Determination of styrene monomer migrating in foodstuffs from polystyrene food contact articles using HS-SPME-GC-MS/MS: Results from the Greek market.

In this study, a sensitive, accurate and fast headspace - solid phase microextraction - gas chromatography - tandem mass spectrometry method (HS-SPME-GC-MS/MS) was developed and validated for the determination of styrene in various food matrices (mean recovery ranged from 90 to 116% with a relative standard deviation of ≤11%). The method was used for the determination of the concentration of styrene in 23 foodstuffs packed in polystyrene (PS) containers, as well as the levels of styrene migrating into various foods (water, milk, cheese or cream) from 14 tableware or kitchenware articles made of styrene plastics. All samples were collected from the Greek market in 2020. Styrene concentrations in the packaged foods ranged from 0.4 to 160 ng g-1 with the highest concentration found in a meat product packed in a foamed PS tray. It is worth noting that 56% of PS packaged dairy products and desserts had a styrene concentration higher than 10 ng g-1. Particularly high levels of styrene that have not previously been reported, up to 46 ng g-1, were found in dairy products for children. The highest level of styrene migration from tableware or kitchenware articles, 89 ng g-1, was observed when disposable cups from foamed PS were filled with milk at 70℃ for 2 hours. The implications of these findings for the assessment of the potential exposure of the Greek consumers to styrene migrating from PS food contact materials are discussed.

Kinetics of maneb degradation during thermal treatment of tomatoes.

The kinetics of maneb degradation in tomato homogenates at high temperatures and at two pH values (4 and 9) and the rate of formation of the toxic metabolite, ethylenethiourea (ETU), were studied. Maneb was measured as carbon disulfide by headspace gas-chromatography and ETU by high-performance liquid chromatography with photodiode array detection. First-order kinetics adequately described the degradation of maneb in tomato homogenates. The degradation rate constants exhibited an Arrhenius temperature dependence in the range from 50 to 90 degrees C and the apparent activation energy (E(a)) was calculated to be 36 KJ mol(-1) in homogenates with natural pH (4). Raising temperature from 60 to 75 and to 90 degrees C, ETU formation was significantly increased. Interestingly, the selectivity toward ETU showed a downward trend when the total conversion increased at longer heating times. When the pH of the tomato homogenates was adjusted to 9, the degradation of maneb proceeded faster at both 60 and 90 degrees C. The combination of alkaline pH and the highest temperature (90 degrees C) resulted in the maximum ETU conversion rates. The results of the present study on the fate of maneb and ETU residues during tomato processing, may prove valuable in estimating potential risk from dietary exposure.