Lebanese Population Exposure to Trace Elements via White Bread Consumption.

The objective of this study was to assess Lebanese population exposure to trace elements (TEs) via white pita consumption. A survey of white pita consumption was achieved among one thousand Lebanese individuals, grouped into adults (above 15 years old, men, and women) and young people (6-9 and 10-14 years old). The most consumed pita brands, labeled B1, B2, and B3, were selected. Levels of TEs (i.e., As, Cd, Co, Cr, Hg, Ni, and Pb) in B1, B2, B3 pitas were measured. The highest contents of TEs in pitas were: Ni (1292 µg/kg) and Co (91 µg/kg) in B1; As (400 µg/kg) and Cd (< 15 µg/kg) in B2; Cr (363 µg/kg), Pb (260 µg/kg), and Hg (0.89 µg/kg) in B3. The pita brand B3 was the source of the highest TEs exposure, except for Ni for which it was B1. Daily exposures to TEs due to the fact of pita consumption were compared to safety levels. There were no safety concerns for Hg, Cd, Cr or Co (except the 95th percentile of 6-9 years old). An excess of the Ni tolerable daily intake was observed for the most exposed populations. The very low margins of exposure for As and Pb suggest a worrying risk for the Lebanese population.

Empirical models to predict the effect of sterilisation and storage on bisphenols migration from metallic can coatings into food simulants.

Based on response surface methodology, empirical models were built to predict the influence of can processing (heat treatment) and storage conditions (time and temperature) on the migration of bisphenol compounds from the inner lacquer of tinplate cans (4 brands) into several food simulants. Analysis using liquid chromatography revealed the presence of BADGE.2H2O and BPA in all samples. Models were significant in fitting the levels of these two bisphenols in food simulants depending on the input variables, with excellent adjusted coefficients of determination. Their prediction performance was validated through running new data sets. Further comparison of predicted values with bisphenols levels measured in canned vegetables revealed that the proposed models are conservative. By the desirability of the response output, the models are capable of proposing the range of can processing and storage conditions that limit migration for further compliance with the regulation. The proposed approach could be a convenient tool for the industries to control processing conditions in order to ensure the conformity of canned foods.

Bioaccessibility of lead in Dittrichia viscosa plants and risk assessment of human exposure around a fertilizer industry in Lebanon.

Total and bioaccessible lead (Pb) concentrations in Dittrichia viscosa and soil samples were considered for estimating the potential health risk, related to both plant intake and accidental soil ingestion by adult and child consumers, near a Lebanese fertilizer plant. A total of 27 plant samples, from 9 uncultivated sites situated around the plant, were analyzed in order to assess the total and bioaccessible Pb content. Physiologically based extraction test (PBET) was used to estimate oral bioaccessibility of Pb in edible plant parts. Washed and unwashed leaves were compared in order to show the importance of good consumer practice on Pb intake. Extracted Pb in the intestinal medium accounted for 24 up to 87% of Pb extracted in the gastric medium. The total hazard quotient (HQtot) and the total bioaccessible hazard quotient (BHQ), related to both plants' intake and soil ingestion, for two maximalist child and adult scenarios, were calculated in order to estimate human health risk assessment. HQtot estimations considering the total concentration of Pb in soil and plant suggest that this metal is a contributor in elevating health risks problems on local plants' consumers, especially children inhabitants. However, the integration of bioaccessible concentrations of Pb in risk estimations reduces remarkably the potential risk.

Bioaccessibility and radioisotopes of lead in soils around a fertilizer industry in Lebanon.

The use of phosphate ore by fertilizer industries is considered a major source of soil contamination by trace metals and radionuclides. Despite its low mobility and bioavailability, lead (Pb) is among soil contaminants that pose a serious risk to human health. This study evaluates the potential impact of a fertilizer factory in North Lebanon on the total content of Pb and the activity concentration of its radioisotopes in residential, non-agricultural lands around the industry, as well as its mobility and bioaccessibility in soil samples collected at different depths. Chemical extractions by EDTA and in vitro physiologically based extraction test were used to estimate, respectively, the available and bioaccessible fractions of Pb in soils. Radioisotopes 214Pb, 212Pb and 210Pb have been analyzed by gamma spectrometry. Different physicochemical soil parameters, such as pH, carbonate content, electrical conductivity, cation exchange capacity, clay, total nitrogen and redox potential, were studied. The pseudo-total Pb varied between 12.8 and 68.5 mg kg-1, while the extractable fractions were more variable, between 12 and 72% of total Pb concentration for the EDTA extracted fraction and up to 28.5% for the bioaccessible fractions. The processing of the data shows the decreases with depth in most sites of the total and available Pb and of the activity concentration of 210Pb and their positive correlations with total nitrogen. These variations and relationships with the location of studied sites show the influence of emissions from the factory or the transport of ore and by-products. The correlations between available and bioaccessible Pb on one hand, between available Pb and 210Pb on another hand, raise the question of health risk assessments taking into account the bioaccessibility of Pb and its radioisotopes.

