Use of an Acetyl Derivative to Improve GC-MS Determination of Norbuprenorphine in the Presence of High Concentrations of Buprenorphine in Urine.

Certain patients being treated with Suboxone™ or Subutex™ can exhibit very high buprenorphine and low norbuprenorphine concentrations in urine. Very high buprenorphine can interfere with buprenorphine-D4 used as an internal standard, causing errors in norbuprenorphine determination by gas chromatography-mass spectrometry (GC-MS). We used a modified method of Wu et al.