Search

The analysis of sterols in biological fluids allows the clinical study of cholesterol related diseases. This research is focused on reducing the sample processing time of the determination of free and bonded sterols in human serum. Ten sterols were studied: cholesterol precursors (desmosterol, lanosterol, and cholestanol); phytosterols (stigmasterol, campesterol, sitosterol, and sitostanol) and oxysterols (7-α-hydroxy-4-cholesten-3-one, 24-hydroxycholesterol, and 27-hydroxycholesterol). Ultrasound assistance was used to diminish the reaction time during the alkaline hydrolysis for determining total sterols. Different retention mechanisms of solid-phase extraction were compared, two reversed-phase sorbents DSC-18 and polymeric Oasis-HLB and a novel zirconia-coated silica phase. DSC-18 and zirconia-coated silica were the most suitable sorbents to analyze these metabolites. The resulting extracts were analyzed by liquid chromatography coupled to mass spectrometry. The analytical parameters were determined and better values were observed with DSC-18 cartridges for most sterols. LOQ were in the low ng/mL level. Recoveries were in the range 85-99%. Average intermediate precision was 15%. Accuracy for both cartridges was more than 92%. Zirconia-coated silica showed better performance for the oxysterols, with recoveries around 90%. The procedure allows the determination of free and bonded sterol precursors, phytosterols, and oxysterols in human serum., (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Adhesives are often responsible for off-flavors in food in contact with packaging. The aim of this investigation was to identify by GC-O-MS the odorous compounds in five different types of adhesive (hotmelt, vinyl acetate ethylene, starch, polyvinyl acetate and acrylic) used in food packaging. In order to obtain a substantial number of compounds, they were extracted by two complementary extraction methods: HS-SPE and HS-SPME. Fifteen minutes extraction time using PDMS fiber for hotmelt adhesive and DVD/CAR/PDMS fiber for the other adhesives were the best conditions for defining a representative solvent-free adhesive extract using a rapid and simple D-GC-O technique. Thirty-three compounds were identified by GC-O-MS. These include butyric acid, acetic acid, methyl butyrate, 1-butanol and nonanal, which were present in most of the adhesives under study producing cheesy, rancid, sour, medicinal and green aromas, respectively. The concentrations were determined, the most abundant compound being acetic acid with concentrations from 22.9 to 8930 μg g(-1) of adhesive., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Ethyl Lauroyl Arginate (LAE) is a cationic tensoactive compound, soluble in water, with a wide activity spectrum against moulds and bacteria. LAE has been incorporated as antimicrobial agent into packaging materials for food contact and these materials require to comply with the specific migration criteria. In this paper, one analytical procedure has been developed and optimized for the analysis of LAE in food simulants after the migrations tests. It consists of the formation of an ionic pair between LAE and the inorganic complex Co(SCN)(4)(2-) in aqueous solution, followed by a liquid-liquid extraction in a suitable organic solvent and further UV-Vis absorbance measurement. In order to evaluate possible interferences, the ionic pair has been also analyzed by high performance liquid chromatography with UV-Vis detection. Both procedures provided similar analytical characteristics, with linear ranges from 1.10 to 25.00 mg kg(-1), linearity higher than 0.9886, limits of detection and quantification of 0.33 and 1.10 mg kg(-1), respectively, accuracy better than 1% as relative error and precision better than 3.6% expressed as RSD. Optimization of analytical techniques, thermal and chemical stability of LAE, as well as migration kinetics of LAE from experimental active packaging are reported and discussed., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Essential oils (EOs) are excellent antimicrobial agents sometimes used in active food packaging. This work studies the susceptibility of 48 clinical isolates and 12 reference strains of Gram-negative bacilli to oregano essential oil, cinnamon essential oil, and combinations of both. Furthermore, the tendency of the clinical isolates to develop resistance to these EOs and to different antibiotics after sequential oregano or cinnamon exposure was studied. For this purpose, antibiotic susceptibility (through disk diffusion assays and minimum inhibitory concentration [MIC] determination) and oregano and cinnamon susceptibility (through MIC and minimum bactericidal concentration [MBC] determination) were compared after 50 passages in the presence or absence of subinhibitory concentrations of oregano and cinnamon essential oils. The results showed that all strains were susceptible to both EOs and their combination independently of the antibiotic resistance profile. In addition, neither synergistic nor antagonistic effects were observed between oregano and cinnamon essential oils at the concentrations tested. After the sequential exposure to both EOs, only Serratia marcescens, Morganella morganii, and Proteus mirabilis treated with oregano changed their antibiotic resistance profile and/or increased their resistance to this EO. However, the changes in antibiotic and oregano resistance were not related.

