Ion mobility quadrupole time-of-flight mass spectrometry for the identification of non-intentionally added substances in UV varnishes applied on food contact materials. A safety by design study

Varnishes are normally applied on printed food packaging to protect it from smearing and scratching. Moreover, they may be applied on the food contact surface in order to improve resistance towards moisture and fat. Some of the compounds that make up the varnish formulation could migrate to the food. In this work, the ion mobility quadrupole time-of-flight mass spectrometry has been used to obtain drift time-aligned mass spectra in which accurate the mass of precursor ions and their fragments are used to identify both intentionally and non-intentionally added substances (NIAS). The compound 2-propenoic acid,1,1'-[2-[[3-[2,2-bis[[(1-oxo-2-propen-1-yl)oxy]methyl]butoxy]-1-oxopropoxy]methyl]-2-ethyl-1,3-propanediyl] ester was identified as a NIAS formed from the varnish monomer 2-propenoic acid, 1,1'-[2-ethyl-2-[[(1-oxo-2-propen-1-yl)oxy]methyl]-1,3-propanediyl] ester. The compound 5, 11-diethyl-7-oxo-4,6,10,12-tetraoxopentadecane-3,13-diyl diacrylate is a NIAS derived from the varnish monomer 2-propenoic acid, 1,1'-[oxybis(methyl-2,1-ethanediyl)] ester, and was found to migrate into the food simulant tested at a level of 0.03 mg kg^-1. Finally, the NIAS, 2-{2-[2-(acryloyloxy)-1-methylethoxy]-1-methylethoxy}-1-methylethyl acrylate, an impurity of a photoinitiator used for UV curing of the varnish, was identified, and its migration of 0.14 mg kg^-1 exceeded the threshold established as safe for human consumption.

Phenolic content and antioxidant activity of olive by-products and antioxidant film containing olive leaf extract

The antioxidant activity of olive leaf (OL) and cake (OC) extracts with different solvents was evaluated. 70% of aqueous ethanol extract of OL was chosen as the most antioxidant extract based on antiradical activity (DPPH) (95.4±0.3%) and oxygen radical absorbance capacity (ORAC) (0.82±0.07g equivalent Trolox per g of solution) assays. This OL extract was incorporated in two multilayer materials consisting of (i) polyethylene/polyethylene (PE/PE) film and (ii) polyethylene/paper (PE/P). These multilayers were exposed to a gas stream enriched in free radicals to evaluate the scavenging capacity of both materials. PE/PE film exhibited the highest scavenging activity of free radicals (78.8%). Migration of the phenolic compounds from olive by-products into two simulants was performed and demonstrated a non-migrating behavior. The limits of detection and quantification for oleuropein were 0.5μgkg(-1) and 1.7μgkg(-1) and for Luteolin-7-O-glucoside 1.3μgkg(-1) and 4.3μg kg(-1) respectively.

New UPLC coupled to mass spectrometry approaches for screening of non-volatile compounds as potential migrants from adhesives used in food packaging materials

The objective of this study was to identify the non-volatile compounds as potential migrants from adhesives used in food packaging. A number of the current acrylic adhesive formulations were extracted and prepared for analysis. The extracts were screened using ultra-performance liquid chromatography coupled to a time-of-flight mass spectrometer detector (UPLC-TOF-MS). This approach allowed the identification of several components by a combination of exact mass and in-source collision induced dissociation (CID). Due to the lack of freely available information on adhesive formulations further analyses were undertaken using ultra-performance liquid chromatography coupled to high definition mass spectrometry (UPLC-HDMS). Using the Mass Fragment tool to interrogate fragmentation data, a wide series of compounds were identified, demonstrating the usefulness and importance of these tools for difficult problems. Moreover, using several packaging materials containing adhesives, qualitative migration tests were performed with Tenax as a food simulant. Several non-volatile compounds were identified as well in the Tenax which emphasizes the importance of this work and demonstrates that even the non-volatile compounds have the potential to migrate into food which is in contact with packaging materials. The main characteristics of the screening study and the results obtained are shown and discussed.

