Analysis of food packaging UV inks for chemicals with potential to migrate into food simulants

Covalent organic framework-V modified porous polypropylene hollow fiber with detachable dumbbell-shaped structure for stir bar sorptive extraction of benzophenones

Polypropylene hollow fiber is a kind of ideal material for stir bar sorptive extraction (SBSE) which possesses the advantages of porous structure, large specific surface area, high mechanical strength, and good solvent resistance. In this work, a novel SBSE device using the polypropylene hollow fiber-based stir bar with the detachable dumbbell-shaped structure was designed and prepared. Covalent organic framework-V (COF-V), which possesses porous structure, sphere shape with large specific surface area, was synthesized at room temperature and grown on polypropylene hollow fiber by polydopamine modification method. Compared with previous studies which used etched poly(ether ether ketone) as supporting material, polypropylene hollow fiber omitted the complicated, difficult and dangerous pretreatment process with high concentrated sulfuric acid. The immobilization of COF-V on the polypropylene hollow fiber significantly endows them with multiple interaction abilities including hydrophobic interaction and π-π interaction. The stir bar showed good performance and stability for the extraction of four benzophenones including BP-1, BP-6, BP-3 and Ph-BP. By coupling with HPLC-UV, the COF-V@polypropylene hollow fiber based SBSE method showed wide linear range (0.1-200 ng/mL), excellent linearity (R² ≥ 0.9979), high sensitivity (LODs in the range of 0.02-0.03 ng/mL), and good repeatability (RSD ≤ 5.21%). This method was successfully applied to the analysis of benzophenones in soil and sunscreen samples.

Occurrence and Distribution of Photoinitiator Additives in Paired Maternal and Cord Plasma in a South China Population

Photoinitiators (PIs) are widely used in industrial polymerization and have been detected as emerging contaminants in environmental matrixes. It has been reported that humans are exposed to PIs, but the maternal-fetal transmission of PIs has not been documented. In this study, we analyzed 21 PIs (9 benzophenones, BZPs; 8 amine co-initiators, ACIs; and 4 thioxanthones, TXs) in matched maternal-cord plasma samples from 49 pregnant women in South China. Sixteen of the 21 target PIs were found in maternal plasma at concentrations of ∑PIs (sum of the detected PIs) from 303 to 3500 pg/mL. Meanwhile, 12 PIs were detected in cord plasma with ∑PIs from 104 to 988 pg/mL. The PIs detected in both maternal and cord plasma samples were dominated by BZPs, followed by ACIs and TXs. Different groups of PIs showed structure-dependent placental transfer efficiencies (PTEs). The PTEs were generally less than 100% for BZPs but greater than 100% for ACIs and TXs. By further theoretical calculation, we revealed the critical structural features of PIs that affect PTEs. This is the first study to investigate the occurrence and distribution of PIs in paired maternal and cord plasma, and it sheds light on the potential mechanism of structure-dependent placental transfer.

Synthesis of New Polyether Ether Ketone Derivatives with Silver Binding Site and Coordination Compounds of Their Monomers with Different Silver Salts

Polyether ether ketone (PEEK) is a well-known polymer used for implants and devices, especially spinal ones. To overcome the biomaterial related infection risks, 4-4′-difluorobenzophenone, the famous PEEK monomer, was modified in order to introduce binding sites for silver ions, which are well known for their antimicrobial activity. The complexation of these new monomers with different silver salts was studied. Crystal structures of different intermediates were obtained with a linear coordination between two pyridine groups and the silver ions in all cases. The mechanical and thermal properties of different new polymers were characterized. The synthesized PEEKN5 polymers showed similar properties than the PEEK ones whereas the PEEKN7 polymers showed similar thermal properties but the mechanical properties are not as good as the ones of PEEK. To improve these properties, these polymers were complexed with silver nitrate in order to “cross-link” with silver ions. The presence of ionic silver in the polymer was then confirmed by thermogravimetric analysis (TGA) and X-ray powder diffraction (XRPD). Finally, a silver-based antimicrobial compound was successfully coated on the surface of PEEKN5.

[Development of injection containers for patient and medical staff]

Recently, there has been a transition from glass to plastic injection containers in Japan. In our previous study, we suggested that plastic containers had less impurity contamination than glass containers. However, the use of some plasticizers has been limited because of their endocrine disrupting effects. Therefore, contamination has been a concern due to chemicals in injection solution packed with plastic containers. Indeed, in our recent study, photoinitiators were detected in an injection solution coming from plastic containers. Photoinitiators mainly exist in ink. We therefore speculated that ink originating from a photoinitiator directly printing on plastic containers had migrated into the injection solutions. In a clinical setting, plastic containers are very tractable because they are lightweight and less breakable. On the other hand, from a safety view point, these containers may be hazardous because of permeation by steam, ambient air or photoinitiators. In the present symposium, we will discuss the risk of photoinitiators leaking into injection solution packed with plastic containers, and countermeasures to avoid this risk.

