How do organic solvents cause Pipette leaks?

These leaks are caused by the difference between the vapor pressure of the solvent and pressure of the air cushion between the piston and the sample. [b]Solution:[/b] 1. Use a positive-displacement pipette because it has no air cushion. 2. If you are using an air-displacement pipette, saturate the air cushion of your pipette with solvent vapor by aspirating and distributing solvent repeatedly. The leak will stop when pressure equilibrium is reached. (This answer was sourced from [url=http://www.mandel.ca]Mandel Scientific Company[/url])