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.

New cinnamon-based active paper packaging against Rhizopusstolonifer food spoilage

A new active paper package based on the incorporation of cinnamon essential oil to solid wax paraffin as an active coating is proposed, developed, and evaluated. The antifungal activity of the active paper is tested against Rhizopusstolonifer, and the results demonstrate that 6% (w/w) of the essential oil in the active coating formulation completely inhibits the growth of R. stolonifer, whereas 4% still has strong antimicrobial activity in in vitro conditions. Then, active paper is evaluated with actual food, sliced bread, using different storage times. After 3 days of storage, almost complete inhibition is obtained with 6% cinnamon essential oil. Qualitative analysis by solid-phase microextraction and determination of cinnamaldehyde in the sliced bread were also performed and confirmed the strong correspondence between the inhibition of the mold and the amount of cinnamaldehyde in the bread.

Determination of bile acids in human serum by on-line restricted access material-ultra high-performance liquid chromatography-mass spectrometry

This paper describes a new, fully automated on-line method combining restricted access material (RAM) extraction and ultra high-performance liquid chromatography (UHPLC) with mass spectrometric (MS) detection for determining congeners of bile acids (BAs) in human serum. In this method, low-pressure RAM and high-pressure UHPLC-MS are hyphenated by using a 2.5-mL loop-type interface. The compatibility problem between the large volume (1.2mL) of strong solvent (methanol) used for RAM elution and the need for a weak solvent in UHPLC injection has been addressed by using an auxiliary pre-column cross-flow of 0.1% aqueous formic acid. In this way, the complete 2.5mL loop volume can be injected into the UHPLC system, thereby maximizing sensitivity while maintaining good chromatographic performance. The optimised method allows the simultaneous analysis of 13 bile acids in a single run, including glycine- and taurine-conjugated bile acids, cholic acid (CA), deoxycholic acid (DCA), chenodeoxycholic acid (CDCA), ursodeoxycholic acid (UDCA), and litocholic acid. The complete analysis of a 100-microL single serum sample is performed in 30 min, providing detection limits in the pg range (corresponding with clinically relevant concentration levels) for all of the analytes except lithocholic acid, intra-day precision values (%R.S.D.) below 4% (except ursodeoxycholic acid) and inter-day precision lower than 15% (except ursodeoxycholic, glycoursodeoxycholic acid (GUDCA) and lithocholic acid).

Selective three-phase liquid phase microextraction of acidic compounds from foodstuff simulants

A three-phase liquid phase microextraction (LPME) technique with high selectivity for five aromatic carboxylic acids and three phenolic compounds has been developed and optimized. The system consists of an acidified donor phase, a thin layer of solvent inside the wall pores of a hollow fiber, and an alkaline acceptor phase located inside the hollow fiber. The analysis of the compounds in the acceptor phase was carried out by capillary electrophoresis with UV detection. Eugenol, thymol, and carvacrol were efficiently extracted from the aqueous solution using chloropentane as organic phase, with recoveries from 73.8% to 93.8%. However, using 2-octanone as the organic phase, the recoveries for the aromatic carboxylic acid compounds ranged from 60.7% to 93.7% whereas the phenols were not extracted. 2,6-naphthalene-dicarboxylic acid was found to remain in the organic phase. The influence of 10% ethanol and 3% acetic acid in the donor phase was deeply studied as these solutions are commonly used as food simulants. AS4 silicone oil was found to be the best organic phase for the extraction of phenols both in 3% acetic acid and matrices with a high content of alcohol. The results obtained are shown and discussed.

