Content Determination of the Enantiomers of Formoterol Fumarate in Formoterol Fumarate Powder Inhaler by Chiral NACE

OBJECTIVE  To establish a chiral nonaqueous capillary electrophoresis(NACE) method, L(+)-tartaric acid–boric acid complex was used as the chiral selector for the chiral separation of formoterol fumarate(FMT·FUM) and determination of the enantiomers of FMT·FUM in FMT·FUM powder inhaler.

METHODS  An uncoated fused silica capillary(65 cm × 50 μm, 45.0 cm) was used as the separation channel, along with the applied voltage of 20 kV, detection wavelength of 214 nm, room temperature. The optimized background buffer was the methanol solution containing 40 mmol·L⁻¹ L(+)-tartaric acid, 400 mmol·L⁻¹ boric acid, and 0.4% triethylamine.

RESULTS  The two enantiomers of FMT·FUM could be completely separated under the optimized chiral separation conditions, and the Rs was 9.5. The migration order was the former RR-FMT·FUM and the later SS-FMT·FUM. Good linearity of the peak area for the two enantiomers were showed in the concentration range of 2.5–250.0 μg·mL⁻¹, respectively. The recoveries of RR-FMT·FUM and SS-FMT·FUM were 99.2%–101.8%, with relative standard deviations(RSDs) of 1.0%–1.9%, indicating good accuracy of the method. The percentage of labeled quantities were 98.5% and 99.1% for RR-FMT·FUM and SS-FMT·FUM, with RSDs of 1.3% and 1.5%, respectively.

CONCLUSION  The method is suitable for the determination of the enantiomer contents in FMT·FUM powder inhaler.