Supercritical fluid extraction of volatile N-nitrosamines in fried bacon and its drippings: method comparison

N-Nitrosopyrrolidine (NPYR) and N-nitrosodimethylamine (NDMA), known animal carcinogens, are consistently formed in bacon during frying. As a result, commercial bacon has been subject to regulatory monitoring and compliance for the past 20 years to ensure that N-nitrosamines do not exceed the 10 ppb volatile level. Currently, time-consuming distillation-solvent extraction and solid-phase extraction (SPE) methods are used for this purpose. With an emphasis on reducing solvent use, we investigated supercritical fluid extraction (SFE) using supercritical carbon dioxide (SC-CO2) for isolation of volatile nitrosamines common to fried bacon. Eighteen fried bacon samples were analyzed for NPYR and NDMA by SFE, SPE, mineral oil distillation (MOD), and low-temperature vacuum distillation (LTVD) methods, using the same gas chromatographic-chemiluminescence detection (thermal energy analyzer) conditions. The range of values for SFE was 0.7 to 20.2 ppb for NPYR and none detected (ND) to 2.4 ppb for NDMA. Analysis of variance of the NPYR data showed a significant difference (p < 0.05) between SFE and SPE results and significant differences between these and those obtained by MOD and LTVD. Overall, SFE was superior to the other methods with the highest recoveries, best repeatability, rapidity of analysis, and solvent-sparing characteristics. Similar results were obtained for SFE after comparison with distillation and SPE methods for determining the same nitrosamines in fried bacon drippings.