Development of flexible antimicrobial films using essential oils as active agents

The antimicrobial activity in the vapor-phase of laboratory-made flexible films of polypropylene (PP) and polyethylene/ethylene vinyl alcohol copolymer (PE/EVOH) incorporating essential oil of cinnamon ( Cinnamomum zeylanicum), oregano ( Origanum vulgare), clove ( Syzygium aromaticum), or cinnamon fortified with cinnamaldehyde was evaluated against a wide range of microorganisms: the Gram-negative bacteria Escherichia coli, Yersinia enterocolitica, Pseudomonas aeruginosa, and Salmonella choleraesuis; the Gram-positive bacteria Listeria monocytogenes, Staphylococcus aureus, Bacillus cereus, and Enterococcus faecalis; the molds Penicillium islandicum, Penicillium roqueforti, Penicillium nalgiovense, Eurotium repens, and A spergillus flavus and the yeasts Candida albicans, Debaryomyces hansenii, and Zigosaccharomyces rouxii. Films with a nominal concentration of 4% (w/w) of fortified cinnamon or oregano essential oil completely inhibited the growth of the fungi; higher concentrations were required to inhibit the Gram-positive bacteria (8 and 10%, respectively), and higher concentrations still were necessary to inhibit the Gram-negative bacteria. PP films were more effective than PE/EVOH films. The atmospheres generated by the antimicrobial films inside Petri dishes were quantitatively analyzed using headspace-single drop microextraction (HS-SDME) in combination with gas chromatography-mass spectrometry (GC-MS). The analyses showed that the oregano-fortified PP films released higher levels of carvacrol and thymol, and the cinnamon-fortified PP films released higher levels of cinnamaldehyde, during the first 3-6 h of incubation, than the corresponding PE/EVOH films. Shelf-life tests were also performed, demonstrating that the antifungal activities of the films persisted for more than two months after their manufacture. In addition, migration tests (overall and specific) were performed, using both aqueous and fatty simulants, to ensure that the films meet EU regulations regarding food contact materials. Following contact with the tested films, the substances that had migrated into the aqueous simulants were recovered by direct immersion-single drop extraction (DI-SDME) and then analyzed by GC-MS. The fatty stimulant (isooctane) was directly injected into the chromatographic system.

Combination of analytical and microbiological techniques to study the antimicrobial activity of a new active food packaging containing cinnamon or oregano against E. coli and S. aureus

The aim of this work is the optimization and application of a group of analytical and microbiological techniques in the study of the activity of essential oils (EOs) incorporated in a new antimicrobial packaging material and the research in depth of the interaction between the microbial cells and the individual compounds present in the active material. For this purpose the antimicrobial activity of the active packaging containing cinnamon or oregano was evaluated against E. coli and S. aureus. The vapour phase activity and the direct contact between the antimicrobial agents themselves, or once incorporated in the packaging material, and the microbial cells have been studied. The direct contact was studied using a broth dilution method. The vapour phase was evaluated by using a new method which involves the use of a filter disk containing the EOs. Furthermore, the kill time assay was used to determine the exposure time for the maximum efficiency in packaging, and transmission electron microscopy was used to investigate the antimicrobial activity and the possible mechanism of action against E. coli and S. aureus. Finally, the compounds absorbed by cells were identified. The results showed that the techniques used provide relevant information about the antibacterial activity of cinnamon and oregano in direct contact as well as in the vapour phase. The antimicrobial packaging showed a fast efficiency which supports its likely application as a food packaging material. Bacteria treated with EOs exhibit a wide range of significant abnormalities; these include formation of blebs, coagulation of cytoplasmatic constituents, collapse of the cell structure and lack of cytoplasmatic material. Some of these observations are correlated to the ability of some of these substances to disrupt envelop structure, especially the inner membrane. After an extraction from dead cells, cinnamaldehyde was detected by GC-MS in E. coli exposed to the active packaging containing cinnamon.

UPLC–MS as a powerful technique for screening the nonvolatile contaminants in recycled PET

The possibility of using recycled polyethylene terephthalate as a food contact material is being seriously considered, but the potential migration of nonvolatile compounds from it must be assessed to ensure that it is safe to do so. In the study presented here, four samples of recycled PET were each exposed to three food simulants under the harsh extraction conditions stipulated by European legislation regarding migration tests. The nonvolatile compounds that migrated from them were determined by ultra performance liquid chromatography-mass spectrometry using three different cone voltages, and both positive and negative ionization modes. A total of 36 chemical compounds were detected, some of which were identified, including common additives such as N,N'-di-beta-naphthyl-p-phenylenediamine (antioxidant) and 2,4-di-tert-butyl-6-(5-chloro-2H-benzotriazol-2-yl)phenol (light stabilizer) as well as degradation compounds such as ethylene terephthalate dimers and trimers. In addition, specific migration values of three common components of polyethylene terephthalate (diethylene glycol, terephthalic acid, and isophthalic acid) were determined and found to occur at levels of <1 mg/kg-much lower than the specific migration limits stipulated by European legislation.

