The role of oxidative stress on the effect of 1,4,7,10,13,16-hexathiacyclooctadecane on copper and zinc toxicity in HepG2 cells.

Experiments have shown that 1,4,7,10,13,16-hexathiacyclooctadecane (L3) increased the Cu2+ toxicity on HepG2 cells, whereas the combination Zn(2+)/L3 was less toxic relative to the metal control. In all cases, glutathione (GSH) levels were decreased and vitamins C and E supplementation partially counteracted the increased toxicity in the Cu(2+)/L3-treated cells. The previously observed effects of this hexathiamacrocyclic ligand (L3) on the Cu2+ and Zn2+ toxicity were further investigated by first depleting the intracellular GSH levels by means of L-buthionine S,R-sulphoximine. Combined treatment with Cu(2+)/L3 resulted in complete cell death, whereas for Zn(2+)/L3 no severe effects were observed. Direct measurement of reactive oxygen species (ROS) revealed that Cu2+ induced a high degree of oxidative stress on the cells. This was not the case for Zn2+. The results proved a previously proposed mechanism in which GSH is used to conjugate the metal-ligand complex, but as a result of this, GSH is no longer available for inactivation of ROS. Also, both the intracellular copper and zinc content were determined for each experiment by means of inductively coupled plasma-atomic emission spectroscopy. According to these data, zinc is depleted in Cu(2+)/L3-treated cells, which could have consequences on superoxide dismutase and as a result of this on the amount of oxidative stress.

Speciation study of aluminium in beverages by Competitive Ligand Exchange-Adsorptive Stripping Voltammetry.

Competitive Ligand Exchange-Adsorptive Stripping Voltammetry (CLE-AdSV) was used for determining the speciation of aluminium in commonly consumed beverages (water, tea, infusion, coffee, orange juice, tomato juice, beer and red wine). Aluminium determination involves the adsorption of Al-complexes with the ligand cupferron onto a hanging mercury drop electrode. All samples were studied at pH 6.5 with an accumulation step at -0.60 V (all potential values in the paper are given versus the Ag/AgCl, [KCl]=3 M reference electrode) during 60 s, and a final cupferron concentration of 4 × 10(-4)M. These conditions were used to establish (i) the concentration of electro-labile aluminium, (ii) the range of ligand concentrations and (iii) the conditional stability constants of beverage samples using titration procedures. The results based on Ruzic plots were compared to computer simulation with Visual MINTEQ. This comparison suggests that labile monomeric Al-forms and soluble organic complexes of low molecular weight can be quantified by the CLE-AdSV procedure. Overall the relative uncertainties on the determination of the electro-active Al fraction and the complexing parameters, i.e., concentration and conditional stability constant of natural ligands in the samples, are less than 15%. Thanks to these results, information on Al bioavailability in beverages was collected and discussed. This study also illustrates the value of computer simulations when complex, time-consuming voltammetric techniques are applied.

Evaluation of the migration of 15 photo-initiators from cardboard packaging into Tenax(®) using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS).

Photo-initiators are widely used to cure ink on packaging materials used in food applications such as plastic films or cartonboards. In migration studies, food simulants are very often used to simulate food, like Tenax(®), which is the simulant for dry foodstuffs. In this paper a fast and reliable confirmation method for the determination of the following photo-initiators in Tenax(®) is described: benzophenone (BP), 4,4'-bis(diethylamino)benzophenone (DEAB), 2-chloro-9H-thioxanthen-9-one (CTX), 1-chloro-4-propoxy-9H-thioxanthen-9-one (CPTX), 2,4-diethyl-9H-thioxanthen-9-one (DETX), 2,2-dimethoxy-2-phenyl acetophenone (DMPA), 4-(dimethylamino)benzophenone (DMBP), 2-ethylanthraquinone (EA), ethyl-4-dimethylaminobenzoate (EDMAB), 1-hydroxylcyclohexyl phenyl ketone (HCPK), 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (HMMP), 2-isopropyl-9H-thioxanthen-9-one (ITX), 4-methylbenzophenone (MBP), Michler's ketone (MK), and 4-phenylbenzophenone (PBZ). After the migration study was completed, the simulant Tenax(®) was extracted using acetonitrile, followed by analysis on ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Quantification was carried out using benzophenone-d10 (BP-d10) as internal standard. The presented method is validated in terms of matrix effect, specificity, linearity, recovery, precision and sensitivity, showing the method can detect all photo-initiators at very low concentrations (LOD < 0.125 µg g(-1) for all substances). Finally, the procedure was applied to real samples, proving the capabilities of the presented method.

