Simultaneous quantification of buprenorphine, norbuprenorphine, buprenorphine glucuronide, and norbuprenorphine glucuronide in human placenta by liquid chromatography mass spectrometry.

A LCMS method was developed and validated for the determination of buprenorphine (BUP), norbuprenorphine (NBUP), buprenorphine glucuronide (BUP-Gluc), and norbuprenorphine glucuronide (NBUP-Gluc) in placenta. Quantification was achieved by selected ion monitoring of m/z 468.4 (BUP), 414.3 (NBUP), 644.4 (BUP-Gluc), and 590 (NBUP-Gluc). BUP and NBUP were identified monitoring MS(2) fragments m/z 396, 414 and 426 for BUP, and 340, 364 and 382 for NBUP, and glucuronide conjugates monitoring MS(3) fragments m/z 396 and 414 for BUP-Gluc, and 340 and 382 for NBUP-Gluc. Linearity was 1-50 ng/g. Intra-day, inter-day and total assay imprecision (% RSD) were <13.4%, and analytical recoveries were 96.2-113.1%. Extraction efficiencies ranged from 40.7-68%, process efficiencies 38.8-70.5%, and matrix effect 1.3-15.4%. Limits of detection were 0.8 ng/g for all compounds. An authentic placenta from an opioid-dependent pregnant woman receiving BUP pharmacotherapy was analyzed. BUP was not detected but metabolite concentrations were NBUP-Gluc 46.6, NBUP 15.7 and BUP-Gluc 3.2 ng/g.