In this work, we develop a sensitive electrochemical based sensor, incorporating solid-state ultramicroelectrode sensors, that allows detection of EtBr contamination (nanomolar) in real time and apply this to the detection of EtBr of swab samples from a microbiology laboratory. Our approach is shown schematically in Figure . First a cotton swab is wiped across to the area under test and then immersed in 0.5 mL of phosphate buffer and let stand for 5 minutes. The buffer is then agitated to ensure a homogeneous mixture and the placed into the sample well of a chip holder. Electrochemical analysis is then undertaken, and an EtBr concentration (time to result) obtained after 12 seconds. The approach is rapid and yields quantitative results unlike current approaches using dyes or a UV lamp .