A New Methodology for Mass Spectrometry Preparation
AbstractThis paper presents a new methodology for utilizing microfluidic techniques to prepare samples for Liquid Chromatography Mass Spectrometry (LCMS). Using microchip-based capillary electrophoresis, the Liquid Chromatography (LC) column was bypassed permitting a direct interface to the Mass Spectrometer; thus reducing the number of preparation steps. This technique is demonstrated in an experiment using commercial vanilla extract. New interface techniques were used to enable the application of the needed pressure and electrical fields that drive the channel flow required to separate the vanilla extract in preparation for the LCMS.
Introduction
Microfluidics is the study of fluid interaction at a scale of 10-6 L. Fluids at this volume behave differently than fluids at a larger scale because of the following factors; surface tension, energy dissipation, and fluid resistance. Microfluidic separation is rapidly becoming a key research technique among the life science industry. This new method will allow researchers to both electrophoretically separate and analyze biochemical materials via mass spectrometry at the microfluidic level.
Procedure
Usage | Solution |
Running Buffer | 1% HPLC grade Acetonitrile (CH3N) |
Sample | Dilute Spice Islands Vanilla Extract (ratio 1ul to 900ml) |
Chart 1: Solution preparation for separation and analysis.
Prepare microchannel according to Figure 1a.
Figure 1a: Microchip with labeled wells.
Arrange Microport interfaces according to Figure 1b.
Figure 1b: Microport interface set-up.
Using the MFP-HV Microport interface, fill the buffer channel with running buffer. Fill the sample reservoir with 3μL of sample, apply the EBP Microports and run High Voltage Power Supply (HVPS) according to Chart 2.
Step | Duration | Sample Reservoir | Buffer Reservoir | Sample Waste | Buffer Waste |
Plug formation | 20 sec. | 1.5KV | 1.1KV | Ground | 2.0KV |
Separation | 30 sec. | 6.0KV | 5.4KV | 5.4KV | Ground |
Chart 2: Voltages and run times for HVPS[1]
Upon completion of the electrophoretic separation, drive the components of the microchannel into a Shimadzu LCMS 2010A mass spectrometer using ~ 200 PSI on a 10 mL syringe filled with 2 mL of 1% HPLC grade acetonitrile buffer.
Settings for the mass spectrometer are as follows; interface temperature 250°C, CDL temperature 230°C, gas flow 0.18 L/m, heat block 200°C. The acquisition mode is scan, with an event time of 1 second, detector voltage of 15 kV. The data was acquired over the range from 50 m/z to 300 m/z.
Results
Figure 2: Total Ion Chromatogram
Figure 3: Mass Spectrum Graph
Discussion
The most abundant isotope in the total ion chromatograph is at an m/z of 223. Vanillamide n, n- diethyl has an m/z ratio of 223,[2] thus indicating that the Spice Islands vanilla extract was indeed separated.
The new method using microfluidic technologies to prepare samples is waiting further testing. While vanillamide n, n-diethyl was found, there are no known standards to compare this experiment to. There has been little published work done on the components of Spice Islands vanilla extract making data comparison a challenge. To continue the work, an Application Note on the detection of β Amyloid Protein was selected.[3] Further testing will continue upon return from this conference.
