Current-use of developers in thermal paper from 14 countries using liquid chromatography coupled to quadrupole time-of-flight mass spectrometry

Thermal printing is a fast, widespread and inexpensive technology that uses a developer to produce a print on the paper, among many applications. A common developer is bisphenol A (BPA), used for this purpose in its free form. Consequently, the handling of thermal paper, as evaluated by the European Food Safety Authority, was reported to be the second largest source of external human exposure to this endocrine disrupting chemical. Recently, reports have been made on the substitution of BPA by alternative developers, which are yet less studied. In this study, 311 receipts and other thermal paper products were collected from 14 countries in Europe, Asia, North America and Oceania and analysed using liquid chromatography coupled to quadrupole time-of-flight mass spectrometry. BPA was the most frequently used main developer and was detected in 194 thermal paper samples, which represents a detection frequency of 63%. A statistically significant difference in the detection of BPA was shown between continents. BPA was followed by bisphenol S (BPS) which was detected in 64 samples as the main developer. Pergafast 201 was the third most abundant main developer and detected in 37 samples as the main developer. Less frequently used main developers included BPS-MAE, TGSA, D-8, and D-90, many of them being BPS derivatives. Two oligomers of D-90 (n = 1 and n = 2) were also identified. The sensitizer diphenyl sulphone (DPS) was identified using high-resolution mass spectrometry for the first time and detected in combination with other developers than BPS for the first time. Despite the lack of structural, nation-wide legislation prohibiting the use of BPA in thermal paper, it is clear that alternative developers are currently globally in use for the manufacturing of thermal paper.