Optimization of preconcentration procedure using magnetic nanoparticles for the determination of manganese in cereal samples

In the present study, we developed a magnetic nanoparticle adsorbent that uses iron oxide nanoparticles as the core and 1-(2-pyridylazo)-2-naphthol (PAN) as manganese ion exchange groups in cereal samples. This adsorbent was shown to be quick and efficient for the adsorption of manganese due to higher specific surface area, lower mass removal resistance and the absence of internal diffusion resistance. This method is simple and rapid for the preconcentration and determination of manganese in food samples by inductively coupled plasma optical emission spectrometry (ICP OES). The technical feasibility of magnetic nanoparticles for the removal of manganese was investigated under batch studies. It was based on (PAN)-modified magnetic nanoparticles. Four variables (pH of solution, amount of extractant (E), amount of nanoparticles (N) and time) were regarded as factors in the optimization. Results of the two-level fractional factorial design (2^4?1) based on an analysis of variance demonstrated that only the pH, amount of extractant (E) and amount of nanoparticles (N) were statistically significant. Optimal conditions for the extraction of manganese were obtained using Box–Behnken design. For optimum recovery of manganese, the variables pH of solution, amount of nanoparticles and amount of extractant values were 9.44, 3.46 mg and 3.91 mg, respectively. In the optimum experimental conditions, the limit of detection and enrichment factor of the proposed method were 0.1 μg L^?1 and 28, respectively. The precision as RSD was 3.6% for concentration of 50 μg L^?1. The accuracy of the proposed procedure was evaluated by analysis of certified reference material. The method was applied to the determination of manganese in barley, wheat and rice flour samples. The manganese content in the samples analyzed varied from 7.8 to 19.9 μg g^?1.     

Genetic diversity of nutritionally important carotenoids in 94 pea and 121 chickpea accessions

Biofortification of staple crops via breeding is an attractive strategy for reducing human micronutrient deficiencies. The objective of this research was to examine the concentration of carotenoids in diverse pea and chickpea accessions grown in Saskatchewan (Canada) using high performance liquid chromatography. In pea accessions mean concentration of lutein was highest (11.2 μg g⁻¹) followed by β-carotene (0.5 μg g⁻¹), zeaxanthin (0.3 μg g⁻¹), and violaxanthin (0.3 μg g⁻¹). Green cotyledon pea accessions were richer in β-carotene and total carotenoids compared to yellow cotyledon accessions. In chickpea accessions mean concentration of lutein (8.2 μg g⁻¹) was highest followed by zeaxanthin (6.2 μg g⁻¹), β-carotene (0.5 μg g⁻¹), β-cryptoxanthin (0.1 μg g⁻¹), and violaxanthin (0.1 μg g⁻¹). Desi chickpea accessions had higher carotenoid concentration than kabuli accessions. This research identified pea and chickpea accessions that can be utilized in breeding for the improvement of carotenoid concentration through biofortification.     

Levels and sources of volatile organic compounds including carbonyls in indoor air of homes of Puertollano,the most industrialized city in central Iberian Peninsula. Estimation of health risk

Twenty nine organic air pollutants including carbonyl compounds, alkanes, aromatic hydrocarbons and terpenes were measured in the indoor environment of different houses together with the corresponding outdoor measurements in Puertollano, the most industrialized city in central Iberian Peninsula. VOCs were sampled during 8 weeks using Radiello^® passive samplers, and a questionnaire on potential VOCs sources was filled out by the occupants. The results show that formaldehyde and hexanal was the most abundant VOCs measured in indoor air, with a median concentration of 55.5 and 46.4 μg m⁻³, respectively followed by butanal (29.1 μg m⁻³), acetone (28.4 μg m⁻³) and acetaldehyde (21.4 μg m⁻³). After carbonyls, n-dodecane (13.1 μg m⁻³) and terpenes (α-pinene, 13.4 μg m⁻³ and limonene, 13.4 μg m⁻³) were the compounds with higher median concentrations. The indoor/outdoor (I/O) ratios demonstrated that sources in the indoor environment are prevailing for most of the investigated VOCs especially for limonene, α-pinene, hexanal, formaldehyde, pentanal, acetaldehyde, o-xylene, n-dodecane and acetone with I/O ratio >6. Multiple linear regressions were applied to investigate the indoor VOC determinants and Spearman correlation coefficients were used to establish common sources between VOCs. Finally, the lifetime cancer risk associated to formaldehyde, acetaldehyde and benzene exposure was estimated and they varied from 7.8 × 10⁻⁵ to 4.1 × 10⁻⁴ for formaldehyde, from 8.6 × 10⁻⁶ to 3.5 × 10⁻⁵ for acetaldehyde and from 2.0 × 10⁻⁶ to 1.5 × 10⁻⁵ for benzene. For formaldehyde, the attributed risk in most sampled homes was two orders of magnitude higher than the one (10⁻⁶) proposed as acceptable by risk management bodies.     