Adhesives used in food packaging to glue different materials can provide several substances as potential migrants, and the identification of potential migrants and migration tests are required to assess safety in the use of adhesives. Solid-phase microextraction in headspace mode and gas chromatography coupled to mass spectrometry (HS-SPME-GC-MS) and ChemSpider and SciFinder databases were used as powerful tools to identify the potential migrants in the polyurethane (PU) adhesives and also in the individual plastic films (polyethylene terephthalate, polyamide, polypropylene, polyethylene, and polyethylene/ethyl vinyl alcohol). Migration tests were carried out by using Tenax(®) and isooctane as food simulants, and the migrants were analyzed by gas chromatography coupled to mass spectrometry. More than 63 volatile and semivolatile compounds considered as potential migrants were detected either in the adhesives or in the films. Migration tests showed two non-intentionally added substances (NIAS) coming from PU adhesives that migrated through the laminates into Tenax(®) and into isooctane. Identification of these NIAS was achieved through their mass spectra, and 1,6-dioxacyclododecane-7,12-dione and 1,4,7-trioxacyclotridecane-8,13-dione were confirmed. Caprolactam migrated into isooctane, and its origin was the external plastic film in the multilayer, demonstrating real diffusion through the multilayer structure. Comparison of the migration values between the simulants and conditions will be shown and discussed.

The study of antioxidant mechanisms is a difficult task that involves the monitoring and identification of unknown intermediate and final products. Most of the time, the lifetime of intermediates is too short to allow their isolation and subsequent identification by nuclear magnetic resonance (NMR). The developments of ultra-high performance liquid chromatography (UHPLC) coupled with the advances in the acquisition rates of mass spectrometry could facilitate the research on antioxidant mechanisms. This work is based on the reaction involved in the Oxygen Radical Antioxidant Capacity (ORAC) and Total Radical trapping Antioxidant Parameter (TRAP) assays. Hence, the reaction between 2,2'-azobis(2-amidinepropane)dihydrochloride (AAPH) radicals and an antioxidant was carried out in the thermostatized autosampler of a chromatographic device. Then, the reaction media were injected every six minutes, and the compounds were separated by UHPLC and detected by mass spectrometry in scan mode. Nine consecutive injections were registered in a unique file, then the evolution of the reaction for one hour in a single run was monitored. In this way, the reaction mechanisms of Trolox and eugenol with AAPH were studied, leading to the detection of nine and thirteen different compounds, respectively. An exhaustive analysis of the spectra obtained in product ion scan mode led to the identification of the compounds. Most of them were species previously found in the literature, but others have never been reported, so tentative structures were suggested. All this allowed the proposal of several steps within the antioxidant mechanisms of Trolox and eugenol, showing the great performance of UHPLC-MS/MS to complement the use of NMR in antioxidant mechanistic studies.

Six different species of lichens (Parmelia sulcata Tayl., Evernia prunastri (L.) Ach., Ramalina farinacea, Pseudevernia furfuracea (L.) Zopf., Usnea sp. and Lobaria pulmonaria (Schreb.) Hoffm.) were collected in two mountain valleys in Central Pyrenees: the Aspe and Aragon valleys. Two multivariate techniques have been applied with different purposes, ANOVA and Discriminant Analysis (DA), to evaluate the data. The PAHs spatial distribution was studied in the three more abundant and widespread species in the area: P. sulcata, E. prunastri (L.) Ach. and R. farinacea in terms of total PAHs, PAHs related to the combustion processes and toxicity. Different behaviour of each lichen species to trap PAHs was found, being P. sulcata the best one to monitor the most persistent PAHs of pyrogenic origin and E. prunastri the most appropriate to provide information about pyrogenic and petrogenic PAHs. Traffic was the most relevant influence in PAHs bioaccumulation in lichen species.

The surface of peach (Prunus persica 'Calrico') is covered by a dense indumentum, which may serve various protective purposes. With the aim of relating structure to function, the chemical composition, morphology, and hydrophobicity of the peach skin was assessed as a model for a pubescent plant surface. Distinct physicochemical features were observed for trichomes versus isolated cuticles. Peach cuticles were composed of 53% cutan, 27% waxes, 23% cutin, and 1% hydroxycinnamic acid derivatives (mainly ferulic and p-coumaric acids). Trichomes were covered by a thin cuticular layer containing 15% waxes and 19% cutin and were filled by polysaccharide material (63%) containing hydroxycinnamic acid derivatives and flavonoids. The surface free energy, polarity, and work of adhesion of intact and shaved peach surfaces were calculated from contact angle measurements of water, glycerol, and diiodomethane. The removal of the trichomes from the surface increased polarity from 3.8% (intact surface) to 23.6% and decreased the total surface free energy chiefly due to a decrease on its nonpolar component. The extraction of waxes and the removal of trichomes led to higher fruit dehydration rates. However, trichomes were found to have a higher water sorption capacity as compared with isolated cuticles. The results show that the peach surface is composed of two different materials that establish a polarity gradient: the trichome network, which has a higher surface free energy and a higher dispersive component, and the cuticle underneath, which has a lower surface free energy and higher surface polarity. The significance of the data concerning water-plant surface interactions is discussed within a physiological context.

