Abstract: An auxiliary electrode was used to improve the electric field distribution between the nESI emitter and the MS sampler. The results show an improvement in the ratio of signal to noise for nanoliter electrospray using a home-made nanoliter electrospray tip, evaluated by spraying a 25 pg/μL reserpine solution. In addition, the average ratios of signal to noise of reserpine acquired within 30 min at different concentrations were compared with those obtained with an auxiliary electrode. The experimental results suggest that an auxiliary electrode could dramatically improve the ratio of signal to noise and provide confident trends for future application of auxiliary electrode in nanoliter electrospray.

Key words: Auxiliary electrode, Nanoliter electrospray, Reserpine