Arsenosugar extracted from algae: Assessment of countercurrent chromatography for isolation.

Arsenosugars are the predominant species of arsenic in most seaweed. The analysis of these compounds is hampered by the lack of calibration standards needed in their unambiguous identification and quantification. This affects the availability of reliable information on their potential toxicity, which is scarce and controversial. Knowing the potential of centrifugal partition chromatography (CPC) as a preparative separation technique applied to a number of natural compounds, the aim of this work is to investigate the feasibility of CPC in the case of isolation and purification of arsenosugars from algae extracts. Several biphasic solvents systems have been studied to evaluate the distribution of the As species. Given the physical characteristics of these compounds, the presence of strong acids, the formation of ionic pairs or the presence of salts at high ionic strength have been considered. System 1-BuOH/EtOH/sat.(NH4)2SO4/water at a volume ratio 0.2:1:1:1 originates adequate distribution constants of analytes that allows the required separation. The total arsenic content and the arsenic speciation of the eluted solutions from CPC were analyzed by ICP-MS and IC-ICP-MS, respectively. The developed CPC procedure allows us to obtain of the three arsenosugars with a purity of 98.7 % in PO4-Sug, 90.4 % in SO3-Sug and 96.1 % in SO4-Sug.

Survey of arsenic content in edible seaweeds and their health risk assessment.

Since humans are especially sensitive to arsenic exposure, predominantly through diet, a strict control of the most widely consumed seaweeds is mandatory. Total arsenic contents and arsenic species in twenty-five different seaweeds from five different origins were studied. Seaweeds selected, included Phaeophyta (brown seaweed), Chlorophyta (green seaweed) and Rhodophyta (red seaweed) genera. The highest arsenic content appears in the Phaeophyta seaweed in the range from 11 to 162 mg kg-1 dried weight. Arsenosugars were found to be the predominant species of arsenic in most seaweeds, being up to 99.7% of total arsenic in some samples. The arsenic dietary intakes for seaweeds studied were assessed and the Target Hazard Quotients (THQ) and the Target Cancer Risk (TCR) were calculated, taking into account inorganic arsenic contents (iAs). iAs species in seaweeds showed low risk of arsenic intake except for Hizikia fusiforme samples.

Arsenosugar extracted from algae: Isolation by anionic exchange solid-phase extraction.

Obtaining reliable speciation data for evaluating dietary exposure, and increasing understanding of arsenic biochemistry in algae, are hindered by the availability of suitable standards of arsenosugars, the major species in these types of samples. Moreover, chemical syntheses of such compounds have been reported to be complex and tedious. The aim of this work was to investigate the feasibility of the anionic exchange SPE cartridges (SAX and WAX) as an easy and quick alternative for the isolation and preconcentration of arsenosugars. Two commercial silica-based SPE cartridges strong anion exchange sorbent (DSC-SAX) and weak anion exchange sorbent (DSC-NH2) were compared for the SPE of three arsenosugars (PO4-Sug, SO3-Sug and SO4-Sug). The effect of pH, ionic strength, type of salt and elution solvent on the elution protocols of these arsenosugars are studied. Eluted solutions from SPE were analyzed by ICP-MS for total arsenic content and IC-ICP-MS for the study of arsenic speciation. The developed SPE procedure allows to obtain a solution containing the three arsenosugars isolated from other arsenic species with recoveries over 75% for SO3-Sug and SO4-Sug, whereas for PO4-Sug were around 45%.

Data Fusion Approaches for the Characterization of Musts and Wines Based on Biogenic Amine and Elemental Composition.

