Determination of the l-DOPA/l-tyrosine ratio in human plasma by high-performance liquid chromatography: Usefulness as a marker in metastatic malignant melanoma

摘要: Abstract A first procedure was devised for determining 3,4-dihydroxyphenylalanine ( l -DOPA) in human plasma by isocratic RP-HPLC coupled with electrochemical detection. second 3-hydroxyphenylalanine -tyrosine) fluorescence These methods were used to ascertain the -DOPA/ -tyrosine ratio of patients melanoma. Reference values established analysis 35 normal healthy subjects. For 29 diagnosed as having melanoma without metastasis, (11.96×10−5±2.69×10−5) level not significantly different from that controls (11.20×10−5±2.92×10−5). However, this increased (p