Improved Analytical Performance of Negative ^sup 63^Ni Ion Mobility Spectrometry for On-line Measurement of Propofol Using Dichloromethane as Dopant

On-line monitoring of propofol in exhaled air is a potential way to evaluate the anaesthesia depth for patients during surgery. In this study, a negative 63Ni ionization high resolution ion mobility spectrometer with Bradbury-Nielsen-Gate-Grid structure was built to measure propofol with reactant ions Cl–(H2O) n using dichloromethane as dopant. Instead of forming three propofol ions (M – H)–, M · O2 –, and (M2 – H)– with reactant ions O2 –(H2O) n , only product ion M · Cl– was produced when introducing dichloromethane gas. The peak-to-peak resolution (R p-p) between reactant ions Cl–(H2O) n and product ion M · Cl– was 17.4, which was 1.6 times larger than that between O2 –(H2O) n and product ion. Furthermore, the linear response range using reactant ions Cl–(H2O) n was 3.5 times wider than that obtained with reactant ions O2 –(H2O) n . [Figure not available: see fulltext.]