A method for the determination of volatile organic compounds (VOCs) in recycled polyethylene terephthalate and high-density polyethylene using headspace sampling by solid-phase microextraction and gas chromatography coupled to mass spectrometry detection is presented. This method was used to evaluate the efficiency of cleaning processes for VOC removal from recycled PET. In addition, the method was also employed to evaluate the level of VOC contamination in multilayer packaging material containing recycled HDPE material. The optimisation of the extraction procedure for volatile compounds was performed and the best extraction conditions were found using a 75 μm carboxen-polydimethylsiloxane (CAR-PDMS) fibre for 20 min at 60 °C. The validation parameters for the established method were linear range, linearity, sensitivity, precision (repeatability), accuracy (recovery) and detection and quantification limits. The results indicated that the method could easily be used in quality control for the production of recycled PET and HDPE., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Different analytical methods were optimized and applied to quantify certain surrogate contaminants (toluene, chlorobenzene, phenol, limonene and benzophenone) in samples of contaminated and recycled flakes and virgin pellets of polyethylene terephthalate (PET) coming from the industrial challenge test. A screening analysis of the PET samples was carried out by direct solid-phase microextraction (SPME) in headspace mode (HS). The methods developed and used for quantitative analysis were a) total dissolution of PET samples in dichloroacetic acid and analysis by HS-SPME coupled to gas chromatography-mass spectrometry (GC-MS) and, b) dichloromethane extraction and analysis by GC-MS. The concentration of all surrogates in the contaminated PET flakes analyzed by HS-SPME method was lower than expected according to information provided by the supplier. Dichloroacetic acid interacted with the surrogates, resulting in a tremendous decrease of limonene concentration. The degradation compounds from limonene were identified. Dichloromethane extraction and GC-MS analysis evidenced the highest values of analytes in these PET samples. Based on the foregoing data, the efficiency of the recycling process was evaluated, whereby the removal of 99.9% of the surrogates proceeding from the contaminated flakes was confirmed., (Copyright © 2010. Published by Elsevier B.V.)

This article reports on the antimicrobial efficiency of a new active packaging concept based on the use of two essential oils (cinnamon and oregano) and their chemical descriptors (cinnamaldehyde, thymol, and carvacrol) against the Gram-positive bacterium Listeria monocytogenes, the Gram-negative bacterium Salmonella choleraesuis, the yeast Candida albicans, and the mold Aspergillus flavus. Complete inhibition of these microorganisms with either bactericidal or bacteriostatic effect has been demonstrated. It has been proven that the inhibition provided by these solutions is related not to the total amount of the active chemical released but to the amount of active compounds that reach the agar surface at a critical time. This critical time is notably related with the duration of the lag phase, as demonstrated for the bacteria, and shows that kinetic behavior has a critical role in the antimicrobial properties of the active packaging. Two different active films, polypropylene and the complex polyethylene-ethylenvynil alcohol, have been studied and a higher efficiency was found for polypropylene, mainly because of the mentioned kinetic reasons. These results can be used to understand the mechanism of action of the chemicals and provide valuable data for the development of the active packaging concept.

The efficiency of photo-oxidation, chemical oxidation by sodium hypochlorite, and ozonization for the industrial-scale removal of volatile organic compounds (VOCs) and odors from gaseous emissions was studied by applying these treatments (in an experimental system) to substances passing through an emission stack of a factory producing maize derivatives. Absorption and ozonization were the most efficient treatment, removing 75% and 98% of VOCs, respectively, while photo-oxidation only removed about 59%. The emitted chemical compounds and odors were identified and quantified by gas chromatography-mass spectrometry (in full-scan mode). In addition to presenting the results, their implications for selecting optimal processes for treating volatile emissions are discussed.

