alpha-Dicarbonyl compounds are of major interest in food chemistry and biochemistry as important precursors of, for example, protein modifications and flavor. Due to their high reactivity most of the published structures were identified and quantitated as stable derivatives after reaction with trapping reagents. However, the present study showed for the first time that the trapping reagents are of dramatic impact on the final qualitative and quantitative alpha-dicarbonyl spectrum. As important representatives, aminoguanidine and o-phenylenediamine were used to compare trapping characteristics and to monitor the dicarbonyl structures arising from the degradation of an Amadori compound. Dicarbonyl structures with a reductone moiety could not be or were only insufficiently detected by slow-reacting reagents such as aminoguanidine. On the other hand, fast-reacting chemicals such as o-phenylenediamine imposed high oxidative stress on the investigated system and led to enhanced or false positive formation of dicarbonyl compounds generated by oxidative pathways.