Figure 2

Comparison of compound stability at 4°C and at room temperature (patient II). Stability of alpha hydroxy alprazolam (black circle), alprazolam (black square), norbuprenorphine (black triangle), and buprenorphine (black diamond) in urine samples stored at 4°C (C, solid marker) and at room temperature (RT, open marker). Drug recovery after 30 days of storage, alpha hydroxy alprazolam (85% at 4°C, 89% at RT); alprazolam (95% at 4°C, 90% at RT); norbuprenorphine (92% at 4°C, 95% at RT); and buprenorphine (104% at 4°C, 85% at RT).