Capillary gas chromatographic-mass spectrometric profiles of trimethylsilyl derivatives of organic acids from amniotic fluids of different gestational age.

Amniotic fluid from different gestational age patients was partitioned into neutral, acidic and basic fractions. The organic acids were trimethylsilylated and analyzed by glass capillary gas chromatography-mass spectrometry. A marked difference in the level of hippuric acid was observed between samples from early (15-22 weeks) and late (30-38.5 weeks) pregnancy. This difference probably reflects the degree of maturity in the fetal liver and kidney. The procedures establish amniotic fluid profiles of substances of varying gestational age and should be useful in determining alterations caused by diseases.