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Total Arsenic and Arsenic Speciation in Human Biological Samples (pdf)
Arsenic Speciation in Soils and Sediments (pdf)
Trace (ppt level) Arsenic and Selenium Analysis (pdf)
Applied
Speciation can perform a variety of analytical methods for arsenic
speciation analysis. These methods utilize Ion Chromatography
Coupled to an ICP-MS to achieve the lowest detection for different
matrix types. Introduction: Arsenic is the 20th most abundant
element in the earth's crust.(1) The weathering of the 200+
arsenic-containing minerals and human activities (arsenical
pesticides, leaching of wood preservatives, application of
fertilizers, irrigation, dust from the burning of fossil fuels, and
disposal of industrial and animal wastes) are responsible for the
current levels of arsenic in the environment.(2) Different forms of
arsenic have different properties and these properties can have
significant impacts on the toxicity and treatment efficiency of a
water system requiring investigation in the form of speciation
analysis. With more stringent regulations on arsenic levels in
drinking waters and industrial discharges, accurate determination of
arsenic species at sub-ppb levels is a requirement. Arsenic is a
tough analyte because of the interferences it faces with every
analytical technique and the detection limit requirements of the
environmental industry. In order to circumvent various matrix and
analytical interferences, Applied Speciation employs the separation
power of ion chromatography and couple it with the detection power
of ICP-MS (IC-ICP-MS).
Methods
for Arsenic Speciation Analysis: Aqueous samples can be analyzed by
IC-ICP-MS to determine arsenite, arsenate, and methylated, and other
organic forms of arsenic. The separation power of ion chromatography
is extremely important for the determination of arsenic speciation
in tissues. Arsenic can be present in a variety of different forms
and it is not uncommon to observe more than 10 different arsenic
containing species in tissue extracts. In the presence of sulfide
and reducing conditions, arsenic can be present as thio-arsenic
species. While these species produce false positives for inorganic
arsenic in other methods, with IC-ICP-MS, it is possible to
determine these different forms of arsenic.
The experience of Applied Speciation comes into play when arsenic
speciation in difficult matrices is to be determined. We have
developed a variety of different methods that utilize different
chromatographic separation modes. These methods allow us to provide
the lowest detection limits to our clients for their toughest
samples. For instance, arsenic speciation in a 10,000 ppm Fe, Ca, Al
and high sulfate matrix or highly saline samples (up to 3%) can be
determined with ppt detection limits.
The most important variable associated with sampling for arsenic
speciation analysis is to maintain sample integrity. Immediately
after any sample is removed from its ambient environment the
equilibrium may change inducing species conversion. Identification
of proper sampling protocols cannot be identified without first
understanding the environment the sample is being extracted from.
Many variables can assist in identifying sample protocols including,
but not limited to: other metals concentrations, redox, pH,
concentration of organics, structure of environment (air, water,
soil, tissue, etc.). Generic application of any sample preservation
protocol for arsenic speciation analysis will ultimately result in
highly biased results that will eventually cost time and money to
the client.
Our experience with a variety of matrices allow us to choose
sampling protocols depending on the target species and the sample
environment. For arsenic speciation analysis, possible sampling
methods may cryo-freezing in the field, hydrochloric acid, EDTA, and
acetic acid.
If you have any questions or would like a quotation, please feel
free to email us at info@appliedspeciation.com or call
(425) 483-3300.
1) O'Neil, P. In Heavy metals in soils; B.J. Alloway Ed.; Blackie:
Glasgow,1990; p83
2) Sandberg, G.R.; Allen, I.K. In Arsenical Pesticides; E.A. Woolson
Ed.; American Chemical Society: Washington, DC, 1975; p124
Feel free to visit our website on a regular basis as we will be
providing scientific discussions and useful links to save you time
and money.
- US National Library of Medicine information on arsenic poisoning with links to reviews and articles.
- Arsenic Project at Harvard University
- EPA Air Toxics Website provides information on selenium and selenium compounds