MALDI-MS and colorimetric analysis of diisocyanate and polyol migrants from model polyurethane adhesives used in food packaging

The identification of the migrants, into food simulants, from a series of polyurethane adhesives used in the manufacture of plastic film laminates for use in common food packaging is described. Commercial materials, based on four different model adhesive systems, were prepared by an industrial collaborator. The MALDI-MS fingerprint patterns of the three polyether and one polyester polyol components of these adhesives were obtained for reference purposes. The decrease in the level of diisocyanate as a migrant versus time after lamination was confirmed by colorimetric measurements. The migration of the standard polyol samples through polyethylene pouches into water at 70 degrees C has been demonstrated and also the attenuation effect for different polyols. Cured laminates in the form of pouches were used to carry out the migration experiments into distilled water, inside the pouch, at 70 degrees C over a period of 2 h. Comparison of the migration results from the food packaging laminates with those from the polyethylene film confirmed the migration of unreacted polyol components for the polyether-based systems. Cyclic oligomers from the polyol starting materials were identified as the migrants from the polyester-based adhesive.     

Injector-internal thermal desorption from edible oils. Part 2: chromatographic optimization for the analysis of migrants from food packaging material

Injector-internal thermal desorption from edible oil or fat is a convenient sample preparation technique for the analysis of solutes in lipids or extracts from fatty foods. The injector temperature is selected to vaporize the solutes of interest while minimizing evaporation of the bulk material of the oil. This technique has been in routine use for pesticides for some time. Now its potential is explored for migrants from food contact materials, such as packaging, into simulant D (olive oil) or fatty/oily food, which means extending the range of application towards less volatile compounds. The performance for high boiling components was investigated for diisodecyl phthalate (DIDP) and diundecyl phthalate (DUP). Since the injector temperature needs to be as high as 260degreesC, some bulk material of the oil enters the column and must be removed after every analysis. This is achieved by a coated precolumn backflushed towards the end of each analysis. Desorption of the solutes is particularly efficient in the initial phase, when a thin sample film is spread on the liner wall, and is largely determined by the diffusion speed in the oil after the latter has contracted to droplets. An increased carrier gas flow rate during the splitless period supports the transfer into the column. It is concluded that the technique is attractive for migrant analysis, with DUP being at the upper limit of the boiling point.     

Identification of non-volatile compounds and their migration from hot melt adhesives used in food packaging materials characterized by ultra-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry

The identification of unknown non-volatile migrant compounds from adhesives used in food contact materials is a very challenging task because of the number of possible compounds involved, given that adhesives are complex mixtures of chemicals. The use of ultra-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UPLC-MS/QTOF) is shown to be a successful tool for identifying non-targeted migrant compounds from two hot melt adhesives used in food packaging laminates. Out of the seven migrants identified and quantified, five were amides and one was a compound classified in Class II of the Cramer toxicity. None of the migration values exceeded the recommended Cramer exposure values.     

Determination of fifteen active compounds released from paraffin-based active packaging in tomato samples via microextraction techniques

Automated headspace solid-phase microextraction (HS-SPME) and hollow-fibre liquid-phase microextraction (HFLPME) methods for the determination of 15 active chemicals released from essential-oil-based active packaging have been considered. The HS-SPME procedure demonstrates good performance and was therefore optimised and validated, providing detection limits in the low microgram per kilogramme range and wide and convenient linear ranges from 40.0 to 900.0 μg/kg. Extraction temperature has been demonstrated to be the most critical experimental parameter requiring accurate monitoring.     

Multi-elemental analysis of non-food packaging materials by inductively coupled plasma-time of flight-mass spectrometry

Commercial non-food packaging materials of four different matrices (paper, low density polyethylene (LDPE), polyethylene-polypropylene (PE-PP) and high density polyethylene (HDPE)) were examined for the content of Cr, Ni, Cu, Zn, As, Mo, Cd, Sb, Ba, Hg, Tl, Pb and U. The examined samples (0.17–0.35 g) were digested in HNO₃ and H₂O₂ (papers, LDPE and PE-PP) and in HNO₃, H₂SO₄ and H₂O₂ (HDPE) using microwave assisted high pressure system. The inductively coupled plasma-time of flight-mass spectrometry (ICP-TOFMS) has been employed as the detection technique. All measurements were carried out using internal standardization. Yttrium and rhodium (50 ng g⁻¹) were used as internal standards. The detection and quantification limits obtained were in the range of 0.005 ng g⁻¹ (⁵²Cr) to 0.51 ng g⁻¹ (⁶⁶Zn) and 0.015 μg g⁻¹ (⁵²Cr) to 2.02 μg g⁻¹ (⁶⁶Zn) of dry mass, respectively. The evaluated contents (mg kg⁻¹) of particular elements in the examined materials were as follows: 0.22–219; <1.05–9.03; 1.25–112; <2.02–449; <0.98–<1.30; <0.36–2.06; <0.29–113; <0.22–44.1; <0.06–57.4; <0.66–<0.88; <0.08–0.24; <0.13–1222 and <0.08–0.44 for Cr, Ni, Cu, Zn, As, Mo, Cd, Sb, Ba, Hg, Tl, Pb and U, respectively.     