Application of salicylic acid dosimetry to evaluate hydrodynamic cavitation as an advanced oxidation process

The generation of OH* radicals inside hydrodynamic cavitation bubbles was monitored using a salicylic acid dosimeter. The reaction of this scavenger with OH* produces 2,5-dihydroxybenzoic acid (2,5-DHB) and, to a lesser degree, 2,3-DHB. The former, is a specific reaction product that can be determined with a very high sensitivity using HPLC-IF. This method has been applied to study the influence of the flow-rate and the solution pH for a given cavitation chamber geometry. The salicylic dosimetry has proven especially suitable for the characteristic time scales of hydrodynamic cavitation (higher than those of ultrasonic cavitation), which usually gives rise to recombination of radicals before they can reach the liquid-phase. Working at low pH the hydrophobic salicylic acid migrates to the gas-liquid interface and reacts with the OH* radicals, increasing the trapping efficiency of the dosimeter. Hydrodynamic cavitation works as a very low frequency sonochemical reactor, and therefore its potential as an Advanced Oxidation Process might be limited to reactions at the gas-liquid interface and inner bubble (i.e. with volatiles and/or hydrophobic substances).

Kinetic migration studies using Porapak as solid-food simulant to assess the safety of paper and board as food-packaging materials

Porapak has been studied as a solid-food simulant in experiments on paper and board packaging. Three samples of paper with different recycled pulp content and surface treatment, and of different grammage and thickness, were used for the studies. Kinetic behaviour from 25 degrees C to 100 degrees C and different contact times ranging from 5 min at 100 degrees C to 10 days at 25 degrees C were studied using Porapak or, occasionally, Tenax or milk powder. Similar results were obtained with Porapak and Tenax but those from Porapak were more stable with temperature. Porapak behaves as good solid-food simulant even at high temperature.

Design of a method for generation of gas-phase hydroxyl radicals, and use of HPLC with fluorescence detection to assess the antioxidant capacity of natural essential oils

The use of natural antioxidants is of increasing importance in the human diet, because they are recognised as compounds essential to health which minimize or delay the aging process. Despite apparent simplicity, however, it is very difficult to measure and quantify such properties, for which a robust analytical method is required. Because oxidation usually is caused by the presence of OH* radicals, a new method involving the in-situ, vapour-phase generation of these radicals and their quantification in the presence and absence of potential antioxidant extracts has been developed. The oxidant atmosphere generated from hydrogen peroxide is carried by an air stream through an empty quartz chamber in which UV radiation promotes the formation of radicals by a photochemical reaction. The products then pass through a cartridge containing the essential oil, finally bubbling into an impinger containing an aqueous solution of salicylic acid, at pH 4.5, which reacts with the OH* radicals forming 2,5-dihydroxybenzoic acid. This solution is quantified by RP-HPLC using UV and fluorescence detectors connected in series. Detection and quantification limits for OH* radicals were approximately 0.01 pg g(-1) air. Description and optimization of the method are discussed, as also is the antioxidant performance of an extract of ginger (Zingiber officinale R.), which reduced the oxidation process by up to 92%.

