Room temperature solvent extraction for simple and fast determination of total concentration of Ca, Cu, Fe, Mg, Mn, and Zn in bee pollen by FAAS along with assessment of the bioaccessible fraction of these elements using in vitro gastrointestinal digestion.

BACKGROUND AND AIM: Bee pollen is recognized to be a source of different nutrients, including minerals. As a food supplement, its quality and safety due to concentrations of essential macro- and microelements, and harmful trace elements has to be verified. Fast and simple element analysis of bee-collected pollen can be regarded as an important part of its quality assurance and control. The present study aimed at developping a new method for determination of selected elements (Ca, Cu, Fe, Mg, Mn, Zn) of bee pollen based on solvent extraction and completely avoiding a high temperature treatment with concentrated reagents. In addition, in vitro gastrointestinal digestion was used to assess bioavailability of elements from this food supplement. METHODS: Bee pollen samples were dried and pulverized. Total concentrations of Ca, Cu, Fe, Mg, Mn, and Zn were determined by flame atomic absorption spectrometry (FAAS) in sample solutions obtained by wet digestion (WD) in concentrated HNO3 or alternatively by solvent extraction (SE) with diluted solutions of HNO3. Gastrointestinal digestion was mimicked using simulated solutions of gastric and intestinal juices followed by determination of Ca, Cu, Fe, Mg, Mn and Zn concentrations in the bioaccessible fraction by FAAS. RESULTS: A new simple and fast method for determination of total concentrations of Ca, Cu, Fe, Mg, Mn, and Zn in bee pollen was developed and validated. The method combined room temperature, two-hour SE with 0.5 mol L-1 HNO3 with FAAS measurements versus simple standard solutions. It provided precision within 1-5 % and trueness better than 8%, and was shown to be suitable for fast analysis of different polyfloral bee pollens. In vitro gastrointestinal digestion revealed that elements were well (70-85 % for Ca, Mg) and fairly (27-43 % for Cu, Fe, Mn, and Zn) bioaccessible from bee pollen. By pouring with water and swelling overnight, bioaccessibility of studied elements from such prepared bee pollen was increased on average by less than 15 % (Mn), 20 % (Ca, Cu, Fe, Zn) or 30 % (Mn). CONCLUSIONS: Avoiding long-lasting, high-temperature wet digestion with concentrated reagents, the proposed sample treatment along with FAAS provided precise and true results of total concentrations of Ca, Cu, Fe, Mg, Mn, and Zn in bee pollen. The method was simple and fast, and enabled to analyze a higher number of samples. Simulated gastrointestinal digestion of bee pollen have shown for the first time that Ca and Mg are the most bioaccessible from this bee product. Bioaccessibility of Cu, Fe, Mg, and Zn from bee pollen are close to or lower than 40 %.

Evaluation of a single extraction test to estimate the human oral bioaccessibility of potentially toxic elements in soils: Towards more robust risk assessment.

Intake of soil by children and adults is a major exposure pathway to contaminants including potentially toxic elements (PTEs). However, only the fraction of PTEs released in stomach and intestine are considered as bioaccessible and results from routine analyses of the total PTE content in soils, therefore, are not necessarily related to the degree of bioaccessibility. Experimental methods to determine bioaccessibility usually are time-consuming and relatively complicated in terms of analytical procedures which limits application in first tier assessments. In this study we evaluated the potential suitability of a recently developed single extract method (ISO-17586:2016) using dilute (0.43M) nitric acid (HNO3) to mimic the bioaccessible fraction of PTEs in soils. Results from 204 soils from Portugal, Brazil and the Netherlands including all major soil types and a wide range of PTEs' concentrations showed that the extraction efficiency using 0.43M HNO3 of Ba, Cd, Cu, Ni, Pb and Zn in soils is related to that of in vitro methods including the Simple Bioaccessibility Extraction Test (SBET) and Unified BARGE Method (UBM). Also, differences in the degree of bioaccessibility resulting from differences in parent material, geology and climate conditions did not affect the response of the 0.43M HNO3 extraction which is a prerequisite to be able to compare results from different soils. The use of 0.43M HNO3 as a first screening of bioaccessibility therefore offers a robust and representative way to be included in first tier standard soil tests to estimate the oral bioaccessibility. CAPSULE: The single dilute (0.43M) nitric acid extraction can be used in first tier soil risk assessment to assess both geochemical reactivity and oral bioaccessibility of PTEs.

Tissue integrity, costs and time associated with different agents for histological bone preparation.