Active packaging is an emerging food technology to improve the quality and safety of food products. Many works have been developed to study the antimicrobial activity of essential oils. Essential oils have been traditionally used as flavorings in food, so they have an important odor impact but they have as well antimicrobial properties that could be used to protect the food. Recent developments in antimicrobial active packaging showed the efficiency of essential oils versus bread and bakery products among other applications. However, one of the main problems to face is the odor and taste they could provide to the packaged food. Using some aromas to mask the odor could be a good approach. That is why the main objective of this paper is to develop an antimicrobial packaging material based on the combination of the most active compounds of essential oils (hydrocinnamaldehyde, oregano essential oil, cinnamaldehyde, thymol, and carvacrol) together with some aromas commonly used in the food industry. A study of the concentration required to get the antimicrobial properties, the organoleptic compatibility with typical aroma present in many food systems (vanilla, banana, and strawberry), and the right combination of both systems has been carried out. Antimicrobial tests of both the mentioned aromas, the main components of some essential oils, and the combination of both groups were carried out against bacteria (Enterococcus faecalis, Listeria monocytogenes, Bacillus cereus, Staphylococcus aureus, Salmonella choleraesuis, Yersinia enterocolitica, Escherichia coli), yeasts (Candida albicans, Debaryomyces hansenii, Zygosaccharomyces rouxii), and molds (Botrytis cinerae, Aspergillus flavus, Penicillium roqueforti, Eurotium repens, Penicillium islandicum, Penicillium commune, Penicillium nalgiovensis). The sensory properties of the combinations were evaluated with a triangular test and classification was by an order test; the odor threshold of the aroma compounds was also studied. The results reveal that none of the aromas had antimicrobial properties. The most antimicrobial compounds are thymol, carvacrol, and cinnamaldehyde, but none of them could be combined with banana aroma, whereas only thymol with strawberry aroma gave the right combined organoleptic profile. All of the antimicrobials under study could be combined with vanilla aroma, providing both antimicrobial property and the odor expected.

Primary aromatic amines (PAAs) have been broadly studied due to their high toxicity. In this work a method for the analysis of 22 PAAs in aqueous simulants has been developed. The method is based on a solid-phase extraction step using cation-exchange cartridges and the subsequent analysis of the extracts by ultra-high-performance liquid chromatography with mass spectrometric detection. The recoveries obtained for all the amines analyzed ranged between 81 and 109%, linear range was between 0.03 and 75 microg L(-1), with the RSD values between 4.5 and 13.4% and an average value of 7.5% and limits of detection at microg L(-1) level. The method has been applied to two real samples obtained from migration experiments of polyurethane based laminates to simulant B (water with 3% (w/v) acetic acid) which represents the worst case for the migration of aromatic amines. The main amines found in both samples were methylenedianiline isomers, obtained from the corresponding residual diisocyanates used during polyurethane adhesive polymerization. The total amine concentration found was 26 and 6.3 microg of aniline equivalents per kg of food simulant.

The determination of specific migration in the three aqueous food simulants (water, 3% acetic acid and 10% ethanol) from experimental active packaging polypropylene-based films containing natural essential oils as active agents has been carried out for the first time by a two-phase hollow fibre liquid phase microextraction (HFLPME). Due to the high number of variables involved, an experimental design has been applied. High throughput, with six samples running simultaneously in a highly automated system working in dynamic extraction mode, has been achieved. The main analytical characteristics are detection limits as low as 0.01 microg kg(-1), linearity higher than 0.99 for almost 5 magnitude orders, average precision below 16% as RSD and concentration factors ranging from 4 to 189. Migration of 43 compounds including terpenes, alkanes, plastic additives and degradation compounds is reported. According to the results obtained and European legislation, the packaging prototypes tested could be safely marketed.

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.

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).

The aim of this work was to identify the degradation compounds produced during irradiation of multilayer polyamide 6 (PA-6) films and to study their migration into water and 95% ethanol food simulant. After irradiation of multilayer PA-6 films at 3, 7 and 12 kGy, degradation compounds were extracted using solid-phase microextraction, for which the time and temperature of extraction and stirring were optimized, and identified by gas chromatography-mass spectrometry. Caprolactam, 2-cyclopentylcyclopentanone and aldehydes, among other compounds, were identified in the headspace of the films. Polydimethylsiloxane was considered the best fiber for extraction. The optimum conditions of time, temperature and stirring to extract the compounds were 20 min, 80 degrees C and 225 rpm. For validation purposes, the compounds were quantified in water and 95% ethanol and the results showed high sensitivity, good precision and accuracy. Migration of compounds from irradiated and non-irradiated multilayer PA-6 films into water and 95% ethanol food simulants was carried out at 40 degrees C for 10 days. The method was efficient for the quantification of decaldehyde, 2-cyclopentylcyclopentanone and caprolactam that migrated from multilayer PA-6 films into food simulants.