Development of a solid-phase microextraction method for direct determination of pentachlorophenol in paper and board samples: Comparison with conventional extraction method

A solid-phase microextraction (SPME) method has been developed for the determination of pentachlorophenol (PCP) in paper and board samples. The analytical procedure involves direct extraction of PCP from paper and board samples and determination by gas chromatography with electron capture detection (GC-ECD). Two kinds of commercially available fibres; 100 microm polydimethylsiloxane (PDMS), apolar, and 85 microm polyacrylate (PA), quite polar, were evaluated to determine the extraction efficiency of pentachlorophenol. Parameters affecting the extraction process, such as temperature and time, were studied. Moreover, time of desorption and the effect of addition of salt were also investigated. The optimized procedure was applied to the analysis of pentachlorophenol (PCP) in five samples of virgin and recycled paper and board. The PCP content was determined by GC-ECD. To evaluate the effectiveness of the proposed method, it was compared with conventional extraction method with liquid-liquid extraction and derivatization. Detection limit of 0.015 microg/g for PCP in paper was achieved with a RSD of 14%.

Solid- and vapor-phase antimicrobial activities of six essential oils: susceptibility of selected foodborne bacterial and fungal strains

The antimicrobial activity of essential oils (EOs) of cinnamon (Cinnamon zeylanicum), clove (Syzygium aromaticum), basil (Ocimum basillicum), rosemary (Rosmarinus officinalis), dill (Anethum graveolens), and ginger (Zingiber officinalis) was evaluated over a range of concentrations in two types of contact tests (solid and vapor diffusion). The EOs were tested against an array of four Gram-positive bacteria (Staphylococcus aureus, Bacillus cereus, Enterococcus faecalis, and Listeria monocytogenes), four Gram-negative bacteria (Escherichia coli, Yersinia enterocolitica, Salmonella choleraesuis, and Pseudomonas aeruginosa), and three fungi (a yeast, Candida albicans, and two molds, Penicillium islandicum and Aspergillus flavus). The rationale for this work was to test the possibility of creating a protective atmosphere by using natural compounds that could extend the shelf life of packaged foodstuffs while minimizing organoleptic alterations. In the solid diffusion tests, cinnamon and clove gave the strongest (and very similar) inhibition, followed by basil and rosemary, with dill and ginger giving the weakest inhibition. The fungi were the most sensitive microorganisms, followed by the Gram-positive bacterial strains. The Gram-negative strain P. aeruginosa was the least inhibited. The composition of the atmosphere generated by the EOs, and their minimum inhibitory concentrations (MICs), were determined using a disk volatilization method, in which no inhibition from rosemary or basil was observed. Cinnamon and clove, once again, gave similar results for every microorganism. As a general rule, MIC (fungi) << MIC (bacteria) with no clear differences between Gram-positive or -negative strains except for P. aeruginosa, which was not inhibited by any of the EOs in the vapor phase. The atmosphere generated from the EOs was analyzed by means of solid-phase microextraction combined with gas chromatography-ion trap mass spectrometry. Differences among the volatiles in the EOs, which may be responsible for the differences in their antimicrobial performances, were found.

Supercritical Fluid Extraction of Energetic Nitroaromatic Compounds and Their Degradation Products in Soil Samples

This paper explores the use of supercritical fluid extraction (SFE), in combination with various analyte collection strategies, for extracting energetic nitroaromatic compounds and their degradation products from soil samples. The required selectivity has been achieved by a combination of an SFE program and active trapping. Several different collection strategies were tested, using a selection of liquids (methanol, toluene, methyl tert-butyl ether, acetonitrile), inert and solid-phase extraction materials (Nexus, Oasis, LiChrolut), and 1-cm liquid chromatography precolumns (porous graphitic carbon, PGC). The best results were obtained using SFE in combination with a PGC precolumn. This setup allows on-line cleanup of the extract, and comparable results were obtained using either GC-ECD or GC-chemical ionization-MS for confirmatory analysis. The time required for a complete analysis was less than 60 min, and only 1 mL of toluene was needed for a 0.5-g representative sample. In contrast, the EPA standard method 8330 required 18-h sonication and 20 mL of acetonitrile for a 4.0-g sample and further time for sample cleanup and HPLC analysis. The method presented here provides method detection limits in the low-nanogram range, with relative standard deviations lower than 7%. The optimized method has been compared and validated with EPA method 8330 in terms of efficiency parameters such as robustness, accuracy (trueness and precision), and capability of detection. The validation demonstrated that the two analytical methodologies give comparable performance for the determination of nitroaromatic compounds, but SFE is superior for analyzing amine degradation products.

