Validated hydrophilic interaction LC–MS/MS method for determination of N-methyl-2-pyrrolidinone residue: Applied to a depletion study of N-methyl-2-pyrrolidinone in swine liver following intramuscular administration of drug N-methyl-2-pyrrolidinone formul

A hydrophilic interaction high-performance liquid chromatography coupled with tandem mass spectrometry method for determination of N-methyl-2-pyrrolidinone in swine liver was developed and validated. After the fortification of N-methyl-d3-2-pyrrolidinone-d6 as the deuterium-labeled internal standard, N-methyl-2-pyrrolidinone in swine liver was extracted by acetonitrile and the supernatant was led through a C18 + WAX mixed-mode SPE cartridge for removal of the matrix interferences. The final eluate was acidified by formic acid and then injected onto a 3 μm 15 cm × 2.1 mm TX column for hydrophilic interaction chromatographic analysis. Mass spectrometry detection was carried on a PE Sciex API 4000 triple quadrupole mass spectrometer using positive turbo-ion spray ionization mode. The MRM transitions were 100 → 58 for N-methyl-2-pyrrolidinone and 109 → 62 for N-methyl-d3-2-pyrrolidinone-d6. Solvent calibration standards could be readily used for quantitative analysis of N-methyl-2-pyrrolidinone with excellent precision and accuracy, although there are endogenous levels of N-methyl-2-pyrrolidinone in many blank matrices. The true recovery was nearly 100% and the MRM signal of N-methyl-2-pyrrolidinone was suppressed about 30% because of the matrix effect. Nevertheless, N-methyl-d3-2-pyrrolidinone-d6 completely compensated the ion-suppression effect and the injection-to-injection variation. The detection limit was 5 ng g−1 swine liver. The validated method was applied to a depletion study of N-methyl-2-pyrrolidinone in swine liver following intramuscular administration of a drug N-methyl-2-pyrrolidinone formulation.