title: Simultaneous determination of phenylalanine and tyrosine in peripheral capillary blood by HPLC with ultraviolet detection.
abstract: OBJECTIVE
  Phenylalanine (Phe) and tyrosine (Tyr) are the most reliable indicators for the diagnosis of phenylketonuria (PKU). The purpose of this study is to establish a simple and rapid method for the determination of Phe and Tyr in peripheral capillary blood from newborns and children by high performance liquid chromatography with ultraviolet detection (HPLC-UV).
  
  
  METHODS
  Peripheral blood specimens were taken from newborns or children by heel stick or skin puncture on the fingers. Blood samples were deproteinized by equal volume of 5% perchloric acid. Amino acid separation was carried out on a Hypersil C8 column. The mobile phase containing 5% acetonitrile (v/v) was run at a flow rate of 1.5 mL/min. Phe and Tyr were determined in the ultraviolet detector at 210 nm.
  
  
  RESULTS
  The determination was within 10.0 min. The linear range was from 6.0 to 1512.0 μmol/L for Phe and 5.5 to 1250.0 μmol/L for Tyr. Although Phe and Tyr levels from peripheral blood samples were relatively lower than those from serum or plasma, the data showed a good agreement between them.
  
  
  CONCLUSIONS
  The method we developed is simple, rapid and convenient. It is useful for screening and diagnosis of PKU in newborns and children.
authors.affiliation: Department of Clinical Laboratory, The Second Xiangya Hospital, Central South University, Changsha, 410011, Hunan, PR China.
authors.forename: Xi-Ming
authors.initials: XM
authors.lastname: Mo
authors.affiliation: Department of Clinical Laboratory, The Second Xiangya Hospital, Central South University, Changsha, 410011, Hunan, PR China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Clinical Laboratory, The Second Xiangya Hospital, Central South University, Changsha, 410011, Hunan, PR China. Electronic address: aiguotang@yahoo.com.cn.
authors.forename: Ai-Guo
authors.initials: AG
authors.lastname: Tang
authors.affiliation: Department of Clinical Laboratory, The Second Xiangya Hospital, Central South University, Changsha, 410011, Hunan, PR China.
authors.forename: Ya-Ping
authors.initials: YP
authors.lastname: Ren
mesh_terms: D000925:Anticoagulants / Q000494:pharmacology; D002138:Calibration; D002648:Child; D002675:Child, Preschool; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D005260:Female; D006262:Health; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D010649:Phenylalanine / Q000097:blood*; D012015:Reference Standards; D013696:Temperature; D013997:Time Factors; D014443:Tyrosine / Q000097:blood*; D014466:Ultraviolet Rays
chemical_list: D000925:Anticoagulants; D014443:Tyrosine; D010649:Phenylalanine
keywords: High performance liquid chromatography; Phenylalanine; Phenylketonuria; Tyrosine; Ultraviolet detection