title: Determination of six pterins in urine by LC-MS/MS.
abstract: BACKGROUND
  The present work describes an analytical method for urinary pterins by LC-MS/MS, with emphasis on the separation of 6- and 7-positional isomers of bio- and neopterins.
  
  
  RESULTS
  Urine sample preparation consisted of oxidation by MnO(2), filtration and direct dilution in the mobile phase. The method was validated in urine spiked at five concentration levels with true triplicates of each level. Separation of the pterins, including the positional isomers, was achieved by employing a LUNA amino column. Six pterins were quantified (pterin, isoxanthopterin, 6-biopterin, 7-biopterin, 6-neopterin, 7-neopterin) and a linear behavior was observed; LOD varied from 7 to 360 pg/ml and correlation coefficients above 0.98 were obtained for all pterins. In addition, pterin levels were evaluated in 41 urine samples of healthy subjects, in ten urine samples of patients with classical phenylketonuria (PKU) and in one with atypical PKU.
  
  
  CONCLUSIONS
  The proposed method allowed to identify, separate and quantify six pterins in urine, using a simple and rapid sample preparation. The atypical PKU was unequivocally differentiated from the classical form, demonstrating that this method could be very useful for characterization and follow-up of diseases.
authors.affiliation: Laboratório de Erros Inatos do Metabolismo (LABEIM/LADETEC), Instituto de Química, Universidade Federal do Rio de Janeiro, Cidade Universitária Rio de Janeiro, Brasil. gabiallegri@yahoo.com.br
authors.forename: Gabriella
authors.initials: G
authors.lastname: Allegri
authors.forename: Heleno José Bezerra
authors.initials: HJ
authors.lastname: Costa Netto
authors.forename: Luiz Nelson Lopes
authors.initials: LN
authors.lastname: Ferreira Gomes
authors.forename: Maria Lúcia
authors.initials: ML
authors.lastname: Costa de Oliveira
authors.forename: Fernanda Bertão
authors.initials: FB
authors.lastname: Scalco
authors.forename: Francisco Radler
authors.initials: FR
authors.lastname: de Aquino Neto
mesh_terms: D001708:Biopterins / Q000031:analogs & derivatives / Q000652:urine; D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D007536:Isomerism; D057230:Limit of Detection; D019798:Neopterin / Q000652:urine; D010661:Phenylketonurias / Q000652:urine*; D011622:Pterins / Q000652:urine*; D053719:Tandem Mass Spectrometry / Q000379:methods*; D014976:Xanthopterin / Q000652:urine
chemical_list: D011622:Pterins; D001708:Biopterins; C056246:primapterin; C008217:isoxanthopterin; D019798:Neopterin; D014976:Xanthopterin