Diffusion-limited extraction of organic ions by a track-membrane interfaced vacuum inlet

Glycerol-wetted track membranes (polyethylene terephthalate) were used to interface a low-vacuum facility (∼10^-3 Torr) to an ambient pressure liquid analyte. High-field charge extraction conditions were routinely maintained between the liquid samples and a grid collector. The latter was positioned just near to the vacuum-facing side of such membranes. Upon establishing a steady-state charge-extraction regime, the collector currents were monitored and recorded at various solute concentration levels. The collector currents, which depend on solute concentration, were found to agree with recent theoretical treatments of such processes. Both positively- and negatively-charged species from organic solutions were routinely extracted. Ion injection for the low- and the high-mobility species has favored the diffusion-limited and the evaporation-limited schemes, respectively. Variable concentrations of 1-pyrenoylmethylpyridinium bromide as well as naphthylacetic and anthracenecarboxylic acids in glycerol were used.