A rapid, simple, and sensitive capillary electrophoresis (CE) method was developed and validated for the simultaneous determination of amlodipine (AML) and valsartan (VAL) in pharmaceuticals and human plasma using a UV photodiode array detector. Electrophoretic conditions were optimized to improve separation, sensitivity, and rapidity. The optimal conditions were 25 mM phosphate buffer at pH 8.0, injection time 10.0 s, voltage 25 kV, and column temperature 25C, with detection at 214 nm. The method was found to be linear in the range of 1.035 and 1.0350 mg/L, with weighted regression 0.9999 and 0.9994, for AML and VAL, respectively. Validation of the method showed acceptable intraday and interday accuracy (85.595.3) and precision (RSD 1.644.2) in pharmaceutical formulation and human plasma analysis. The sensitivity of the method was enhanced by both optimization of the CE procedure and preconcentration performed by liquidliquid extraction. The LOD for both AML and VAL was 0.03 mg/L, which allows analysis at the level of the drugs possibly found in human plasma. Therefore, the proposed method is suitable for QC in pharmaceutical laboratories and therapeutic drug monitoring in clinical laboratories.

Objective: A simple, rapid, and sensitive high performance liquid chromatography-mass spectrometry (HPLC-MS) method was developed and validated for the simultaneous determination of ofloxacin (OFL) and cefixime (CEF) in human plasma using the moxifloxacin as internal standard. Methodology: Analytes were separated using an Agilent LCMS system equipped with a Zorbax eclipse XBD C ₁₈ column (150 mm × 4.6 mm i.d., 5 μm) and using a mobile phase consisting of a mixture of acetonitrile, methanol and 0.5% formic acid in a ratio of 23:10:67% v/v and flow rate was set at 0.6 mL/min. Plasma samples were extracted using the protein precipitation with acetonitrile and analyzed by positive ion mode. Results: The linearity of the proposed method was investigated in the concentration range of 4-500 ng/mL (r = 0.9996) for OFL and 40-6000 ng/mL (r = 0.9998) for CEF. The lower limits of quantification were 4 ng/mL and 40 ng/mL for OFL and CEF respectively, which reach the level of both drugs possibly found in human plasma. Further, the reported method was validated as per the ICH guidelines and found to be well within the acceptable range. Conclusion: The proposed method is simple, rapid, accurate, precise, and appropriate for pharmacokinetic and therapeutic drug monitoring in the clinical laboratories.

A capillary zone electrophoretic (CZE) method was developed, validated, and applied for the assay of metformin (MET) and pioglitazone (PIO) in pharmaceutical formulations. The optimum running buffer composition was found to be 75 mmol/L phosphate buffer containing 30% acetonitrile (ACN) at pH 4.0. The optimum instrumental conditions were found to be injection time, 10 s; applied voltage, 25 kV; hydrodynamic injection pressure, 0.5 psi for 10 s, capillary temperature, 25 °C; and the detection wavelength, 210 nm. The quantifications were calculated based on the ratio of the peak areas of analytes to atenolol as an internal standard. The CZE method was validated in terms of accuracy (98.21–104.81%), intra- and inter-day precision of migration time and peak area (relative standard deviation ≤ 5%), linearity (correlation coefficients ≥ 0.9985), limit of detection (≤0.277 μg/mL), and limit of quantitation (≤0.315 μg/mL). The proposed method was applied for the analysis of PIO and MET both individually and in a combined dosage tablet formulation. All electrophoretic parameters were calculated and evaluated. A previously reported high-performance liquid chromatographic (HPLC) method was also applied to the same samples. A comprehensive comparison was then carried out for the analytical features of both methods CZE and HPLC. Comparable results were obtained with the advantage of reagent consumption and separation efficiency of CZE over HPLC and shorter analysis time by HPLC compared with CZE.