Improved one-dimensional thin-layer chromatography of phospholipids in amniotic fluid.

With this extraction procedure and chromatographic method, six amniotic fluid phospholipids [phosphatidylcholine (lecithin), sphingomyelin, phosphatidylinositol, phosphatidylserine, phosphatidylethanolamine, and phosphatidylglycerol] are completely resolved in less than 70 min from the time the specimen is received. The mobile phase (chloroform/petroleum ether/methanol/acetic acid, 5/3/1.6/1, by vol) is used with commercially available 7.5 X 10 cm silica-gel plates. The phospholipids are made visible by immersing the plate in cupric acetate/phosphoric acid. Lecithin/sphingomyelin (L/S) ratios are determined densitometrically. Rf values are well reproducible for both samples and standards, as are L/S ratios, and the method is simple and inexpensive. The relation between L/S ratios (for 100 specimens of amniotic fluid measured by this method) and fetal status is consistent with other reports. We confirm phosphatidylglycerol to be a sensitive indicator of fetal lung maturity: when it was detectable in amniotic fluid, the newborn invariably showed no symptoms of the respiratory distress syndrome.