Small-sized microplastics and pigmented particles in bottled mineral water.

Up to now, only a few studies about microparticle contamination of bottled mineral water have been published. The smallest analysed particle size was 5 µm. However, due to toxicological reasons, especially microparticles smaller than 1.5 µm are critically discussed. Therefore, in the present study, 32 samples of bottled mineral water were investigated for contamination by microplastics, pigment and additive particles. Due to the application of aluminium coated polycarbonate membrane filters and micro-Raman spectroscopy, a lowest analysed particle size of 1 µm was achieved. Microplastics were found in water from all bottle types: in single use and reusable bottles made of poly(ethylene terephthalate) (PET) as well as in glass bottles. The amount of microplastics in mineral water varied from 2649 ±â€¯2857 per litre in single use PET bottles up to 6292 ±â€¯10521 per litre in glass bottles. While in plastic bottles, the predominant polymer type was PET; in glass bottles various polymers such as polyethylene or styrene-butadiene-copolymer were found. Hence, besides the packaging itself, other contamination sources have to be considered. Pigment particles were detected in high amounts in reusable, paper labelled bottles (195047 ±â€¯330810 pigment particles per litre in glass and 23594 ±â€¯25518 pigment particles per litre in reusable paper labelled PET bottles). Pigment types found in water samples were the same as used for label printing, indicating the bottle cleaning process as possible contamination route. Furthermore, on average 708 ±â€¯1024 particles per litre of the additive Tris(2,4-di-tert-butylphenyl)phosphite were found in reusable PET bottles. This additive might be leached out from the bottle material itself. Over 90% of the detected microplastics and pigment particles were smaller than 5 µm and thus not covered by previous studies. In summary, this is the first study reporting about microplastics, pigment and additive particles found in bottled mineral water samples with a smallest analysed particle size of 1 µm.

A rapid LC-MS/MS method for the determination of moniliformin and occurrence of this mycotoxin in maize products from the Bavarian market.

A simple LC-MS/MS method was developed for the determination of moniliformin (MON) in maize and applied for the analysis of samples within the official food surveillance. The homogenized samples were extracted with acetonitrile/water 50/50 (v/v) which proved to have the highest extraction efficiency compared to other tested solvents. The centrifuged extracts were diluted with acetonitrile and were measured after chromatographic separation by HILIC (hydrophobic interaction liquid chromatography)-HPLC without any cleanup (dilute and shoot approach). The LOD and LOQ achieved by this procedure were 2.6 and 8.8 µg/kg, respectively. Thirty-nine samples of popcorn, maize meal, and semolina were collected in 2014 and 2015 at mills, cinemas, wholesale, and retail from the Bavarian market (Germany). The rate of contamination with MON was very high (97%) with levels ranging between the LOD and 847 µg/kg. The mean level was 118 µg/kg and the median, 39 µg/kg. The maximum value was detected in maize meal. The results are discussed with respect to possible health implications for the consumer.

Development of an optimal filter substrate for the identification of small microplastic particles in food by micro-Raman spectroscopy.

When analysing microplastics in food, due to toxicological reasons it is important to achieve clear identification of particles down to a size of at least 1 µm. One reliable, optical analytical technique allowing this is micro-Raman spectroscopy. After isolation of particles via filtration, analysis is typically performed directly on the filter surface. In order to obtain high qualitative Raman spectra, the material of the membrane filters should not show any interference in terms of background and Raman signals during spectrum acquisition. To facilitate the usage of automatic particle detection, membrane filters should also show specific optical properties. In this work, beside eight different, commercially available membrane filters, three newly designed metal-coated polycarbonate membrane filters were tested to fulfil these requirements. We found that aluminium-coated polycarbonate membrane filters had ideal characteristics as a substrate for micro-Raman spectroscopy. Its spectrum shows no or minimal interference with particle spectra, depending on the laser wavelength. Furthermore, automatic particle detection can be applied when analysing the filter surface under dark-field illumination. With this new membrane filter, analytics free of interference of microplastics down to a size of 1 µm becomes possible. Thus, an important size class of these contaminants can now be visualized and spectrally identified. Graphical abstract A newly developed aluminium coated polycarbonate membrane filter enables automatic particle detection and generation of high qualitative Raman spectra allowing identification of small microplastics.