Determination of Pharmacologically Active Nitrogen-Containing Compounds on Silica Doubly Modified with 6,10-Ionene and Dextran Sulphate by High-Performance Liquid Chromatography–Tandem Mass Spectrometry

Abstract

An adsorbent for HPLC, silica doubly layer-by-layer modified with 6,10-ionene and dextran sulfate, is obtained. The adsorbent has both hydrophobic and hydrophilic and ion-exchange properties (because of the presence of hydrophobic anions and cations on the surface). A possibility of using the obtained adsorbent in HPLC with tandem mass spectrometric detection is shown. The conditions for the separation of caffeine, paracetamol, doxylamine, and chlorpheniramine in the isocratic mode are selected in elution with mixtures of acetonitrile and an acetate buffer solution. The most successful results are achieved by eluting the separated substances with the mobile phase acetonitrile–15 mM acetate buffer solution (glacial acetic acid/ammonium acetate with pH 5.55 in the ratio 10 : 90, vol). Gradient elution conditions are selected, a methodology is developed for determining traces of pharmaceuticals in human serum in the multiple reaction monitoring (MRM) mode using the internal standard method. The source and MRM transition parameters are selected individually for each compound. The linear range of the calibration curve for paracetamol and caffeine is 0.5–200 ng/mL and for doxylamine and chlorpheniramine, 0.05–50 ng/mL. The concentration of pharmacologically active compounds of caffeine, paracetamol, doxylamine, and chlorpheniramine in the blood serum of patients taking appropriate drugs is 165.2, 17.3, 10.2, and 35.3 ng/mL, respectively.