New materials from new catalysts

The polyolefins, especially polypropylene and polyethylene, industry of today is very different from that of 10 years ago. The development of highly active and stereospecific catalysts, represented by Ti/Mg supported catalysts, have made the gas-phase polymerization process practical. The trend in catalyst development is shifting from an emphasis on improving the stereospecificity and activity toward improving the polymer physical properties, processability and morphology. Many hybrid thermoplastic olefins, such as high-impact copolymers, propylene–ethylene–butene terpolymers, and very low density polyethylene, have already been developed by utilizing the features of the gas-phase polymerization process. These hybrid thermoplastic olefins cover a very broad range of products. They cannot be clearly identified as polyethylenes, polypropylenes or elastomers. Incidentally, metallocene catalysts for polyolefins have been under development for the past 15 years, and are now in the early stage of commercialization. These catalysts differ significantly from the conventional heterogeneous catalysts. They can polymerize not only ethylene, propylene and other linear α-olefins, but also styrene, cycloolefins and functional monomers In addition, they can control the microstructure of polymer molecules by varying the transition metals and the cyclopentadienyl ligands. Because of these features, we have to be confident that the development of metallocene catalysts, or more widely homogeneous catalysts, may be a dominant force throughout the 1990s in the polyolefin industries.     

Radiation treatment for sterilization of packaging materials

Treatment with gamma and electron radiation is becoming a common process for the sterilization of packages, mostly made of natural or synthetic plastics, used in the aseptic processing of foods and pharmaceuticals. The effect of irradiation on these materials is crucial for packaging engineering to understand the effects of these new treatments. Packaging material may be irradiated either prior to or after filling. The irradiation prior to filling is usually chosen for dairy products, processed food, beverages, pharmaceutical, and medical device industries in the United States, Europe, and Canada. Radiation effects on packaging material properties still need further investigation. This paper summarizes the work done by different groups and discusses recent developments in regulations and testing procedures in the field of packaging technology.     

An overview of polylactides as packaging materials

Polylactide polymers have gained enormous attention as a replacement for conventional synthetic packaging materials in the last decade. By being truly biodegradable, derived from renewable resources and by providing consumers with extra end-use benefits such as avoiding paying the "green tax" in Germany or meeting environmental regulations in Japan, polylactides (PLAs) are a growing alternative as a packaging material for demanding markets. The aim of this paper is to review the production techniques for PLAs, summarize the main properties of PLA and to delineate the main advantages and disadvantages of PLA as a polymeric packaging material. PLA films have better ultraviolet light barrier properties than low density polyethylene (LDPE), but they are slightly worse than those of cellophane, polystyrene (PS) and poly(ethylene terephthalate) (PET). PLA films have mechanical properties comparable to those of PET and better than those of PS. PLA also has lower melting and glass transition temperatures than PET and PS. The glass transition temperature of PLA changes with time. Humidity between 10 and 95% and storage temperatures of 5 to 40 degrees C do not have an effect on the transition temperature of PLA, which can be explained by its low water sorption values (i.e. <100 ppm at Aw = 1). PLA seals well at temperatures below the melting temperature but an appreciable shrinking of the films has been noted when the material is sealed near its melting temperature. Solubility parameter predictions indicate that PLA will interact with nitrogen compounds, anhydrides and some alcohols and that it will not interact with aromatic hydrocarbons, ketones, esters, sulfur compounds or water. The CO2, O2 and water permeability coefficients of PLA are lower than those of PS and higher than those of PET. Its barrier to ethyl acetate and D-limonene is comparable to PET. The amount of lactic acid and its derivatives that migrate to food simulant solutions from PLA is much lower than any of the current average dietary lactic acid intake values allowed by several governmental agencies. Thus, PLA is safe for use in fabricating articles for contact with food.     