The selection of an appropriate demineralizing solution in pathology laboratories depends on several factors such as the preservation of cellularity, urgency of diagnostic and financial costs. The aim of this study was to test different decalcification bone procedures in order to establish the best value of these in formalin-fixed and paraffin-embedded samples. Femurs were removed from 13 adult male Wistar rats to obtain 130 bone disks randomly divided into five groups that were demineralized in different concentrations of nitric acid (Group I); formic acid (Group II); acetic acid (Group III); EDTA, pH7.4 (Group IV) and Morsés solution (Group V). Serial, 3-µm-thick sections were obtained and stained with hematoxylin-eosin to calculate the percentage of osteocyte-occupied lacunae. The sections were also stained with Masson's trichrome in conjunction with picrosirius red under polarized light followed by a semi-quantitative analysis to verify the adjacent muscle-to-bone integrity and preservation of collagen fibres. The highest percentage of osteocyte-occupied lacunae was found with 10% acetic acid solution (95.64 ± 0.95%) and Group I (nitric acid) demanded the shorter time (0.8-5.7days). Of all solutions, 5% nitric acid incurred the lowest cost to achieve complete demineralization compared with other solutions (p < .001). Group IV (EDTA) had the highest integrity of muscle and collagen type I and III (P < 0.01). Demineralization with 10% acetic acid was the most effective at preserving bone tissue, while 5% EDTA was the best at maintaining collagen and adjacent muscle to bone. In conclusion, nitric acid at 5% showed the most efficient result as it balanced both time and cost as a demineralizing solution.

Aluminium content of foods originating from aluminium-containing food additives.

Aluminium (Al) levels of 90 food samples were investigated. Nineteen samples contained Al levels exceeding the tolerable weekly intake (TWI) for young children [body weight (bw): 16 kg] when consuming two servings/week. These samples were purchased multiple times at specific intervals and were evaluated for Al levels. Al was detected in 27 of the 90 samples at levels ranging from 0.01 (limit of quantitation) to 1.06 mg/g. Of these, the Al intake levels in two samples (cookie and scone mix, 1.3 and 2 mg/kg bw/week, respectively) exceeded the TWI as established by European Food Safety Authority, although the level in the scone mix was equivalent to the provisional TWI (PTWI) as established by Joint Food and Agriculture Organization of the United Nations/World Health Organization Expert Committee on Food Additives. The Al levels markedly decreased in 14 of the 19 samples with initially high Al levels. These results indicated reductions in the Al levels to below the PTWI limits in all but two previously identified food samples.

Evaluation of several flocculants for flocculating microalgae.

Flocculation of microalgae with chitosan, polyacrylamide, Al2(SO4)3, NaOH and HNO3 was evaluated. Their flocculation efficiencies and optimal dosages were discussed. The effects of the flocculants on cells viability were also investigated and the cells were found to be intact during the flocculation process. Moreover, the effects of flocculants on the extractions were evaluated. Lipid content after flocculants treatments showed no significant differences. Carbohydrate content was lower but protein content was higher after NaOH treatment than those after other treatments. Furthermore, the five flocculated media maintained approximate growth yields to that of the fresh medium in microalgal cultivation, indicating the five flocculated media could be recycled, thereby reducing the cost of biodiesel production from microalgae. Finally, economic comparison of the flocculants was made and the cost of using HNO3, including flocculating cells and recycling medium, was found to be the lowest.

Assessment of a geochemical extraction procedure to determine the solid phase fractionation and bioaccessibility of potentially harmful elements in soils: a case study using the NIST 2710 reference soil.

Three mineral acid sequential extraction regimes (HNO(3) only, HNO(3) followed by HCl and aqua regia) were applied to the NIST 2710 contaminated reference soil. The major and trace element chemical analysis data from the extractions were subjected to a chemometric self-modelling mixture resolution procedure which identified that 12 distinct physico-chemical components were extracted. The fractionation of As, Cd, Ni and Pb between these components were determined. Tentative assignments of the mineralogical sources of the components were made. The human ingestion bioaccessible fraction of As, Cd and Pb were determined using the in vitro BARGE UBM bioaccessibility test and were found to be 51.6%, 68.0% and 68.4% respectively. The relationship between the lability of the physico-chemical components and the bioaccessible fraction of the soils was investigated and the bioaccessible fractions were assigned to specific components. The extraction scheme using aqua regia was found to be the most suitable as it was the only one which extracted the iron sulphide phase in the soil.

