Volume 84, Issue 2

Trace elements are a vital ingredient in our food, which directly relates to our health and well-being. The study of health effects related to the abundance or deficiency of trace elements that we are exposed to in our daily life is of prime importance in order to understand mechanisms and interactions of those elements within the human body. Trace elements taken up with food may exert toxic actions (e.g., in the case of arsenic or mercury), others are essential and a deficiency in these trace elements (e.g., iron, selenium, zinc, or iodine) can have drastic health effects and cause diseases. Therefore, toxic as well as essential aspects of trace elements must be studied and understood, so that regulating or governing bodies may advise on permissible levels for toxic elements, or recommend daily doses for the uptake of essential elements. The 4th International Conference on Trace Elements in Food (TEF-4) addressed a range of issues related to the health effects of trace elements and provided a podium for researchers from different scientific backgrounds: analytical chemists, toxicologists, nutritionists, environmental scientists, and members of health authorities came together to present and discuss recent advances and findings. The conference was held from 19 to 22 June 2011 in the King’s Conference Centre at the University of Aberdeen in Scotland (UK), with Prof. John Beattie (Rowett Institute for Nutrition and Health/University of Aberdeen) and Prof. Jörg Feldmann (University of Aberdeen) acting as Conference Chairs. TEF-4 attracted 150 delegates from 39 countries; 38 oral lectures were presented, 13 of which were given by internationally renowned invited speakers. The scientific program also included a poster exhibition with 108 papers and was completed by 9 exhibiting sponsors, including major analytical instrument manufacturers and representatives of reference material laboratories and government institutes. The scientific program comprised four larger themes, each of which was represented by invited speakers and further oral presentations on the following topics: - source and transfer of trace elements into food and feed - trace elements in nutrition and health - toxicology and risk assessment of trace elements in food - analytical advances in trace elements in food Special attention was paid to selenium as an essential element, and a variety of talks explored the toxic actions of arsenic in different foodstuffs and in epidemiology, completed with topics on mercury, zinc, manganese, iodine, cerium, and other trace metals. The collection of papers in this issue of Pure and Applied Chemistry is a representation of the main topics covered in the lectures held during TEF-4, providing an overview of recent advances in research techniques and findings. We hope that it proves a useful source of new and exciting results, leading the way into the future of food analysis, and that fruitful interdisciplinary collaboration will enhance the impact of fundamental and applied research. Eva M. Krupp Conference Editor

Some elements in food are notoriously toxic, whereas others are considered essential for human health. Information on the exact chemical form in which an element is present in food is of paramount importance to determine the safety and nutritional quality of food. This critical review discusses the state of the art of analytical approaches to speciation of trace elements in food products. The topics addressed include (i) responding to regulations concerning some toxic elements (As, Hg, Sn); (ii) quality control of food and feed supplements; and (iii) characterization, in terms of element speciation, of nutritional plants (natural and genetically modified) and food supplements produced by biotechnology. The maturity of analytical techniques allowing the determination of individual well-defined metal species is highlighted. On the other hand, the recent developments of multidimensional hyphenated techniques and the democratization of electrospray high-resolution mass spectrometry (Orbitrap) start permitting fine characterization of element speciation in natural products.

Concentrations of 20 minor, trace, and ultratrace elements relevant to human health (Ag, Al, As, Cd, Co, Cr, Cu, Fe, Hg, Li, Mn, Mo, Ni, Pb, Sb, Se, Si, Sn, V, and Zn) were determined in three varieties of Lebanese bread (white and brown double loaf bread, Saj bread) sampled at five geographical regions (Grand Beirut, South of Lebanon, North of Lebanon, Mount of Lebanon, and Beka’a) during the wet and dry seasons. The analyses were carried out by double-focusing sector-field inductively coupled plasma-mass spectrometry (DF-SF-ICP-MS). The data were discussed in terms of nutritional elements supplied by type of bread, the risk of contamination by toxic elements (As, Cd, Pb) owing to the manufacturing process, and variations related to geographic distribution and seasonal sampling.

