Direct Analysis of Trace Elements in Seawater Using ICP-MS with Versatile Reaction Modes

Instrumentation Focus: Reducing Interferences in ICP/MS
Poster Presentation

Prepared by L. Xing, C. Stephan
Perkinelmer, 501 Rowntree Dairy Road, Unit #6, Woodbridge, ON, L4L 8H1, Canada


Contact Information: [email protected]; 17788864258


ABSTRACT

The determination of trace elements in seawater is usually considered to be challenging for ICP-MS due to the high total dissolved solids (TDS) in this matrix. The high concentrations of matrix components in seawater, such as sodium, magnesium, and chloride ions, may form polyatomic spectral interferences and complicate the determination of elements, such as As, Co, V, Zn, Cu, and Fe. Even for elements like Cd, Sn, and Pb that are less affected by spectral interferences, the low ppt concentrations in seawater make them difficult to determine with good accuracy and precision.
Both NexION® 2000 ICP-MS and NexION 5000 Multi-Quadrupole ICP-MS are equipped with Universal Cell Technical (UCT), which allows for samples to be run in Standard, Collision with Kinetic Energy Discrimination (KED), and Reaction with Dynamic Bandpass Tuning (DBT) modes. Compared to NexION 2000, NexION 5000 Multi-Quadrupole ICP-MS is a four quadrupole ICP-MS system that combines tandem mass analyzers (Q1 and Q3) with UCT (Q2) to achieve interference-free analysis.
In respect of sample preparation, a few techniques have been developed to reduce the matrix load such as liquid dilution, gas dilution, matrix separation, analyte preconcentration, flow injection, hydride generation techniques, etc., most of which requires either offline sample preparation or extra equipment and/or complexed setup.

Here, we reported a direct analysis procedure using online dilution with a combination of liquid dilution and gas dilution. The matrix load is further reduced by using HTS (High Throughput System), a flow injection technology. A variety of reaction/collision gas modes were applied to demonstrate the versatility of the method. The accuracy of the method is validated by the analysis of seawater certified reference materials NASS-7, CASS-6, and MX014. The robustness is demonstrated by the excellent recovery of internals standards and a continuous calibration standard over a 12-hour running sequence.