High-Throughput Solvent Assisted Ionization Inlet for Use in Mass Spectrometry

Abstract

In this work we developed a multiplexed analysis platform providing a simple high-throughput means to characterize solutions. Automated analyses, requiring less than 5 s per sample without carryover and 1 s per sample, accepting minor cross contamination, was achieved using multiplexed solvent assisted ionization inlet (SAII) mass spectrometry (MS). The method involves sequentially moving rows of pipet tips containing sample solutions in close proximity to the inlet aperture of a heated mass spectrometer inlet tube. The solution is pulled from the container into the mass spectrometer inlet by the pressure differential at the mass spectrometer inlet aperture. This sample introduction method for direct injection of solutions is fast, easily implemented, and widely applicable, as is shown by applications ranging from small molecules to proteins as large as carbonic anhydrase (molecular weight ca. 29,000). MS/MS fragmentation is applicable for sample characterization. An x,y-stage and common imaging software are incorporated to map the location of components in the sample wells of a microtiter plate. Location within an x,y-array of different sample solutions and the relative concentration of the sample are displayed using ion intensity maps.

Zero volt paper spray ionization mass spectrometry for direct analysis of samples on filter paper substrate

“…The analytical sensitivity (LLOD) of zvPSI‐MS was estimated to be in the range of sub‐nmol per filter levels (Supplementary Fig. S‐11, see Supporting Information), which was 2 to 3 orders of magnitude higher (= low sensitivity) than the values reported for SAII . On the other hand, Fig.…”

“…Extraction solvent is typically deposited at once on the paper and dissolves analyte(s) of interest. The extract is subsequently introduced into a mass spectrometer by the aspiration force between the end of a filter slip and the inlet capillary, which is based on the same principle reported for SAII . The shape of filter paper in zvPSI‐MS is different from that of the standard PSI.…”

Novel ionization processes for use in mass spectrometry: ‘Squeezing’ nonvolatile analyte ions from crystals and droplets

“…A number of different mass spectrometers, in terms of analyzer types and vendors, have been used with the novel ionization processes demonstrating the importance of pressure, temperature, and collisions in optimizing ion formation . An example is shown in Figure for bovine serum albumin (BSA), 66 kDa, using mass spectrometers to ionize this 66 kDa protein intact and multiply charged using the new ionization processes.…”

“…A motivation of our research is to make inroads into the daunting task of chemical analysis of complex biological materials, such as in the study of temporal chemical changes in brain chemistry . The newly developed ionization processes potentially have advantages of unprecedented analysis capabilities by accomplishing traditional applications with limited user expertise and nearly unattended operation . The methods can be rapid and provide good spatial resolution for imaging with and without the use of a laser, as well as mass range extension, an attribute common to multiply charged ions.…”

“…TLC plates and other surfaces have been analyzed in a similar fashion from both vacuum and atmospheric pressure . Laser‐free imaging using such simple ionization processes is certainly a real opportunity …”