Stable isotope dilution analysis of orotic acid and uracil in amniotic fluid

Cornelis Jakobs, Lawrence Sweetman, William L. Nyhan, Larry Gruenke, J. Cymerman Craig, Sybe K. Wadman

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


Rapid, sensitive and accurate stable isotope dilution assays were developed for the measurement of orotic acid and uracil in amniotic fluid. The method utilizes [15N2]orotic acid and [15N2]uracil as internal standards, isolation by liquid partition chromatography and quantitation by chemical ionization selected ion monitoring gas chromatography-mass spectrometry. Orotic acid at a concentration of 0.26 ± 0.05 μmol/1 and uracil at a concentration of 0.55 ± 0.13 μmol/l were detectable in normal amniotic fluid. As affected fetuses with argininosuccinate synthetase or ornithine carbamoyl transferase deficiency showed no significant elevation of orotic acid and/or uracil in their surrounding amniotic fluids, this method unfortunately seemed not to be useful for prenatal diagnosis of these inherited disorders. Nevertheless, it provides significant advantage over available methods for the quantitation of orotic acid and uracil in which the analysis of these compounds must be very accurate, highly specific and sensitive (e.g. detection of heterozygosity for omithine carbamoyl transferase deficiency).

Original languageEnglish (US)
Pages (from-to)123-133
Number of pages11
JournalClinica Chimica Acta
Issue number2
StatePublished - Nov 15 1984
Externally publishedYes


  • Amniotic fluid
  • Orotic acid
  • Prenatal diagnosis
  • Stable isotope dilution
  • Uracil
  • Urea cycle disorders

ASJC Scopus subject areas

  • Biochemistry
  • Clinical Biochemistry
  • Biochemistry, medical


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