br Material and methods br Results and

Material and methods
Results and discussion
Conclusions
Conflict of interest
Acknowledgements Tiina Maaninen, Pekka Ontero, Mikko Hietala and Arto Ranta-Panula (VTT) are thanked for their assistance in the R2R manufacturing and characterisation of enzymatic electrodes. In addition, Asta Pesonen (VTT), Anu Vaari (VTT) and Prof. Kyösti Kontturi (Aalto University) are gratefully thanked for technical and academic assistance. The research was funded by the Printed Enzymatic Power Source with embedded capacitor on next generation devices – Project (PEPSecond) supported by Tekes, the Finnish Funding Agency for Technology and Innovation.
Introduction Stable ionic liquids are molten salts with a melting point close to or below room temperature. Their good solvating properties, high conductivity, non-volatility, low toxicity, as well as large electrochemical window and good electrochemical stability make them tremendously popular for electrochemical sensing [1,2] Various ionic liquids have been used in electrochemical sensing, such as imidazole ionic-liquids (ILs) [3,4], pyridinium (ILs), [5,6] and other functionalized (ILs) [7–9]. NButyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (BMPyNTf2) is one of the pyrrolidinium ionic liquids (PILs) with excellent electrochemical properties [10]. There is an ever increasing demand for simple, selective and inexpensive methods for determining the presence of chemical species in the environment. These problems could be conceivably avoided by replacing conventional electrochemical solvents with room temperature ionic liquids. These low melting salts display large electrochemical windows, negligible vapor pressure, good thermal stability and electrical conductivity which make them quite attractive. In fact, some amperometric sensors were recently proposed which were assembled by casting a thin layer of ionic liquid on the surface of either a three electrode cell or a microelectrode array. Even though these chemi-sensors are able to operate as membrane-free amperometric devices, their responses remain conditioned by the rate of both gas dissolution into the ionic liquid and its glycyrrhetinic acid through the medium towards the working electrode. Thus, their sensitivity and response time continue to be affected by fairly slow steps, even though they are faster compared to permeation through membranes. In particular, it is advisable to achieve a very close contact between the electrode material and ionic liquid, thus allowing analytes from gaseous samples to undergo electron transfer just as they reach the working-electrode-material/ionic-liquid inter-phase, without involving any analyte diffusion and/or dissolution step [11]. Recently it is discovered room temperature ionic liquids showing continual interest to replace volatile organic compounds. In addition, it has been evidenced that ionic liquids are exceptional and versatile solvents in a host of analytical and chemo-sensing applications [12,13]. ILs have also continual concern in environmental areas because of their potential as greener solvent for many organic, inorganic, and polymeric substances as compared to conventional environmentally damaging organic solvents [14]. The good thermal stability, high ionic conductivity, miscibility with other solvents, no effective vapor pressure, and non-reactive and recyclable nature of ILs are a few other properties that make these compounds appropriate solvents for different applications [15–17]. RTILs belong to a class of potentially benign solvents and are molten salts that are liquid around ambient conditions [18]. Both ILs and molten salts are composed of ions. The presence of bulky organic cations in ILs interrupts the crystal packing and lowers the melting temperature. RTILs have potential for many different applications, including catalysis and synthesis. For instance, conventional organic solvents have been replaced by ILs in organic synthesis [19]. They have also been used in solvent extractions [20], liquid–liquid extractions [21], enzymatic reactions [22], pharmaceutical studies [23], electrochemical studies [24], dye-sensitized solar cells and batteries [25], as buffer additives in capillary electrophoresis [26], as stationary phases in gas–liquid chromatography [27], and as ultralow volatility liquid matrixes for matrix-assisted laser desorption/ionization (MALDI) mass spectrometry [28]. In addition, the high thermal stability allows the use of ILs for high temperature gas sensing [29]. Recently, there has been a large focus on the effectiveness of ILs as environmentally friendly, “green” solvents and as a host of practical applications to which they are amenable [30]. In addition, understanding the mechanism and solvation in ILs is a difficult and challenging task because of their complex nature [31,32]. Most of analytical methods involve fast atom bombardment (FAB) mass spectrometry [33], X-ray crystallography [34], and X-ray absorption fine structure (XAFS) [35]. These methods have shown considerable promise in studying the physicochemical properties of room temperature ionic liquids.