Fentanyl d5

Reagents and standards of furanylFentanyl, 4-fluorobutyrFentanyl, acrylFentanyl, butyrylFentanyl, and 4-anilino-N-phenethyl-piperidine (4-ANPP) were produced by Chiron (Trondheim, Norway). AcetylFentanyl and carfentanil were obtained by Toronto Research Chemicals (North York, Canada) while ocfentanil and norFentanyl were purchased from Sigma-Aldrich (Milan, Italy). CyclopropylFentanyl, α-methylFentanyl, and β-hydroxyFentanyl were provided by National Institute of Health (ISS). Fentanyl and the deuterated internal standards (norFentanyl-d₅, Fentanyl-d₅) were produced by Cerilliant (Round Rock, Texas, USA). All other chemicals were purchased from Sigma-Aldrich (Milan, Italy). Ultra-pure water was obtained using a Milli-Q® UF-Plus apparatus (Millipore, Bedford, MA, USA). All stock standard solutions were prepared in methanol at 1 mg/mL and stored at − 20 °C until used. Working solutions were prepared at the final concentration of 1000 ng/mL by dilution with methanol.

Adenosine, phosphate buffered saline (PBS), polyethylene glycol (PEG) 400, Triton™ X-100, dimethyl sulfoxide (DMSO), and 1-pentanol were purchased from Sigma Aldrich (Oakville, ON, Canada). Dextromethorphan, fentanyl, and fentanyl-D5 were acquired from Cerilliant (Round Rock, TX, USA). Urine was purchased from BioIVT (Westbury, NY, USA). The HPLC-grade methanol and acetonitrile were bought from Caledon Laboratory Chemicals (Georgetown, ON, Canada) and J.T. Baker (Radnor, PA, USA), respectively. Deionized water (18 MΩ) was produced in-house using a Millipore Integral 10 water purification system (Billerica, MA, USA).

Fentanyl-D5 was produced by Cerilliant (Round Rock, TX, USA); the working solution was prepared at the final concentration of 1.000 ng/mL by dilution with methanol.
Acetonitrile and formic acid were provided by Sigma Aldrich (Milan, Italy). Ultra-pure water was obtained using a Milli-Q^® UF-Plus apparatus (Millipore, Bedford, MA, USA).
Fentanyl-D5, norFentanyl-D5, AH-7921-d6, MDMA-d5, cocaine-d3, morphine-d3, nordiazepam-d5, fentanyl, heroin, cocaine, diazepam, ketoprofen, U-47700, and MDMA were obtained from Chiron (Trondheim, Norway, Sigma-Aldrich (Milan, Italy) and the National Institute of Health (ISS). Dulbecco’s modified Eagle’s medium (Sigma-Aldrich, Milan, Italy), glutamine, non-essential amino acids (Sigma-Aldrich, Milan, Italy), bovine fetal serum (FBS) (Sigma-Aldrich, Milan, Italy), antibiotic and antimycotic solution (10,000 units of penicillin, 10 mg of streptomycin and 25 μg amphotericin B per mL) (Sigma-Aldrich, Milan, Italy), β-glucuronidase from Helix Pomatia, HepG2 cell line (American Type Culture Collection, USA), and trypsin-EDTA (Sigma-Aldrich, Milan, Italy) were also obtained.