Samples from various winemaking stages of the production of sparkling wines using different grape varieties were characterized based on the profile of biogenic amines (BAs) and the elemental composition. Liquid chromatography with fluorescence detection (HPLC-FLD) combined with precolumn derivatization with dansyl chloride was used to quantify BAs, while inductively coupled plasma (ICP) techniques were applied to determine a wide range of elements. Musts, base wines, and sparkling wines were analyzed accordingly, and the resulting data were subjected to further chemometric studies to try to extract information on oenological practices, product quality, and varieties. Although good descriptive models were obtained when considering each type of data separately, the performance of data fusion approaches was assessed as well. In this regard, low-level and mid-level approaches were evaluated, and from the results, it was concluded that more comprehensive models can be obtained when joining data of different natures.

Arsenosugar standards extracted from algae: Isolation, characterization and use for identification and quantification purposes.

Sulfate (SO4-sug) and sulfonate (SO3-sug) arsenosugar standard solutions were obtained using preparative liquid chromatography. Several commercial algae samples were characterized (total contents and speciation) to select the most appropriate in relation to their arsenosugar contents. Water extracts from the selected sample (Fucus vesiculosus) were fractionated using a Hamilton PRP-X100 preparative column, and the presence of arsenic species in the isolated fractions was ascertained by IC-ICP-MS. Two of the fractions successfully presented only one arsenic species corresponding to sulfate and sulfonate arsenosugars at suitable concentrations. To unequivocally confirm the presence of both compounds, high-resolution mass spectrometry (ESI-TOF/MS) was used and the exact mass determined with errors lower than 0.5 ppm. The standard solutions obtained were successfully used to identify and quantify SO4-sug and SO3-sug in several edible algae samples purchased in local market. Total arsenic content for analyzed samples ranged from 34 to 57 mg kg-1, concentration values found for SO3-sug ranged from 5 to 36 mg As kg-1 and SO4-sug was only found in fucus with a concentration of 9.3 mg As kg-1.

Assessment of arsenic bioaccessibility in raw and cooked edible mushrooms by a PBET method.

The present study reports arsenic analysis in Lentinula edodes, Agaricus bisporus and Pleurotus ostreatus before and after being cooked. Furthermore, arsenic in raw and cooked mushroom was determined in the gastric and gastrointestinal bioaccessible fractions obtained after simulating human digestion by means of an in vitro physiologically based extraction test (PBET). Several certified reference materials (SRM 1568a, SRM 1570a, CRM 7503-a, BC211 and IPE-120) were analysed to evaluate the proposed methods. Total arsenic content was 1393, 181 and 335µgAskg(-1) for L. edodes, A. bisporus and P. ostreatus, respectively, and decreased by between 53% and 71% in boiled mushroom and less than 11% in griddled mushroom. High bioaccessibility was observed in raw, boiled and griddled mushroom, ranging from 74% to 89% and from 80% to 100% for gastric and gastrointestinal extracts, respectively, suggesting the need to consider the potential health risk of consumption of the mushrooms analysed.

New quality-control materials for the determination of alkylphenols and alkylphenol ethoxylates in sewage sludge.

The determination of alkylphenols in sewage sludge is still hindered by the complexity of the matrix and of the analytes, some of which are a mixture of isomers. Most of the methods published in the literature have not been validated, due to the lack of reference materials for the determination of alkylphenols in sludge. Given this situation, the objectives of the present study were to develop a new quality-control material for determining octylphenol, nonylphenol and nonylphenol monoethoxylate in sludge. The material was prepared from an anaerobically digested sewage sludge, which was thermally dried, sieved, homogenized and bottled after checking for the bulk homogeneity of the processed material. Together with the sewage sludge, an extract was also prepared, in order to provide a quality-control material for allowing laboratories to test the measuring step. The homogeneity and 1-year stability of the two materials were evaluated. Statistical analysis proved that the materials were homogeneous and stable for at least 1 year stored at different temperatures. These materials are intended to assist in the quality control of the determination of alkylphenols and alkylphenol ethoxylates in sewage sludge.

Certified reference materials for analytical mercury speciation in biological and environmental matrices: do they meet user needs?; a review.

