A first of its kind, simple, rapid, and sensitive liquid chromatography mass spectrometry (LC-MS/MS) method was developed and validated for quantification of perindopril and perindoprilat in both human plasma and breast milk. The analytes and internal standards (phenazone and acetyl salicylic acid) were extracted from biological matrices by protein precipitation. A Phenomenex® C-18 column was used to provide an appropriate chromatographic separation of the analytes, followed by detection with tandem mass spectrometry. Gradient chromatographic and mass spectrometric detection conditions with mobile phases (A: 5% methanol + 0.1% formic acid in water v/v, and B: 95% methanol + 0.1% formic acid in water v/v) were developed to achieve a LOQ of 0.5 ng/mL in both human plasma and milk. The method was suitable of evaluating clinical samples. The mass transition was followed as m/z 369.10/172.00 for perindopril, m/z 339.00/168.10 for perindoprilat, m/z 188.90/55.95 for phenazone, and m/z 179.04/137.02 for acetyl salicylic acid. The developed method was optimized and validated with a linear range of 0.1-200 ng/mL (r 2 = better than 0.99 for both perindopril and perindoprilat). The precision and accuracy values were within 15% CV. The overall recovery of the analytes was 80-110%. The method has good specificity and repeatability. Stability studies were conducted in both human plasma and bovine milk for up to 3 months, at the storage conditions of 25, 4, and -80 °C.
Keywords: Human breast milk; Human plasma; LC-MS/MS; Lactation; Perindopril; Perindoprilat.