Analysis of Nitrosamines in Cooked Bacon by QuEChERS Sample Preparation and Gas Chromatography-Tandem Mass Spectrometry with Backflushing.

Abstract

Nitrites are added as a preservative to a variety of cured meats, including bacon, to kill bacteria, extend shelf life, and improve quality. During cooking, nitrites in the meat can be converted to carcinogenic nitrosamines (NAs), the formation of which is mitigated by the addition of antioxidants. In the past, the U.S. Department of Agriculture (USDA) Food Safety and Inspection Service (FSIS) monitored NAs in pan-fried bacon, but FSIS terminated monitoring of NAs in the 1990s due to the very low levels found. FSIS recently chose to conduct a risk assessment of NAs in cooked bacon to determine if current levels warrant routine monitoring of NAs again. To meet FSIS needs, we developed, validated, and implemented a new method of sample preparation and analysis to test cooked bacon for five NAs of most concern, which consist of N-nitroso-dimethylamine, -diethylamine, -dibutylamine, -piperidine, and -pyrrolidine. Sample preparation was based on the QuEChERS (quick, easy, cheap, effective, rugged, and safe) approach and analysis by gas chromatography-tandem mass spectrometry. Ruggedness was improved markedly in the analysis of the complex fatty extracts by backflushing the guard column, injection liner, and half of the analytical column after every injection. Validation results were acceptable with recoveries of 70-120% and <20% RSDs for the five NAs, with a reporting limit of 0.1 ng/g. NA concentrations in 48 samples were all <15 ng/g, with most <1 ng/g and many <0.1 ng/g. Also, microwave cooking of bacon gave slightly lower concentrations overall compared to pan-frying.