To evaluate the accuracy and robustness of an extraction method, utilizing an -alkaline-ethanolic solution and microwave heating, the certified reference material (CRM) TORT-2 was subjected to three different instrumental methodologies: high-performance liquid chromatography (HPLC), coupled with and without post-column hydride generation; inductively coupled plasma-mass spectrometry (ICP-MS); and HPLC-hydride generation-atomic fluorescence spectrometry (HPLC-HG-AFS). The three methods gave a consistent value of inorganic arsenic (As) which is near the mean value of the reported values in the literature, which, however, range by a factor of 10. Inorganic As, defined here as all As species that do not have an As–C bond, that is, the sum of arsenite and arsenate and any thiol-bound As, was found to be less than 4 % of total As concentration in 12 samples of fish meal when subjected to this extraction method followed by HPLC-ICP-MS. To date, there is no certified value of inorganic As in a seafood-based reference material to compare to in order to validate the findings. This illustrates the difficulties in quantitative determination of inorganic As in seafood and the need for a reference material for inorganic As and proficiency tests in order to introduce legislation for a maximum level of inorganic As in seafood and feed.

Current knowledge indicates that total urinary arsenic is not a suitable biomarker of exposure to toxic, i.e., inorganic, arsenic (iAs), whereas measurement of iAs and its methylated metabolites in urine using speciation analysis provides much more reliable estimates of exposure. The relative proportions of urinary iAs, monomethylarsonate (MA), and dimethylarsinate (DMA) can be used as a measure of methylation capacity, provided that there are no confounding factors such as consumption of food rich in DMA or containing As compounds metabolized to DMA.We analyzed by gradient elution anion-exchange HPLC-ICP-MS (high-performance liquid chromatography-inductively coupled plasma-mass spectrometry) urine samples from 153 residents in Latium (central Italy) chronically exposed to iAs via water and food. Excluding 26 subjects that excreted high concentrations of arsenobetaine (AB) (≥50 μg As/L) due to seafood consumption, iAs and related metabolites summed up about 75 % of total urinary As as measured by ICP-MS. AB and other organoarsenic compounds were detected at low concentrations in all urine samples. Considering all subjects, the sum of iAs and metabolites ranged 2–72 μg/L and relative proportions were iAs 14 %, MA 13 %, and DMA 72 % (median values), with a wide individual variability.In addition to the above arsenocompounds, the analytical method used in this study enabled the detection of dimethylthioarsinic acid (DMTA), which was found to be present in 33 % of the samples at concentrations ranging mostly from trace amounts to ~6 μg As/L. We found that part of the certified DMA content of human urine reference material SRM 2669 was present as DMTA. Four unknown arsenicals were also detected as minor species in a small proportion of samples.

Arsenic (As) exposure to humans is pervasive, and, increasingly, studies are revealing adverse health effects at ever lower doses. Drinking water is the main route of exposure for many individuals; however, food can be a significant source of As to individuals, especially if their diet is rice-based. Infants are particularly susceptible to dietary exposure, since many first foods contain rice and infants have a low body mass. Here we report on As concentration and speciation in infant formulas and first foods. Speciation is essential for food analysis because of the much greater toxicity of inorganic As species and the possibility that As in food (unlike water) may be present in either inorganic or organic forms. Infant milk formulas were low in total As (2.2–12.6 ng g –1 , n = 15). Non-dairy formulas were significantly higher in As than dairy-based formulas. Arsenic in formula was almost exclusively inorganic. Arsenic concentration in purees ( n = 41) and stage 2/3 foods ( n = 18) ranged from 0.3 to 22 ng g –1 . Rice-fortified foods had significantly higher total As concentrations than non-rice-based foods. Again, As speciation was predominantly inorganic with lower concentrations of dimethylarsenic acid (DMA) also present. These data confirm that infants are exposed to As via diet, and suggest that careful attention to diet choices may limit this exposure.

A full validation of inorganic arsenic (iAs), methylarsonic acid (MA), and dimethyl arsinic acid (DMA) in several types of rice and rice-based infant cereals is reported. The analytical method was developed and validated in two laboratories. The extraction of the As species was performed using nitric acid 0.2 % and hydrogen peroxide 1 %, and the coupled system liquid chromatography-inductively coupled plasma-mass spectrometry (LCICP-MS) was used for speciation measurements. Detection limit (DL), quantification limit, linearity, precision, trueness, accuracy, selectivity, as well as expanded uncertainty for iAs, MA, and DMA were established. The certified reference materials (CRMs) (NMIJ 7503a, NCS ZC73008, NIST SRM 1568a) were used to check the accuracy. The method was shown to be satisfactory in two proficiency tests (PTs). The broad applicability of the method is shown from the results of analysis of 29 samples including several types of rice, rice products, and infant cereal products. Total As ranged from 40.1 to 323.7 μg As kg –1 . From the speciation results, iAs was predominant, and DMA was detected in some samples while MA was not detected in any sample.

