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What is Speciation?

What is SpeciationA chemical species is the specific form of an element defined as to isotopic composition, electronic or oxidation state, and/or complex or molecular structure. Speciation analysis is the analytical activities of identifying and/or measuring the quantities of one or more individual chemical species in a sample. Chemical speciation analyses have focused primarily on organic molecules (carbon based) historically, for a good reason. Who would want to eat a piece of coal instead of a nutritious apple? But what about the rest of the periodic table beyond carbon? Every element on the periodic table can exist in different molecular forms that have impact on the world around us. Understanding the concentration and ratios of different chemical species is important for determining toxicity, mobility, bioavailability, effect on treatment options (both from a medical and industrial perspective), as well as many other characteristics. As a greater understanding emerges around the utility of speciation analyses, the idea of making important decisions with just total metals or elemental data is seen as risky and, in some cases, possibly catastrophic to the success of a project or the health of a population. An excellent example is if a blood test shows a patient has elevated arsenic levels, then the physician may apply a treatment to get reduce the concentration of this heavy metal. Speciation analysis would have elucidated that the arsenic is in the form of arsenobetaine and the physician could have questioned the patient as to whether or not they consume a lot of fish. If that was the case, the arsenic would be excreted, naturally, from the patient’s body without deleterious effects. One approach, using total elemental analysis shows there may be a problem, while a more focused approach, speciation analysis, identifies the true risk as well as if treatment is required. Imagine if this example is applied to treating groundwater, making pharmaceuticals products better, altering mining practices, or finding out why an industrial process succeeded or failed. One of the greatest challenges with speciation analyses is that there are very few standardized methods that exist. And, the ones that do exist are mostly based on older technologies and have not kept up with the times. Over the years, Brooks Applied Labs has continued to invest in-house R&D to generate an abundance of new analytical speciation methods spanning much of the periodic table. Bringing advanced analytical technologies to the commercial marketplace requires a deep understanding of the science as well as robust quality systems to ensure maximum defensibility of results. At Brooks Applied Labs, you will find the most advanced speciation capabilities for the greatest number of metals and elements on the periodic table available in any industry. Visit our speciation page for more details.

Educating the Next Generation of Metals Chemists

UW Bothell School of STEMDr. Hakan Gürleyük, Brooks Applied Labs’ Technical Director and Sr. Scientist, was recently a Chemistry Seminar Series guest lecturer at the University of Washington – Bothell’s School of STEM. On March 13th Hakan led a class of approximately 45 undergraduate chemistry students as they learned about “Speciation Analysis Using ICP-MS”. Visit our website if you would also like to learn more about trace metals speciation, or to receive a copy of the slide deck from this presentation, please contact us.

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The Importance of Selenium Speciation

Got SeleniumThe topic of selenium has garnered attention in various industries for decades now, but the challenge associated with removing selenium from wastewaters has not diminished. In order to understand the most effective form of treatment for this unusual element that is both an essential micronutrient but also toxic at relatively low concentrations, the molecular form, or speciation, of selenium must be understood.

The two most common inorganic forms present in industrial wastewaters and agricultural runoff are selenite and selenate. Numerous treatment options are available for selenite, but conventional options like iron co-precipitation are ineffective for selenate. Several reviews have identified biological treatment as one of the best options for selenate removal, in part because it is cost-effective and has been proven in full-scale installations. Therefore, it is prudent for industries needing to implement selenium treatment and collaborative service providers to characterize waste streams via speciation analysis before and during bench- or pilot-scale studies.

Systems for biological treatment of selenium-laden waters take many forms, but anaerobic bioreactors are one of the most common iterations. In most of these systems, reduction of selenite and selenate to elemental selenium (Se0) is the desired outcome. This elemental selenium is mostly insoluble and can be removed from the effluent via filtration or temporarily retained in the reactor until backflushing of the system can be performed. Well-maintained and optimized bioreactors have been shown to treat industrial wastewaters containing mg/L concentrations of selenium down to single-digit µg/L levels.

Depending on the bacterial strains involved, the chemical environment, proper operation and maintenance, and the availability of nutrients, other less-desirable selenium species may be formed by bioreactor systems. Figure 1 shows a chromatogram of an effluent from a bioreactor used to treat a wastewater initially containing only selenite and selenate. Of particular note are the appreciable concentrations of the reduced selenium species, selenosulfate and selenocyanate (SeCN), as well as the organic selenium species that are present. While the toxicity of all these species have not been fully characterized and their bioaccumulation can be influenced by other constituents in the water, it has been shown that the bioavailability of certain species like selenomethionine can be several orders of magnitude higher than those of inorganic selenium.

