Atmospheric Pressure Photoionization with Tandem Mass Spectrometry (APPI-MS/MS) and Desorption Electrospray Ionization (DESI) for the Analysis of Bisphenols in Thermal Paper Receipts, Currency, and Recycled Paper Product

The measurement of BPA and bisphenol analogs in thermal paper receipts and transfer of bisphenols from receipts to currency notes is of increasing importance to assess human dermal exposure routes to this class of compounds. While native sulfone bisphenols and sulfone derivatized bisphenols (such as BPS and BPSIP) are amenable to electrospray (ESI) mass spectrometry (MS), alternative mass spectrometric ionization methods such as atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI) were investigated to analyze non-derivatized, non- sulfone containing bisphenols (such as BPA and BPZ). Ionization of 7 different bisphenols (BPA ,BPS BPB, BPAB, BPSIP, BPZ, and BPF) using negative ion APPI was compared to negative ion ESI and negative ion APCI for their relative abilities to produce [M--H] -- precursor ions for subsequent collision activated dissociation (CAD) in a triple quadrupole mass analyzer. Multiple reaction monitoring (MRM) transitions were optimized for these bisphenols using the most sensitive ion transitions and coupled with high performance liquid chromatographic (HPLC) separation to detect and quantify BPA, BPB, B PF, BPZ, BPAP, BPS, and BPSIP. APPI provides a more universal sensitivity over ESI toward the classes of bisphenols studied with detection limits of 20-50 pg on- column. The LC -APPI - MS/MS method was used to examine the levels of these seven bisphenols i n thermal paper receipts, U.S. paper currency , and recycled cardboard. In these items, BPA and BPS were the dominant bisphenols found in the paper. Finally , DESI -MS was evaluated as a means to probe surface BPA and BPS transfer from coated receipts to U.S. currency notes . DESI - MS was also evaluated as a method to rapidly identify bisphenols in alternative forms of thermal paper such as: transportation tickets, barcodes, and packaging labels.