Analysis of Nitrosamines in Beer

Keywords food safety nitrosamines beer GC-MS/MS MRM quantitation confirmation 

The classical nitrosamine analysis was performed for many years by gas chromatography using a thermal energy analyzer (TEA) as detector. This special TEA detector was used due to its selectivity for nitrosamines based on the specific chemiluminescent reaction of ozone with the detector generated NO from nitrosamines. Today, with increased sensitivity requirements, the detection limits of the TEA, and also its complex operation, do not comply any more with the required needs for low detection limits and sample throughput. Mass spectrometric methods have increasingly replaced the TEA. 

The EPA method 521 by Munch and Bassett from 2004 provided at that time a suitable GC-MS method based on chemical ionization (Cl) using an ion trap mass spectrometer with internal ionization (Munch and Bassett, 2004 March and Hughes, 1989), in contrast to standard quadrupole or ion trap mass spectrometers 

This application describes a turn-key GC-MS/MS method for routine detection and quantitation of food borne nitrosamine compounds. The food matrix used here has been different malt beer products and as a final food product regular commercial beer. 

The sample preparation is adapted and slightly modified from AOAC Official Method (2000), 982.11 (AOAC, 2000). An SPE column extraction method using a celite column and elution with DCM (dichloromethane) to isolate the nitrosamines from the beer samples was developed. 

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In the last fifteen years there has been considerable interest in the analysis of volatile N-nitrosamines in foods. The primary focus has been on meat cured with nitrite (3 ) although nitrosamines have been shown to occur occasionally in other foods such as fish and cheese (, 3) Recently, attention has been directed to volatile nitrosamines in beer and other alcoholic beverages. The purpose of this paper is to review current information on the presence of nitrosamines in beer, and to discuss work done in our laboratory and elsewhere on the mode of formation of nitrosamines in beer. 

Spiegelhalder, B., G. Eisenbrand, and R. Preussmann Volatile A-nitrosamines in beer and other beverages by direct extraction using a kieselguhr column in Environmental carcinogenesis Selected methods of analysis, Vol. 6 A-Nitroso compounds, edited by H. Egan, R. Preussmann, I.K. O Neill, G. Eisenbrand, B. Spiegelhalder, and H. Bartsch, lARC, Lyon, France, lARC Sci. Publ. 45 (1983) 135-142. 

N-Nitrosamines are widely distributed in various human environments. The concern was initially focused on their widespread occurrence in food and consumer products, as beer, meats cured with nitrite, smoked fish, tobacco and tobacco smoke, rubber products including baby bottle nipples and pacifiers, cosmetics, drug formulations, or herbicides formulations. Much data of their occurrence have been obtained by inadequate analytical methods and must await confirmation. Considerable progress has been made in the development of adequate and specific methods for trace analysis of nitrosamines, and reliable information is expected in the near future. 

The data in Table I are also significant in terms of the type of analysis to determine the presence of NDMA. In all cases analysis was done using gas chromatography coupled with a Thermal Energy Analyzer, a sensitive, relatively specific nitrosamine detector (12). Further, in six of the studies, the presence of NDMA in several samples was confirmed by gas chromatography-mass spectrometry (GC-MS). The mass spectral data firmly established the presence of NDMA in the beer samples. 

From the large variety of potential nitrosamines the compounds that had been included in this method are those that are reported to be of relevance in the germinated malt drying process. Samples analyzed included malt beer as unspiked samples with 4% ethanol as sample blanks. In case of the analysis of other food matrices, additional compounds can be added to this method as described in the method setup by AutoSRM (Thermo Fisher Scientific, 2012a,b Chen etal., 2013). 

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