Quantitation and human monocyte cytotoxicity of the polymerization agent 1-hydroxycyclohexyl phenyl ketone (Irgacure 184) from three brands of aqueous injection solution

In this study, levels of the photoinitiator 1-hydroxycyclohexyl phenyl ketone (1-HCHPK) in aqueous injection solutions were analyzed by GC-MS. In our previous studies, photoinitiators such as 2-methyl-4'-(methylthio)-2-morpholinopropiophenone (MTMP) were detected in intravenous (i.v.) injection bag solution, and they were found to be cytotoxic to human monocytes. Therefore, we hypothesized that 1-HCHPK might display similarly cytotoxicity. The purpose of this study was to quantitate the amount of contaminants from plastic containers such as those used for peripheral parenteral nutrition and to determine the cytotoxicity of such extracts on human monocytes. The sample extraction procedure for GC-MS analysis involved a liquid-phase extraction. The solvent was evaporated under a stream of nitrogen at 50°C to yield a residue, which was dissolved in n-hexane and injected into a GC-MS. Normal human peripheral blood mononuclear cells (PBMC), isolated from the buffy coat by centrifugation, were suspended in RPMI 1640 medium supplemented with 10% (v/v) heat-inactivated fetal calf serum. In the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cell viability assay, cells (1×10(4)) were treated with 1-HCHPK for 24 h or 48 h at 37°C. From the GC-MS analysis, 6.13-8.32 µg/mL of 1-HCHPK was found in 20 mL vials of water for injection solution. In the MTT assay, 1-HCHPK decreased cell viability for both the 24 h and 48 h incubation periods. In conclusion, our findings suggest that 1-HCHPK could promote adverse events in patients. Future studies will clarify the possible health risks of photoinitiator accumulation in human cells.

Targeted multidimensional gas chromatography using a heart-cutting device and cryogenic focusing for the determination of benzophenone derivatives in foodstuffs

Photoinitiators are used to promote the polymerization process during the curing of varnishes or inks on cartonboard packaging. Depending on storage conditions and shelf life, these substances are able to migrate through the packaging layer into the foodstuff. This type of contamination phenomenon is therefore becoming a critical issue in terms of food safety. In order to tackle this problem, a fast and selective method was developed for the determination of benzophenone and three methylbenzophenone isomers in cereal-based foodstuffs and their cardboard packaging. Food samples or packages were efficiently extracted by pressurized liquid extraction using acetonitrile, and the extracts were directly injected onto the analytical system. The analysis was performed by multidimensional gas chromatography-mass spectrometry using a heart-cutting approach to reduce the background noise from complex matrices. The strategy employed two distinct cuts each containing its proper deuterated internal standard leading to accurate quantification. By integrating a cryofocusing effect, an enhancement in signal/noise ratio was achieved by a factor >10, which markedly decreased the sensitivity threshold. Moreover, baseline separation of the critical isomers allowed their unequivocal determination. The method was fully validated on cereal-based foodstuffs based upon an analysis of variance, and excellent performances were obtained at the decision limit making this method well suited for official food controls.

Elastic properties of some selected two-monomer systems as studied by Brillouin spectroscopy

We present results obtained by Brillouin scattering method for four two-component systems comprising of a high viscosity monomer and a low viscosity monomer. The monomers used were crosslinking (divinyl) or linear (monovinyl) ones. The investigated systems were: divinyl/divinyl-bis-GMA/TEGDM; divinyl/monovinyl-bis-GMA/PEGMM; monovinyl/divinyl-bis-MGMA/TEGDM and monovinyl/monovinyl-bis-MGMA/PEGMM; they were formulated at various molar ratios. The measurements have been performed in temperature range 293-353 K. The following physical parameters characterizing the investigated systems were estimated: hypersonic velocity V, attenuation coefficient α and adiabatic compressibility β, all as a function of temperature and monomer molar ratio. The obtained results have been discussed in terms of the influence of the system composition and viscosity on their elastic properties. Speed of changes of the adiabatic compressibility β as derivative have been also discussed in terms of both, the temperature as well as the component of molar ratio.