Microscale chemistry-based design of eco-friendly, reagent-saving and efficient pharmaceutical analysis: a miniaturized Volhard's titration for the assay of sodium chloride.

This work demonstrates the extended application of microscale chemistry which has been used in the educational discipline to the real analytical purposes. Using Volhard's titration for the determination of sodium chloride as a paradigm, the reaction was downscaled to less than 2 mL conducted in commercially available microcentrifuge tubes and using micropipettes for the measurement and transfer of reagents. The equivalence point was determined spectrophotometrically on the microplates which quickened the multi-sample measurements. After the validation and evaluation with bulk and dosage forms, the downsized method showed good accuracy comparable to the British Pharmacopeial macroscale method and gave satisfactory precision (intra-day, inter-day, inter-analyst and inter-equipment) with the relative standard deviation of less than 0.5%. Interestingly, the amount of nitric acid, silver nitrate, ferric alum and ammonium thiocyanate consumed in the miniaturized titration was reduced by the factors of 25, 50, 50 and 215 times, respectively. The use of environmentally dangerous dibutyl phthalate was absolutely eliminated in the proposed method. Furthermore, the release of solid waste silver chloride was drastically reduced by about 25 folds. Therefore, microscale chemistry is an attractive, facile and powerful green strategy for the development of eco-friendly, safe, and cost-effective analytical methods suitable for a sustainable environment.

An inexpensive high-throughput nuclear magnetic resonance tube cleaning apparatus.

Large-scale nuclear magnetic resonance (NMR) tube cleaning is currently a bottleneck in high-throughput NMR ligand affinity screens. Expensive alternatives include discarding the NMR tubes after a single use (~US $2-$8/tube), using commercial NMR tube cleaners (~$15,000), and abandoning NMR tubes for flow probe technology (~$75,000). Instead, we describe a relatively inexpensive (~$400) and easily constructed apparatus that can clean 180 NMR tubes per hour while using a modest amount of solvent. The application of this apparatus significantly shortens the time to recycle NMR tubes while avoiding cross-contamination and tube damage.

In vitro gastro-intestinal method for the assessment of heavy metal bioavailability in contaminated soils.

INTRODUCTION: Balya and its associated villages which is a town of the Balikesir region of Turkey have very rich zinc, lead, and manganese mines. These mines have been operating since the thirteenth century and now there is heavy metal contamination in both the soil and natural waters in these areas. MATERIALS AND METHODS: Soils were collected from Sari su, Enverpasa, and Hastanetepe which are in Balya town and Kadiköy, Kasikci, Müstecap, Patlak, Çakallar, and Bengiler which are the villages near Balya and the mine areas. Nine trace analytes (As, Ba, Cd, Cr, Cu, Mn, Ni, Pb, and Zn) were determined using an acid extraction procedure as well as from PBET in vitro gastro-intestinal experiments using ICP-OES. RESULTS AND DISCUSSION: The results showed that high As, Ba, Pb, Zn, and Cd concentrations were found in these soils. The amounts ingested by pica behavior of children at the rate of 10 g day(-1) are calculated using the results of in vitro intestinal bio-accessibility experiments. CONCLUSION: The results showed that the amount of As, Pb, Ba, and Cd levels ingested by pica behavior are substantially higher than tolerable daily intake values in most of the soils. When normal ingestion is taken into account, the tolerable daily limits are only exceeded for one element (Pb) and even then, only at two sites.

Facile synthesis of polyaniline "sunflowers" with arrays of oriented nanorods.

Polyaniline (PANI) "sunflowers" made of arrays of oriented nanorods were synthesized by chemical oxidative polymerization of aniline in the presence of cetyltrimethylammonium bromide (CTAB) and suitable concentration of HNO3 at about 0 degrees C (ice bath). The reaction conditions, such as the concentration of reagents and reaction temperature were systematically investigated and controlled on the preparation of PANI "sunflowers". The results also suggest that HNO3 probably plays a key role in forming PANI "sunflowers". A possible forming mechanism of the PANI nanostructures is offered.

Kinetic and safety assessment for salicylic acid nitration by nitric acid/acetic acid system.

The nitration process of salicylic acid for the production of the important intermediate 5-nitrosalicylic acid is studied from thermokinetic and safety points of view. Investigations carried out by considering, as process deviations, the loss of the thermal control point out the possibility of runaway phenomena due to the occurrence of polynitration reactions. Isothermal experiments are carried out in various conditions to assess the involved reaction network and reaction kinetics.