Direct determination of carnosic acid in a new active packaging based on natural extract of rosemary

A new antioxidant film is being developed that incorporates a natural extract of rosemary and is intended for contact with food. The rosemary extract has been screened and carnosic acid and carnosol have been determined as the major antioxidant components (6.96% and 0.88%, respectively) that are responsible for the antioxidant properties of the whole extract. Thus, a fast method for the direct determination of carnosic acid in the packaging material, in order to evaluate the antioxidant capacity of the new active plastic, has been developed and optimized. The method consists of extraction from the plastic with methanol, followed by anion exchange solid-phase extraction and final analysis by UPLC–MS. Using this process, the recovery of carnosic acid is about 99%. The complete analytical performance of the method developed here is also assessed. The analytical features of the method, such as the relative standard deviation, reproducibility, repeatability, linear range, and detection and quantification limits, are shown. This method can be subsequently modified to monitor other active components in different packages, and it constitutes a crucial step forward in research into new and improved commercial antioxidant packages.     

Biodegradation of packaging materials: composting of polyolefins

The compostability of LDPE, PP and heterophasic E-P Copolymers was studied for 5 months under normal and accelerated composting environments. Bio-susceptibility of pre-UV (290 nm) treated films (∼ 100μm, 5 X 5 cm) was measured by monitoring the weight loss, intrinsic viscosity [η], chain scission, functional group evolution (FT-IR) and surface morphology (SEM). It was found that with the increasing time of UV treatment, weight loss was increased in compost. Almost linear decrease in [η] was observed for irradiated and composted samples. The temperature of compost and extra addition of thermophilic microbes significantly influenced the biodegradation. In general, it was concluded that the composition of copolymer markedly affected the compostability and increased ethylene content, slowed down the microbial activity.     

Sample handling strategies for the analysis of non-volatile organic compounds from environmental water samples

There is a need for faster, simpler and automated methods for concentration and isolation of organic compounds from environmental water samples. On-line coupling of sample preparation to chromatographic analysis is a powerful strategy but trace-level determination requires selective solid-phase extractions to remove matrix interferences. Means for achieving selective sample handling are reviewed.     

Positively charged covalent organic framework and its application in the dispersive solid-phase extraction of ultraviolet-filters from food packaging material migrants

Abstract

Covalent organic frameworks (COFs) show excellent property, such as high porosity and excellent structure stability and were well applied in fields such as catalysis and adsorption, but most of the COFs showed similar structure and thus similar adsorption performance. Modification of simple COFs to enhance its adsorption performance in separation technique is an important issue. In this study, quaternary ammonium groups with long hydrophobic chain were introduced into a simple COF (TpPa-1) for the first time. The positively charged COF (PC-TpPa-1) can form electrostatic interaction and hydrophobic effect with negatively charged analytes, and showed good adsorption performance for ultraviolet-filters (UV filters). Under the optimum conditions, i.e. adsorbent amount 20?mg, pH?=?7, 1.0?mL acetonitrile as eluent, the obtained recoveries for all UV filters were in the range of 86.4–96.7%.The developed method was successfully applied to the determination of UV filters from food packaging material migrants with the aid of HPLC as a detector.     

