Instrumentation Focus: Reducing Interferences in ICP/MS
Prepared by W. Yang1, . Sureka2, . Kutscher2, S. Antonio1
1 - ThermoFisher Scientific, 3000 Lakeside Dr Suite 116N, Bannockburn, IL, 60015, United States
2 - Thermo Fisher Scientific, Hanna-Kunath-Str. 11, 28199, Bremen, , Germany
Contact Information: [email protected]; 419-357-2473
Toxic elements, such as arsenic, cadmium, mercury, and lead, need to be monitored in the environment to protect the surrounding nature from contamination and keep water resources safe. Therefore, the analysis of drinking waters, surface waters and waste waters, as well as monitoring the level of potential contaminants in solid waste or sewage sludges, is an important task.
ICP-MS is the preferred analytical solution for trace element determination at the lowest concentration levels. In the US, the analysis of common environmental samples using ICP-MS is governed by the EPA method 200.8 for drinking waters, and EPA method 6020 B for soil samples.
Single quadrupole ICP-MS systems, equipped with a collision/reaction cell (CRC) are commonly used in many laboratories, combining consistent interference removal with short measurement times, and hence enabling robust, high-throughput analysis. However, the use of a collision cell is not approved in EPA method 200.8, so that in many cases, less abundant isotopes need to be used for specific elements, or mathematical correction has to be applied. For EPA method 6020 B, the use of CRC technology is fully approved, and interference removal is often accomplished using helium in order to remove the most common polyatomic interferences. However, this approach is ineffective for other types of interferences, such as doubly charged interferences or polyatomic species in the high mass range.
This presentation will describe an alternative approach for removal of all types of interferences based on the use of triple quadrupole ICP-MS (TQ-ICP-MS). Although TQ-ICP-MS is known to offer superior interference removal based on the use of reactive gases, it is often not considered to be fit for purpose in applied testing laboratories due to the potential extension of the sample turnover time when multiple modes for analysis are used. However, using only oxygen as a reactive gas, together with a mass filtration step before the CRC, efficient and complete interference removal can be achieved with little to no impact on sample turnover time or detection limits, compared against single quadrupole ICP-MS systems.