Abstract
Commercially available Pt screen printed electrodes (SPEs) have been employed as possible electrode materials for methylamine (MA) and hydrogen chloride (HCl) gas detection. The room temperature ionic liquid (RTIL) 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2mim][NTf2]) was used as a solvent and the electrochemical behaviour of both gases was first examined using cyclic voltammetry. The reaction mechanism appears to be the same on Pt SPEs as on Pt microelectrodes. Furthermore, the analytical utility was studied to understand the behaviour of these highly toxic gases at low concentrations on SPEs, with calibration graphs obtained from 10 to 80 ppm. Three different electrochemical techniques were employed: linear sweep voltammetry (LSV), differential pulse voltammetry (DPV) and square wave voltammetry (SWV), with no significant differences in the limits of detection (LODs) between the techniques (LODs were between 1.4 to 3.6 ppm for all three techniques for both gases). The LODs achieved on Pt SPEs were lower than the current Occupational Safety and Health Administration Permissible Exposure Limit (OSHA PEL) limits of the two gases (5 ppm for HCl and 10 ppm for MA), suggesting that Pt SPEs can successfully be combined with RTILs to be used as cheap alternatives for amperometric gas sensing in applications where these toxic gases may be released.
Highlights
Miniaturization has been the driving force for many industries and it is likely that the electrochemical sensor industry is not far behind
The real question is: can room temperature ionic liquid (RTIL) solvents be used with screen printed electrodes in amperometric gas sensors to detect analyte gases at levels at or below the exposure limits?
This work will help determine whether RTILs and SPEs can be used in the design of cheap, portable and robust gas sensors for toxic gases such as methylamine and hydrogen chloride
Summary
Miniaturization has been the driving force for many industries and it is likely that the electrochemical sensor industry is not far behind. SPEs contain various materials (e.g., graphite, carbon black and polymeric binders) that are squeezed through a mesh screen which defines the shape and size of the electrode [7] They are relatively cheap and portable, and can be combined with non-volatile and highly thermally stable room temperature ionic liquid (RTIL) solvents to make more robust sensors. The current (USA) OSHA PEL of HCl is 5 ppm in the gas phase Due to their high toxicity, it is essential to be able to monitor and detect methylamine and hydrogen chloride gases at low ppm concentrations. This work will help determine whether RTILs and SPEs can be used in the design of cheap, portable and robust gas sensors for toxic gases such as methylamine and hydrogen chloride
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