Patent ID: 7095018

Claim:
A method for producing a sample spot on a MALDI target substrate, the method comprising: (a) providing a dispenser having a nozzle which circumferentially surrounds an interior passage extending between a dispensing end and an opposite end; (b) introducing a first fluid into the interior passage of the nozzle, the first fluid comprising either an analyte solution or a MALDI matrix solution; (c) ultrasonically actuating the nozzle at a portion of its circumference at a frequency sufficient to deposit the first fluid from the dispensing end onto the substrate; (d) introducing a second fluid into the interior passage of the nozzle wherein the second fluid comprises either the analyte solution or the MALDI matrix solution, whichever was not introduced as the first fluid; and (e) ultrasonically actuating the nozzle at a portion of its circumference at a frequency sufficient to deposit the fluid from the dispensing end onto the first fluid on the substrate.