The air quality in the Aragón valley, in the central Pyrenees, has been assessed by evaluation of lichen biodiversity and mapped by elaboration of the Index of Air Purity (IAP) based on observations of the presence and abundance of eight kinds of lichen with different sensitivity to air pollution. The IAP values obtained have been compared with quantitative analytical measures of 16 PAHs in the lichen Evernia prunastri, because this species was associated with a wide range of traffic exposure and levels of urbanization. Analyses of PAHs were carried out by the DSASE method followed by an SPE clean-up step and GC-MS analysis. The concentration of total PAHs found in lichen samples from the Aragón valley ranged from 692 to 6420 ng g(-1) and the PAHs profile showed predominance of compounds with three aromatic rings. The influence of the road traffic in the area has been shown because values over the median concentration of PAHs (>1092 ng g(-1)), percentage of combustion PAHs (>50%), and equivalent toxicity (>169) were found in lichens collected at places exposed to the influence of traffic. The combination of both methods suggests IAP as a general method for evaluating the air pollution referenced to PAHs because it can be correlated with the content of combustion PAHs and poor lichen biodiversity can be partly explained by the air pollution caused by specific PAHs.

This paper presents a novel application of active single-drop microextraction (SDME) for the determination of mixtures of four gaseous diisocyanates: 2,4- and 2,6-toluene diisocyanate (TDI), hexamethylene diisocyanate (HDI) and methylene diphenyl diisocyanate (MDI). The optimised simultaneous extraction, preconcentration and derivatization method utilizes a 2.3-microL Milli-Q water drop containing dibutylamine (DBA) as a derivatization reagent and phenylisocyanate (PHI) as an injection standard. A type III screening design, combined with Box-Behnken surface modelling and Simplex optimisation was applied to optimise the method. Several SDME approaches--standard SDME, automatic organic solvent film (OSF) and use of a supported-drop (SD) device--were compared with solid-phase microextraction (SPME) in terms of sensitivity and robustness under varied conditions. Of these SDME alternatives, SD proved to be the most suitable for diisocyanate sampling. The detection limits using SDME followed by UPLC-MS-MS analysis were 0.9 and 0.8 microg m(-3) for 2,4- and 2,6-TDI, respectively, 1.0 microg m(-3) for HDI and 0.2 microg m(-3) for MDI.

An experimental laboratory-made assembly to determine for the first time the antioxidant capacity with respect to hydroxyl (OH*) radicals of several new active packagings directly in the materials has been developed. Gas-phase OH* radicals are generated by UV-light irradiation of an aqueous H(2)O(2) aerosol. After on-line reaction with up to eight parallel test samples, remaining OH* is quantitatively trapped by a salicylic acid solution, and antioxidant capacity is indirectly assessed by HPLC-fluorescence determination of the high sensitive 2,5-dihydroxybenzoic acid formed. Several natural essential oils as well as active plastic films including in their formulation such oils have been subjected to oxidation. Polymers containing clove and oregano were the most efficient ones (up to 7.2 and 4.7 times, respectively, more antioxidant than blanks), whereas rosemary, citronella and propolis showed average efficiency. On the other hand, active materials containing ferulic acid, quercetin, catechin and thymol, as well as commercial active bags with ethylene-absorption properties, showed limited or none antioxidant protection. Experimental results and full details about experimental assembly are given.

A two-phase based hollow fibre liquid-phase microextraction (HFLPME) with a high automatization degree and able to process up to six samples simultaneously by means of a multiple channel syringe pump has been successfully developed. The experimental set-up allows to carry out dynamic extractions with a considerable reduction of sample handling. The system has been applied for the first time to the determination in aqueous food simulant of migrants from prototypes of active packagings to assess their safety before marketing, showing detection limits in the ng g(-1) range, relative standard deviations below 13% and concentration factors ranging from 83 to 338.

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.

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.

Convenient methods that are capable of determining potentially antimicrobial compounds in both vapour and liquid phases are required (inter alia) to facilitate the development of active packaging materials using natural substances. The suitability of single-drop microextraction (SDME) coupled with gas chromatography-mass spectrometry (GC-MS) for this purpose has been assessed by evaluating its ability to determine a range of analytes (mainly terpenes) in vapour samples and three liquid food simulants - distilled water, 10% (v/v) water/ethanol, and 3% (w/v) acetic acid - by headspace-SDME (HS-SDME) and direct immersion-SDME (DI-SDME), respectively. In this contribution, a screening strategy based on the Hildebrand solubility parameter has been used to build a solvent priority list. Solvents were then tested following the list, taking into account additional factors such as low volatility for HS-SDME or buoyancy and relative miscibility for DI-SDME. Other experimental parameters affecting the performance of SDME (such as drop volume, sampling time and temperature, drop position in the sample vial, sample vial size, stirring rate, filling rate and ionic strength of the sample) were investigated using a Plackett-Burman screening design. The method optimisation was completed by means of response surface modelling (RSM). The methods were validated by characterising relevant performance parameters including their robustness, linear range, accuracy (trueness and precision) and capability of detection as described by the International Organization for Standardization.