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.

Potential migration release of volatile compounds from plastic containers destined for food use in microwave ovens

Several commercially available plastic containers of polycarbonate, polypropylene-copolymer, polypropylene-20% talcum, polypropylene random and styrene-acrylonitrile designed for heating food in microwave ovens were studied. The analytical procedure based on a purge & trap (P&T) GC-MS was optimized. It consisted of heating the materials at 100 degrees C in a P&T system coupled in line with GC-MS equipment. The compounds released from the materials were then identified through their mass spectra. Variables such as the time of purge using helium as the carrier gas in the system, sample temperature, the type of solid trap, the desorption temperature and the time as well as chromatographic separation of all the compounds released from the plastic were optimized. Compounds such as methylbenzene, ethylbenzene, 1-octene, xylene, styrene and 1,4-dichlorobenzene were found in all the containers. Quantitative analysis and potential migrations are reported and discussed.

Determination of plastic monomers in water by solid-phase microextraction coupled with liquid chromatography

A method is presented for the determination of 2 major plastic monomers, terephthalic acid and vinyl acetate, which are widely used to manufacture plastics that come in contact with foods. The analytes are extracted from aqueous solution by using solid-phase microextraction, followed by quantitation by liquid chromatography (LC) with UV detection. Multivariate optimization was applied and is described. The optimized method has linear ranges of 5-150 microg/g for terephthalic acid and 7.5-100 microg/g for vinyl acetate. Coefficients of variation at a spiking level of 20 microg/g were 13.6% for terephthalic acid and 3.1% for vinyl acetate; detection and quantitation limits were 0.59 and 1,99 microg/g, respectively, for terephthalic acid and 1.56 and 5.20 microg/g, respectively, for vinyl acetate. The characteristics of both the extraction technique and its coupling with LC are described and discussed.

Use of solid-phase microextraction for the analysis of bisphenol A and bisphenol A diglycidyl ether in food simulants

A new method has been developed to simultaneously analyse bisphenol A (BPA) and bisphenol A diglycidyl ether (BADGE) in aqueous based food simulants. The method consists on direct immersion solid-phase microextraction (SPME) of the analytes from the liquid matrix and subsequent chromatographic analysis by gas chromatography-mass spectrometry. Using the proposed method, a whole analysis (including chromatographic step) can be completed in less than 40 min, with minimum sample handling. The SPME method shows good analytical performance for simultaneous BPA and BADGE analysis, except for BADGE determination in the aqueous alcohol (simulant C) solution. Detection limits ranging from 0.1 to 2.0 ng/g for BPA and from 13 to 15 ng/g from BADGE were obtained, with a linear range from the low-ng/g to several-microg/g range for BPA and from 0.1 microg/g to 40 microg/g for BADGE. A possible optimisation method has been also developed and introduced.

Distribution of Pb, V, Cr, Ni, Cd, Cu and Fe in particles formed from the combustion of waste oils

The determination of Pb, V, Cr, Ni, Cd, Cu and Fe in particles of different size obtained from the combustion of waste oils has been carried out. The study consists of the separation of several fractions according to the size of particles, the wet digestion and the individual analysis by graphite furnace atomic absorption spectrometry of the mentioned metals. Taking into account the volatilization temperature of different compounds containing the metals and their distribution on the size fractions, the mineral speciation of metals is proposed.

Assessing the suitability of recycled plastics used as agricultural soil covers: migration study and experimental harvest

The present work is focused on evaluating the suitability of recycling postconsumer agricultural plastic films again for the same use. The criteria to assess the suitability was based on migration study. Both overall and specific migration tests were performed, and the results obtained (ranging from 0.14 to 1.27 mg/dm(2) for overall migration and from not detectable to 6.98 microg/dm(2) for specific migration) show how, from this point of view, the recycled material can be safely proposed to be used again as agricultural soil covers. A theoretical discussion about the migration process is also presented and a simple mathematical model was applied to the data obtained, showing how total migration which is experimentally detected is theoretically predictable. These conclusions found were used to design and develop a controlled crop of tomato by using this recycled film. The use of the recycled plastic in the whole process and the behavior and properties of the pesticides absorbed in the postconsumer film are discussed.

