Determination of phosphatidylglycerol in amniotic fluid by a simple one-dimensional thin-layer chromatography method

Phosphatidylglycerol (PG) in amniotic fluid is the second important component of lung surfactant phospholipids and may be clinically useful in assessing fetal lung maturity in utero. Although methods for PG determination are available, there are shortcomings in clinical application. We developed an alternative reliable one-dimensional thin-layer chromatography(TLC) method for separating and quantitating PG in amniotic fluid. A mini-TLC plate (8 X 10 cm) was prepared from silica gel H containing 5% ammonium sulfate. The plate was first developed in tetrahydrofuron/dimethoxymethane/methanol/2N ammonium hydroxide (30.0:20.6:5.6:3.0 v/v) and then in chloroform/methanol (60.9, v/v) in the same direction. PG was clearly separated from other phospholipids and neutral lipids, even when large amounts of other phospholipids were present on the TLC plate. The density of the charred PG was directly proportional to the amount of PG up to 8 nmol. The content of PG in nmol in the specimen can be quantitated by comparing with a standard PG. Up to 10% of blood serum or 3% meconium showed no detectable PG, nor did these substances affect PG quantitation in amniotic fluid. This method is sensitive and accurate. It is also time-saving and economical.