The formation, role and removal of NO3-N during corona discharge in air for phenol removal.

Pulsed corona discharge carried out in the gas phase has been shown to be a low cost solution for wastewater treatment. In this study, the results show that the nitrogen dissociated during corona discharge in the gas phase formed nitric acid in solution, which resulted in a drop in solution pH. The phenol removal could be described in accordance with a first-order reaction in a basic buffer solution, but not in initial neutral and basic non-buffered solutions. This indicates that basic conditions facilitate phenol removal, whilst the formation of nitric acid in solution resulted in decrease in the phenol removal rate. This study also shows that most of the oxidants used for phenol removal came mainly from the dissociation of water molecules at the surface of the liquid phase and/or the gas phase very close to the liquid surface in discharging conditions, not from the gas dissociation in the bulk gas phase, and therefore, it is more effective to keep the solution basic than to change the component of gas in the reactor when removing phenol from water using corona discharge.

(S)-Nitroxycarnitine nitrate production from (S)-carnitine by using acetic anhydride/nitric acid/acetic acid mixtures: safety assessment.

The present work aims at assessing both thermodynamic and kinetic parameters of the esterification process of the (S)-carnitine, using calorimetric techniques. The use of the system acetic anhydride/nitric acid/acetic acid as esterifying agent and the explosive behaviour of nitric esters lead to safety considerations that have been investigated by hypothesizing some common process deviations. In particular, it has been investigated in adiabatic conditions both the batch addition of acetic anhydride and the effect of an initial temperature higher than those required by the process.

The impact of plutonium speciation on the distribution coefficients in a sediment-sea water system, and radiological assessment of doses to humans.

When radionuclides are released from a source into the marine environment, the assessment of long term consequences to humans depends on information on the source term, transport in water, interactions with sediments (KD) and biological uptake (CF). Sensitivity analysis of assessment models demonstrates that KD is one of the most sensitive parameters contributing to large uncertainties in the assessment. Furthermore, the interaction of Pu-species with sediments is a time and temperature dependent process. The distribution coefficient, Bq kg(-1) sediment per Bq L(-1) sea water, increases with time until pseudo-equilibrium/equilibrium is reached (KD). Thus, the contact time between contaminated sea water and sediments should be taken into account in dispersion and dose assessment models. In the present work, dynamic tracer experiments have been performed where different Pu-species are added to a sediment-sea water system to obtain information on KD's. After a defined contact time, the samples have been sequentially extracted to determine mobile and bound fractions. The results indicate that the distribution coefficient, KD, for plutonium depends on Pu-species in question. Thus, sediments act as a sink for Pu(III, IV) (high KD), while Pu(III, IV)-organic and Pu(V, VI) should be considered more mobile (low KD). Furthermore, the interaction with inert fractions obtained from sequential extraction depends less on Pu-species but increase with time. For short time interactions, species-specific time functions rather than KD constants should be applied in assessment models. When the accepted KD (10(5) L kg(-1)) is implemented in the model, the estimated collective dose is about 8 x 10(-4) person-Sv, i.e., a factor of about 2 lower than for Pu(III, IV)-organic and Pu(V, VI). So changes in KD have an impact on the assessment of collective dose received from a potential release of plutonium from fallout, reactor accidents, etc., which underlines the need for more detailed studies on speciation, kinetics, and KD's in different sediment-sea water systems.

Soil and waste analysis for environmental risk assessment in France.

In France today, analysis of soil and waste after digestion by strong acids is a technique used for the estimation of environmental risks due to soil pollution and spreading of wastes on cultivated soils. The technique of digestion by strong acid accounts for total or 'near total' content of As, Cd, Cr, Cu, Hg, Ni, Pb, Se and Zn. Risk management based on these methods aims to minimize the risks, since the concentration limits are derived from the geochemical levels. However, this method of analysis gives no idea of the extent to which elements are really transferable or bioavailable. Analytical methods based on partial extraction are used to discern deficiencies in B, Cu, Fe, Mn and Zn in soil. These extractions are carried out using boiling water and EDTA or DTPA solutions. The extraction methods have been standardized for use in agriculture, but have not been tested for assessing the risks due to the pollution by trace elements. One partial extraction method has been standardized for the analysis of wastes. It uses successive water extractions. Researchers have studied different partial extraction methods for estimating the bioavailability of mineral pollutants. Some of them gave results which correlated well with the amounts taken up by plants. However, at present, no general frame of reference has yet been established for the interpretation of results on a broad scale.