Development and Validation of Liquid Chromatography-Tandem Mass Spectrometry Method for Simultaneous Determination of Zinc Pyrithione and Pyrithione in Shampoos

Abstract

A simple, rapid, and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the determination of zinc pyrithione (ZnPT) and pyrithione (PT) in shampoos. The method consisted of a liquid-liquid extraction for sample preparation. The mass spectrometer was operated in multiple reaction monitoring (MRM) mode via the positive electrospray ionization interface. A linear regression (weighted 1/x) was used to fit calibration curves over the concentration range of 50-2000 ng/mL for both ZnPT and PT Excellent linearity (r(2) >= 0.9996) was achieved for all. The method was validated and found to be accurate (95.9-108.2% for ZnPT and 94.9-110.4% for PT), precise, and selective. Analytes in shampoos were found to be stable in the autosampler (6 degrees C for 6 h), in room temperature (for 6 h), and after three freeze-thaw cycles, and recovery of analytes was reproducible (90.8-94.6% for ZnPT and 90.2-96.3% for PT).