Fluoroquinolone antibiotic determination in bovine milk using capillary liquid chromatography with diode array and mass spectrometry detection

A fast and sensitive method has been developed for the determination of five fluoroquinolones and a quinolone in commercial bovine milk by capillary-LC–DAD–MS after simple extraction method based on milk deproteinization with 15% trichloroacetic acid. Separation was carried out in a Zorbax SB-C18 column (150 mm × 0.5 mm, 5 μm) using a mixture of acetonitrile–5 mM ammonium formate (pH 3.7) as mobile phase in gradient elution mode. The sample was prepared in a 5 mM aqueous ammonium formate buffer for focusing purposes and 20 μL were injected. Flow rate and temperature were set at 20 μL min⁻¹ and 25 °C, respectively. Method validation was performed according to the European Commission Decision 657/2002/EC. Sample detection limits were between 2.8 and 25 μg kg⁻¹, and good linearity was observed up to 250 μg kg⁻¹ for all analytes. Acceptable and constant recoveries of 96% for enrofloxacin, 77% for its metabolite ciprofloxacin, and 64% for flumequine, with RSDs (n = 4) lower than 8%, were obtained at the 100 μg kg⁻¹ maximum level permitted in milk. Recoveries between 70% and 83% were obtained when difloxacin, sarafloxacin and ofloxacin (not allowed in animals that produce milk for human consumption) were added to milk samples at levels in the range 75–150 μg kg⁻¹. Decision limit (CC_α), detection capability (CC_β), repeatability, within-laboratory reproducibility and robustness were compliant with European Union regulations.     

Mineral composition and bioaccessibility in Sarcocornia ambigua using ICP-MS

This study evaluates the nutritional potential of Sarcocornia ambigua as new a source of minerals. The mineral concentrations of two different growing populations (natural occurrence and irrigated) of S. ambigua were evaluated using inductively coupled plasma mass spectrometry. In all samples, the mineral present in highest amounts was potassium (K) (19–24 μg g⁻¹), followed by magnesium (Mg) (8.6–14 μg g⁻¹) and then calcium (Ca) (2.6–4.0 μg g⁻¹). In addition, in vitro bioacessibility assay demonstrated that very high fraction (65–80%) of these K and Mg (80 and 65%) of total concentration of these elements is bioacessible from S. ambigua analyzed. The trace elements vanadium (V), chromium (Cr), cobalt (Co), copper (Cu) and lithium (Li) have more than above 50% of total concentration was found bioaccessible. In all cases, mass balance was verified by carrying out the total digestion of the remaining residue and the relationship between total concentration and bioaccessibility. The data related to the concentrations and the bioaccessible fractions of the minerals provide a starting point for more complex and in-depth evaluations from the nutritional point of view, including the establishment of a recommended daily dietary intake for this plant.     

Single-run analysis of vitamin D photoproducts in oyster mushroom (Pleurotus ostreatus) after UV-B treatment