Selenium (Se) is an important dietary micronutrient required for sustaining optimal health. Se is incorporated into proteins, many of which are antioxidants that protect the body against oxidative damage. As oxidative damage may contribute to the development of chronic diseases including cardiovascular disease (CVD), Se has been proposed to provide a protective role against this disease. Studies in vitro and in animals continue to provide increasing insight into the role of Se in promoting vascular health and ameliorating CVD. Se within vascular cells limits the adhesion together of such cells, an important early step in the development of vascular disease. Organic forms of Se may also afford vascular cells greater protection against oxidative challenge compared to inorganic forms. Nevertheless, current studies in humans investigating the relationship between Se and CVD have so far proved equivocal; larger randomized trials with different Se exposures in populations spanning the broad physiological Se status are needed to determine the criteria whereby Se may influence CVD outcome within different populations. Further studies are also needed to explore the effects of different Se species and the role of different selenoprotein genotypes in modifying Se status and their resultant impact on cardiovascular function.

Selenium (Se) is an essential trace element important for several biological functions, such as thyroid hormone metabolism, anti-aging, and antioxidant protection. Even though reports on Se species in different food products are increasing, the scientific knowledge on the bioaccessible amount of Se species from these products is not as well known. In this work, Se-enriched chicken meat was digested by an in vitro model using human gastro-intestinal (GI) juices and different commercial enzymes. The aim of the study was to gain information on the bioaccessible amount of Se from meat after digestion by different relevant enzymes with the approach of replacing human liquids with commercial enzymes that could mimic the digestion in the human GI tract. The digestion with commercial enzymes such as pepsin, protease, and lipase resulted in highly variable extraction yield of Se in isotonic salt water (50–90 %). Se proteins were degraded into SeMet, while Se species with higher molecular mass were present in the extracts from human juices. The extraction yield using human juices was only about 70 % of Se from the meat, but Se in the extracts was normally distributed with a low standard deviation (4 %), indicating stability of the results from digested extract.

For the study, cabbage ( Brassica oleracea var. capitata L.) and red cabbage ( Brassica oleracea var. capitata L. f. rubra) were treated with Na selenate. Cabbage was foliarly sprayed twice with 20 mg Se(VI) L –1 , while red cabbage was fertilized twice with 0.5 mg Se(VI) L –1 . Despite the high dose of Se, no toxic effects were observed on cabbage plants. The total Se concentration in cabbage leaves was 4.80 ± 0.25 μg Se g –1 (DM) and in red cabbage 0.96 ± 0.04 μg Se g –1 (DM). Soluble Se compounds were extracted from parts of cabbage with protease XIV, resulting in 49 % of soluble Se from roots, 59 % from leaves, and 65 % from stems. In red cabbage, the corresponding figures were 28 % of soluble Se in roots, 31 % in stems, and 43 % in leaves. Se species were determined in the enzymatic extracts using ion exchange high-performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS). The main Se species found in all parts of cabbage and red cabbage was selenomethionine (SeMet), which in roots represented 94 and 55 % of the soluble Se content in cabbage and red cabbage, respectively. In stems and leaves of cabbage, SeMet represented only 23 % of the soluble Se content. In stems of red cabbage SeMet represented 80 % and in leaves 41 % of the soluble Se content. We observed that traces of Se(VI) were present in upper parts of both plants.

The optimization of culture conditions for selenium (Se) bioaccumulation in the microalgae Chlorella sorokiniana growth in a Na 2 SeO 4 -enriched medium was explored, in order to obtain a suitable approach for the biotechnological production of a Se-enriched food. Se concentration (as Na 2 SeO 4 ) in the culture medium until 100 μg ml –1 allows the growth of algae colonies during long periods of time, until 300 h, but higher concentrations cause the collapse of the colony. The bioaccumulation process causes a concentration of Se in algae in the order of 3 μg g –1 in about 100 h. A metallomic analytical approach based in the coupling high-performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS), which uses two chromatographic switched columns (C-18 and chiral columns) with ICP-MS detection, has been applied to characterize the different Se metabolites, including chiral forms, in both the algae and culture medium. The results reveal that selenate present in the culture is biotransformed in selenocystine (SeCys 2 ), selenomethylselenocysteine (SeMeSeCys), and mainly selenomethionine (SeMet) by the algae, although appreciable concentration of Se(VI) is also present in cells. When algae are cultured under sulfur (S) deficiency conditions, the accumulation of Se in the cell is enhanced owing to the great chemical similarity between S and Se that promotes the substitution of S by Se in the cell metabolism, therefore, SeMet concentration in the algae increases from about 7 to 15 μg g –1 and Se(VI) from 15 to 25 μg g –1 , after 500 h of exposure.

