Sequential Extraction for Arsenic Speciation in Soils
It has become increasingly common for risk assessment and treatability studies to require arsenic speciation data to determine the potential mobility of this toxic contaminant at varying sites.
Looking at arsenite [As(III)] and arsenate [As(V)] values can be helpful for these studies; however, this approach can only provide a snapshot of how much arsenic is readily leachable at any given time. In situ, the conditions in soil and sediment samples can change over time depending on many factors, including the amount of rainfall, contaminant plume movement, and the hydrogeology at each individual site. Arsenic trapped in various mineral phases can be mobilized under varying site conditions, and even the treatment technologies used to remediate a site can affect the chemistry of the targeted environment and the subsequent arsenic lability.
At Brooks Rand Labs (BRL), we have a proprietary procedure for the selective sequential extraction of groups of arsenic species in soluble, adsorbed, and precipitated forms of arsenic compounds in soils, sediments, and similar solid matrices using a series of solutions with an increasing ability to solubilize and extract the solid-phase arsenic. Rather than identify specific arsenic species, the arsenic is fractionated in accordance with its interaction with iron oxyhydroxides, manganese oxyhydroxides, aluminum oxides, and other substrate components. The applied extraction solutions are designed to target the different substrate components and stabilize the respective arsenic species within each of the defined fractions below. The typical arsenic compounds listed for each fraction are only representative of how the method can perform and will fluctuate with different sites and conditions.
The BRL arsenic sequential extraction method accompanied by analysis of each fraction for total arsenic and other elements can be a powerful tool to help predict how much arsenic will be mobilized under different conditions. This type of information can be of enormous value for modeling, risk assessment, and design/engineering of treatment technologies.
If you would like more information about the selective sequential extraction procedure for arsenic speciation and whether it would be appropriate for your project, please contact us.
Human exposure to natural and synthetic contaminants has recently come to the forefront of public concern with frequent stories in the media about the potential harm from metals in our environment. Fish consumption, vaccines, contaminated food products, and poorly regulated supplements are all potential threats to human health. Assessing human biomonitoring samples can be quite challenging because every sample has its own unique chemistry depending on lifestyle and genetics, as well as differences from food and supplement intake. Brooks Rand Labs can support the elemental and molecular quantitation of metals and halogenated compounds for every distinctive sample submitted. For more than a decade, Brooks Rand Labs has provided analytical method development and specialized analysis of ions, small molecules, amino acids, proteins, and other more complex molecular forms in a variety of human tissues and fluids, including blood, urine, organ tissue, hair, and teeth. If you would like further information or a quotation for your next project, please 
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For large sample collection tubing and equipment orders, BRL requests at least three weeks’ notice in order to ensure all equipment is certified clean for low-level metals analysis. We take great pride in ensuring equipment meets your data quality objectives by taking several days (to weeks) for cleaning, testing, and quality assurance review.
In 1983, the first inductively coupled plasma-mass spectrometer (ICP-MS) was introduced, revolutionizing metals analysis. The new technology allowed for metals to be analyzed with unprecedented productivity and the ability to attain ultra-low detection limits with excellent precision and accuracy. While there are many benefits with ICP-MS metals analysis, there are also drawbacks inherent to the methodology and many different types of interferences, such as isobaric, polyatomic, and double-charged, ions that can result in skewed data. Employing various interference reduction technologies, such as collision cell and reaction cell, work great for many of these interferences; however, the different mechanisms utilized by each method have uniquely inherent limitations. The more recent technology employed by the Agilent 8800 ICP Triple Quad (ICP-QQQ) utilizes non-reactive gases such as helium as well as reactive gases like ammonia, oxygen, and hydrogen. The unique configuration of this instrument greatly reduces variability, ensuring delivering greater accuracy and more consistent results. Unless you know exactly what all the constituents are in your sample, you cannot predict what kind of interference you may have and the ability to run an instrument in different modes and look for matching results between the modes increases the probability of a successful project while lowering the overall cost.
Technically, rare earth elements (Ce, Dy, Er, Eu, Gd, Ho, La, Lu, Nd, Pr, Pm, Sm, Sc, Tb, Tm, Yb, and Y) are not truly rare (with a few exceptions), and they may be found liberally dispersed within the Earth’s crust. Most of the rare earth elements (REE) are mined in China (95%), but in response to a recent increase in demand for REEs used in manufacturing of modern technology, former and new mining facilities have been placed in production throughout North America.
Brooks Rand Labs authored a method for the analysis of the “Big 4” (arsenic, cadmium, lead, and mercury) in food that was recently published as an AOAC First Action Official Method of Analysis. AOAC Method 2015.01 for Heavy Metals in Food by Inductively Coupled Plasma – Mass Spectroscopy (ICP-MS) is applicable to the analysis of a wide variety of matrix types, such as chocolate, fruit juice, fish, infant formula, and rice. The method was specifically written for detection of low-level concentrations of these contaminants, with reporting limits in the 8 – 10 μg/kg (ppb) range, and it utilizes the robust sample preparation power of microwave digestion along with the sensitivity and specificity of ICP-MS detection. The 
Spectroscopy published an article last month summarizing Brooks Rand Labs’ 2013 
Brooks Rand Labs currently offers lead (Pb) stable isotope ratio testing for application to environmental forensic studies. Lead has a unique isotopic pattern and small differences in the ratios of these isotopes can help in identification of the source, transport, and biogeochemical fate of the element in atmospheric bulk deposition, soils, freshwater, and seawater matrices. More information on the stable isotope ratio analysis for lead can be found on our