TFMU-ADPr triethylamine is a general substrate for monitoring poly(ADP-ribose) glycohydrolase (PARG) activity. TFMU-ADPr triethylamine can directly report on total PAR hydrolase activity via release of a fluorophore. TFMU-ADPr triethylamine has excellent reactivity, generality, stability, and usability. TFMU-ADPr triethylamine is a versatile tool for assessing small-molecule inhibitors in vitro and probing the regulation of ADP-ribosyl catabolic enzymes.