Chiral separation of dioxopromethazine in eye drops by CZE with charged cyclodextrin.

Capillary zone electrophoresis (CZE) with carboxyethyl-beta-cyclodextrin (CE-beta-CD) dissolved in the operating buffer was used for the separation and determination of enantiomers of phenothiazine antihistaminic, dioxopromethazine, in commercial pharmaceutical preparation, eye drops. This chiral selector, negatively charged under given separating conditions (20 mmol/l epsilon -aminocaproic acid, acetic acid, pH 4.5), was effective in enantioresolution of the antihistamine even at its low concentrations (3-6 mg/ml) in the buffer solution. CZE identification and quantitation of the relevant constituents present in the preparation (dioxopromethazine enantiomers, phenylephrine) were based on the response of photometric absorbency detector, operating at a 275 nm detection wavelength. Changes in pH, type and concentration of chiral selector were studied in relation to chiral resolution. Acceptable validation criteria for sensitivity, precision, linearity and repeatability are included.