Used to measure the activity of phenylalanine ammonia-lyase (PAL) in human biological samples such as serum, plasma, or tissue extracts. This assay is commonly applied in research settings to study metabolic disorders related to phenylalanine metabolism, including phenylketonuria (PKU). It helps evaluate enzyme function, monitor disease progression, and assess the effectiveness of therapeutic interventions like enzyme replacement therapy. The kit enables high-throughput, quantitative analysis in clinical laboratories and pharmaceutical research.