Stability-indicating micellar electrokinetic chromatography technique for simultaneous measurement of delapril and manidipine from a combination drug formulation.

A stability-indicating micellar electrokinetic chromatography (MEKC) method was developed and validated for simultaneous analysis of delapril (DEL) and manidipine (MAN) using salicylic acid as an internal standard. The MEKC method was performed using a fused-silica capillary (effective length of 72 cm) with 50 mM of borate buffer and 5 mM of anionic surfactant sodium dodecylsulfate at pH 9.0 as the background electrolyte. The separation was achieved at 25 kV applied voltage and 35 degrees C. The injection was performed at 50 mbar for 5 s, with detection at 208 nm. The method was linear in the range of 15-150 microg/mL (r2 = 0.9966) for DEL and 5-50 microg/mL (r2 = 0.9985) for MAN with adequate results for the precision (< or = 1.87%) and accuracy (98.94% for DEL and 100.65% for MAN). The specificity of the method and its stability-indicating capability was demonstrated through forced degradation studies, which showed that there was no interference from the excipients. The Plackett-Burman experimental design was used for robustness evaluation, giving results within the acceptable range. The method was successfully applied for analysis of the drugs, and the results were compared to an LC method, resulting in nonsignificant differences (P = 0.78 and 0.84 for DEL and MAN, respectively).

Micellar electrokinetic chromatographic method for mianserin hydrochloride and analysis of degradation products by mass spectrometry.

A simple, stability-indicating micellar electrokinetic chromatography (MEKC) method was developed and validated for the analysis of mianserin hydrochloride in coated tablets. The method employed (hydroxymethyl)aminomethane (TRIS) 50 mM to which sodium dodecyl sulfate (SDS) 50 mM was added at pH 10.6 as the electrolyte and the voltage applied was 25 kV. The capillary used was 48.5 cm long (40.0 cm effective length and 50.0 µm i.d.) and the detection wavelength was 220 nm. Tetracycline was used as internal standard. The method was validated in accordance with the International Conference on Harmonization (ICH) requirements, which involved specificity, linearity, precision, accuracy and robustness. The stability-indicating capability of the method was established by enforced degradation studies combined with peak purity assessment using photodiode array detection. The degradation products formed under photolytic and oxidative conditions were investigated by electrospray ionization mass spectrometry. The method was linear over the concentration range of 50-130 µg/mL. The method was precise as demonstrated by an inter-day and intra-day relative standard deviation of less than 2.0%. The proposed validated MEKC method showed recoveries between 98.16 and 102.80% of the nominal contents. The Plackett-Burman design was applied for the robustness test in order to examine potential sources of variability by screening a large number of factors in a relatively small number of experiments.