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Arsenic speciation in hair extracts.
1Department of Chemistry, University of Aberdeen, Meston Walk, Old Aberdeen, AB24 3UE, Scotland, UK.
Analytical and Bioanalytical Chemistry
|September 2, 2004
Summary
Arsenic accumulates in hair and nails. This study developed a method to extract arsenic species, finding inorganic arsenic is best absorbed by hair, and pentavalent forms dominate after extraction.
Area of Science:
- Environmental Toxicology
- Analytical Chemistry
- Biogeochemistry
Background:
- Ingested arsenic is stored in sulfhydryl-rich tissues like hair, nails, and skin.
- Arsenic accumulation in these tissues serves as a biomarker for exposure.
Purpose of the Study:
- To develop an extraction method for arsenic species from hair, nail, and skin.
- To assess the stability of various arsenic species during the extraction process.
- To investigate the absorption of different arsenic species by hair.
Main Methods:
- Development of a novel extraction technique for arsenic species from biological tissues.
- Stability testing of inorganic arsenic, methylated arsenicals (pentavalent and trivalent), and thio-arsenicals under extraction conditions.
- Incubation experiments to study hair absorption of different arsenic species.
- Analysis of arsenic species in human hair and nail samples from chronically intoxicated individuals.
Main Results:
- Inorganic and pentavalent methylated arsenic species demonstrated stability during extraction.
- Trivalent methylated arsenicals and dimethylarsinothioic acid (DMAS) exhibited reduced stability.
- Hair exhibited higher absorption for inorganic arsenic compared to monomethylarsonic acid (MA(V)) and dimethylarsinic acid (DMA(V)).
- Trivalent arsenic forms were absorbed more readily by hair than their pentavalent counterparts.
- The pentavalent form of methylated arsenicals was dominant after extraction, regardless of the initial incubation form.
- Human samples from chronic arsenic intoxication predominantly contained inorganic arsenic, with minor, variable amounts of MA(V) and DMA(V).
- DMAS was detected only in specific nail samples with high DMA(V) levels, suggesting potential in-situ formation during extraction.
Conclusions:
- The developed extraction method is suitable for stable arsenic species like inorganic arsenic and pentavalent methylated forms.
- Arsenic speciation in hair and nails is influenced by absorption preferences and potential transformation during analysis.
- In chronic arsenic intoxication, inorganic arsenic is the primary species stored in hair and nails, with methylated forms present in lower concentrations.