A simple procedure to eliminate the interference from keto-opiates in the analysis of 6-monoacetylmorphine (6-MAM) by gas chromatography-mass spectrometry is described. The pretreatment of urine samples with sodium bisulfite followed by solid-phase extraction results in the elimination of the bisulfite addition products formed from the reaction of the bisulfite ions with the carbonyl carbon of the keto-opiates. This simple procedure results in the accurate quantitation of 6-MAM at a concentration of 4 ng/mL in the presence of keto-opiates up to 10,000 ng/mL.
Antioxidants Cross Reactions