A method based on precolumn derivatization and ultra high performance liquid chromatography with high-resolution mass spectrometry for the simultaneous determination of phthalimide and phthalic acid in tea

Plastic particles in urban compost and their grain size distribution

Gathering information on plastic particles in composts and the processes they undergo is important in terms of potentially limiting their further entry into the environment, for example, in improving the fertilising properties of soils. Microplastics (MPs) were determined in composts produced from urban greenery. They are present in decreasing order: polyethylene terephthalate, polystyrene, polyethylene, and polypropylene. The determination of polymers and additives used to improve their properties was performed by pyrolysis and gas chromatography with mass spectrometric detection (Py-GC/MS). Additives and microplastics are most concentrated in composts in the 0.315-0.63 and 0.63-1.25 mm grain size class, together with the carbon contained in the compost dry matter. Additives form 0.11-0.13% of MPs in dry matter of compost. The average concentration of microplastics in the particle size class from 0.63 to 1.25 mm is 2434 ± 224 mg/kg; in the total sample of composts, it is 1368 ± 286 mg/kg of P-MPs. For composts with particle size <2.5 mm, a relationship between the C/N ratio and the plastic particle concentration was statistically significant. It documents a similar behaviour of lignocellulose and plastic particles during the degradation processes. A relationship between the concentration of polymer markers and additives in the compost dry matter and their concentrations in the leachate has been demonstrated. The leachability from compost is higher for additives than for chemical compounds originating from the decomposition of the main components of MPs. The suitability of the use of the compost for agricultural purposes was monitored by the germination index (GI) for watercress. The lowest value of the GI was determined in the particle size class from 0.63 to 1.25 mm. The leachability of polymer markers and additives alone cannot explain the low GI value in this grain size class. The GI value is also influenced by the leachability of chemical compounds characterised by the value of dissolved organic carbon (DOC) and water-leachable nitrogen (Nw). A statistically significant dependence between DOC/Nw and the germination index value was found.

Migration study of phthalates from non-food plastic containers used in food preservation

Phthalate acid esters (PAE) are used as additives in the formulation of plastics, to increase their flexibility and transparency. They can migrate from plastic packaging to food, then cause endocrine disruption in consumers. This migration depends on the conditions of use defined for each plastic. Non-food plastics are likely to release more PAE than food-grade plastics. In Cameroon, non-food grade plastics such as old paint buckets are used by people to preserve liquid food. The present work aimed at studying the conditions and mechanism of migration of total PAE from paint buckets to pap. For this purpose, the effects of seven factors were determined through Plackett-Burman experimental design. The interactions of the most influential factors were determined through a full factorial design. The conditions of the migration of total PAE were obtained via face-centered composite design. Then experimental results of migration kinetics were modelled according to equations of pseudo-first order, pseudo-second order and intra-particle diffusion. The results revealed that the most influential factors were pH, temperature and contact time. The effects of these factors are non-linear, and their interactions have to be considered. When pap is preserved in paint buckets according to the conditions: temperature of pap >70 °C, pH of pap ≤4 or ≥10 and contact time > 2 h, as is the case in donut shops in Cameroon, the amount of total PAE released is greater than 50 μg/L. Migration of total PAE from paint buckets to pap is best described by the pseudo-second order model.

Concentrations, generation and risk characterization of phthalimide in tea-derived from folpet or not?

The fungicide folpet is rapidly degraded into phthalimide (PI) during both thermal processing and analytical procedures in sample preparation; thus, its residue definition has been modified into the sum of itself and PI. Tea is one of the world's most popular nonalcoholic beverages, where folpet is not listed as an applicable pesticide. To demonstrate how serious false-positives and overestimation in dietary risk are caused by the application of a new residue definition, the residue pattern of PI in made tea and processed tea leaves, along with its transfer rate during tea brewing and corresponding dietary risk, were investigated in the present study. The results revealed that PI residue in tea ranged from <10 μg/kg to 180 μg/kg with a median value of 10 μg/kg, 7.3 % of which was over the maximum residue limit established by EU (100 μg/kg, expressed as folpet). The PI residue in green tea was obviously higher than that in black, dark and oolong tea. Simulated heating experiments revealed that PI can arise from improper heating of folpet-free fresh tea leaves, and thus green tea bears a higher risk for its manufacturing employing a comparatively higher temperature. The transfer rate of PI during tea brewing was 104 ± 14 %. Nevertheless, the risk of PI through drinking tea was negligible to humans depending on the risk quotient (RQ) value, which was significantly lower than 1.

