Physical/chemical separations in the break-up of highly charged droplets from electrosprays

Highly-charged droplets, as formed by an electrospray process, are known to undergo asymmetric fission to form smaller droplets. We have observed a ch emical and physical separation phenomenon that occurs in the droplet break- up process and is related to a compound's surface activity in solution. Two experimental approaches demonstrated that the smaller satellite droplets a nd the progeny droplets generated by the spray formation and asymmetric fis sion processes to be surfactant-enriched, These smaller droplets were also effectively separated from the larger primary and residual droplets because of their smaller inertia and high surface charge density, and a region att ributed to the initially formed smaller satellite droplets was found to be strikingly confined in a narrow periphery region of the electrospray. The p henomenon may have utility for chemical separations and have significant im plications for the sensitivity and selectivity of electrospray ionization-m ass spectrometry. (C) 2001 American Society for Mass Spectrometry.