The lecithin-sphingomyelin ratio in amniotic fluid by thin layer chromatography: three areas of difficulty.
D000653:Amniotic Fluid / Q000032:analysis*; D002855:Chromatography, Thin Layer / Q000379:methods; D005260:Female; D005325:Fetal Organ Maturity; D006801:Humans; D008168:Lung / Q000196:embryology*; D010713:Phosphatidylcholines / Q000032:analysis*; D011247:Pregnancy; D013109:Sphingomyelins / Q000032:analysis*
D010713:Phosphatidylcholines; D013109:Sphingomyelins