Another alternative is a peak-to-background analysis using EDS. In fact, I'd strongly suggest using EDS for this analysis regardless. As Armstrong mentions in his article in the Green Book, if you use WDS, you should either 1) collect all elements on the same detector; or 2) rotate the sample to keep the same face towards the measuring detector. Either way you are collecting one element at a time. With EDS, all elements are always collected from the same vantage point and, better yet, excited by the same electrons.
The only reason I'd even consider WDS for a particle was for trace elements. And even then, I'd only use WDS for the trace element and EDS for everything else.
With P-to-B, you'd need to mount the particles on a TEM grid or other thin-film substrate. Bulk substrates won't work. Bruker has a good implementation of P-to-B.