Determination of azelaic and sorbic acid in pharmaceuticals by capillary electrophoresis

Capillary electrophoresis with indirect UV detection at 254 nm was applied to simultaneous determination of approximate to20% of azelaic acid and approximate to0.1% of sorbic acid in AKNOREN cream. The acids were separated in fused silica capillary (45 cm x 50 mum) at 30 W Optimised background electrolyte was 30 mM benzoate buffer (pH approximate to 6, adjusted with TRIS) containing 7 mM beta-cyclodextrin and 5% of methanol; internal standard was 2-hydroxyisobutyric acid (HIBA). Rectilinear calibration ranges were 0.4-4 mg mL(-1) for azelaic acid and 2-20 mug mL(-1) for sorbic acid and the recoveries were 972-100.5%. A single analysis took <15 min.