What this group shows is that well designed aptamers (DNA things that are designed to enrich other things -- legitimately you can enrich everything from environmental pollutants through proteins) they can enrich and almost directly analyze what they enriched!
You've got me. Actually, I think that most aptamer assays use fluorescence so MS/MS on the back end. MS/MS would allow you to QC that aptamer to see if it really is grabbing what you want it to. In the example they show it looks like their aptamer grabs a couple of things and by MS/MS signal they can work out the ratios of those things. Having an integrated system for QC'ing aptamers or doing quantification on enriched molecules from multi-purpose aptamers sounds a lot easier than digesting each aptamer individually, so this seems like a smart/weird application.
The MS instrument used was a TripleTOF 4600.