Use of an electrochemical room temperature ionic liquid-based microprobe for measurements in gaseous atmospheres

A simple electrochemical microprobe (EMP) is proposed for the detection of analytes in gaseous atmo-spheres. The EMP consists of two platinum fibres of 25 and 300 m in diameter encased into a thetaglass pipette to form an electrochemical cell in a two-electrode configuration. Ion conductivity betweenthe two electrodes is ensured by a thin film of the room temperature ionic liquid (RTIL), 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, which is applied onto the EMP tip surface by asimple dip-coating procedure. The ionic liquid-coated microprobe (RTIL-EMP) was preliminarily inves-tigated by using ferrocene as an electroactive species to ascertain the mass transport properties of theanalytes that influence the voltammetric responses as well as the stability and reproducibility of theRTIL-EMP in the gas phase. The performance of the RTIL-EMP to gas analysis was afterward evaluatedby using oxygen as electroactive species. The RTIL-EMP was exposed to different synthetic O2/N2(v/v)mixtures and current responses were recorded as a function of O2concentration, using either cyclicvoltammetry (CV) or chronoamperometry (CA). Regression analysis of the experimental current against% O2was linear over the range 0–100% with correlation coefficient and sensitivity of, respectively, 0.996and 0.29 nA/(v/v) % O2in CV and 0.998 and 0.27 nA/(v/v) % O2in CA measurements. Long term stability,reproducibility of the RTIL-EMP recovery of the RTIL film layers to the initial conditions and effects ofhumidity on the current responses were investigated in detai