A method for determination of lecithin/sphingomyelin ratio in amniotic fluid

A method is described for the evaluation of amniotic fluid lecithin/sphingomyelin (L/S) ratios. The acetone precipitation step is eliminated, resulting in higher concentrations of phospholipids. Silica gel-impregnated glass fiber papers are used for rapid chromatography. For spot detection, a bismuth reagent is used which is specific for lecithin and sphingomyelin. The method is simple, inexpensive, rapid and a reliable indicator of the L/S ratio, and useful in laboratories that are not equipped with a densitometer.