Simple direct injection high-performance liquid chromatographic method to determine quinidine in plasma.

High-performance liquid chromatographic methods that use direct injection of plasma include column-switching procedures, modified mobile phases and small-pore modified stationary phases. By using a large-pore (300 A) Selectosil C18 column, developed for the analysis of macromolecules, we have shown that quinidine in plasma and protein solutions can be assayed accurately and rapidly by directly injecting 2 microliters plasma or protein solution onto the column. Column life is not reduced, and the limit of quantitation is 0.01 microM.