A novel micellar per aqueous liquid chromatographic method for simultaneous determination of diltiazem hydrochloride, metoprolol tartrate and isosorbide mononitrate in human serum

A novel micellar per aqueous liquid chromatographic method was investigated to simultaneously determine diltiazem hydrochloride, metoprolol tartrate and isosorbide mononitrate in human serum. Separation and determination of the analytes were performed on a Pinnacle II Cyano column as the stationary phase using the mobile phase consisted of aqueous solution (4.15 × 10−2 mol/L sodium dodecyl sulfate and 0.02 mol/L sodium dihydrogen phosphate) with 10% (v/v) of 1-propanol at pH 7.0. This method was validated by linearity, lower limit of quantification, extraction recovery, stability, precision, and accuracy. The main analytical parameters were linearity (r > 0.9950), intra- and inter-day precisions (intra-day RSD 2.2–3.5%, and inter-day RSD 3.7–9.5%), lower limit of quantification (20 ng mL−1 for isosorbide mononitrate, metoprolol tartrate and diltiazem hydrochloride). The extraction recovery was 63.3% (0.1 μg/mL), 65.6% (1.0 μg/mL), and 69.5% (25 μg/mL) for isosorbide mononitrate; 65.1% (0.1 μg/mL), 69.5% (1.0 μgmL) and 73.5% (2.5 μg/mL) for metoprolol tartrate; 67 .1% (0.1 μg/mL), 68.8% (1.0 μg/mL) and 73.8 % (2.5 μg/mL) for diltiazem hydrochloride. The relative error of stability was <6.4% at the room temperature for 24 h, <3.8% at 4 °C for 1 week, <4.6% at −20 °C for 1 month, and <6.7% for freeze/thaw cycles (n = 3). The results indicated that the proposed method was rapid, sensitive, and accurate for determination of the three antianginal drugs in human serum. The possible separation mechanism of the method was also discussed, and a model of separation mechanism for the analytes was established.