Micro- and Nanotechnologies
Novel sampling strategies and highly miniaturized systems for mass spectrometric analysis
Rapid analysis of the products of chemical reactions produced in high throughput experiments (HTE) are completed by thermal desorption of sub-microliter volume samples into an ionizing gas. The heated ionizing gas completes vaporization of sample typically present in dimethyl-sulfoxide in 1-3 seconds per sample with rapid mass detection.
The utility for Direct Analysis in Real Time (DART) for ionization of chemicals in the presence of aprotic solvents such as DMSO, and DMF has been employed to enable detection of those chemicals from sub-microliter volumes of sample thus eliminating the need for sample dilution prior to analysis by LC/MS. The sub-microliter samples have been prepared by using several sample disposition method including low volume automated pipettor station and a high capacity disposable pin-tool. Using these devices we have chemicals present in concentrations appropriate for high throughput experiments have been deposited onto a wire mesh surface which is then positioned between the DART source exit and the mass detector entrance for analysis. Use of small volume samples reduces the potential for matrix effiects by limiting the abundance of chemicals present in the ionizing gas. Rapid sampling of the small size droplets present on the sample supporting wire mesh enables continuous screening of the samples. We document the performance of each sample method at analysis 1 per second to demonstrate the potential for full 386-well sample plate analysis in under 10 minutes. Automated data analysis of the continuous collection of spectra in the data file is demonstrated using a file parsing software in order to permit archival of the results. An outline of the overall workflow and it utility for simplifying the analytical effort in support of nanochemistry will be discussed.