Compostability of bioplastic packaging materials: an overview

Packaging waste accounted for 78.81 million tons or 31.6% of the total municipal solid waste (MSW) in 2003 in the USA, 56.3 million tons or 25% of the MSW in 2005 in Europe, and 3.3 million tons or 10% of the MSW in 2004 in Australia. Currently, in the USA the dominant method of packaging waste disposal is landfill, followed by recycling, incineration, and composting. Since landfill occupies valuable space and results in the generation of greenhouse gases and contaminants, recovery methods such as reuse, recycling and/or composting are encouraged as a way of reducing packaging waste disposal. Most of the common materials used in packaging (i.e., steel, aluminum, glass, paper, paperboard, plastics, and wood) can be efficiently recovered by recycling; however, if packaging materials are soiled with foods or other biological substances, physical recycling of these materials may be impractical. Therefore, composting some of these packaging materials is a promising way to reduce MSW. As biopolymers are developed and increasingly used in applications such as food, pharmaceutical, and consumer goods packaging, composting could become one of the prevailing methods for disposal of packaging waste provided that industry, governments, and consumers encourage and embrace this alternative. The main objective of this article is to provide an overview of the current situation of packaging compostability, to describe the main mechanisms that make a biopolymer compostable, to delineate the main methods to compost these biomaterials, and to explain the main standards for assessing compostability, and the current status of biopolymer labeling. Biopolymers such as polylactide and poly(hydroxybutyrate) are increasingly becoming available for use in food, medical, and consumer goods packaging applications. The main claims of these new biomaterials are that they are obtained from renewable resources and that they can be biodegraded in biological environments such as soil and compost. Although recycling could be energetically more favorable than composting for these materials, it may not be practical because of excessive sorting and cleaning requirements. Therefore, the main focus is to dispose them by composting. So far, there is no formal agreement between companies, governments and consumers as to how this packaging composting will take place; therefore, the main drivers for their use have been green marketing and pseudo-environmental consciousness related to high fuel prices. Packaging compostability could be an alternative for the disposal of biobased materials as long as society as a whole is willing to formally address the challenge to clearly understand the cradle-to-grave life of a compostable package, and to include these new compostable polymers in food, manure, or yard waste composting facilities.     

Pyrolytic degradation of common polymers present in packaging materials

Journal of Thermal Analysis and Calorimetry - Pyrolysis of polymers with widespread use, such as PET, HDPE, PVC, LDPE, PP and PS, been utilized extensively as plastic packaging materials, is the...     

Capillary gas chromatographic analysis of volatile and non-volatile organic acids from biological samples as the t-butyldimethylsilyl derivatives

A quantitative procedure for the analysis of volatile organic acids and lactic acid in silage is described. The samples were extracted with diethyl ether, derivatized by t-butyldimethylsilylation, and then separated by capillary gas chromatography. The same procedure was useful for the identification by gas chromatography/mass spectrometry of organic acids in samples such as the metabolic fermentation products of anaerobic bacteria.     

Development of methods for testing barriers in food packaging materials

In some countries recycled materials are not allowed to come into contact with food without a protective layer such as plastic or virgin fiber. The purpose of this kind of barrier is to reduce migration of substances form beyond the barrier to the food. Two methods for studying a functional barrier are described. Both utilize migration cells in which one surface of the test specimen (for example a paper plate) is exposed to the food simulant. The first method involves the addition of indidcatsor substances to the non-food contact layer. The second method is to measure the migration of substances originally present in the layers beyond the functional barrier layer. Several kinds of barrier used in commercial papaer plates were studied and differences between them were found.     

Determination of bisphenol-type contaminants from food packaging materials in aqueous foods by solid-phase microextraction-high-performance liquid chromatography

A fast screening method consisting of off-line solid-phase microextraction coupled to HPLC and fluorescence detection, suitable for the analysis of several bisphenol derivatives and their degradation products in aqueous solution, has been developed. Detection limits of 0.7 ng ml(-1) for 2,2-bis[4-(glycidyloxy)phenyl]propane, 0.9 ng ml(-1) for bisphenol A bis(3-chloro-2-hydroxypropyl)ether, 1.1 ng ml(-1) for 2,2-bis(4-hydroxyphenyl)propane and 2.4 ng ml(-1) for bisphenol F diglycidyl ether have been achieved working in the linear range 10-500 ng ml(-1). The good analytical features achieved make the proposed method an interesting option for the direct determination of these compounds in aqueous canned food such as peas, tuna, olives, maize, artichokes or palm hearts. Both the optimization process and the results, including the analysis of real samples, are given and discussed.     

Graphites from the Zavalie deposit as active materials for lithium-ion batteries

We study the utility of standard graphites (GAK-2, GL-1, EUZ-M, and others) produced by the Zavalie Integrated Graphite Plant (ZGP) as active materials in lithium-ion batteries (LIBs). The structure and main electrochemical characteristics of these graphites are studied for choosing the best type of graphite and evaluating its utility for LIB production. The electrochemical characteristics of the best ZGP graphites and graphite for batteries produced by Superior Graphite Co. (USA), a worldwide leader of the graphite industry, are compared. Some tendencies in the effect of the structure and particle-size distribution on the electrochemical characteristics of graphite electrodes are determined. EUZ-M graphite modified by tin with amorphous carbon is prepared. The reversible capacity of this graphite in the cell against LiCoO₂ exceeds 400 mA h/g. The increased reversible capacity is due to the contribution of components having higher specific parameters; the cycling stability is due to the core-shell structure.