DETERMINATION OF DEXAMETHASONE IN PLASMA OF PREMATURE NEONATES USING HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

A high-performance liquid chromatographic assay is described for dexam ethasone in neonatal plasma. Samples (100 mu l) were extracted with et hyl acetate (1.0 ml) containing 50 ng of beclomethasone. The mobile ph ase of acetonitrile-0.01 M phosphate buffer (pH 7.0) (45:55, v/v) was pumped at a flow-rate of 1.0 ml/min through an Ultrasphere ODS column (5.0 mu m particles). Detection was by UV absorbance at 240 nm. Calibr ation plots were linear (r(2) > 0.999) from 10-1000 ng/ml. Within-day and between-day precision (C.V.%, coefficient of variation) between 15 -900 ng/ml was 1.21-20.6%. Inaccuracy was 7.7%, or less. The minimum q uantifiable concentration (C.V. approximate to 20%) was 15 ng/ml. Reco very (20-1000 ng/ml) exceeded 75%. Concomitant neonatal medication did not interfere.