The usefulness of a certified reference material (CRM) for analytical method validation and quality control purposes is attributed mainly to its key properties, namely homogeneity and stability. However, it is also advisable to select suitable CRMs in terms of representativeness. To assess the representativeness of a CRM for analytical mercury speciation, a number of aspects must be considered in regard to the routine samples analyzed: the origin of the matrix, the type of mercury species and the level of concentration. This review critically analyzes the availability of current CRMs for mercury speciation analysis in environmental and biological fields. The characteristics of the CRMs are compared with the matrices and samples covered in papers published in the last five years on mercury speciation, mainly in water, soils, sediments, sewage sludge, seafood, blood, urine and hair.

Comparison of single and sequential extraction procedures for the study of rare earth elements remobilisation in different types of soils.

With the continual increase in the utilisation of rare earth elements (REE) for industrial and agricultural purposes, research into the environmental and biogeochemical behaviour of REE had attracted much interest in recent times. This study principally describes the distribution of REE in four different types of soils like lateritic soil (S-1), in situ natural soil (S-2), soil contaminated by mining activity (S-3) and accidentally polluted soil (S-4) utilizing the optimised BCR sequential extraction procedure and partial extractions with various types of single extractants such as unbuffered salt solutions 0.1 M NaNO(3), 0.01 M CaCl(2), 1 M NH(4)NO(3); complexing agents 0.005 M DTPA and 0.05 M EDTA; acid solutions 0.43 M CH(3)COOH and 1 M HCl. Comparison of the sum of the four BCR fractions, which included an aqua regia attack on the residue, with the pseudo-total aqua regia digest values to assess the accuracy of the BCR partioning approach has been undertaken. Partial extraction results with several single extractants have also been reported for all the REE elements including yttrium which have been analysed by the optimised BCR procedure. Results obtained after 24 h extraction with each of the single extractant have also been discussed. The extraction with 1 M HCl during 24 h yielded similar quantities of REE as those released under the combined steps of 1, 2 and 3 of the BCR sequential extraction for all the four different type of soil samples indicating that this reagent can be used successfully to estimate the total extractable contents of REE in various types of soil samples.

Determination of alkylphenols and alkylphenol ethoxylates in sewage sludge: effect of sample pre-treatment.

A complete characterization of sewage sludge collected from five biological waste water treatment plants was done to determine physico-chemical parameters, heavy metals and alkylphenols, making special emphasis on sampling, homogenization, and sample pre-treatment. Ultrasonic extraction followed by gas chromatrography coupled with mass spectrometry was used to evaluate the effect of sample pre-treatment (untreated sample, freeze-drying, drying at 40 degrees C or drying at 100 degrees C) on the concentration of octylphenol (OP), nonylphenol (NP) and nonylphenol ethoxylates (NP1EO, NP2EO). Untreated samples and samples dried at 100 degrees C gave concentration levels up to 62% and 89% lower, respectively, than freeze-dried samples. In 50% of cases, freeze-dried samples led to significantly higher concentrations than those obtained by drying at 40 degrees C. Thus, freeze-drying is the recommended sample pre-treatment to prevent possible losses of OP, NP, and NP1EO. Using this methodology, concentrations detected were from 3.2 to 199 mg kg(-1) being NP followed by NP1EO found in highest concentration. The total concentration of NP and NP1EO exceeded the limit of 50 mg kg(-1) proposed by the draft European directive on sewage sludge in three out of five samples studied. Contrarily, heavy metals were below the legislated values.

Assessment of extractants for the determination of thallium in an accidentally polluted soil.

Thallium is a rare and easily dispersed element with high toxicity to organisms. Relatively high levels of thallium (approximately 9.58 mg kg(-1)) had been found in aqua regia soil extract of an accidentally polluted soil from south of Spain. To assess the available and leachable portions of thallium in the polluted soil, single and sequential extraction procedures have been utilized. Further, X-ray diffraction and scanning electron microscopic studies have also been used to find out the mineral phases. The amount of thallium extracted by the extracting agents in comparison to aqua regia, as well as the different phase associations are discussed.