Figure shows AFM images of a portion of a gold electrode prior to (left), and, after (right) EtBr detection. As can be seen, there is no clear difference in the two profiles heights but there is other than a slight reduction in the root means square roughness of the electrode, suggesting that if a passivation layer is present then it is extremely thin and that the as the heights didn't change the deposited gold did not delaminate from the electrode surface. To confirm the presence of a passivation layer and elucidate changes in electrode behavior, CV and electrochemical impedance spectroscopy was undertaken at electrodes both pre and post EtBr detection in 5 mM FCA. The CV data presented in Figure (a) exhibited a significant decrease in current falling from ~12 nA to ~0.5nA following EtBr analysis. The observed hysteresis arises from capacitive charging of the electrode . These results strongly suggest that a passivation layer is present. This is further supported by the EIS data presented in Figure To explore the applicability of the electrodes for EtBr detection, swabs were taken from different locations of a microbiology laboratory which regularly uses EtBr, a fluorescent label for nucleic acid detection. Three locations were selected where the potential for detecting EtBr was zero, low, and high, mainly: the post electrophoresis gel tray, the TAE (Tris-acetate-EDTA) buffer tray and the gel preparation fume hood and analyzed as described in the experimental section. Representative CVs with an image of the swabbed area are presented in Figure . As expected, zero or very low concentrations of EtBr were measured for the swabs taken from outside the fume hood. A significant concentration was measured for swabs taken inside the fume cupboard corresponding to ~250 nM of EtBr. This means that significant concentrations of EtBr remain on these surfaces despite UV and cleaning protocols. These results are important as they can inform the preparation of occupational risk assessments highlighting contaminated areas within a laboratory.