An enzymic radiochemical method for determining phosphatidylglycerol in amniotic fluid

We describe an enzymic quantification of phosphatidylglycerol in amniotic fluid. Phosphatidylglycerol is hydrolyzed in alkali and the resulting glycerol is then enzymatically phosphorylated with adenosine 5'-[gamma-32P]triphosphate to yield glycero[32P]phosphate. After removal of excess [gamma-32P]ATP by charcoal, the radioactivity of the glycerophosphate is measured in a liquid scintillation counter. Triglyceride in the amniotic fluid is hydrolyzed by lipase before extraction and thus does not interfere with the analysis. This method is specific for phosphatidylglycerol. Preliminary studies suggest that a phosphatidylglycerol value greater than or equal to 10 nmol/mL correlates with fetal lung maturity.