HILIC-MS-MS for the Quantification of Pidotimod in Human Plasma

A method for fast, sensitive, and specific hydrophilic interaction chromatography combined with tandem mass spectrometry (HILIC-MS/MS) was developed for the first time to determine the level of pidotimod in human plasma. With rosiglitazone as internal standard, analysis was carried out on a HILIC column (150 mm × 2.1 mm, 3.5 ??m) using a mobile phase consisting of methanol:0.2% formic acid (60:40, v/v). Detection was carried out by tandem mass spectrometry using electrospray ionization (ESI). Linear calibration curves were obtained in the concentration range of 11.2?C1.12 × 10⁴ ng mL^?1 for pidotimod, with a lower limit of quantification of 11.2 ng mL^?1. The intra- and inter-day precision values were high, with standard deviations lower than 15%, and the accuracy, in terms of relative error, ranged from ?10.5 to 9.4% at all quality control (QC) levels.