Sensors and Actuators B 192 (2014) 134–142 Contents lists available at ScienceDirect Sensors and Actuators B: Chemical journal h om epage: www.elsevier.com/ locate/snb A “humid electronic nose” for the detection of nerve agent mimics; a case of selective sensing of DCNP (a Tabun mimic) Lluís Pascual a,b , Inmaculada Campos a,b,c , Román Bataller a,b , Cristian Olguín a,d , Eduardo García-Breijo a,d , Ramón Martínez-Ma ˜ nez a,b,c,∗ , Juan Soto a,b a Centro de Reconocimiento Molecular y Desarrollo Tecnológico (IDM), Unidad Mixta Universidad Politécnica de Valencia – Universidad de Valencia, Valencia, Spain b Departamento de Química, Universidad Politécnica de Valencia, Camino de Vera s/n, E-46022 Valencia, Spain c CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Spain d Departamento de Ingeniería Electrónica, Universidad Politécnica de Valencia, Camino de Vera, s/n, 46022 Valencia, Spain a r t i c l e i n f o Article history: Received 1 August 2013 Received in revised form 8 October 2013 Accepted 21 October 2013 Available online 30 October 2013 Keywords: Voltammetry Humid electronic nose Nerve agents CWA PCA PLS a b s t r a c t A “humid electronic nose” device based on pulse voltammetry has been applied to detect nerve agent simulants in gas phase. The “humid electronic nose” consists in a polypropylene piece which contains an array of eight metallic electrodes (i.e., Ir, Rh, Pt, Au Ag, Co, Cu and Ni) divided into two sets of four working electrodes housed inside a homemade steel cylinder, and a salt bridge connection to a reference electrode. The electrochemical system is fitted to a nylon membrane damped with a background solution of sodium tetraborate 0.01 M by a second polypropylene piece. The PCA analysis demonstrated that the system is able to discern principal organophosphorous nerve agent mimics (DCP, DCNP and DFP) from organophosphorous derivatives and some other potential interferents. Besides, the PLS quantification analysis showed sound accuracy in the concentration prediction for DCNP in air, good linearity and a limit of detection (LOD) of some a few ppm. © 2013 Elsevier B.V. All rights reserved. 1. Introduction An electronic nose consists in a device able to mimic the bio- logical olfactory system. An array of non-specific sensors provides a characteristic response pattern which, treated by appropriate data analysis techniques, allows us to identify and quantify certain gas compounds. In the biological olfactory system, olfactory recep- tors respond non-specifically to smelly compounds and the overall response is interpreted by the brain by providing information about volatile derivatives. The first example of an electronic nose was reported by Dodd and Persaud who used three different metal oxide gas sensors to identify several substances in the gas phase [1]. Nowadays, a large number of transducer principles and tech- niques have been applied to electronic noses such as acoustic wave (SAW, BAW) sensors, metal oxide semiconductor field effect tran- sistors (MOSFETs), conducting polymers (CP), optical sensors, gas chromatography, ion mobility spectroscopy, infrared spectroscopy, biosensors, etc. [2–5]. Besides there are many examples of amper- ometric electrochemical sensors to measure target gases. Some typical examples are sensors for oxygen or carbon dioxide [6–11]. ∗ Corresponding author. E-mail address: rmaez@qim.upv.es (R. Martínez-Ma ˜ nez). In these systems, the gas sample permeates to the working elec- trode through the gas permeable membrane where it is detected. More recently, ionic liquids as solvents have been also reported [11] for the electrochemical detection of oxygen, carbon diox- ide, ammonia [12–17] and hydrogen [15] through gas absorption processes. The idea of developing a “humid electronic nose” is based on the concept that such a system may overcome the prob- lems usually found in classical electronic noses based on metal oxides and resistive sensors, such as interference of water vapour. Another advantage of using “humid electronic nose” systems is the possibility of employing typical electrochemical techniques, such as potentiometry, coulometry or voltammetry, as used in elec- tronic tongues [18,19], to analyse volatile derivatives. Recently, we showed the conceptual basis for designing a “humid electronic nose” using an array of potentiometric wire electrodes fitted to a wet nylon membrane [20]. That system was able to detect the volatile compounds generated during microbiological spoilage of wines. Moreover in another recent study, we used a “humid elec- tronic nose” to discriminate between different food samples. The device was based on an array of noble metals electrodes which were in contact with a fabric mesh made of nylon that was damped with NaCl aqueous solution and the use of pulse voltammetry [21]. 0925-4005/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.snb.2013.10.089