In this two-part webinar series, the sources of interferences in ICP-OES and ICP-MS and how to identify them will be described. Software approaches for correcting interfered results which each technique will be presented and the latest instrumental developments for minimizing interference problems will also be discussed.
Interferences are a well-known problem in both inductively coupled plasma–optical emission spectroscopy (ICP-OES) and ICP–mass spectrometry (ICP-MS). They can be subdivided into three main types: chemical, physical, and spectral.
- Chemical interferences are caused by differences in the way sample and calibration solution matrices behave in the plasma, resulting in changes in atomization and ionization that are dependent on the matrix composition of the sample. An example of this type of interference is the enhancement effect (which causes falsely high results) observed on both atom and ion signals for elements such as arsenic and selenium, when carbon is present in the samples but not the calibration solutions.
- Physical interferences are also caused by matrix differences between samples and calibration solutions. Examples of this type of interference include signal suppression (due to high amounts of easily ionized elements, such as sodium, in the samples), drift and signal variability from sample to sample caused by, for example, changes in nebulization efficiency as a result of viscosity differences between samples. These interferences can cause reported results to be either too high or too low if they are not properly corrected for.
- The last, and most challenging, type of interference is spectral interference. For ICP-OES, these are observed as either direct or partial emission wavelength overlaps on the signals of target analytes from other elements or molecular species in the sample. For ICP-MS, spectral interferences from other elements in the sample appear as either direct (from singly charged ions) or half-mass (from doubly charged ions) overlaps on the target ion isotope signals. With ICP-OES, spectral interferences, like physical interferences, can cause falsely high or falsely low results. With ICP-MS, the overlaps caused by interfering signals generate false positive signals, but if incorrect mathematical corrections are applied to the data, falsely low results can also be reported.
Key learning objectives
- Understand what types of interferences exist in ICP-OES and ICP-MS and how they affect your results.
- Learn strategies for identifying and managing these interferences.
- Find out how innovations in hardware help reduce interferences, improve accuracy, and remove the need to re-run samples.
- Discover how intelligent software tools enable easier, interference-free method development.