Analysis and migration of phthalates in infant food packed in recycled paperboard

The contamination of infant food with substances from its packaging due to migration processes is still a problem. Most recently, great attention was paid to the migration of epoxidized soybean oil (ESBO) and phthalates from twist-off closures into baby food packed in glass jars. Besides, packaging made of recycled fiber materials such as paper and paperboard were found to be the source of contaminants in dry and powdery foodstuffs such as sugar, rice, and maize flour. In this study 20 infant food samples packed in recycled paperboard containers were tested for phthalates and diisopropyl naphthalenes (DIPN), known incorporated substances in recycled paper. Furthermore, the barrier function of different secondary packaging materials (paper and aluminum-coated foil) was investigated. The highest contents of phthalates (mainly diisobutyl phthalate, DiBP) and DIPN in infant food samples were found for those foods packed in inner bags made of paper. Migration experiments were performed under authentic conditions to evaluate possible transfer mechanism (gas phase, direct contact) of phthalate esters into foodstuff. It is shown that paper does not provide an appropriate barrier against migration of semipolar compounds such as phthalates. The air space itself otherwise effectively prevents migration of the less volatile phthalates under the applied conditions.

Development of a method to study the migration of six photoinitiators into powdered milk

The aim of the present work was to develop a rapid multimethod for the analysis of six photoinitiators (PIs) in powdered milk and to study the migration of these PIs from LDPE packaging into powdered milk. The optimized HPLC-DAD method showed high correlation coefficients (>0.9999) over a concentration range of 0.1-10.9 mg/L. The kinetics of migration of the photoinitiators from LDPE packaging into powdered milk were determined at different temperatures. The key parameters of migration phenomena (diffusion and partition coefficients) were determined. The diffusion coefficients at 5 degrees C ranged between 8.4 x 10(-12) (for ITX) and 5.1 x 10(-10) (for benzophenone) and those at 40 degrees C between 5.9 x 10(-10) (for ITX) and 6.1 x 10(-9) (for Irgacure 184). The diffusion coefficients of the six model migrants under study increased with temperature and showed a good Arrhenius relationship between 5 and 40 degrees C.

Determination of 2-isopropyl thioxanthone and 2-ethylhexyl-4-dimethylaminobenzoate in milk: comparison of gas and liquid chromatography with mass spectrometry

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) and gas chromatography-mass spectrometry (GC-MS) have been compared for the analysis of 2-isopropyl thioxanthone (ITX) and 2-ethylhexyl-4-dimethylaminobenzoate (EHDAB). Pressurized liquid extraction (PLE) was applied for the extraction of ITX and EHDAB from milk and milk-based beverages. Samples were homogenized with sea sand and anhydrous sodium sulfate, and were extracted with ethyl acetate at 100 degrees C and 10.3 x 10(6) Pa in one cycle of 10 min at 90% flush. Both, GC-MS and LC-MS/MS were suitable to determine these photoinitiators in the PLE extracts, providing appropriate identification and quantification. The recoveries obtained ranged from 70 to 99% for ITX and from 70 to 95% for EHDAB. These recoveries were equal as those obtained by a conventional liquid-liquid partitioning with acetonitrile and tert-butyl methyl ether-hexane. The quantification limits using GC-MS, based on a signal-to-noise ratio of 10, were 0.5 microg/L for ITX and 1 microg/L for EHDAB. The repeatability of the method, as indicated by the relative standard deviations, was within the range 0.9-16.1%. The same parameters calculated using LC-MS/MS result in quantification limits of 0.1 microg/L for ITX and 0.02 microg/L for EHDAB and repeatability within the range 5.2-19.4%. These results pointed out that both techniques are appropriate to determine these compounds in food samples. The method was applied to milk and milk-based beverages from different supermarkets. The ITX and EHDAB contents ranged from 2.5 to 325 microg/L and from 8 to 126 microg/L, respectively.

2-Isopropylthioxanthone (2-ITX) in food and food packaging materials on the German market

To elucidate the occurrence of the photo-initiator, 2-isopropylthioxanthone (2-ITX), more than 100 food products on the German market, packed in cartons, plastic cups and foils, were investigated. For this, a rapid method to detect 2-ITX in food packaging materials was established. In case of positive findings, the accompanying foodstuffs were analysed in a subsequent step using different extraction methods, depending on the fat content of the food. Determination of the photo-initiator was done by high-performance liquid chromatography with diode array and fluorescence detection (HPLC-DAD/FLD). Recoveries ranged between 94 and 106% for non-fatty (RSD <or= 1.1) and between 80 and 105% for fatty foods (RSD <or= 8.5). The limit of detection and limit of quantification were determined to 2 and 5 microg l(-1). 2-ITX was detected in 36 of 137 packages (26%) and significant migration occurred in 75% of the packaging materials tested positive. The levels of 2-ITX ranged up to 357 microg kg(-1) in orange juice.

