Removal of a component interfering with phosphatidylglycerol estimation in the "Helena" system for amniotic fluid...

A simple " prechromatography " step removes a component of amniotic fluid ("pseudo PG") that otherwise co-chromatographs with phosphatidylglycerol in the system for amniotic fluid analysis developed by Touchstone et al. (Lipids 15: 61-62, 1980) and incorporated into the Helena "Fetal-Tek" kit. The final positions of the major phospholipids are practically unchanged but the faster migrating, more neutral components are swept into a tight band near the solvent front, providing improved general resolution. The resulting change in the ratio of "phosphatidylglycerol" to sphingomyelin ("PG"/S) is as much as 0.5 for some specimens, but no change is seen for others. In 20% of the 73 cases examined, including four of the six fluids associated with respiratory distress syndrome, the PG initially reported was found to be "pseudo PG" and was completely removed by the prechromatography step. This step produces a negligible decrease in the lecithin to sphingomyelin (L/S) ratio in amniotic fluid.