Direct determination of theophylline in human serum by high-performance liquid chromatography using zwitterionic micellar mobile phase. Comparison with an enzyme multiplied immunoassay technique
Abstract
A liquid chromatographic procedure is reported for the direct determination of theophylline in human serum. It includes the use of a micellar zwitterionic mobile phase [10–3 mol l–1 3-(dimethyldodecylammonio)] propanesulfonate (also known as C12 DAPS)z–propanol (97 + 3, v/v) and a µBondapak phenyl column. Detection is based on ultraviolet absorption at a wavelength of 273 nm. After dilution with the mobile phase, the serum is injected into the chromatography; no solvent extraction or deproteinization is performed. The linearity of the method described was excellent over the range 0.5–20 mg l–1. The within-run precision was better than 2%, and the recovery of the theophylline approached 98%. Two hundred direct injections of serum samples did not affect the column life. The total analysis time, including chromatography, was approximately 15 min. As little as 0.5 mg l–1 of theophylline could be detected, and the results were in good agreement with those of an enzyme multiplied immunoassay technique.