X. Zhang, D.A. Narcisse, K.K. Murray, On-line single droplet deposition for MALDI mass spectrometry,Β J. Am. Soc. Mass Spectrom.15Β (2004) 1471–1477. doi:10.1016/j.jasms.2004.06.016.


A single droplet generator was coupled with a rotating ball inlet matrix-assisted laser desorption/ionization (MALDI) time of flight (TOF) mass spectrometer. Single droplets with 100 picoliter volume were ejected by a piezoelectric-actuated droplet generator and deposited onto a matrix-coated rotating stainless steel ball at atmospheric pressure. The single droplet deposit was transported to the vacuum side of the instrument where ionization was accomplished using a UV pulsed laser. Using this on-line interface, it was possible to obtain protonated molecule signal from as little as 10 fmol analyte.

Diagram of the single droplet deposition device: A, 19 mm diameter stainless steel ball; B, drive shaft; C, gasket; D, ISO 100 flange; E, ground grid; F, droplet generation electronics; G, syringe pump for matrix solution; H, syringe pump for solvent; I, capillary; J, translation stage for capillary; K, droplet generator; L, translation stage for droplet generator; M, cleaning system (Teflon holder and felt); N, peek plastic tube for waste; O, syringe pump for analyte solution.