Hi,
The vortexing of the compound alone in DMSO is used to make sure the compound is fully dissolved and the solution homogeneous. The vortexing of the solution before the NMR is run is again to make sure that the solution is homogeneous. The vortex helps preventing/gets rid of air bubbles that can be detrimental to the waterLOGSY (bad baseline, not being able to lock or shim).
The vortex was listed in the equipment list:
Scientific Industries SITM Vortex-GenieTM 2 (Scientific Industries, model: SI-0266 , catalog number: 15557335 )
I hope this helps.
bw.