A single-run high performance liquid chromatography (HPLC) with diode array detector (DAD) based method was developed for the separation, identification and comprehensive quantification of degradation products of ergosterol formed in oyster mushroom (Pleurotus ostreatus) after UV-B exposure. After 60 min, 10 substances involved in the photoprocess were separated, identified by their characteristic DAD spectrum and distinguished by their molecular weight, in cases where spectra were identical: vitamin D₂, previtamin D₂, tachysterol₂, lumisterol₂ and ergosterol, and, in minor quantity, their structural analogues of the 22,23-dihydroergocalciferol (vitamin D₄) series. Sample preparation protocol affected the total yields and the ratios of previtamin and vitamin D₂/D₄. Hot alkaline hydrolysis resulted in the best digestion of the mushroom matrix and accordingly gave the highest vitamin D yield (D₂: 141.32 μg g⁻¹ dry matter, DM; D₄: 22.72 μg g⁻¹ DM). Limit of detection for vitamin D_2/4 was 0.02 μg g⁻¹ dry matter (DM) and was estimated for previtamin D_2/4 (0.06 μg g⁻¹ DM), tachysterol_2/4 (0.02 μg g⁻¹ DM) and lumisterol_2/4 (0.06 μg g⁻¹ DM). Recovery of spiked vitamin D₂ was 97 ± 0.7%. The study provides an analytical tool to assess the process of vitamin D generation after UV-B treatment for the production of oyster mushrooms with a balanced nutritional profile of vitamin D compounds.     

Determination of trace amounts of germanium in food and fruit by spectrophotometry with p-methybenzeneazosalicylflurone

A novel spectrophotometric method was developed for determination of germanium in food and fruit using p-methybenzeneazosalicylflurone as a new chromogenic reagent. Under optimum reaction conditions, the reagent reacts with germanium(IV) to form a red complex with a maximum absorption at 502 nm. The apparent molar coefficient of the complex was 2.0×10⁵ L mol⁻¹ cm⁻¹, and a linear absorbance was obtained for 0–7 μg of germanium in 10 mL solution. The reaction completed rapidly and the absorbance of the complex remains stable for at least 24 h at room temperature. The effect of various substances on the determination of germanium was investigated in succession. The results indicated that all studied co-existing substances can be tolerated in considerable amounts, e.g., 4000-fold molybdenum(VI) and tin(II) do not interfere with the determination of germanium; its selectivity is obviously better than other reagents in the literature. The detection limit, calculated using three times the standard error of estimate of the calibration graph, is 0.006 μg g⁻¹of germanium with the pre-concentration of germanium in digested solution using ferric hydroxide as the co-precipitator.     

Essential and non-essential elements in Brazilian infant food and other rice-based products frequently consumed by children and celiac population

Rice and its derivatives are important source of essential and non-essential elements. Essential elements as cobalt (Co) and selenium (Se) are vital for human homeostasis. However, non-essential elements such as arsenic (As), cadmium (Cd) and lead (Pb) may be present in rice-based food and consequently, people can be exposed—especially children and the celiac population. This study aimed to determine essentials and non-essentials elements in rice-based products and baby food and also to evaluate nutritional risk by estimating the daily intake of non-essential elements. Regarding essential elements, Co and Se presented the highest concentrations in rice flour (56 μg kg⁻¹) and porridge (254 μg kg⁻¹), respectively. For non-essential elements, the highest concentrations of As, Cd and Pb were 104 μg kg⁻¹ (porridge), 16 μg kg⁻¹ (flour), and 188 μg kg⁻¹ (bread), respectively. Total As concentration in Brazilian rice-based baby food was <29 μg kg⁻¹. However, As-speciation revealed inorganic-As (i-As) as the main specie. The highest estimated daily intake of Cd, Pb and i-As were 1.37 (rice-based baby food); 10.39 (pasta); and 3.34 (pasta) μg d⁻¹, respectively. Therefore, continuous food monitoring for nutritional and toxicological purpose is necessary, especially concerning these particular populations and discussions for maximum levels of non-essential elements.     

A fast and effective method of quantitative analysis of VB1, VB2 and VB6 in B-vitamins complex tablets based on three-dimensional fluorescence spectra

Scattering signals and partial overlapping of target peaks usually appear in fluorescence determination. In this study, the improved wavelet moment method was proposed and applied to the quantitative determination of multiple target components in real B-vitamins complex tablets based on three-dimensional (3D) fluorescence spectra. The correlation coefficients (R) were more than 0.9939, and the correlation coefficients of leave-one-out cross-validation (R_LOO-cv) were more than 0.9376. The inter-day and intra-day variations were less than 5.8% and 6.1%, respectively. The recovery ranged from 97.6% to 109.4%. The limits of detection (LODs) and quantification (LOQs) were less than 0.07 μg mL⁻¹ and 0.13 μg mL⁻¹, respectively. All the statistical parameters indicated that the method was stable and reliable. The application to the practical samples confirmed that wavelet moment method effectively extracted the features of target components in 3D spectra and the proposed method could be applied to the analyses of food or other complex samples.     

