Improved Analytical Performance of Negative 63Ni 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 63 Ni ionization high resolution ion mobility spectrometer with Bradbury-Nielsen-Gate-Grid structure was built to measure propofol with reactant ions Cl – (H 2 O) n using dichloromethane as dopant. Instead of forming three propofol ions (M – H) – , M · O 2 – , and (M 2 – H) – with reactant ions O 2 – (H 2 O) n , only product ion M · Cl – was produced when introducing dichloromethane gas. The peak-to-peak resolution ( R p-p ) between reactant ions Cl – (H 2 O) n and product ion M · Cl – was 17.4, which was 1.6 times larger than that between O 2 – (H 2 O) n and product ion. Furthermore, the linear response range using reactant ions Cl – (H 2 O) n was 3.5 times wider than that obtained with reactant ions O 2 – (H 2 O) n . Graphical Abstract ᅟ