Determination of isopropyl-9H-thioxanthen-9-one in packaged beverages by solid-phase extraction clean-up and liquid chromatography with tandem mass spectrometry detection

A simple method was developed and validated for the trace determination of 2-isopropylthioxanthone (ITX) in packaged drinks. Samples were extracted from the food matrix using acetonitrile:water (60:40, v/v), and further subjected to clean-up and preconcentration using solid-phase extraction prior to analysis by liquid chromatography-tandem mass spectrometry using multiple reaction monitoring (MRM) mode. The use of 2-isopropyl-[(2)H7]thioxanthen-9-one was incorporated into the method as an internal standard. Excellent 3-day interday precision data (RSD 0.72%, n=10), and intraday precision data (RSD 0.52%, n=10) were obtained on a 0.10 microg/L standard solution. Spiked samples (n=8) were used to gauge the accuracy of the method at the concentration levels of 2.5, 100, and 500 microg/kg in food; recoveries ranged from 97.0 to 103.0%. These excellent validation data suggest the exciting possibility of using this method for the determination of low levels of ITX migrating from printed food packaging materials into beverages with a method quantitation limit of 0.50 microg/kg. For the first time, analysis on a range of milk, juice, tea and yoghurt drinks, as well as their respective food packaging materials were performed for comparative studies on their ITX content.

Direct analysis of isopropylthioxanthone (ITX) in milk by high-performance liquid chromatography/tandem mass spectrometry

A fast screening method is presented for detecting isopropylthioxanthone (ITX) contamination in milk. The method is based on direct high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS) analysis of milk samples. Sample preparation is limited to the addition of a deuterated ITX solution in acetonitrile that serves both as internal standard and to precipitate proteins. The method is highly accurate and sensitive. Isomeric specific analyses of 2-ITX and 4-ITX are possible at 6 microg/L levels with about 5% precision and accuracy. This approach has been used to check contamination in samples like milk, soy milk, baby milk, in their packaging material. Out of 37 milk samples analyzed, 16 were positive with concentrations ranging from 173-439 microg/L for 2-ITX and from <6 (lower than limit of quantification) to 25 microg/L for 4-ITX.

Benzophenone in cartonboard packaging materials and the factors that influence its migration into food

Benzophenone may be present in cartonboard food-packaging materials as a residue from UV-cured inks and lacquers used to print on the packaging. It may also be present if the cartonboard is made from recycled fibres recovered from printed materials. A method has been devised to test for benzophenone in cartonboard packaging materials and to test for migration levels in foodstuffs. Packaging is extracted with solvent containing d10-benzophenone as the internal standard. Foods are extracted with solvent containing d10-benzophenone and the extract defatted using hexane. The extracts are analysed by GC-MS. For analysis of food, the limit of detection was 0.01 mg x kg(-1) and the limit of quantification was 0.05 mg x kg(-1). The calibration was linear from 0.05 to 20 mg x kg(-1). The method for food analysis was validated in-house and it also returned satisfactory results in a blind check-sample exercise organized by an independent laboratory. The methods were applied to the analysis of 350 retail samples that used printed cartonboard packaging. A total of 207 (59%) packaging samples had no significant benzophenone (<0.05 mg x dm(-2)). Seven (2%) were in the range 0.05- 0.2 mg x dm(-2), 60 (17%) were from 0.2 to 0.8 mg x dm(-2) and 76 (22%) were from 0.8 to 3.3 mg x dm(-2). A total of 71 samples were then selected at random from the 143 packaging samples that contained benzophenone, and the food itself was analysed. Benzophenone was detected in 51 (72%) of the foods. Two food samples (3%) were in the range 0.01-0.05 mg kg(-1). A total of 29 (41%) were from 0.05 to 0.5 mg kg(-1), 17 (24%) were from 0.5 to 5 mg x kg(-1) and three (4%) food samples exceeded 5 mg x kg(-1). The highest level of benzophenone in food was 7.3 mg x kg(-1) for a high-fat chocolate confectionery product packaged in direct contact with cartonboard, with room temperature storage conditions and with a high contact area:food mass ratio. When the mass fraction of benzophenone migration was calculated for the different contact and storage regimes involved, the attenuation effects of indirect contact and of low temperature storage were cumulative. Thus, there was a sixfold reduction in migration for indirect contact compared with direct contact, a sixfold reduction for chilled/frozen storage compared with ambient storage, and 40-fold reduction for the two contact conditions combined.