Marta Zeisbergerová

This study deals with the nonaqueous capillary electrophoretic separation of dextromethorphan and its metabolites using a methanolic background electrolyte. The optimization of separation conditions was performed in terms of the resolution of dextromethorphan and dextrorphan and the effect of separation temperature, voltage, and the characteristics of the background electrolyte were studied. Complete separation of all analytes was achieved in 40 mM ammonium acetate dissolved in methanol. Hydrodynamic injection was performed at 3 kPa for 4 s. The separation voltage was 20 kV accompanied by a low electric current. The ultraviolet detection was performed at 214 nm, the temperature of the capillary was 25°C. These conditions enabled the separation of four analytes plus the internal standard within 9 min. Further, the developed method was validated in terms of linearity, sensitivity, and repeatability. Rat liver perfusate samples were subjected to the nonaqueous capillary electrophoretic method to illustrate its applicability.

This study presents the in‐capillary enzymatic biotransformation of dextromethorphan, an antitusive drug and opioid receptor antagonist, and subsequent electrophoretic separation of its products. The study includes the optimization of separation parameters to fulfill the requirements of an online microreaction. The analyses were performed in a bare fused‐silica capillary using 100 mM sodium tetraborate (pH 10.0) mixed with linear polyacrylamide (20%, v/v) and 2‐propanol (10%, v/v). This BGE was suitable for monitoring both off‐line and in‐capillary incubations. The partial filling technique enabled the enzymatic reaction to be carried out in its optimal environment (20 mM sodium phosphate, pH 7.4). Finally, in‐capillary microreaction in the presence of cytochrome P450 3A4 gave satisfactory outcomes.