Determination of Phenylalanine and Tyrosine by Liquid Chromatography/Mass Spectrometry

Abstract

Phenylketonuria is a common metabolic disorder disease. Those affected appear normal at birth, but without treatment they develop severe psychomotor retardation. Throughout life, they must control their blood levels of phenylalanine (Phe) and consume a diet containing adequate amounts of Phe and tyrosine (Tyr). We have developed a liquid chromatographic/mass spectrometric (LC/MS) method for the quantitative evaluation of Phe and Tyr in food samples. This method takes advantage of the good separation of LC and the selective and reliable quantification provided by MS in the electrospray ionization mode. The LC/MS method is very suitable for the determination of selected amino acids in various matrixes. It is sensitive to levels as low as about 0.30 ppm for Tyr and 0.70 ppm for Phe and robust. Nearly 100 nondietary food samples were analyzed by the developed method.

Tunable Coffee Ring Formation on Polycarbonate Nanofiber Film for Sensitive SERS Detection of Phenylalanine in Urine

“…Comparing with the literature reported methods, our developed method is competitive as the reported detection limits are in the range of 0.1–15 μM. 47−52 For instance, separation techniques combined with mass detection showed a detection limit within 1–6 μM 49,50 and SERS methods gave a detection limit around 10 μM. 47,48…”

“…This detection limit indicates that our developed method improves the sensitivity in SERS detection by controlling the formation of coffee rings. Comparing with the literature reported methods, our developed method is competitive as the reported detection limits are in the range of 0.1–15 μM. − For instance, separation techniques combined with mass detection showed a detection limit within 1–6 μM , and SERS methods gave a detection limit around 10 μM. , …”

Surface Plasmon Resonance Based on Molecularly Imprinted Polymeric Film for l-Phenylalanine Detection

“…For that reason, the desired PKU levels in the plasma is 21–137 μM for infants and children and 35–85 μM for adults [ 11 , 12 ]. For the diagnosis of PKU disease, phenylalanine, known as an indicator substance in the diagnosis of PKU disease, has different methods, including the amount of plasma determining Guthrie test, microbial inhibition, fluorimetric, chromatography and mass spectrometry [ 13 , 14 , 15 , 16 ]. However, these methods are time consuming and expensive, insufficient sensitivity, complex instrumentation, special laboratory facilities and highly experienced labor force requirements limit their use in routine analysis.…”