Internal standard with low T1 for NMR quantification of ammonia

I am trying to quantify low levels of ammonia with NMR. The good news is that ammonia has a very low T1 (<0.5) which shortens d1 a lot. However, I cannot find any internal standard with a T1 that is as low as ammonia so that I can use absolute qNMR for quantification. For example maleic acid would require around 10 times longer relaxation, because the T1 is around 3-5s which reduces the LOD of cause. 


Regards,
Martin


