Analysis of theophylline by automated multidimensional high-performance liquid chromatography involving direct plasma...

A procedure of direct injection of whole plasma for the analysis of theophylline by an automated multidimensional high-performance liquid chromatographic (HPLC) technique is described. The procedure requires as little as 30 microliters of plasma sample and has a linear range of 0.25-30 micrograms/ml. Unknown plasma samples, after the addition of internal standard, are directly injected into the HPLC system. The chromatographic procedure is fully automated, thus the attention and time required from the analyst is reduced to a minimum. About 70 samples can be analyzed per day with approximately 3 hr of analyst time.