This paper deals with the study of the kinetic migration of a series of organic compounds representative of potential contaminants in packaging materials and used as surrogates (o-xylene, acetophenone, dodecane, naphthalene, 2,3,4-trichloroanisole, benzophenone, isomeric mix of diisopropylnaphthalene, diisobutyl phthalate and methyl stearate). Migration to one side of a solid simulant, Tenax, also referred to as MPPO (modified polyphenylene oxide), was investigated in this study. One spiked sample of multilayer material was used to optimise the extraction procedures for the multilayer paper-based material and the Tenax as well as to perform kinetic migration studies. Three sequential extractions using ethanol were necessary for the strips of the multilayer material but only one extraction was necessary for the solid simulant to obtain >70% recovery of the surrogates. These results enabled us to specify the extraction requirements of the multilayer sample and the solid simulant and as well as those of the migration tests at high temperature using Tenax as solid simulant. The matrix effect associated with the extraction of the contaminants from the multilayer sample is also discussed.

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.

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.

The aim of the study presented here was to gain knowledge about the vapor-phase antimicrobial activity of selected essential oils and their major putatively active constituents against a range of foodborne bacterial and fungal strains. In a first step, the vapor-phase antimicrobial activities of three commercially available essential oils (EOs)-cinnamon (Cinnamomum zeylanicum), thyme (Thymus vulgaris), and oregano (Origanum vulgare)-were evaluated against a wide range of microorganisms, including Gram-negative bacteria (Escherichia coli, Yersinia enterocolitica, Pseudomonas aeruginosa, and Salmonella choleraesuis), Gram-positive bacteria (Listeria monocytogenes, Staphylococcus aureus, Bacillus cereus, and Enterococcus faecalis), molds (Penicillium islandicum and Aspergillus flavus), and a yeast (Candida albicans). The minimum inhibitory concentrations (MICs) were generally lower for oregano EO than for the thyme and cinnamon EOs, especially against the relatively resistant Gram-negative. The persistence of the EOs' antimicrobial activities over time was assessed, and changes in the composition of the atmosphere they generated over time were determined using single-drop microextraction (SDME) in combination with gas chromatography-mass spectrometry (GC-MS) and subsequent analysis of the data by principal component analysis (PCA). More relevant chemicals were selected. In addition, the vapor-phase activities of putatively key constituents of the oils were screened against representative Gram-positive (L. monocytogenes) and Gram-negative (S. choleraesuis) bacteria, a mold (A. flavus), and a yeast (C. albicans). Of the tested compounds, cinnamaldehyde, thymol, and carvacrol showed the strongest antimicrobial effectiveness, so their MICs, defined as the minimum vapor concentrations that completely inhibited detectable growth of the microorganisms, were calculated. To check for possible interactions between components present in the EOs, cinnamon EO was fortified with cinnamaldehyde and thyme EO with thymol, and then the antimicrobial activities of the fortified oils were compared to those of the respective unfortified EOs using fractional inhibitory concentration (FIC) indices and by plotting inhibition curves as functions of the vapor-phase concentrations. Synergistic effects were detected for cinnamaldehyde on A. flavus and for thymol on L. monocytogenes, S. choleraesuis, and A. flavus. In all other cases the fortification had additive effects, except for cinnamaldehyde's activity against S. choleraesuis, for which the effect was antagonistic. Finally, various microorganisms were found to cause slight changes over time to the atmospheres generated by all of the EOs (fortified and unfortified) except the fortified cinnamon EO.

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).

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.

