Environmental Context. A new group of arsenic compounds, namely thio-arsenosugars, has recently been discovered in some marine samples, including seafood products. We do not yet understand how these arsenic compounds are produced by living organisms, nor do we know their implications for human health. Their unusual chromatographic properties are the reason that they are difficult to detect by existing methods. We present a new method for finding these thio-arsenosugars, and we also report two new thio-arsenosugars.
Abstract. Two new thio-arsenosugars were identified in aqueous and methanol extracts from the gonad and the muscle of the great scallop by using high-performance liquid chromatography–inductively coupled plasma mass spectrometry (HPLC–ICPMS) and HPLC–electrospray ionization mass spectrometry (ESMS). The gonad of the scallops contained thio-arsenosugar–sulfonate [0.067 mg (As) kg−1; dry mass ± 3.7%] and thio-arsenosugar–sulfate [0.267 mg (As) kg−1; dry mass ± 1.2%]. The muscle also contained both thio-arsenosugar–sulfonate [0.030 mg (As) kg−1; dry mass ± 2.6%] and thio-arsenosugar–sulfate [0.200 mg (As) kg−1; dry mass ± 2.6%]. Methanol increased the extraction efficiency threefold for the two thio-arsenosugars as compared to water. Fresh and freeze-dried samples from both parts of the scallop showed no significant difference with respect to the concentration of the two thio-arsenosugars. In order to confirm the presence of the thio-arsenosugars, a new method for their determination with HPLC–ESMS was developed. Under optimized conditions [Hamilton PRP-X100; 150 by 1.0 mm; 20 mM NH4HCO3 with 55% (v/v) methanol at pH 10.3] we succeeded in determining the pseudomolecular ions of thio-arsenosugar–glycerol, thio-arsenosugar–phosphate, thio-arsenosugar–sulfonate, and thio-arsenosugar–sulfate at concentrations less than 5 µg (As) dm−3 in standard solutions and real samples.
In the present work a new HPLC method for the determination of mercury species in biological samples with ICP-MS detection was developed. Separation of inorganic (Hg 21 ) and methylmercury (CH 3 Hg 1 ) was accomplished on a Hamilton PRP-X200 polymer-based cationexchange column with a mobile phase of 50 mmol l À1 pyridine, 0.5% w/w L-cysteine and 5% v/w MeOH, at pH 2, within 8 min. The influence of chromatographic parameters, such as pH, salt concentration, organic modifier, and ion-pair reagent on the retention behaviour was evaluated. Based on peak areas, the experimental detection limits for inorganic and methylmercury were 0.05 and 0.08 mg Hg l À1 , which corresponds to an absolute detection limit of 1.0 and 1.6 pg of mercury (20 ml injection volume). The liquid chromatographic method was successfully applied to the determination of inorganic and methylmercury in the two certified reference materials DORM-2 and DOLT-3, after a rapid and simple sample preparation procedure using hydrochloric acid.
This study on aquaculture ponds investigated how diet sources affect methyl mercury (MeHg) bioaccumulation of the worldwide key diet fish, common carp (Cyprinus carpio). We tested how MeHg concentrations of one and two year-old pond-raised carp changed with different food quality: a) zooplankton (natural pond diet), b) cereals enriched with vegetable oil (VO ponds), and c) compound feeds enriched with marine fish oils (FO ponds). It was hypothesized that carp preferentially feed on supplementary diets with the highest biochemical quality (FO diet over VO diets over zooplankton). Although MeHg concentrations were highest in zooplankton of FO ponds, MeHg concentrations of carp were clearly lower in FO ponds (17–32 ng g− 1 dry weight) compared to the reference (40–46 ng g− 1 dry weight) and VO ponds (55–86 ng g− 1 dry weight). Stable isotope mixing models (δ13C, δ15N) indicated selective feeding of carp on high quality FO diets that caused MeHg concentrations of carp to decrease with increasing dietary proportions of supplementary FO feeds. Results demonstrate that carp selectively feed on diets of highest biochemical quality and strongly suggest that high diet quality can reduce MeHg bioaccumulation in farm-raised carp.
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