Mercury (Hg) is a global pollutant and can transform into methylmercury (MeHg), a highly toxic and bioaccumulative organic form. Recent surveys showed that rice ( Oryza sativa L. ) rather than fish is the main source of human MeHg exposure in Hg mining and retorting regions in Guizhou province, southwestern China, where rice is a traditional staple food. Here we report that MeHg in rice grown at an active Hg mining and retorting region in Shaanxi province, northwestern China, characterized with different climate compared to Guizhou, contained levels up to 240 μg kg –1 MeHg in bran, 78 μg kg –1 MeHg in polished rice, and 30 μg kg –1 MeHg in hull, respectively. Although the polishing process may reduce MeHg content, the mass balance calculation showed that greater than 50 % of total MeHg mass can be observed in white rice (polished rice). The ongoing Hg retorting activities, which account for the high levels of ambient air Hg, result in high levels of MeHg in rice grains. Our results further demonstrate that the accumulation of MeHg is a common feature of rice.

Iodine is an essential trace element, and its deficiency has caused concern in many countries. Foods are the principal source of iodine, and its levels are generally low. In this study, selected food items were obtained from food market outlets in Brisbane, Australia. Food samples of dietary intakes of selected healthy children in Brisbane, Australia, were also collected for analysis and assessment of iodine nutritional status. In Australia, there has been little study on iodine dietary intakes, particularly in young children. The aims of this study were to provide further information on iodine levels in foods for Australian food composition data, and to estimate the iodine daily intakes of selected healthy children. Food samples were analyzed for iodine concentrations using inductively coupled plasma-mass spectrometry (ICP-MS) after alkaline digestion with tetramethylammonium hydroxide (TMAH), and the method was validated using a certified reference material of nonfat milk (NIST, SRM 1549). The results of this study indicated a wide variation of iodine in foodstuffs, which ranged from <0.02 to 0.101 mg/kg for cereals, 87 to 299 μg/kg for milk, and 86 to 271 μg/kg for cheese products. The study also showed that the daily intakes of iodine in these children ( n = 15) varied widely and ranged from 36.9 to 288.1 μg/day (mean ± s.d, 93.1 ± 76.7 μg/day).

The objectives of this work were to get information on Zn species in two different specimens of edible plants (pumpkin seeds and iceberg lettuce) and simulation of their behavior in the human gastrointestinal tract. An array of analytical techniques was used to aid in this research: ultrasound-assisted variable volume extraction, size exclusion chromatography (SEC), and physiologically based extraction tests (PBETs); elemental detection was performed by inductively coupled plasma-mass spectrometry (ICP-MS). Results show that pumpkin seeds and iceberg lettuce have different Zn species fingerprints (in water extracts) with a high (ca. 70 %) low-molecular-weight fraction (ca. 500 Da) in iceberg lettuce and a high (ca. 60 %) intermediate/high-molecular-weight fraction (10–20 kDa) in pumpkin seeds. When these Zn species are subjected to conditions simulating the human stomach (pH ~ 2) complete scrambling to their basic ionic form (Zn 2+ ) takes place. Under conditions simulating the digestion in the intestines (pH ~ 7) formation of insoluble Zn complexes occurs, especially for pumpkin seeds, which may be related to antinutrients like naturally present phytate, leading to reduced Zn bioaccessibility in the small intestine.

