Determination of styrene in olive oil by an automatic purge-and-trap system coupled to gas chromatography-mass spectrometry

An Insight into the Growing Concerns of Styrene Monomer and Poly(Styrene) Fragment Migration into Food and Drink Simulants from Poly(Styrene) Packaging

Poly(styrene) (PS) has been heavily utilised in disposable food packaging due to its insulating properties, optical translucency, and long-shelf life. Despite these desirable characteristics, (PS) poses toxicity concerns to human’s health through styrene monomer leaching into foodstuffs. Environmental and marine hazards are another growing concerns due to improper and/or absence of recycling strategies and facilities. This preliminary work aims to investigate the effect of temperature, food composition and contact times on the migration of the styrene monomer from poly(styrene) food contact materials into food simulants. Poly(styrene) cups showed a relatively low level of styrene migration with the highest being 0.110 µg/mL, whereas food containers showed a much higher level of styrene leaching with up to 6 µg/mL. This could be due to an increase in the hydrophobicity of the simulants’ characteristics from low to high fat content and the increase in the testing temperatures from 5 °C to 70 °C. ANOVA statistical analysis is used to compare the means of three or more groups of data, whereas t-test analysis is used to compare means of two groups. This was carried out on each individual sample to determine the significance of changing the temperature, simulant type, or both on the level of migration observed in the results. All significant values were tested at 95% confidence level p < 0.05, concluding that fat content and high temperatures were found to significantly increase the level of styrene migration. Nile Red staining method was used to demonstrate that particulate poly(styrene), as well as styrene monomer, migrated into tested food simulants from typical containers, which is becoming a cause for concern as evidence of microplastic ingestion increases.

Efficiency of whole and skimmed powdered milk for trapping volatile compounds released from plastic containers in high-temperature applications

Plastic food containers used for high-temperature applications are not completely inert, and potentially harmful chemicals may be transferred to foodstuffs when such containers are heated. The aim of this work was to investigate the role of food fat content on the efficiency of trapping volatile organic compounds from heated plastic packaging. Relatively simple food matrices such as powdered skimmed and whole milk were evaluated with respect to their retention of several selected migrants: toluene, 1-octene, ethylbenzene, o-, m-, and p-xylene, styrene, and 1,4-dichlorobenzene released from containers made of polypropylene (random and copolymer), polycarbonate, and styrene-acrylonitrile copolymer, which are all commonly used in high-temperature applications. The analytical method (purge and trap gas chromatography and mass spectrometry) was optimized for each matrix. The developed procedure had detection limits of 0.01 to 1.2 ng, depending on the analyte and sample matrix, and both reproducibility and repeatability (expressed as relative standard deviation) were below 15%. This method was applied to the different plastic materials. The concentrations of the volatile compounds in both matrices were well below the established specific migration limits. Temperature and fat content of powdered milk were the most influential variables in mass transfer processes. These values were compared with those obtained with either Tenax TA (alternative test medium for fatty food simulants) or Porapak Q (another widely used sorbent). Similar results were found in skimmed powdered milk and Tenax TA, but significant differences were observed for whole powdered milk.

Use of new generation poly(styrene-divinylbenzene) resins for gas-phase trapping-thermal desorption

Two new generation polymeric resins, Bond Elut ENV (styrene-divinylbenzene) from Varian and LiChrolut EN (ethylvinylbenzene-divinylbenzene) from Merck, commonly used in liquid--solid-phase extraction (SPE) were evaluated as sorbents for gas-phase sampling followed by thermal desorption and compared to Tenax TA, a reference sorbent in this kind of applications. The three resins were tested against seven volatile organic compounds (VOCs): 1-octene, ethylbenzene, (p-, m-, o-)xylenes, styrene and 1,4-dichlorobenzene. Elution curves for all compounds were determined at temperatures from 120 to 180 degrees C, and from such curves, different parameters, such as retention factor (k), distribution coefficient (K), height equivalent to a theoretical plate (H), asymmetry factor (Fa) and breakthrough volume (VB) were calculated and extrapolated at room (25 degrees C) and desorption (220 degrees C) temperatures in order to estimate breakthrough and elution volumes. In average, retention in LiChrolut EN is 10 and 200 times stronger than in Bond Elut ENV and Tenax TA, respectively, but its chromatographic behavior is rather poor giving quite asymmetric elution profiles (Fa >1.8 at 120 degrees C). Bond Elut ENV exhibited the best chromatographic behavior, with H values two or five times lower than those of LiChrolut EN or Tenax TA. An additional advantage of the new sorbents is that retention decreases with T much faster than it does in Tenax (8 or 20 times for Bond Elut ENV or LiChrolut EN). Modeling has finally shown that beds with 60-80 (for Bond Elut ENV) or 300-400 (for LiChrolut EN) times less of sorbent have the same retention properties than standard Tenax TA tubes and similar (LiChrolut EN) or five to six times smaller (Bond Elut ENV) elution volumes. These predictions have been experimentally confirmed.

Parts-per-trillion determination of styrene in yoghurt by purge-and-trap gas chromatography with mass spectrometry detection

Headspace sampling methods prior to capillary gas chromatography have been widely used for the determination of volatile compounds present in very different kinds of samples. This paper describes an automated and rapid system to determine volatiles from yoghurt. Thirty-five volatile organic compounds (VOCs) were identified in polystyrene cups used for yoghurt packaging and 42 VOCs from yoghurt samples. Quantitation of styrene in several samples from the Spanish retail market was carried out.