Migration of 18 trace elements from ceramic food contact material: influence of pigment, pH, nature of acid and temperature.

The effect of pH, nature of acid and temperature on trace element migration from ceramic ware treated with 18 commercially available glazes was studied. Besides of the well-studied lead and cadmium, migration of other toxic and non toxic elements such as aluminum, boron, barium, cobalt, chrome, copper, iron, lithium, magnesium, manganese, nickel, antimony, tin, strontium, titanium, vanadium, zinc and zirconium was investigated in order to evaluate their potential health hazards. Trace element concentrations were determined with Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). This study suggests that there is indeed a health risk concerning the possible migration of other elements than lead and cadmium. At low pH (2

Comparison of four analytical techniques based on atomic spectrometry for the determination of total tin in canned foodstuffs.

Different techniques for the determination of total tin in beverages and canned foods by atomic spectrometry were compared. The performance characteristics of inductively coupled plasma-mass spectrometry (ICP-MS), hydride generation-inductively coupled plasma-atomic emission spectrometry (HG-ICP-AES), electrothermal atomisation-atomic absorption spectrometry (ETA-AAS) and inductively coupled plasma-atomic emission spectrometry (ICP-AES) were determined in terms of linearity, precision, recovery, limit of detection, decision limit (CCα) and detection capability (CCß) (Decision 2002/657/EC). Calibration ranges were covered from ng l⁻¹ to mg l⁻¹ level. Limits of detection that ranged from 0.01, 0.05, 2.0 to 200 µg l⁻¹ were reached for ICP-MS; HG-ICP-AES; ETA-AAS and ICP-AES, respectively. Precision, calculated according to ISO 5725-2 for repeatability and within-laboratory reproducibility and expressed as relative standard deviation (RSD), ranged from 1.6% to 4.9%; and recovery, based on Decision 2002/657/EC, was found to be between 95% and 110%. Procedures for the mineralisation or extraction of total tin were compared. Wet digestion, sequentially, with nitric acid and hydrogen peroxide provided the best results. The influence of possible interferences present in canned food and beverage was studied, but no interference in the determination of tin was observed. Since maximum levels for tin established by European Union legislation vary from 50 mg kg⁻¹ in canned baby foods and infant foods up to 200 mg kg⁻¹ in canned food, ICP-AES was chosen as the preferred technique for routine analysis thanks to its good precision, reliability and ease of use. The accuracy of this routine method was confirmed by participation in six proficiency test schemes with z-scores ranging from -1.9 to 0.6. Several canned foodstuffs and beverage samples from a local market were analysed with this technique.

Tea brewed in traditional metallic teapots as a significant source of lead, nickel and other chemical elements.

An environmental inquiry conducted by the Brussels Inter-communal Laboratory of Chemistry and Bacteriology (BILCB) has revealed that in 2000a traditional metallic teapot caused in Brussels lead intoxication among a family of Morocco origin. Following this case study of lead poisoning and subsequent preliminary results carried out by the BILCB, which confirmed the dangerousness of this kind of item, samples of traditional metallic teapots were collected from North African groceries in Brussels by the Institute of Public Health (IPH) in collaboration with the BILCB and the Federal Agency for the Safety of the Food Chain (FASFC). Aluminium, copper, iron, nickel, lead and zinc were analysed to identify metals with a potential to migrate into tea solutions. Simulants (natural tea, tea acidified with citric acid and citric acid) were brewed in those teapots in order to identify the leaching potential of migration at boiling point temperature for different contact periods. Multi-elementary analysis was carried out by inductively coupled plasma-atomic emission spectrometry (ICP-AES). It was concluded that the concentrations of those leached metals depend on the nature of the migration liquids, the type of teapots and the contact periods. Most teapots showed a high level of toxic metals in leachates for lead and to a less extent for nickel, which can contribute significantly to the risk of serious poisoning. A comparison of the results with the toxicological reference values was done. The teapots were withdrawn from the market by the FASFC.

