Bisphenol determination in UHT milk and packaging by paper spray ionization mass spectrometry

This study evaluates the use of paper spray ionization mass spectrometry (PSI-MS) for rapid determination of bisphenol A (BPA) and bisphenol S (BPS) in UHT milk and milk packaging. The packages were analyzed by cutting the cartons into triangular shapes and submitting them to PSI-MS analysis. The milk samples were subjected to a simple liquid-liquid extraction and the supernatant was deposited onto a triangular paper that was subsequently used for PSI-MS analysis. In milk, BPS and BPA levels ranged from 60.0 to 150.8 ng mL^-1. The LOD and LOQ values were 1.5 and 4.8 ng mL^-1 for BPA, and 4.8 and 16.0 ng mL^-1 for BPS, respectively. Linearity was R² > 0.98 for both compounds. Precision values were below 20%, and recoveries close to 100%. The PSI-MS can be used as a simple, rapid, and accurate methodology to determine bisphenols in milk and milk packaging.