The determination of semicarbazide (N-Aminourea) in commercial bread products by liquid chromatography-mass spectrometry

Recently, semicarbazide has been found in food in jars sealed with cap liners that were manufactured using azodicarbonamide as a blowing agent. These reports raised the concern that the use of azodicarbonamide-an approved dough conditioner-may result in semicarbazide residues in bread. To answer this question, a method based upon the previously reported liquid chromatography/tandem mass spectrometry determination of the semicarbazone of o-nitrobenzaldehyde was utilized. The method adopted for this work includes an extensive cleanup and reaction with o-nitrobenzaldehyde at pH 3.5, rather than with the widely used 0.1 M HCl;, to form the semicarbazone derivative. A stable isotope dilution assay was used to determine the free semicarbazide present in the bread products. Levels of semicarbazide ranged from 10 to 1200 ppb in commercial bread products with azodicarbonamide listed among their ingredients.