Two new generation polymeric resins, Bond Elut ENV (styrene-divinylbenzene) from Varian and LiChrolut EN (ethylvinylbenzene-divinylbenzene) from Merck, commonly used in liquid--solid-phase extraction (SPE) were evaluated as sorbents for gas-phase sampling followed by thermal desorption and compared to Tenax TA, a reference sorbent in this kind of applications. The three resins were tested against seven volatile organic compounds (VOCs): 1-octene, ethylbenzene, (p-, m-, o-)xylenes, styrene and 1,4-dichlorobenzene. Elution curves for all compounds were determined at temperatures from 120 to 180 degrees C, and from such curves, different parameters, such as retention factor (k), distribution coefficient (K), height equivalent to a theoretical plate (H), asymmetry factor (Fa) and breakthrough volume (VB) were calculated and extrapolated at room (25 degrees C) and desorption (220 degrees C) temperatures in order to estimate breakthrough and elution volumes. In average, retention in LiChrolut EN is 10 and 200 times stronger than in Bond Elut ENV and Tenax TA, respectively, but its chromatographic behavior is rather poor giving quite asymmetric elution profiles (Fa >1.8 at 120 degrees C). Bond Elut ENV exhibited the best chromatographic behavior, with H values two or five times lower than those of LiChrolut EN or Tenax TA. An additional advantage of the new sorbents is that retention decreases with T much faster than it does in Tenax (8 or 20 times for Bond Elut ENV or LiChrolut EN). Modeling has finally shown that beds with 60-80 (for Bond Elut ENV) or 300-400 (for LiChrolut EN) times less of sorbent have the same retention properties than standard Tenax TA tubes and similar (LiChrolut EN) or five to six times smaller (Bond Elut ENV) elution volumes. These predictions have been experimentally confirmed.

Lichens of the species Parmelia sulcata were collected from sites on both sides of the Somport tunnel (which links France and Spain) and atmospheric particles were collected by air samplers installed within and on either side of the tunnel. Polycyclic aromatic hydrocarbons (PAHs) in the lichen and particle samples were then extracted, identified, quantified, and compared to evaluate the potential utility of lichens as pollution biomonitors in remote areas. The origin of the PAHs was also assessed using the Phe/Ant, Flu/Pyr, Ant/Ant+Phe, Flu/Flu+Pyr, and BaA/BaA+Chr concentration ratios. The total concentration of 16 priority PAHs ranged from 6.79 to 23.3 microg/g in particles outside the tunnel, from 18.3 to 265.2 microg/g in particles inside the tunnel, and from 0.91 to 1.92 microg/g in the lichen samples. The PAH ratios found in the lichens and particulate matter indicate that they were of pyrogenic origin and that road traffic was a major contributor. Results from the lichen samples suggest that they may be excellent biomonitors of pollution in remote areas.

A new antioxidant active packaging material for food has been designed and developed, consisting of a polypropylene film in which some natural antioxidants have been immobilized. The antioxidant properties of the new material have been tested by using both pure myoglobin and fresh beef steaks. Two different cell configurations (glass vial and Petri dish) and four different myoglobin concentrations-according to the common content of this compound in fresh meat and meat derivatives (1080, 1995, 3332, and 4414 microg g(-1), respectively)-have been evaluated in oxidation studies. Furthermore, three different concentrations of natural antioxidants in the film (designated as PR1, PR2, and PR3) were evaluated. Once myoglobin samples and the active films were introduced in the cell, they were exposed to cool white fluorescent light to accelerate oxidation for a period of time ranging from 5 to 30 days. Remaining myoglobin concentration was measured by molecular absorption UV-vis spectrophotometry at 409 nm. Organoleptic properties and color, texture, and physical characteristics of fresh meat packaged with the new active film have also been measured to evaluate the shelf life of the packaged meat. Results showed that, compared to normal polypropylene, the active film containing natural antioxidants efficiently enhanced the stability of both myoglobin and fresh meat against oxidation processes, thus being a promising way to extend the shelf life of fresh meat.

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%.

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%.

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.

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.

Both specific and overall migration tests have been applied to new experimental food packaging-active plastic films with antioxidant properties, including in its composition a natural rosemary extract. Determination of volatile and semivolatile compounds migrating from plastic to the four established simulants showed that both specific and overall migration was very low. The results obtained gave values 20 times lower than the established limits in the worst case. So, from the point of view of health risk, the new active packaging can be considered as safe. Analytical procedure used provided the necessary information about the migration behavior, with good analytical characteristics and detection limits in the sub mug kg(-1) range. Besides, no significant difference was found between laboratory and factory-made samples, which is an important issue for industrial production, the next step in the development of the new antioxidant active film.

A new procedure for the determination of sterols in serum samples is proposed. The system consists of coating a Solid Phase Microextraction (SPME) microfiber in headspace mode with the derivatizing agent N,O-bis(trimethylsilyl)trifluoracetamide (BSTFA) and then applying this coated fiber to the simultaneous extraction and derivatization of three precursors in the cholesterol biosynthesis pathway (desmosterol, lathosterol and lanosterol) and two phytosterols (sitosterol and sitostanol) in serum samples. Optimization of the analytical procedure via the application of an experimental design, a study of matrix effects, and an analysis of serum pool samples are all described and discussed.