Determination of cobalt and manganese in food seasonings by flame atomic absorption spectrometry after preconcentration with 2-hydroxyacetophenone-functionalized polyurethane foam

The use of chelating reagents impregnated or incorporated into solid sorbents has been widely employed for the preconcentration of metal species. The determination of metal concentrations in foods is very important because the diet is the main route of intake for these elements. In this work, polyurethane foam (PUF) functionalized with 2-hydroxyacetophenone through a covalent group (–NC–) was applied as a preconcentration system for the determination of cobalt and manganese in food. PUF was reacted with 2-hydroxyacetophenone in a dioxane medium. The mixture was heated to 90 °C and held at reflux for 72 h with continuous stirring. The solid sorbent produced was used in a preconcentration system for the determination of Co and Mn. Chemical and flow variables affecting the preconcentration were studied. Under optimized conditions, the enrichment factors were 36-fold and 27-fold for cobalt and manganese, respectively. The limits of detection obtained for the solid sample analysis were 0.4 μg g^?1 (Co) and 0.4 μg g^?1 (Mn). The method was applied to the determination of cobalt and manganese in several common food seasonings.     

Determination of folic acid in fortified wheat flours

A reversed-phase high-performance liquid chromatography (HPLC) method with ultraviolet detection to determine folic acid (FA) in fortified wheat flour is described. The method includes FA extraction with tetraborate and trichloroacetic acid buffer solution and purification by solid-phase extraction with strong anion-exchange cartridges. Good results were obtained with respect to repeatability (relative standard deviation ⩽8.8) and recovery (⩾97%). Detection and quantification limits were 0.06 and 0.19 μg g⁻¹, respectively. The comparison between the HPLC method and both microbiological and immunoenzymatic assays revealed similar results. FA determination results on 33 wheat flours samples revealed that 51% of these samples had below 1.50 μg g⁻¹ FA concentration added, the enrichment level established by Brazilian Regulation.     

An efficient,rapid and microwave-accelerated dispersive liquid–liquid microextraction method for extraction and pre-concentration of some organophosphorus pesticide residues from aqueous samples

In this paper, microwave-accelerated dispersive liquid–liquid microextraction has been developed for the extraction/preconcentration of some organophosphorus pesticides from aqueous samples prior to their analysis by gas chromatography–flame ionization detection. In this method, temperature of a high volume of aqueous sample is elevated by a microwave oven and then a mixture of extraction and disperser solvents is rapidly injected into the aqueous phase. After cooling to room temperature, the phase separation is accelerated by centrifuging. The main experimental factors affecting performance of the method including type and volume of the extraction and disperser solvents, temperature, pH, and salt addition were investigated and optimized. Under the optimum extraction conditions, the method resulted in low limits of detection and quantification within the ranges of 0.65–1.3 and 2.2–4.5 μg L⁻¹, respectively. Relative standard deviations were in the range of 2–7% (C = 40 or 100 μg L⁻¹) for intra-day (n = 6) and inter-day (n = 4) precisions. Finally, the proposed method was successfully applied to analysis of the target analytes in surface water and well water and fruit juice samples; diazinon was determined at μg L⁻¹ level in apple juice.     

Short-term toxicity tests on the harpacticoid copepod Tisbe battagliai: Lethal and reproductive endpoints

Short-term bioassays based on lethal and reproductive responses of Tisbe battagliai were applied to determine responses of copepods to copper and LAS. Percentage of spawning females, fecundity (F), and total newborn production (N) for 48 and 72 h were calculated for both substances. It was observed percentage of spawning females was not affected by sublethal concentrations of both compounds. Following values were obtained: EC₅₀(N)-48 h of 670±30 μg LAS L^?1 and EC₅₀(F)-48 h of 670±30 μg LAS L^?1; and EC₅₀(N)-72 h of 44.5±1.8 μg Cu L^?1 and EC₅₀(F)-72 h of 30.8±1.1 μg Cu L^?1. Lethal effects of the two substance-types were also assessed, obtaining the LC₅₀-24 h of 1980±160 μg LAS L^?1; and LC₅₀-48 h of 83.1±10.5 μg Cu L^?1 for nauplii; and LC₅₀-72 h of 157±25 μg Cu L^?1, and LC₅₀-72 h of 2660±270 μg LAS L^?1 for adults. Fecundity and total newborn production are sensitive endpoints for determining effects of toxicants.     

