Improving data quality for Arsenic and Selenium detection using TQ-ICP-MS in environmental laboratories

Metals and Metal Speciation Analysis in Environmental Samples
Oral Presentation

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High throughput laboratories dealing with environmental analysis often use ICP-MS to analyze multi-elements from hundreds of samples following EPA method 200.8 or SW846 method 6020. Generally, ICP-MS is one of the most powerful detectors that is used for elemental analysis. It provides the advantage of easy quantification of trace elements, high sample throughput and the possibility of speciation analysis when coupled with other analytical tools. For high throughput laboratories, accessories allowing a high degree of automation are available, which is critical for dilution of heavy matrix samples with unknown concentration, or for re-runs of failed quality controls.

However, for some samples it is not the matrix content that leads to a failure, but rather spectral interferences which lead to false positives, and hence manual screening of data and subsequent re-runs. Especially difficult to overcome in single quadrupole (SQ) ICP-MS are isobaric and sometimes polyatomic interferences. While there are different techniques to circumvent false positive results, in most cases the detection limits rises to the point that a reliable quantification of ultra-trace elements cannot be achieved. Some elements that are highly prone to such interferences are arsenic and selenium, which are an ever remaining challenge for ICP-MS analysis.

In contrast, triple quadrupole (TQ) ICP-MS is well capable of eliminating all interferences even in most difficult environmental samples, comprising both a high salt load and a complex composition leading to multiple interferences. Using TQ-ICP-MS, analysis time for such samples can be drastically reduced by gaining accurate results in the first analysis, even for more challenging samples. Consequently, lowest detection limits can be achieved by improved interference suppression.

At the same time, through dedicated design in both hardware and software, the underlying complexity of TQ-ICP-MS is reduced for the operator, so that this powerful technique is as easy to use as well established SQ-ICP-MS.