Online Standard Additions Technique for La-ICP-MS Using a Desolvating Nebulizer System

Historically, quantification with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has been limited to the ability to matrix match both standards and samples. This can prove problematic when a particular matrix matched standard is not readily available. Liquid standard addition has been shown^1-4 as an alternative technique for quantification that does not require matrix matching; however, further fundamental study is needed especially considering the different mass flow rates delivered to the plasma from traditional pneumatic nebulizers and laser ablation itself.

In this work, the authors combine a specialized low-flow desolvating nebulizer system with LA-ICP-MS. This nebulizer system efficiently removes water vapour, thereby significantly reducing oxide based mass spectral interferences. For the instrument setup, the output from the laser is combined with the dried aerosol from the nebulizer system prior to entering the ICP-MS source. By using two sources of dry aerosol, mixing efficiency is improved whilst minimising plasma power lost to solvent (water vapour) processing.

The method was applied to both USGS Green River Shale and an Arkansas Womble Shale. The results showed a number of elements that were correctly quantified using the technique as compared to reference values.

References

1. Gunther, D., Cousin, H., Magyar, B., Leopold, I., J. Anal. Atom. Spectrom., 1997, 12, 165 – 170.

2. Leach, J.J., Allen, L. A., Aeschliman, D.B., Houk, R.S., Anal. Chem., 1999, 71, 440 – 445.

3. O’Conner, C.J.P., Sharp, B.L, Evans, P.J., Anal. Atom. Spectrom., 2006, 21, 556.

4. Yang, C.K., Chi, P.H., Lin, Y.C., Sun, Y.C., Yang, M.H., Talanta, 2010, 80, 1222 – 1227.