Wouldn't a quantitative phosphopeptide standard be great!?

I think if you really spent enough time looking you might turn up 50 different ways to enrich phosphopeptides.

If you wanted to assess them or if you're developing your own chemisty --- wouldn't quantitative recovery be an awesome metric? Maybe even better than the elusive # of distinct phosphopeptides?

And that's what this is -- a strategy for building a TMT phosphostandard!!