Exposure to light, as well as wear and tear from aging can affect the integrity of Polycarbonate (PC) plastics. PC degradation has also been linked to the release of its monomer, bisphenol A (BPA). If this plastic is used as a food container, BPA can be released into foods and affect human health.1 Because research studies are not yet in agreement as to what conditions are most likely to cause the largest release of BPA, Bignardi, C, et al. have developed a new method to identify and quantify bisphenol A and other common additives employed in plastic manufacturing in hopes of better understanding this phenomenon.2
The method developed by this research group uses ultra-performance liquid chromatography with electrospray ionization high resolution and accurate mass spectrometry (UHPLC-ESI-Orbitrap). The team collected fourteen tableware samples produced by the same company (between 1996 and 2013) for analysis. The tableware also had different degrees of surface damage, and three samples (all produced in 2013) had never been used.
The researchers filled containers with two food simulants (ethanol 95 % (v/v) and isooctane) and placed them in a climate controlled chamber at 40 ° C for 1 hour (repeating the experiments three consecutive times) covering the sample with glass plates to prevent solvent evaporation. Each aliquot obtained after each migration test was evaporated by rotary evaporator and re-dissolved in 1 mL of ethanol for LC analysis.
They analyzed aliquots using an Ultimate 3000 RSLC nano system operating in capillary-flow mode coupled to a Q Exactive mass spectrometer. The team also used Pierce LTQ Velos ESI Positive ion and Pierce LTQ Velos ESI Negative ion calibration solutions to calibrate the mass spectrometer, as well as m. Chromeleon 6.8 and XCalibur 2.2 software to control the machine and analyze data (all from Thermo Scientific)
Using this method, the team was able to detect and quantify Bisphenol A, three UV light absorbers, and one whitening agent including Cyasorb UV5411, Tinuvin 327, Tinuvin 234, and Uvitex OB, respectively. They found that ethanol 95% v/v extracted larger amounts of the additives compared with isooctane. The team found that older plastic samples released less amount of additives. They posited this finding was due to the fact that these substances were not widely employed in past years.
Looking to BPA, they team found a connection between a higher release of BPA in older samples, and that the condition- whether there were scratches and cracks in the plastic was less important in determining how much BPA would be released.
The team also notes, that the quantities of plastic additives and BPA were all below the limits reported by legislation. Bignardi, et al. sees potential in applying this technique to evaluating the possible migration of PC degradation products constituted by dimers or oligomers.
1. Hoekstra, EJ, Simoneau C (2013) “Release of bisphenol A from polycarbonate—a review.” Critical Reviews in Food Science and Nutrition 53:(pp. 386–402)
2. Bignardi, C et al. (2015) “UHPLC-high-resolution mass spectrometry determination of bisphenol A and plastic additives released by polycarbonate tableware: influence of ageing and surface damage.” Analytical and Bioanalytical Chemistry. 2015 Oct;407(26):7917-24. doi: 10.1007/s00216-015-8958-x. Epub 2015 Aug 22.