Enantioselectivity and residue analysis of cycloxaprid and its metabolite in the pile and fermentation processing of Puer tea by ultraperformance liquid chromatography–high‐resolution mass spectrometry

The residues of cycloxaprid enantiomers and metabolites are investigated by ultraperformance liquid chromatography–high‐resolution mass spectrometry (UPLC‐HRMS) during raw and ripen Puer tea processing. A Chiralpak AG column with chiral stationary phase of amylose tris (3‐chloro‐5‐methylphenylcarbamate) is succeed to separate the 1R, 2S‐cycloxaprid, 1S, 2R‐cycloxaprid, and their metabolite, which is identified as nitrylene‐imidazolidine. It is not conversed 1R, 2S‐cycloxaprid into 1S,2R‐cycloxaprid during Puer tea processing. The estimated half‐lives of the 1R,2S‐cycloxaprid and 1S,2R‐cycloxaprid are 0.97 and 1.1 h, respectively, and 1R,2S‐cycloxaprid decreases more quickly than the 1S,2R‐cycloxaprid. During raw Puer tea processing, the half‐lives of 1R, 2S‐cycloxaprid and 1S, 2R‐cycloxaprid are 1.68 h and 1.77 h, but the residue is still detected even if it is over 730 day. However, the half‐lives of 1R,2S‐cycloxaprid and 1S,2R‐cycloxaprid are 0.60 day and 0.63 day during ripen tea processing. The amounts of metabolite are more in raw tea than in ripen tea; the terminal residues are still detected until 730 days during raw tea. A significant enantioselectivity of 1R, 2S‐cycloxaprid and 1S, 2R‐cycloxaprid is observed during raw tea or ripen tea processing. The degration result shows the enantioselectivity of cycloxaprid in raw or ripen Puer tea processing.

De novo formation of phthalimide from ubiquitous phthalic acid derivatives during the drying process of tea (Camellia sinensis) and selected herbal infusions

It is well documented that under some circumstances phthalimide, a known degradation product of the fungicide folpet, can be formed as an artifact during gas chromatographic analysis. This fact explains one phthalimide source, but does not explain a great number of positive findings in the group of dried plant commodities obtained with an artifact-free analysis. Therefore, in the framework of this study, herbal and tea plants were grown in a glasshouse under the best possible protection against external environmental influences and ensuring the exclusion of the use of folpet. It was demonstrated that relevant amounts of phthalimide are formed during the drying process as part of the routine production of tea and herbals and in the absence of folpet. In this context, the presence of the widespread environmental chemical phthalic anhydride and its impact was investigated. We conclude that phthalimide is no reliable indicator for the active use of folpet.

Phthalimide Residue in Coffee: Does It Solely Derive from Folpet?

Folpet, a fungicide used on several crops, easily degrades into phthalimide (PAI) at high temperatures and basic pH. The maximum admitted limit for Folpet in foodstuffs as coffee is defined by the sum of its amount and that of PAI. Noteworthy, PAI can also arise from the reaction between ubiquitous phthalate derivatives and NH₃. This work aims to demonstrate that the detection of PAI in roasted coffee is not necessarily diagnostic for Folpet as it can also originate from the reaction between phthalic anhydride (PAA), derived from phthalates, and amino acids (AAs), as a NH₃ source. Thermal treatment of AAs with PAA confirmed that PAI generation follows a temperature-dependent path. Experiments with diethyl phthalate (DEP) and AAs have shown that maximum PAI generation via heating occurs at 200 °C for 60 min. PAI generation has also been proven for Folpet-free green coffee beans that were heated under laboratory and industrial roasting conditions.

Quantitative structure-retention relationships of the chromatographic retentions of phthalic acid ester contaminants in foods

The harmful health effects caused by phthalic acid esters have been supported from the increasing scientific evidence, developing the efficient methodologies to monitor the levels of phthalic acid esters in various foods become especially important from the aspects of human exposure assessment and their migration mechanistic understanding. In this study, quantitative structure-retention relationship studies on both the gas and liquid chromatographic retention times of 23 phthalic acid esters were performed by genetic function approximation, and the optimal quantitative structure-retention relationship models (r²  > 0.980, r² _CV  > 0.960, and r² _pred  > 0.865) passed the statistical tests of cross-validation, randomization, external prediction, Roy' r_m ² metrics, Golbraikh-Tropsha' criteria and applicability domain. The established predictive models elucidate the structural requirements for the retention of phthalic acid esters over different chromatographic columns, which were finally used to predict the retention times of 11 new phthalic acid esters. Hopefully, this work could provide useful guidelines for better understanding and accurate prediction of the retention behavior of undetermined phthalic acid esters when lacking standard samples or under poor experimental conditions, and make the simultaneous identification and quantification of numerous phthalic acid esters possible.