Analysis of benzophenone and 4-methylbenzophenone in breakfast cereals using ultrasonic extraction in combination with gas chromatography-tandem mass spectrometry (GC-MS(n)).

Benzophenone (BP) and 4-methylbenzophenone (4MBP) are photo-initiators that are generally used to cure ink on carton boards. In this contribution, a fast and reliable method for the determination of BP and 4MBP in breakfast cereals is described. The sample was extracted ultrasonically using a mixture of dichloromethane and acetonitrile (1:1), followed by a clean-up of the extract using solid phase extraction with a silica cartridge. Finally, the extract was analysed by GC-MS(n). Benzophenone-d(10) was used as internal standard. The presented method is validated in terms of linearity, recovery, repeatability and intra-laboratory reproducibility, specificity, limit of detection and limit of quantification. In conclusion, this method is able to detect both BP and 4MBP at very low concentrations (LOD=2microg kg(-1)) in breakfast cereals.

Open digestion under reflux for the determination of total arsenic in seafood by inductively coupled plasma atomic emission spectrometry with hydride generation.

A method for the determination of arsenic (As) in seafood by inductively coupled plasma atomic emission spectrometry with continuous hydride generation is described. Several analytical parameters have been investigated and optimised. The analytical features of the method (recovery, precision, accuracy and limit of detection) were calculated. Practical detection limit of 3.6mug/kg fresh weight for As has been reached. The precision of the method expressed as relative standard deviation (R.S.D.) was in the range of 2.7-3.7% and the recovery percentage ranged from 98.4 to 101.8%. The reliability of the developed method was checked by analysing several certified reference materials. A complete mineralization was obtained for arsenobetaine (AsB) containing reference material with a mixture of nitric and sulphuric acids followed by adding hydrogen peroxide in an open digestion system. This method can be applied to routine analysis without any risks of interferences.

Cadmium and lead concentrations in acid food simulants: the values of validation parameters are predominantly affected by interspecific differences of utensils.

The obvious toxicity of cadmium and lead is at the basis of compulsory concentration determinations for lixiviation solutions of ceramic and earthenware household receptacles such as cups, plates, bowls and others. Concentrations in the food simulant which exceed 0.100 +/- 0.005 mg Cd dm-2 and 1.00 +/- 0.05 mg Pb dm-2 for flat receptacles, 0.500 +/- 0.025 mg Cd l-1 and 5.00 +/- 0.25 mg Pb l-1 for low volume (< 5 l) receptacles and 0.250 +/- 0.025 mg Cd l-1 and 2.50 +/- 0.25 mg Pb l-1 for high volume (> 5 l) receptacles are not acceptable and measures were taken by the EU member state authorities to enforce these norm concentrations. Generally, the uncertainty on the results forwarded by the legislation amounts to 5%. This value does not at all match the pronounced variability observed for several 'identical' trade samples, but rather represents the inherent variability of spectrometric analyses alone. Considering that the coefficients of variation can be as high as approximately 30%, either the ranges of acceptable concentrations or the maximal allowable concentrations should be corrected. Aware of the negative health effects of heavy metal contamination and of the risk increase due to dietary intake, a downward adjustment of the acceptable concentration ranges to 0.07 mg Cd dm-2 +/- 12%, 0.30 mg Cd l-1 +/- 12% and 0.10 mg Cd l-1 +/- 12% and to 0.8 mg Pb dm-2 +/- 13%, 4.0 mg Pb l-1 +/- 13% and 1.50 mg Pb l-1 +/- 13% is suggested.