Since the goal of the treatment process is to reduce the uptake of selenium in the aquatic environment, conversion of inorganic selenium into forms that are significantly more bioavailable must be avoided. Otherwise, there is the potential that the treatment process itself will enhance the biomagnification of selenium. Methods that can quantify low levels of organic selenium species in the aquatic environment are also required due to the high bioavailability of these forms. Figure 2 shows an example of one such method performed at Brooks Applied Labs, high-performance liquid chromatography inductively coupled plasma collision reaction cell mass spectrometry (HPLC-ICP-CRC-MS). Using this method, selenomethionine can be reliably quantitated down to 5 ng/L (or part-per-trillion, ppt) in natural waters and certain industrial wastewaters.
Selenium speciation analysis is essential for not only selecting an appropriate treatment system but also monitoring its performance, thereby increasing the probability that it serves the goals of mitigating selenium ecotoxicity and corporate liability. Routinely monitoring the speciation of the effluent (in addition to standard parameters such as pH and ORP) allows system operators to make timely adjustments to maintain optimal reactor performance.  To find out more about how Brooks Applied Labs can support your selenium treatment system, please contact us today!

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Choosing the Appropriate Method for Arsenic Speciation

When routine analytical testing indicates that a sample contains elevated levels of arsenic, more detailed characterization is often warranted. Performing arsenic speciation analysis – where specific molecular forms of arsenic are individually quantified – is often critical; however, if you don’t select the most appropriate analytical method, you can end up without the data you need or paying too much for data that is not helpful. But with dozens of potential arsenic species and numerous analytical options available, deciding what analyses to request can sometimes seem overwhelming. Brooks Applied Labs has decades of experience offering advanced arsenic speciation services and can help you choose an appropriate approach to meet the objectives and budget of your project.

Differentiating between the two most common forms of inorganic arsenic, arsenite and arsenate, is generally required for determining an appropriate treatment method for water samples known to contain elevated arsenic concentrations. This is because arsenate is typically directly amenable to conventional treatments like adsorption or co-precipitation, but arsenite is not. While arsenite and arsenate may be the most common arsenic species in simple waters, those from reducing environments or with significant biological activity can contain more unique species such as thioarsenicals or organic arsenicals like monomethylarsonic acid, dimethylarsinic acid, and trimethylarsine oxide. Moreover, certain sample types like landfill gas condensates can even contain volatile arsenic species like trimethylarsine. Brooks Applied Labs has developed methods tailored for the collection, preservation, and analysis of not just simple waters, but also these more complex ones to ensure that our clients can trust the integrity of their data.

While individually quantifying arsenite and arsenate provides crucial information for water samples, it is often unnecessary for biota and food. Most promulgated or proposed regulations for these latter sample types only set limits on the inorganic arsenic content, which they define as the sum of arsenite and arsenate. Examples of such regulations are California’s Proposition 65, the US FDA’s proposed limits for juices and infant rice cereal, and the WHO-FAO and EC limits for inorganic arsenic in rice products. Therefore, requesting inorganic arsenic quantitation in food and biota, rather than differentiation between arsenite and arsenate, typically suffices and can save clients money. But quantifying other species beyond inorganic arsenic is vital as an additional quality control check: comparing the sum of detected arsenic species against the separately determined total arsenic concentration (i.e., determining the mass balance) helps evaluate the completeness and accuracy of the data. Measuring other less common arsenic species can also be important for projects investigating the bioavailability, toxicity, or metabolism of arsenic.

Brooks Applied Labs understands that each project is unique, and a one-size-fits-all approach is never in the client’s interest. We offer numerous preparatory and analytical methods, customized for the sample matrix and target analytes, and have experienced staff available to help you decide what fits your individual needs. Should your next project require more detailed characterization for arsenic in waters, biota, food, soils, sediments, or another matrix, please contact us to see how we can help!

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Come Visit BAL at the Business & The Environment Conference and Expo

logo business and environmentBrooks Applied Labs will be exhibiting at the Business & the Environment Conference & Expo in Portland December 11-12. This conference, organized by the Northwest Environmental Business Council (NEBC), is the Northwest’s largest environmental conference, with educational sessions covering topics such as environmental protection, sustainable business practices, and trending policy issues. Elizabeth Madonick will be there to answer any questions you may have about how our specialty elemental analyses and speciation services can support your projects. If you are going to be at the conference, be sure to come by and say hello!

BAL is On the Road Again…

SETAC logoThe SETAC North America 39th Annual Meeting will be held in Sacramento November 4-8 this year. Come learn more about the unexpected ways alligators can potentially cause you harm you when Elizabeth Madonick, BAL Technical Services Specialist, presents a poster on the concentrations of total mercury and methylmercury in alligator meat on Tuesday, November 6th! Contact us any time after November 8th if you would like to receive a PDF copy of this interesting research.

 

The same week, Russ Gerads and Jamie Fox will be attending the International Water Conference in Scottsdale, Arizona. Jamie will be presenting on “Compliance with Selenium Aquatic Life Criterion and the Importance of Speciation for Treatment Selection and Monitoring” during the session on Trace Contaminants: Detection, Removal, and Recovery on November 5th. If you are interested in receiving a copy of this presentation, please feel free to contact us after November 12th.