Gas chromatographic determination with flash methylation of palmitic acid in amniotic fluid in prediction of fetal lung maturity.

A new method for determination of palmitic acid in amniotic fluid was developed. The dipalmitoyl lecithin was hydrolysed, and after extraction the palmitic acid was flash methylated in the injector of the gas chromatograph. The between batch coefficient of variation was 6.0% at 40 and 70 mumol/l of palmitic acid concentrations in 500 microliters amniotic fluid. The accuracy of the method was demonstrated by linearity, recovery and correlation studies. The correlation coefficient was 0.98 between the new and bortrifluoride methylating method. The concentrations of lecithin and palmitic acid in amniotic fluid showed a correlation coefficient of 0.97. If the concentration of palmitic acid falls below 80 mumol/l respiration distress syndrome is likely. The new method was simple and easy to carry out and could be adjusted for haemoglobin contamination of the amniotic fluid. It was concluded that the determination of palmitic acid in amniotic fluid was a reliable method for the assessment of fetal lung maturity that could replace the determination of lecithin concentration.