title: Specificity and reproducibility of acetone precipitation in identifying surface-active phosphatidylcholine in amniotic fluid.
abstract: We show the thoretical and actual variability in the amount of surface-active lecithin precipitated in the acetone-precipitation step of determining lecithin/sphingomyelin (L/S) ratios in the clinical laboratory. Lecithins precipitated may range from 60 to 90% of the total surface-active lecithins present. The range is sufficient to account for the occasional "immature" L/S ratios (less than 2/1) found in amniotic fluid from women bearing mature fetuses.
mesh_terms: D000096:Acetone; D000653:Amniotic Fluid / Q000032:analysis*; D000818:Animals; D011232:Chemical Precipitation; D005260:Female; D006801:Humans; D008722:Methods; D010713:Phosphatidylcholines / Q000032:analysis*; D011247:Pregnancy; D011650:Pulmonary Alveoli / Q000032:analysis; D011817:Rabbits; D013109:Sphingomyelins / Q000032:analysis
chemical_list: D010713:Phosphatidylcholines; D013109:Sphingomyelins; D000096:Acetone