Simultaneous LC-MS/MS determination of phenylbutyrate, phenylacetate benzoate and their corresponding metabolites phenylacetylglutamine and hippurate in blood and urine.
Inborn errors of urea metabolism result in hyperammonemia. Treatment of urea cycle disorders can effectively lower plasma ammonium levels and results in survival in the majority of patients. Available medications for treating urea cycle disorders include sodium benzoate (BA), sodium phenylacetate (PAA), and sodium phenylbutyrate (PBA) and are given to provide alternate routes for disposition of waste nitrogen excretion. In this study, we develop and validate a liquid chromatography tandem mass spectrometry (LC-MS/MS) method for simultaneous determination of benzoic acid, phenylacetic acid, phenylbutyric acid, phenylacetylglutamine, and hippuric acid in plasma and urine from children with inborn errors of urea synthesis. Plasma extracts and diluted urine samples were injected on a reverse-phase column and identified and quantified by selected reaction monitoring (SRM) in negative ion mode. Deuterated analogues served as internal standards. Analysis time was 7 min. Assay precision, accuracy, and linearity and sample stability were determined using enriched samples. Quantification limits of the method were 100 ng/ml (0.3-0.8 μmol/L) for all analytes, and recoveries were >90%. Inter- and intraday relative standard deviations were <10%. Our newly developed LC-MS/MS represents a robust, sensitive, and rapid method that allows simultaneous determination of the five compounds in plasma and urine.
Laryea
Maurice D
MD
Department of General Pediatrics, University Children's Hospital, Heinrich-Heine-University, Moorenstraße 5, 40225 Düsseldorf, Germany. Laryea@med.uni-duesseldorf.de
Herebian
Diran
D
Meissner
Thomas
T
Mayatepek
Ertan
E
D001565:Benzoates / Q000097:blood / Q000627:therapeutic use / Q000652:urine; D015415:Biomarkers / Q000097:blood / Q000652:urine; D001711:Biotransformation; D002138:Calibration; D056148:Chromatography, Reverse-Phase / Q000592:standards; D005973:Glutamine / Q000031:analogs & derivatives* / Q000097:blood / Q000652:urine; D006626:Hippurates / Q000097:blood / Q000652:urine; D006801:Humans; D022124:Hyperammonemia / Q000097:blood / Q000188:drug therapy / Q000652:urine; D057230:Limit of Detection; D016014:Linear Models; D010648:Phenylacetates / Q000097:blood / Q000627:therapeutic use / Q000652:urine; D010654:Phenylbutyrates / Q000097:blood / Q000627:therapeutic use / Q000652:urine; D011237:Predictive Value of Tests; D012015:Reference Standards; D015203:Reproducibility of Results; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry / Q000592:standards; D056806:Urea Cycle Disorders, Inborn / Q000097:blood / Q000188:drug therapy / Q000652:urine
D001565:Benzoates; D015415:Biomarkers; D006626:Hippurates; D010648:Phenylacetates; D010654:Phenylbutyrates; D005973:Glutamine; C003089:phenylacetylglutamine; C025136:phenylacetic acid; C030514:hippuric acid