LC-MS determination of MPTP at sub-ppm level in pethidine hydrochloride

An HPLC-MS with electrospray ionisation method for the determination of MPTP at sub-ppm level in pethidine hydrochloride has been developed and validated. Ionisation is performed by positive-ion electrospray and the quadrupole filter mass spectrometer is operated in the single ion recording mode. Chromatographic separation was achieved in gradient elution using a symmetry C18, 5 microm, 150 mm x 2.1 mm i.d. The mobile phase comprised water containing 0.1% formic acid (v/v) and acetonitrile containing 0.1% formic acid (v/v). The method showed to be linear in the range between 0.2 and 2.2 ng/ml, the estimated LOD was lower than 0.1 ng/ml and the LOQ was lower than 0.2 ng/ml.