Multicomponent recycled plastics: considerations about their use in food contact applications

Two multicomponent post-use recycled plastics named as NPP40A3 (formulated with 85% HDPE and 15% of a PP-PS-PVC mixture) and NPP40A6 (formulated with 80% NPP40A3, 10% ABS and 10% HIPS), both of them with 3.1% of plasticizer and 0.6% of stabilizer to obtain a better final product, have been analysed. Plastics were extracted both with dichloromethane and methylbenzene, and analysed by HPLC and GC-MS to identify the maximum possible number of compounds. Major additives quantified were di(ethylhexyl)phthalate (3.262% and 2.955% respectively) and Irganox 1010 (0.473% and 0.498% respectively). Several degradation compounds have been detected. In order to check if these plastics could be used in food contact applications, global and specific migration tests have been applied. The results obtained are discussed.

Speciation of ionic alkyllead compounds in human urine by gas chromatography-mass spectrometry after butylation through a Grignard reaction

One analytical procedure for the determination of ionic alkyllead in human urine has been studied. The system consists of the extraction of Me3Pb+, Et3Pb+ and Pb2+ at pH 9.0 with diethyldithiocarbamate to an organic phase. Then, the ionic compounds are butylated with BuMgCl and the final organic solution is analyzed by GC-MS-SIM. The elimination of both foam and gels in the extraction step and the general procedure for the urine are discussed. The recovery of compounds ranges from 105.1% for Me3Pb+ to 97.2% for Et3Pb+ using hexane as extracting agent and detection limits are 18.4 pg/ml of Me3Pb+ and 19.2 pg/ml of Et3Pb+ in urine. The speciation of ionic alkylleads in the urine of a petrol station worker showed a value of 27.9 pg/ml of Me3Pb+ in urine and Et3Pb+ was below the detection limit.

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.

Design of a test for migration studies in the vapour phase

A new test for migration studies in the vapour phase has been developed. The system consists of placing the packaging material containing the potential migrants in a glass vial together with the solid adsorbent, Tenax GC. The vial is introduced into an oven at a controlled temperature for different periods of time. Once the migration test has finished, Tenax is extracted by supercritical fluid chromatography (SFE) and analysed by GC-ECD. Migration conditions of 7 days at 80 degrees C are proposed. The results obtained are discussed.

Determination of UV stabilizers in PET bottles by high performance-size exclusion chromatography

A Size Exclusion Chromatography-High Performance Liquid Chromatography (SECHPLC) method to determine antioxidants and UV stabilizers in PET bottles has been developed. In only a single run a synthetic mixture of the stabilizers was separated and quantified. The detection limit obtained for BHT, Tinuvin 326, Cyasorb UV 5411, and Tinuvin P was about 0.1 microgram/g and for Irgafos 168 it was 1.0 microgram. RSD values were lower than 3%. Tinuvin P was identified and quantified in PET bottle extracts. Olive oil, soybean oil and sunflower oil showed well defined separation from Tinuvin P at the same conditions of analysis. Cyclic dimers were identified in the PET extracts.

Behaviour of Chimassorb 81 in the recycling process of agricultural films used as soil covers

Two different films, low density polyethylene (LDPE) and an ethylene-vinyl acetate copolymer (EVA), used as agricultural soil covers were studied. The films were recycled five and ten times respectively, and both the tensile strength and the content of Chimassorb 81, a UV-stabilizer, were analysed in each cycle. Losses of 17.44% in tensile strength and 23.69% (Thermic film) and 13.22% (EVA) in the concentration of Chimassorb 81 were found after five recycling cycles. The extraction of Chimassorb 81 from the film is optimized. As these films can be recycled for the same application or even for use as food-contact materials, the standard migration tests with established simulants have been carried out. The results obtained are discussed.