Two low-volume solvent continuous extraction methods are applied to the extraction of paper matrices. In the methods reported here, a complex mixture of fluorescent whitening agents (FWAs) and azo dyes (AZOs) used in paper materials intended to come into contact with foodstuffs was extracted by using subcritical water extraction (SWE) and dynamic sonication-assisted solvent extraction (DSASE). Rationale for the work is based upon migration concerns of these groups of analytes from the packaging to the packaged items, thus compromising their subjective and/or objective quality. In SWE, sample was extracted in 21 min with 0.5 mL of water, whereas the DSASE method required 11 min and used 7 mL of water. DSASE was further developed by incorporating an organic modifier in order to change water polarity, thus improving extraction of moderately polar analytes. This way, modified-DSASE used a total organic volume of 0.9 mL which represents a reduction of 200 times in organic solvent consumption (200 mL versus approximately 1.0 mL) and 11 times in extraction time (2h versus 11 min) compared to the existing methods. SWE was able to extract only 9 out of 12 test analytes with average recoveries between 10 and 25% whereas modified-DSASE succeed in extracting all the target analytes with an average recovery of 89%. Complete discussion and explanation concerning these differences are provided in the text.

A fast and simple method, using static single-drop microextraction (SDME), has been developed to facilitate the identification and quantification of seven dialkyl phthalate esters in the three aqueous food simulants. The simulants were: A, distilled water; B, 3% (w/v) acetic acid/water; and C, 15% (v/v) ethanol/water. The extraction is performed by simply suspending a drop of organic solvent in the aqueous sample using a conventional gas chromatography (GC) microsyringe. Following extraction, the organic phase is withdrawn into the syringe and analyzed by gas chromatography and flame ionization detection (FID). The optimized method yields a linear calibration curve over three orders of magnitude for all the simulants, and method detection limits (MDLs) allowing detection of all the studied compounds at concentrations below migration limits established by the European Union. The accuracy of the SDME method was tested and compared to that of solid-phase microextraction (SPME) by recovery experiments using spiked samples, with results ranging from 85 to 115% in most cases.

The determination of several compounds present in a commercial polycarbonate container intended to be used in microwave ovens which could be considered as potential migrants has been carried out by reversed-phase high-performance liquid chromatography (HPLC) with both ultraviolet (UV) and fluorescence detectors. Total dissolution with dichloromethane and polymer reprecipitation with methanol have been used to evaluate 100% potential migration as the worst case. The extract consisted of a complex mixture containing monomers, oligomers, UV stabilizers, antioxidants, degradation products, and other additives. Phenol, Bisphenol A, 2,4-di-tert-butylphenol, Cyasorb UV5411, bis(2-ethylhexylphthalate), Irganox 1076, and Irgafos 168 were identified by both retention times and fluorescence-to-UV ratios. Additional confirmation was achieved by HPLC with diode array detection and gas chromatography-mass spectrometry. Recovery percentages were in the range of 73.8-94.4%, the lowest one being for the antioxidant Irgafos 168 due to its transformation into the phosphate form and 2,4-di-tert-butylphenol. The concentrations of the studied analytes present in the polycarbonate container ranged between 0.9 and 240 microg.g(-)(1). The total dissolution conditions that may affect the final concentration of analytes, mainly Bisphenol A, are discussed.

The behavior of two synthetic adsorbents, Tenax and Porapak, as food simulants in contact with some plastic containers commercially available, recommended to be used for heating food in microwave ovens, has been studied. Containers of polycarbonate (PC), polypropylene (PP), polypropylene random (PP-random), polypropylene-20% talcum (PP%T), and the copolymer styrene-acrylonytrile (SAN) have been studied at 150 degrees C (PC) and 120 degrees C (the others). The volatile compounds released from the plastics and trapped into Tenax and Porapak have been analyzed by thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS). The results obtained from these migration studies at high temperature are shown and discussed. Tenax performs better than Porapak at low temperature since the former desorbs the compounds at high temperature.

The optimization of supercritical fluid extraction using CO2 for the extraction of contaminants in 15 samples of recycled paper and board (P&B) has been studied. An experimental design was used for simultaneous optimization of the variables involved in both the extraction step and the collection of the extract. Methanol was used as modifier. Several plastisizers such as diethyl phthalate, diisobutyl phthalate, di-n-butyl phthalate, dioctyl adipate, and diethylhexyl phthalate (from 2 to 100 microg/g of paper) were found in the recycled P&B samples. A discriminate analysis applied to all results obtained allow us to classify the samples in three different groups according to the content of recycled pulp (0, 10-30, and > 80% of recycled pulp), the sample thickness (from <300 to >600 microm), and the surface treatment of the paper. The analytical behavior and the results are discussed.

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.

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.