Determination Of Dexamethasone In Plasma Research Articles

Determination of dexamethasone in plasma of premature neonates using high-performance liquid chromatography.

A high-performance liquid chromatographic assay is described for dexamethasone in neonatal plasma. Samples (100 microliters) were extracted with ethyl acetate (1.0 ml) containing 50 ng of beclomethasone. The mobile phase 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 microns particles). Detection was by UV absorbance at 240 nm. Calibration plots were linear (r2 > 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 quantifiable concentration (C.V. approximately 20%) was 15 ng/ml. Recovery (20-1000 ng/ml) exceeded 75%. Concomitant neonatal medication did not interfere.

Determination of Dexamethasone in Plasma by High-Performance Liquid Chromatography with Chemiluminescence Detection

Determination of Dexamethasone in Plasma by High-Performance Liquid Chromatography with Chemiluminescence Detection

A rapid and highly sensitive method for the quantitative determination of dexamethasone in plasma, synovial fluid and tissues by combined gas chromatography/negative ion chemical ionization mass spectrometry

A new, simple and highly sensitive assay is developed for the quantitative measurement of very low levels of dexamethasone in human plasma, synovial fluid and tissues following a topical administration of the drug. Dexamethasone and the internal standard, flumethasone, are measured by gas chromatography/negative ion chemical ionization mass spectrometry with methane as the reagent gas. After a three-step extraction procedure, the two compounds of interest are converted to their trimethylsilyl ether derivatives using trimethylsilylimidazole and formamide as the base catalyst. Under soft derivatization conditions only one chromatographic peak corresponding to the trisubstituted derivative is observed. The mass spectrometer is focused to monitor abundant and stable characteristic high-mass ions (m/z 446 and 464) which are generated in the ion source by an electron capture process. This assay requires only 1 ml of plasma or 0.5 ml of synovial fluid and the detection limit of the method is equal to 0.1 ng ml-1 with a relative standard deviation lower than 6%.