Simultaneous migration of bisphenol compounds and trace metals in canned vegetable food.

For the very first time, this study investigates the simultaneous migration of several metals and bisphenol compounds from coated tinplate cans into vegetable foods highly consumed worldwide. The role played by heat treatment, food type and brand, storage conditions, can denting and cooking food directly in cans is also assessed. Migration of bisphenol compounds (only BPA and BADGE·2H2O detected) was mainly affected by sterilization, whereas metal release was greatly influenced by storage. Based on a Principal Component Analysis different migration pattern groups were highlighted: BPA and Zn (and Pb to a lesser extent) showed similar migration trends, with dependence on food type, brand and storage temperature. Cd, Ni and Cu were similarly influenced by food type and can brand. Fe has a particular trend, with clear influence of storage time, and to a lesser extent of food type. Overall Fe and BADGE·2H2O migration were favored in acidic food.

Effect of sterilisation and storage conditions on the migration of bisphenol A from tinplate cans of the Lebanese market.

The use of bisphenol A (BPA) in lacquer coating of food cans has been restricted by different authorities in many countries, such as in Europe. However, such regulation does not exist in many other countries including Lebanon. Due to the lack of data on the quality of Lebanese can production; this study investigates the migration of BPA from two types of tinplate cans manufactured in Lebanon, before and after sterilisation. Cans were analysed under different storage conditions (time and temperature) and filled with an aqueous simulant. The determination of BPA was carried out using UPLC with fluorescence detection, and further confirmed by MS detection. After sterilisation BPA levels drastically increased from an average of 0.15 to 109 µg/kg, giving a BPA migration around 10.5 µg/dm2 for both types of cans. Storage temperature and time had no significant influence on BPA levels in sterilised cans (p-value > 0.05); however, these factors significantly affected BPA levels in non-sterilised cans.

Attenuated total reflectance-mid infrared spectroscopy (ATR-MIR) coupled with independent components analysis (ICA): A fast method to determine plasticizers in polylactide (PLA).

Compliance of plastic food contact materials (FCMs) with regulatory specifications in force, requires a better knowledge of their interaction phenomena with food or food simulants in contact. However these migration tests could be very complex, expensive and time-consuming. Therefore, alternative procedures were introduced based on the determination of potential migrants in the initial material, allowing the use of mathematical modeling, worst case scenarios and other alternative approaches, for simple and fast compliance testing. In this work, polylactide (PLA), plasticized with four different plasticizers, was considered as a model plastic formulation. An innovative analytical approach was developed, based on the extraction of qualitative and quantitative information from attenuated total reflectance (ATR) mid-infrared (MIR) spectral fingerprints, using independent components analysis (ICA). Two novel chemometric methods, Random_ICA and ICA_corr_y, were used to determine the optimal number of independent components (ICs). Both qualitative and quantitative information, related to the identity and the quantity of plasticizers in PLA, were retrieved through a direct and fast analytical method, without any prior sample preparations. Through a single qualitative model with 11 ICs, a clear and clean classification of PLA samples was obtained, according to the identity of plasticizers incorporated in their formulations. Moreover, a quantitative model was established for each formulation, correlating proportions estimated by ICA and known concentrations of plasticizers in PLA. High coefficients of determination (higher than 0.96) and recoveries (higher than 95%) proved the good predictability of the proposed models.

Independent components analysis coupled with 3D-front-face fluorescence spectroscopy to study the interaction between plastic food packaging and olive oil.

Olive oil is one of the most valued sources of fats in the Mediterranean diet. Its storage was generally done using glass or metallic packaging materials. Nowadays, plastic packaging has gained worldwide spread for the storage of olive oil. However, plastics are not inert and interaction phenomena may occur between packaging materials and olive oil. In this study, extra virgin olive oil samples were submitted to accelerated interaction conditions, in contact with polypropylene (PP) and polylactide (PLA) plastic packaging materials. 3D-front-face fluorescence spectroscopy, being a simple, fast and non destructive analytical technique, was used to study this interaction. Independent components analysis (ICA) was used to analyze raw 3D-front-face fluorescence spectra of olive oil. ICA was able to highlight a probable effect of a migration of substances with antioxidant activity. The signals extracted by ICA corresponded to natural olive oil fluorophores (tocopherols and polyphenols) as well as newly formed ones which were tentatively identified as fluorescent oxidation products. Based on the extracted fluorescent signals, olive oil in contact with plastics had slower aging rates in comparison with reference oils. Peroxide and free acidity values validated the results obtained by ICA, related to olive oil oxidation rates. Sorbed olive oil in plastic was also quantified given that this sorption could induce a swelling of the polymer thus promoting migration.

Rapid discrimination of plastic packaging materials using MIR spectroscopy coupled with independent components analysis (ICA).

