Simultaneous determination of phosphatidylglycerol and the lecithin/sphingomyelin ratio in amniotic fluid.

We describe a single-dimension thin-layer chromatographic method by which one can simultaneously determine the lecithin/sphingomyelin ratio and the proportion of phosphatidylglycerol in amniotic fluid. The phospholipids are conveniently detected by an improved molybdenum-blue spray reagent, which immediately produces blue spots on a white background. The stained phospholipids are stable for at least 90 min after spraying, and densitometry results in symmetrical peaks that are easily quantitated.