Major and trace elements levels in multifloral and unifloral honeys in Croatia

Different honey types were collected in Croatia during 2010 and 2011: 7 multifloral orchard honeys, 7 multifloral meadow honeys, 19 black locust, 9 chestnut, 11 lime and 6 sage honeys. Elements were measured using graphite (As, Cu, Cd, Pb, Se) and flame atomic absorption spectrometer (Ca, Fe, K, Mg, Na, Zn) and by mercury analyser (Hg). Significant differences in Ca, Fe, K, Mg, Zn, As and Hg levels were observed between honey types. In chestnut honey were determined (K, Ca, Mg: mg kg⁻¹; Hg, Ad, Cd: μg kg⁻¹): the highest concentrations of K 2824.4, Ca 486.7, Mg 59.1 and Hg 2.52; the lowest of As 24.1 and Cd 2.52. Lime honey has been shown the highest content of Cu (20.6 mg kg⁻¹), Zn (6.78 mg kg⁻¹), Cd (2.14 μg kg⁻¹) and Pb (810.3 μg kg⁻¹). The lowest levels of following elements were determined in black locust honey (Fe, K, Mg: mg kg⁻¹; Hg: μg kg⁻¹): Fe 2.77, K 304.7, Mg 8.02 and Hg 0.82. Sage honey had the lowest Ca and Na content (173.9 and 31.8 mg kg⁻¹). Among the multifloral honeys, the following was determined (Fe, Na, Cu: mg kg⁻¹; As, Pb: μg kg⁻¹): orchard honey – highest of Fe 5.17 and As 276.1, lowest Pb 301; meadow honey – highest Na 36.1, lowest Cu 4.38. The average Ca, Cu and Pb levels found in multifloral honey types were much higher than those reported in other European countries. Calcium levels in lime, chestnut and black locust were higher than those from other countries.     

Comparison of the chemical composition of British and Continental European bottled waters by multivariate analysis

The elemental composition of 37 bottled waters from the UK and continental Europe has been determined. Ca, K, Mg, Na, Al, As, Ba, Cd, Cr, Co, Cu, Fe, Mn, Mo, Ni, Pb, Sb, Sr, U, V and Zn were determined by ICP-OES and ICP-MS, in addition to inorganic and total organic carbon. The composition of all the waters analysed fell within the guideline values recommended by the World Health Organization. Na, Ca, Sr and Ba showed the widest variation in concentrations, ranging over two orders of magnitude. Levels of Fe were below the limit of detection (30 μg L⁻¹) in all samples analysed. Waters produced in the UK generally showed lower levels of most major elements and trace metals, with the exception of Ba (up to 455 μg L⁻¹). Italian waters showed the highest concentrations of Sr (3000–8000 μg L⁻¹) and U (8–13 μg L⁻¹), whereas waters produced in Slovakia and the Czech Republic showed the highest levels of Pb (0.7–4 μg L⁻¹). The use of multivariate analysis reveals an association between high alkaline metal content and high concentrations of As and Cr. There also appears to be a correlation between high Ca and Sr content and high levels of U. Analysis of variance (ANOVA) indicates that the composition of bottled water can be distinguished primarily by the country of origin, over other factors including the geological environment of the source. This would suggest that composition reflects, and is biased towards, consumer preferences.     

Proximate composition and fatty acid profile of Bombyx mori L. chrysalis toast

The objective of the present study was to analyze the nutritional composition of Bombyx mori (L.) chrysalis (worm) toast. The results have revealed that this sub-product of the silk thread industry is a rich source of protein (51.1%); lipid (34.4%); essential fatty acids such as the linolenic acid (C18: 3n-3, 24.4%); zinc (244 μg g⁻¹) and potassium (4.77 mg g⁻¹). The composition of this sub-product shows good polyunsaturated/saturated (0.99) and n-6/n-3 (0.30) fatty acids ratios. Chrysalis (worm) toast could balance human nutrition and could be used as an alternative dietary supplement of proteins and fatty acids, or could be used as animal feed.     

