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 Å) 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 μl plasma or protein solution onto the column. Column life is not reduced, and the limit of quantitation is 0.01 μM.