High-performance thin-layer chromatographic determination of theophylline in plasma

A high-performance thin-layer chromatographic method for quantification of theophylline from plasma is described. The calibration curves of theophylline in methanol and in plasma were linear in the range 20-100 ng. The correlation coefficients were 0.9971+/-0.0011 and 0.9955+/-0.0003 for standard curves in methanol and in plasma, respectively. The limit of quantitation of theophylline in human plasma (assay sensitivity) was 20 ng and no interference from endogenous compounds was observed. The recovery of theophylline from human plasma using the described assay procedure was 89%. The mean relative standard deviations for intra- and inter-day analyses were 1.67% and 2.34% for 50 ng and 2.25% and 3.14% for 75 ng theophylline concentration, respectively. The method was utilized to monitor plasma concentration of theophylline post-administration of sustained release tablets in human patient volunteers.