The general population is increasingly exposed to cerium (Ce), which is contained in industrial products or is present as nuclear Ce fission products. Some studies suggested a link between elevated Ce levels and endomyocardial fibrosis. Since breast milk is the optimal, and directly after birth, usually the sole nutrition for newborns, exposure of females to Ce and its transfer to infants by breast-feeding is of concern in neonate protection. Consequently, the transfer rate of Ce from blood to breast milk is of interest for elucidating the Ce exposure of infants. Biomonitoring of paired serum and breast milk samples provides such information about Ce transfer to human milk. Therefore, this study is aimed at clarification of the relationship between Ce in human milk and serum from respective mothers for elucidating Ce enrichment in human milk with possible nutritional risk for newborns. As a prerequisite a strictly quality-controlled Ce determination method applicable to very low Ce concentration was developed, and its figures of merit were determined and found to be sufficient for our purpose. It turned out that Ce concentration in milk from Munich (Germany) and Madrid (Spain) showed a median of 13 ng/L. Ce concentrations in serum were at limit of quantification (LOQ) 10 ng/L (Munich) or 21.6–70.3 ng/L (Madrid), suggesting a higher Ce intake in Madrid. No enrichment from blood to milk was seen, and no elevated nutritional risk for breast-fed babies from Ce was found. Ce in serum, but not in milk, could indicate environmental Ce.

Among the factors associated with the risk of colorectal cancer and other large bowel diseases are gender, with women having lower incidence than men, and free-radical mediated oxidation. Dietary fiber has been attributed a protective role in human gastro-intestinal health. The main aim of this study was to determine the degree of association between dietary fiber consumption and fecal free-radical production in healthy rural and urban Guatemalan women, moreover, to look for associations between gender and fecal reactive oxidative species (ROS) basal production, a marker of in situ colonic free-radical-based oxidation. For this purpose, we assessed the dietary fiber consumption, using two 24-h recalls, in urban and rural females, and compared the baseline data, i.e., of iron-supplement-free periods, in three previous studies. Two of these trials quantified the fecal ROS generation as total hydroxylated products resulting from free-radical attack on salicylic acid along with residual non-heme iron content in stool samples from 27 Fe-replete men. The third study assessed the same variables in 20 rural and 20 urban women, all consuming their respective habitual diets. The average fiber consumption for females was more than double in the rural group than in the urban population. As for the average ROS responses, a 2.5-fold difference was observed between men and women, with men having the higher concentrations of total hydroxylated products. This difference was sex-linked, unaffected by statistically significant differences in dietary fiber intake, nor by different concentrations of residual fecal non-heme iron between rural and urban women. The difference in background ROS production between men and women suggests a gender-related influence on intraintestinal oxidation that may protect women from harmful effects of dietary oxidants, such as iron.

Remote sensing/satellite observation of land and oceans is a field of research that was developed during the second half of the 20 th century, and its importance is widely recognised because of the amount of information it can provide to the scientific community and the general public. The outcomes of remote sensing/satellite observation can be used to address and study significant aspects of environmental concern, such as habitat destruction, environmental degradation, forest fires, oil spills, and climate change. There is continuous improvement of the methods and means of remote sensing observations in order to achieve more accurate and useful information. The main advantage is the possibility of observing large areas, and the main disadvantage is that it can observe only the water and land surface. The present paper is an effort to review the technologies used in remote sensing and the general applications in a comprehensive manner addressed to scientists who do not specialize in this area of research. Furthermore, this paper reviews case studies/applications in the Mediterranean Sea, an area affected by various polluting activities (industrial cities, agriculture, shipping, etc.) that should be continuously monitored so that the coastal countries are able to successfully manage this sensitive environment.

Like most of the materials used by humans, polymeric materials are proposed in the literature and occasionally exploited clinically, as such, as devices or as part of devices, by surgeons, dentists, and pharmacists to treat traumata and diseases. Applications have in common the fact that polymers function in contact with animal and human cells, tissues, and/or organs. More recently, people have realized that polymers that are used as plastics in packaging, as colloidal suspension in paints, and under many other forms in the environment, are also in contact with living systems and raise problems related to sustainability, delivery of chemicals or pollutants, and elimination of wastes. These problems are basically comparable to those found in therapy. Last but not least, biotechnology and renewable resources are regarded as attractive sources of polymers. In all cases, water, ions, biopolymers, cells, and tissues are involved. Polymer scientists, therapists, biologists, and ecologists should thus use the same terminology to reflect similar properties, phenomena, and mechanisms. Of particular interest is the domain of the so-called “degradable or biodegradable polymers” that are aimed at providing materials with specific time-limited applications in medicine and in the environment where the respect of living systems, the elimination, and/or the bio-recycling are mandatory, at least ideally.