This test method involves chemically modifying tryptophan to form stable, UV- or fluorescence-detectable derivatives before chromatographic separation. Because tryptophan is sensitive to acid hydrolysis, alkaline hydrolysis is commonly used to release tryptophan without degradation. The derivatized tryptophan is then separated on a reversed-phase UPLC column and detected using UV or fluorescence detectors. This method allows accurate and sensitive quantification of tryptophan in a variety of sample types.