Cloud point extraction preconcentration and spectrophotometric determination of copper in food and water samples using amino acid as the complexing agent

A new method for the determination of trace copper was developed by cloud point extraction preconcentration and spectrophotometry. In the proposed approach, amino acid (isoleucine) was used as the chelating agent, and Triton X-100 was selected as the surfactant. Some factors including pH of sample solution, concentration of the chelating agent and surfactant, and equilibration temperature and time, which affected the extraction efficiency of Cu and its subsequent determination, were studied and optimized. Under the optimum conditions, the calibration graph was linear in the range of 10–1000 μg L^?1, preconcentration of 25 mL sample gave an enhancement factor of 22 and a detection limit of 5 μg L^?1. The method was successfully applied to the determination of Cu in food and water samples.     

Comparisons and selection of rice mutants with high iron and zinc contents in their polished grains that were mutated from the indica type cultivar IR64

Developing rice varieties biofortified with iron (Fe) and zinc (Zn) is an important strategy to alleviate nutritional deficiencies in developing countries, where polished rice is consumed as the staple food. In this study, the contents of several macro- and micro-minerals in polished rice grains of cultivar IR64 and its 254 sodium azide-induced mutants (M8 generation) were assessed. The results indicated that the contents of potassium, phosphorus, calcium, magnesium, iron, manganese, copper, and zinc varied among the tested mutants. The polished rice grains of mutants M-IR-75 and M-IR-58 accumulated more Fe (28.10 and 27.26 mg kg⁻¹, respectively) than cultivar IR64 (3.90 mg kg⁻¹). Mutant M-IR-75 also produced higher yield (average of 8.65 ton ha⁻¹ over two crop seasons) than cultivar IR64 (average of 7.27 ton ha⁻¹). Mutants M-IR-180, M-IR-49 and M-IR-175 contained more Zn (26.58, 28.95 and 26.16 mg kg⁻¹, respectively) than cultivar IR64 (16.00 mg kg⁻¹), but only mutant M-IR-180 showed a grain yield comparable to cultivar IR64. Thus, the mutant M-IR-75 can be recommended to rice growers to produce Fe-rich rice grains. Additionally, the high-Fe (M-IR-75 and M-IR-58) and high-Zn (M-IR-180, M-IR-49 and M-IR-175) mutants can be used as genetic resources for rice improvement programs.     

Toxicity and bioaccumulation of copper and lead in five marine microalgae

On five marine microalgae with the same biovolume quantity (Tetraselmis chuii, Rhodomonas salina, Chaetoceros sp., Isochrysis galbana (T-iso) and Nannochloropsis gaditana) 72-h exposure toxicity tests with copper and lead were performed. For both metals, 72-h EC50s showed T. chuii as the most tolerant and R. salina as one of the most sensitive. Besides copper and lead EC₅₀ concentrations, metal concentrations in solution and accumulated on/in the cell where also analysed. T. chuii, the most tolerant species accumulated high copper concentrations (EC_50(Cu)=330 μg L^?1; EC_50(Pb)=2600 μg L^?1), and R. salina the most sensitive to copper, accumulated the highest amount of this metal (EC_50(Cu)=50 μg L^?1). Results of this study show that there is no specific relationship between cell tolerance and accumulated metal on/in the cell. On the other hand, due to an established evidence of the influence of cellular density in microalgae toxicity tests, this effect was also studied. Results showed reduced EC₅₀ values when initial cellular densities decreased.In this study, the term “toxic cellular quota” was used to express all data. This allowed, in a single expression, the combination of two parameters that clearly influence growth, cellular density and toxic concentration.     

A spectrophotometric method for determination of total proteins in cow milk powder samples using the o-nitrophenylfluorone/Mo(VI) complex

A new spectrophotometric method has been developed for the determination of protein in Tween 20 microemulsion medium. The method is based on the interaction between protein and o-nitrophenylfluorone–Mo(VI) complex as a spectral probe. Under the optimal conditions, Beer's Law is obeyed over the range of 0–16 μg mL⁻¹ bovine serum albumin (BSA) with the detection limit being 15 ng mL⁻¹. Both the influence of reaction variables and the interference of coexisting substance are studied. The proposed method has been applied to the whole milk powder samples with satisfactory results. The recoveries are between 97.6% and 105.8%, and the standard relative deviations are less than 4.3%. Molar ratio and slope ratio methods are used to determine the binding number of BSA with the complex and the value 96.