Dataset Information

SI traceable determination of arsenic species in kelp (Thallus laminariae).

ABSTRACT: A dietary supplement, kelp contains a significant amount of arsenic that is mostly arsenosugars. The determination of arsenosugars is difficult due to a lack of arsenosugar calibration standard, because arsenosugar compounds are not commercially available. This work reports the determination of arsenicals in a kelp extract with traceability to the International System of Units (SI). The hydrophilic fraction of arsenicals was reproducibly extracted from a candidate Standard Reference Material (SRM) 3232 Kelp Powder (Thallus Laminariae) in development at the National Institute of Standards and Technology (NIST). Arsenosugars and dimethylarsinic acid (DMA) were separated into fractions using analytical liquid chromatography (LC) cation and anion columns. The arsenic in the fractions was determined using instrumental neutron activation analysis (INAA). Cation exchange separation was used for INAA determination of arsenosugar 3-[5'-deoxy-5'-(dimethylarsinoyl)-?-ribofuranosyloxy]propylene glycol (As(328)) for the first time, while DMA, arsenosugars 3-[5'-deoxy-5'-(dimethylarsinoyl)-?-ribofuranosyloxy]-2-hydroxypropyl 2,3-dihydroxypropyl hydrogen phosphate (As(482)), and 3-[5'-deoxy-5'-(dimethylarsinoyl)-?-ribofuranosyloxy]-2-hydroxypropanesulfonic acid (As(392)) were determined following anion exchange separation. The contents of DMA, As(328), As(482), and As(392) were 0.41 mg kg^-1 ± 0.09 mg kg^-1, 1.10 mg kg^-1 ± 0.25 mg kg^-1, 5.23 mg kg^-1 ± 0.46 mg kg^-1, and 13.17 mg kg^-1 ± 0.67 mg kg^-1, respectively. Separately, components of arsenic species in the kelp extract including DMA, As(328), and inorganic arsenic were determined using LC-inductively coupled plasma mass spectrometry. Results of DMA and As(328) were 0.485 mg kg^-1 ± 0.024 mg kg^-1 and 1.14 mg kg^-1 ± 0.03 mg kg^-1, respectively, which were in good agreement with those determined by INAA in fractions of LC eluent. The most toxic species, AsIII and AsV were found to be < 0.07 mg kg^-1 and 0.231 mg kg^-1 ± 0.018 mg kg^-1, respectively. Results were traceable to SI.

SUBMITTER: Yu LL

PROVIDER: S-EPMC5615412 | biostudies-literature | 2017 Aug

REPOSITORIES: biostudies-literature

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SI traceable determination of arsenic species in kelp (<i>Thallus laminariae</i>).

Yu Lee L LL Stanoyevitch Rachel C RC Zeisler Rolf R

Analytical methods : advancing methods and applications 20170626 29

A dietary supplement, kelp contains a significant amount of arsenic that is mostly arsenosugars. The determination of arsenosugars is difficult due to a lack of arsenosugar calibration standard, because arsenosugar compounds are not commercially available. This work reports the determination of arsenicals in a kelp extract with traceability to the International System of Units (SI). The hydrophilic fraction of arsenicals was reproducibly extracted from a candidate Standard Reference Material (SR ...[more]

PMID: 28966665

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Project description:Insight into the mechanisms for arsenic detoxification by Geobacter species is expected to improve the understanding of global cycling of arsenic in iron-rich subsurface sedimentary environments. Analysis of 14 different Geobacter genomes showed that all of these species have genes coding for an arsenic detoxification system (ars operon), and several have genes required for arsenic respiration (arr operon) and methylation (arsM). Genes encoding four arsenic repressor-like proteins were detected in the genome of G. sulfurreducens; however, only one (ArsR1) regulated transcription of the ars operon. Elimination of arsR1 from the G. sulfurreducens chromosome resulted in enhanced transcription of genes coding for the arsenic efflux pump (Acr3) and arsenate reductase (ArsC). When the gene coding for Acr3 was deleted, cells were not able to grow in the presence of either the oxidized or reduced form of arsenic, while arsC deletion mutants could grow in the presence of arsenite but not arsenate. These studies shed light on how Geobacter influences arsenic mobility in anoxic sediments and may help us develop methods to remediate arsenic contamination in the subsurface. This study examines arsenic transformation mechanisms utilized by Geobacter, a genus of iron-reducing bacteria that are predominant in many anoxic iron-rich subsurface environments. Geobacter species play a major role in microbially mediated arsenic release from metal hydroxides in the subsurface. This release raises arsenic concentrations in drinking water to levels that are high enough to cause major health problems. Therefore, information obtained from studies of Geobacter should shed light on arsenic cycling in iron-rich subsurface sedimentary environments, which may help reduce arsenic-associated illnesses. These studies should also help in the development of biosensors that can be used to detect arsenic contaminants in anoxic subsurface environments. We examined 14 different Geobacter genomes and found that all of these species possess genes coding for an arsenic detoxification system (ars operon), and some also have genes required for arsenic respiration (arr operon) and arsenic methylation (arsM).

Dataset Information

SI traceable determination of arsenic species in kelp (Thallus laminariae).

Publications

SI traceable determination of arsenic species in kelp (<i>Thallus laminariae</i>).

Similar Datasets

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