* WDS cannot determine elements below number 3 (lithium). This restricts WDS when analyzing geologically important elements such as H, Li, and Be. 
* Despite the improved spectral resolution of elemental peaks, some peaks exhibit significant overlap that causes analytical challenges (e.g., VKα and TiKβ). WDS analyses are unable to distinguish the valence states of elements (e.g. Fe vs. Fe) which must be obtained by other techniques such as Mössbauer spectroscopy or electron energy loss spectroscopy. 
* Element isotopes cannot be determined by WDS, but are most commonly obtained with a mass spectrometer.