PNNL

Abstract

The use of a thin film of monolayer protected gold nanoparticles (MPNs) as a stationary phase for gas chromatography (GC) is reported. Dodecanethiol-protected gold nanoparticles were prepared and characterized. Deposition of a MPN film was successfully completed within a 2 m, 530 �m (i.d.) deactivated silica capillary using gravity to force a plug of solution containing the MPN material through the capillary for deposition. The presence of a thin MPN film on the GC capillary inside wall was confirmed with SEM analysis with an average film thickness of 60.7 nm measured. The retention behavior of the dodecanethiol MPN stationary phase was studied using four different classes of compounds (alkanes, alcohols, aromatics and ketones) and their retention orders were compared to a commercially available column (AT-1, 100 nm phase thickness). The separation of an eight-component mixture was performed using both isothermal and temperature programming separation methods with the novel dodecanethiol MPN phase. The isothermal separation was then objectively compared to the commercial AT-1 stationary phase column using the same experimental parameters. The commercial column had an efficiency, N, of 6200 (k’ = 0.33) while the dodecanethiol MPN stationary phase had an efficiency, N, of 5700 (k’ = 0.21) for the same analyte, octane. The reduced plate height, h, for this same analyte was found to be less than 1 at the optimum linear flow velocity. Based upon the efficiencies and reduced plate height studies as a function of linear flow velocity, we conclude that the MPN stationary phase operated at nearly the optimum possible performance level. The robustness of the MPN phase is also discussed with consistent performance observed over several months. Overall, the use of monolayer protected gold nanoparticles as gas chromatographic stationary phase materials appears promising.