. When degraded in soil and water, glyphosate produces aminomethylphosphonic acid (AMPA) as a metabolite. Glyphosate, glufosinate and AMPA are all highly polar compounds, making retention in the reversed-phase mode with HPLC or LC-MS difficult. Therefore, analysis usually employs derivatization using FMOC. This article introduces a method for a high-sensitivity measurement of glyphosate, glufosinate and AMPA that does not require complex pretreatment or time-consuming derivatization. Featuring very simple pretreatment procedures comprising only filtering and dilution, the method obtained favorable recovery factors with actual samples.