At my company, among other things, we make Master Mixes and dNTP blends and stuff like that for PCR. We made one dNTP blend recently, and would consistently get no PCR product when tested. During troubleshooting, we ran it on HPLC and found there was no peak for G, and a correspondingly larger peak for T/U.
Here's the problem. The blend has both T and U in it already, and of course our operators have access to both already also. Is there another analytical test that can be performed to resolve whether it's T or U? (We're also doing inventory verification, but so far that's been inconclusive.)