Electroanalytical characterisation of nitrosamines in different mobile phases as supporting electrolytes

N-nitrosamines (N-NAs), hazardous food contaminants, were submitted to an extensive electrochemical characterization of N-NAs in various mobile phases used as the supporting electrolyte and with metal and carbonaceous electrodes, in order to develop sensitive electrochemical detection methods to be applied in their post-column analysis. N-NAs (N-nitrosodiethylamine, N-nitrosomorpholine, N-nitrosopyrrolidine, and N-nitrosodiphenylamine) with both different structural characteristics and physico-chemical/reactivity properties were used as model compounds. Preliminary experiments by cyclic voltammetry at platinum (PtEs), gold (AuEs) and glassy carbon electrodes (GCEs) were performed to investigate their electrochemical behavior. The best performances were obtained either by AuEs in 20 mM methanesulfonic acid mobile phases (MSA) operating with pulsed amperometric detection (PAD) technique or by GCEs in organic mobile phases with direct current cathodic detection (DCCD) the latter proposed for the first time for the detection of N-NAs. The detection schemes were characterized in flow injection analysis (FIA) by the evaluation of some important performance parameters, such as limit of detection and response repeatability. For all the investigated N-NAs, PAD at AuEs in MSA and DCCD at GCEs in organic mobile phases showed detection limits in the range 0.8–1.2 µM and 0.4–1.2 µM respectively with RSDs of about 4%, showing the potential of the proposed electrochemical detection methods as an excellent alternative to the current N-NAs post-column detection in liquid chromatography.