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The movement of “zero tolerance” arsenic and selenium associated with drinking water, wastewater, soil, and groundwater regulatory limits necessitates the demand for absolute results. Most analytical techniques applied for arsenic and selenium analysis retain inherent interferences which can often bias results, especially at lower concentrations. Therefore, Applied Speciation employ state-of-the-art methods and instrumentation to surpass current and prospective demands for trace arsenic and selenium analysis.
In the recent years, inductively coupled plasma mass spectrometry (ICP-MS) became one of the most common detectors for the determination of trace metals in environmental samples. While ICP-MS can be used to determine most analytes of environmental concern at ppt levels, conventional ICP-MS instruments can suffer from various issues making trace analysis of arsenic and selenium very difficult.
By utilizing the DRC technology with the methods developed at ASC, detection limits in the range of 10 ng/L (ppt) for Arsenic and Selenium can be achieved easily with negligible bias.

Comparison between HG-AAS/AFS and ICP-DRC-MS

Hydride generation atomic absorption spectrometry and atomic fluorescence spectrometry (HG-AAS and HG-AFS, respectively) facilitates the reaction of sodium borohydride with reduced arsenic and selenium species (arsenite and selenite) to produce volatile hydrides which are purged from solution and detected spectrophotometrically. While these methods can produce very low detection limits (20-500 ng/L), they are prone to severe matrix interferences. The major issue with hydride generation methods is that they are operationally limited to the quantification of arsenite and selenite in solution; requiring pretreatment to convert all arsenic and selenium species to arsenite and selenite before analysis. Due to this inherent limitation, these methods can only provide “total reducible” arsenic and selenium and not “total” results that ICP-MS can provide. In addition, the complexity of the sample matrix can alter the efficiency of the reduction procedure or the hydride generation reaction. The interferences from transition metals, dissolved organic carbon, and salinity are very well documented and allow for significant biases associated with complex matrices, especially at trace levels.

Finally, the tedious sample preparation protocols necessitate commercial laboratories to charge significantly more for this analysis compared to ICP-DRC-MS analysis.

Conclusion

ICP-DRC-MS provides interference elimination and robustness for true total arsenic and selenium analysis in any matrix. The method offers better quality data than hydride generation methods and provide significant reduction in analytical costs. The same technology can also be used for other analytes such as chromium, iron, cadmium, etc.

Also see the following Application Notes:

Total Arsenic and Arsenic Speciation in Human Biological Samples (pdf)

Arsenic Speciation in Soils and Sediments (pdf)

Arsenic Speciation in Blood

Determination of Selenium in FGD Wastewaters

Our scientists have tremendous experience with trace analysis. 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 .

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