Researchers from the US Food and Drug Authority (FDA) published a new method on May 1, 2013 in the peer-reviewed scientific journal Food Additives & Contaminants: Part A that allows screening food contact surfaces of packaging for contamination with photoinitiators (Bentayeb et al. 2013). Photoinitiators are used to promote polymerization processes or the curing of printing inks in the presence of light. The method developed by Benatayeb and colleagues does not require previous preparation of the sample and therefore allows a high sample throughput. They found the two photoinitiators 4-phenylbenzophenone (CAS 2128-93-0) and Speedcure 7005 (CAS 1182753-56-5) to be more susceptible to set-off than other photoinitiators. The same was true for darker (i.e. green and grey) over lighter colors.

Set-off occurs when printed surfaces of packaging material come into contact with the food contact side. Such may be the case during stacking or rolling (see also FPF Glossar) of food contact materials that are printed on the outside. The article’s authors tested the set-off potential of α-amino-morpholino, α-hydroxy benzophenones, thioxanthones, aryl-phosphine oxide and three polymeric versions of these compounds. The researchers claimed that at least three ions of one polymer were needed in order accurately identify a photoinitiator. The method is intended for identification, not precise quantification of photoinitiators on the food contact surface of packaging.


Bentayeb, K., et al. (2013). "Non-visible print set-off of photoinitiators in food packaging: detection by ambient ionization mass spectrometry." Food Additives & Contaminants: Part A: 1-10.