Water from La Pampa, Argentina, was used for washing and cooking rice to examine the in-situ impact of using naturally-contaminated water for food preparation on the elemental dietary intake. Whilst washing with the control tap water (28 μg/L As) reduced the concentration of As in rice by 23%, the use of different well waters (281–1144 μg/L) increased As levels significantly (48–227%) in comparison with the original concentration in the rice (0.056 µg/g). Cooking the rice at a low water-to-rice ratio (2:1) using modern methods increased the levels of As in the cooked samples by 2–3 orders of magnitude for both pre-washed and un-washed rice. Similar trends were observed for vanadium. Although the levels of manganese, iron, copper, zinc and molybdenum in rice were reduced during washing and cooking for most water samples, the molybdenum concentration in the cooked rice doubled (2.2–2.9 µg/g) when using water containing >1 mg/L Mo.

A new kind of solid phase extraction (SPE), which we named in situ surfactant-based solid phase extraction (ISS-SPE), represents a simple, selective and rapid method for preconcentration and determination of manganese from food and water samples. This method has distinct advantages: extraction times are short and recoveries are high; further, we can see formation of fine particles of large specific surface and their good dispersion in the solution. In this work, a small amount of cationic surfactant, n-dodecyltrimethylammonium bromide (DTAB) was injected into the water sample containing Mn ions, which were complexed by 1-(2-pyridylazo)-2-naphthol (PAN). After shaking, a little volume of NaPF6 as an ion-pairing agent was added into the solution by a microsyringe. After preconcentration, the settled phase was dissolved in a specific volume of ethanol and then aspirated into the flame atomic absorption spectrometer by using a homemade microsample introduction system. The effective parameters such as pH, concentration of surfactant, concentration of chelating agent, concentration of ion-pairing agent and effect of salt concentration were optimized by a fractional factorial design to identify the most important parameters and their interactions, and central composite methodology was used to achieve the optimum point of effective parameters to the response. Under the optimum conditions, preconcentration of 10 ml of the sample solution permitted detection of 0.88 μg l−1 with enhancement factor of 45.6, and the relative standard deviation (RSD) for five determinations of Mn ions was 3.5%. The developed method was applied to the determination of trace manganese in various real samples with satisfactory results.

A novel and green method was developed for enrichment of maneb (manganese ethylene-bisdithiocarbamate) with a supramolecular solvent liquid phase microextraction method. The microextraction method has been used for the first time in the literature for separation-preconcentration of maneb. 1-decanol and tetrahydrofuran were used in the supramolecular solvent formation. The Mn²⁺ content of maneb was extracted in the supramolecular solvent phase as 1-(2-pyridylazo)-2-naphthol complex at pH 12.0. Manganese concentration was determined by UV–Vis spectrophotometer at 555 nm. Then, the maneb concentration equivalent to manganese concentration was calculated. The analytical parameters which effective in the method, including pH, volume of reagents, and sample volume were optimized. The limit of detection and the limit of quantification values for maneb were calculated as 2.22 μg L⁻¹ and 7.32 μg L⁻¹, respectively. The method was successfully applied in the analysis of the maneb content of water and food samples.

Although fish is widely consumed by humans for its nutritional properties, accumulation of heavy metals can pose serious health hazards. Widespread common carp Cyprinus carpio is cultured worldwide and represents an economically important species for fisheries in several countries. These include Turkey, where C. carpio often makes for a large part of the sales of the locally marketed fish and also for a traditional dish. This study provides a review of bioaccumulation of metals in tissues of C. carpio from water bodies of Anatolia and also includes reference to worldwide studies. From 42 water bodies across the region, 27 metals in total were studied, of which Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn were the most widely analysed, mainly in the muscle, liver and gill tissues. Amongst the potentially toxic metals, Cd, Cr and Pb occurred in several water bodies at concentrations not only above maximum allowed limits but also higher relative to other water bodies worldwide, even though As, Hg and Ni were also sometimes present at potentially hazardous concentrations. The essential metals Cu, Fe, Mn, Se and Zn were detected at various concentrations, with the latter two occasionally above limit. All water bodies flagged as having especially critical (i.e. above limit) concentrations of toxic metals supported C. carpio fisheries from highly populated regions, raising concern about food safety and calling for preventative measures. Given the significantly lower bioaccumulation levels in the muscle relative to the liver and gill tissues, it is suggested that consumption of C. carpio as fillets may be safer than after processing into e.g. meat balls and sausages. The limits of 1.0 μg/g for Cr and 1.15 μg/g for Se, currently lacking from the Turkish food safety legislation, are proposed, and it is suggested that a similar meta-analytical approach as adopted in this study may benefit other countries where C. carpio represents an important fisheries resource.

A novel method based on the immobilization of N-acetylcysteine on chloro-functionalized multi-walled carbon nanotubes (MWCNTs@NAC) was used for the speciation of manganese ions [Mn (II) and Mn(VII)] in water samples. Also, the total manganese (TMn) in vegetables and food samples was determined by the AT-FAAS. By ultrasound-assisted-dispersive ionic liquid trap micro solid-phase extraction (UA-DILT-μ-SPE), the Mn (II)/Mn(VII) ions were extracted in the presence of MWCNTs@NAC for 50 mL of water samples at a pH of 6.5 and 3.0, respectively. The adsorption capacity of MWCNTs@NAC for Mn(II) and Mn(VII) ions was obtained at 146.7 mg g⁻¹ and 138.8 mg g⁻¹, respectively. Under the optimized conditions, the detection limits (LOD), linear range (LR), and enrichment factor (EF) for Mn(II) and Mn(VII) ions were obtained (0.12 μg L⁻¹; 0.14 μg L⁻¹), (0.48–36 μg L⁻¹; 0.55–38.1 μg L⁻¹) and (100.2; 94.5), respectively. The proposed methodology was successfully validated by the CRM samples.