IR-MALDESI Mass Spectrometry Imaging Source Coupled to Q Exactive™ Plus
Matrix Assisted Laser Desorption Electrospray Ionization (MALDESI) was introduced in 2006 by our research group as the first hybrid ionization source combining laser ablation and electrospray post-ionization using a resonantly excited matrix (endogenous or exogenous) to enhance the desorption of neutral analyte molecules. In IR-MALDESI, a pulsed infrared (IR) laser is used to resonantly excite water at its vibrational O-H stretching modes (2.94 µm), making it possible to analyze fresh tissue sections with little to no sample preparation.
Mass Spectrometry Imaging (MSI) is a technique using MS data collected over the sample area to visualize the spatial distribution of specific analyte molecules. A versatile IR-MALDESI MSI source was designed and implemented in our laboratory and is currently coupled to a high resolving power Q ExactiveTM Plus from Thermo Fisher Scientific. The source has single- or multi-shot capabilities with full control over the laser fluence, repetition rate, as well as the delay between the laser trigger and MS ion accumulation. The source sample plate and moving components fit in a nitrogen purged enclosure where ambient ions and relative humidity can be regulated. A water cooled Peltier cold plate is used to control the sample temperature (-10°C to 80°C).
The IR-MALDESI MSI source is currently used to investigate the fundamentals of the IR-MALDESI process in addition to being routinely employed to visualize analyte distributions in biological, forensic, and pharmaceutical samples.
Thermo Fisher Q Exactive HF Hybrid Quadrupole – Orbitrap Mass Spectrometer Coupled to Easy nLC-1000 and the 908 Devices ZipChip™
The Q Exactive™ HF X system combines a state-of-the-art segmented quadrupole and ultra-high-field Orbitrap mass analyzer to achieve high-performance precursor ion selection with a high-resolution, accurate-mass (HR/AM) to deliver a superior combination of scan speed, resolving power, mass accuracy, spectral quality and sensitivity. High resolving power in both the precursor and fragment ion spectra allow for routine mass accuracies of <3 ppm and <50 ppm, respectively.
When interfaced with a nanoUPLC or a Vanquish UPLC system and ESI source, this system allows for C18 reverse-phase separations using longer columns (>30 cm × 75 µm) and smaller particle sizes (2.6 µm), reducing chromatographic peak widths to less than 20 seconds and enhancing sensitivity. This system is capable of performing both global and targeted analyses of biological samples and is used to study both proteins and metabolites. Combining this cutting-edge separations capability with the acquisition speed of the Q Exactive™ HF X, which allows for data dependent scans to be taken at a rate of 40 Hz., results in deep proteome coverage during a single 4 hour LC-MS/MS run.
When interfaced with an ZipChip™ system from 908 Devices the system is capable of ultralow-flow capillary electrophoresis separations, a valuable orthogonal separation technique to traditional chromatography. The system further reduces the necessary analysis time, observed peak widths, and required loading amounts. The accuracy and speed of this separation method is enabled by the extremely fast data acquisition and high sensitivity of the Q Exactive™ HF X Orbitrap technology.