Abstract: The disclosure addresses methods, compositions, and kits used to detect or quantify polymerase inhibitors in biological samples. The polymerase inhibitors can be therapeutic agents, or metabolites thereof, that have been administered to a subject as part of, for example, antiretroviral therapy (ART) or pre-exposure prophylaxis (PrEP) to address potential infections by, e.g., retroviruses such as HIV and other viruses reliant on reverse transcription. These methods, compositions, and kits can be applied to monitor a subject's compliance with the indicated therapies and can inform potential adjustments to the therapies.