Plastic packaging wastes increased considerably in recent decades, raising a major and serious public concern on political, economical and environmental levels. Dealing with this kind of problems is generally done by landfilling and energy recovery. However, these two methods are becoming more and more expensive, hazardous to the public health and the environment. Therefore, recycling is gaining worldwide consideration as a solution to decrease the growing volume of plastic packaging wastes and simultaneously reduce the consumption of oil required to produce virgin resin. Nevertheless, a major shortage is encountered in recycling which is related to the sorting of plastic wastes. In this paper, a feasibility study was performed in order to test the potential of an innovative approach combining mid infrared (MIR) spectroscopy with independent components analysis (ICA), as a simple and fast approach which could achieve high separation rates. This approach (MIR-ICA) gave 100% discrimination rates in the separation of all studied plastics: polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polystyrene (PS) and polylactide (PLA). In addition, some more specific discriminations were obtained separating plastic materials belonging to the same polymer family e.g. high density polyethylene (HDPE) from low density polyethylene (LDPE). High discrimination rates were obtained despite the heterogeneity among samples especially differences in colors, thicknesses and surface textures. The reproducibility of the proposed approach was also tested using two spectrometers with considerable differences in their sensitivities. Discrimination rates were not affected proving that the developed approach could be extrapolated to different spectrometers. MIR combined with ICA is a promising tool for plastic waste separation that can help improve performance in this field; however further technological improvements and developments are required before it can be applied at an industrial level given that all tests presented here were performed under laboratory conditions.

Chemometric tools to highlight non-intentionally added substances (NIAS) in polyethylene terephthalate (PET).

In an effort to identify non-intentionally added substances (NIAS), which is still a challenging task for analytical chemists, PET pellets, preforms and bottles were analyzed by an optimized headspace solid phase microextraction coupled to gas chromatography-mass spectrometry (HS-SPME/GC-MS). Fingerprints obtained by the proposed method were analyzed by three chemometric tools: Principal Components Analysis (PCA), Independent Components Analysis (ICA) and a multi-block method (Common Components and Specific Weights Analysis CCSWA) in order to extract pertinent variations in NIAS concentrations. Total ion current (TIC) chromatograms were used for PCA and ICA while extracted ion chromatograms (EIC) were used for CCSWA, each ion corresponding to a block. PCA managed to discriminate pellets and preforms from bottles due to several NIAS. Volatiles like 2-methyl-1,3-dioxolane, ethylene glycol, ethylbenzene and xylene were responsible for the discrimination of pellets and preforms. Less volatile compounds like linear aldehydes and phthalates were responsible for the discrimination of bottles. ICA showed more specific discriminations especially for bottles and pellets while CCSWA managed to discriminate preforms. The proposed methodology, combining HS-SPME/GC-MS with chemometric tools proved its efficiency in highlighting NIAS in PET samples in a relatively simple and fast approach compared to classical techniques.

Label-free detection of bacteria by electrochemical impedance spectroscopy: comparison to surface plasmon resonance.

The low but known risk of bacterial contamination has emerged as the greatest residual threat of transfusion-transmitted diseases. Label-free detection of a bacterial model, Escherichia coli, is performed using nonfaradic electrochemical impedance spectroscopy (EIS). Biotinylated polyclonal anti-E. coli is linked to a mixed self-assembled monolayer (SAM) on a gold electrode through a strong biotin-neutravidin interaction. The binding of one antibody molecule for 3.6 neutravidin molecules is determined using the surface plasmon resonance (SPR). The detection limit of E. coli found by SPR is 10(7) cfu/mL. After modeling the impedance Nyquist plot of E. coli/anti-E. coli/mixed SAM/gold electrode for increasing concentrations of E. coli (whole bacteria or lysed bacteria), the main parameter that is modified is the polarization resistance RP. A sigmoid variation of RP is observed when the log concentration of bacteria (whole or lysed) increases. A concentration of 10 cfu/mL whole bacteria is detected by EIS measurements while 103 cfu/mL is detected for lysed E. coli.

Amperometric and impedimetric characterization of a glutamate biosensor based on Nafion and a methyl viologen modified glassy carbon electrode.

An electrochemical biosensor based on a glassy carbon (GC) electrode chemically modified with the perfluorinated cation-exchange polymer Nafion and methyl viologen (MV) is described. The enzyme was immobilized by cross-linking with glutaraldehyde in the presence of bovine serum albumin (BSA), methyl viologen and Nafion. Operating variables such as the enzyme/BSA ratio, cross-linking time in glutaraldehyde vapor, methyl viologen and Nafion percentages were investigated with regard to their influence on the biosensor sensitivity by using glucose oxidase as the enzyme model due to its high stability and low cost. The glutamate biosensor was elaborated by using optimized parameters and its electrochemical properties were investigated by cyclic voltammetry, amperometry and by electrochemical impedance spectroscopy. The glutamate biosensor shows a detection limit of 20 microM and a linear range extended to 0.75 mM. Its selectivity was tested with 15 different amino acids, each with a concentration of 20 microM, 25 microM acetaminophen, 20 microM uric acid and 200 microM ascorbic acid. No amperometric response was observed for the interfering species. This good selectivity allows glutamate detection in biological media without previous separation of the analyte.