Comprehensive Study Shows Versatility of N2O Gas for ICP-MS Measurements

A new study conducted by Shaun T. Lancaster from Montanuniversität Leoben in Austria and the University of Calgary in Canada demonstrates the high versatility of nitrous oxide (N₂O) as a reaction cell gas for routine inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) measurements. The study, published in the Journal of Analytical Atomic Spectrometry, characterizes gas cell reactions for 73 elements using N₂O, with a comparison to the most widely used mass-shift method using oxygen (O₂) as a reaction gas (1). Out of the 73 elements, 59 showed improved sensitivity when performing mass-shift with N₂O compared to O₂, with 8 elements showing no reaction with either gas. Additionally, N₂O demonstrated a collisional focusing effect for 36 elements when measuring on-mass. This effect was not observed using O₂.

Nitrous oxide cylinder vector icon isolated on white background. | Image Credit: © Adam - stock.adobe.com

N₂O is a highly reactive gas that is useful for ICP-MS/MS analysis. It is typically used as a reaction cell gas to reduce spectral interferences. N₂O can be used to mass-shift target analytes to a higher mass-to-charge (m/z) ratio with increased sensitivity, which improves the detection limits of trace elements. Additionally, N₂O can be used to monitor asymmetric charge transfer reactions, which highlights the potential of some elements to become metastable ions that could be used as an alternative mass-shift option. The use of N₂O in ICP-MS/MS analysis has gained more traction in recent years because of its versatility and the growing number of publications that have used it. Overall, N₂O is a valuable tool for routine ICP-MS/MS measurements.

The study highlights the usefulness of N₂O as a highly reactive gas, typically used for mass-shifting only target analytes to a higher mass-to-charge ratio with increased sensitivity. The traditional use of N₂O was limited to selected applications because of the creation of new interferences that also interfere with the detected masses of interest. However, with the advent of ICP-MS/MS, the use of N₂O has gained more traction, with a growing number of publications in recent years.

Moreover, monitoring asymmetric charge transfer reactions with N₂O highlighted 14 elements, primarily non-metals and semi-metals, that enter the gas cell as metastable ions and could be used as an alternative mass-shift option. Overall, the results from this comprehensive study suggest that N₂O is a highly versatile reaction cell gas for routine ICP-MS/MS measurements and can significantly improve sensitivity and accuracy of spectral interferences in a wide range of applications.

Reference

(1) Lancaster, S. T.; Prohaska, T.; Irrgeher, J. Characterisation of gas cell reactions for 70+ elements using N₂O for ICP tandem mass spectrometry measurements. J. Anal. At. Spectrom. 2023, ASAP. DOI: 10.1039/D3JA00025G