A new liquid chromatography–mass spectrometry approach for generic screening and quantitation of potential genotoxic alkylation compounds without derivatization

One of the crucial tasks of pharmaceutical industry is to quantify the potential genotoxic impurities (PGIs) coming from the process of drug production. The European Medicines Agency (EMEA) imposes analytical testing limits in the order of g/g, depending on drug dosage and exposure period, that means the need of a sensitive and selective method of analysis. Liquid chromatography coupled to electrospray ionization mass spectrometry (LC–ESI-MS) has been demonstrated as the most versatile approach to detect PGIs in complex matrices. However, time consuming derivatization processes are needed to enhance sensitivity and selectivity, and to overcome matrix effects (ME) that may arise from active pharmaceutical ingredients (APIs) or excipients. We propose the use of the Direct-EI LC–MS as an alternative approach to detect and quantify PGIs in drug formulations. The Direct-EI LC–MS interface is based on electron ionization (EI) which is well suited for the detection of low molecular weight compounds of different polarity, without derivatization and with no sign of ME. The method has been successfully applied to the detection of PGIs belonging to the class of alkylation agents. Calibration experiments show satisfactory linearity and precision data. Recoveries in low enriched samples spanned from 55 to 82%, and were not affected by ME. The method limits of detection (LODs), varying from 0.13 to 1.5 g/g, were satisfactory for the quantitation of the target PGIs at the level required by regulatory agencies.