Brompheniramine as a novel probe for indirect UV detection and its application for the capillary electrophoresis of adamantane drugs

Brompheniramine, an antihistamine drug, was employed as a novel UV probe for capillary electrophoresis with indirect UV detection of adamantane drugs (memantine, amantadine, and rimantadine). The probe possesses high molar absorptivity of 24 × 10³ L/mol cm at 6 mM, which enables the measurement of these nonchromophore analytes without derivatization. The simple background electrolyte (10 mM sodium dihydrogen phosphate (pH 5.0) containing 5 mM brompheniramine and 6 mM β-cyclodextrin) provided the separation of the analytes in a short time (7.5 min). Under these conditions, brompheniramine had similar mobility to that of the analyte ions resulting in symmetric peaks with minimal electrodispersion. The analytes displace the probe at a one-to-one ratio with transfer values close to unity. β-Cyclodextrin played a role in the resolution of the structurally similar adamantane derivatives. Method validation showed good linearity (r² > 0.98), precision (%RSD ≤ 3.30), and accuracy (recoveries ranging from 98 to 109%). The proposed method was successfully applied to determine the adamantane content in pharmaceutical products.