Matrix-assisted Laser Desorption/Ionization Linear Ion Trap Orbitrap XL (MALDI LTQ Orbitrap XLTM)
In the Thermo Scientific MALDI LTQ Orbitap XLTM instrument a MALDI source is coupled with a hybrid analyzer consisting of a linear ion trap (LTQ) and an Orbitrap. The LTQ provides fast sample analysis which is complementary to the electrospray, while the Orbitrap provides high resolution (minimum resolution 7,500 maximum resolution >100,000 at m/z 400), high mass accuracy (< 3 ppm with external calibration, < 2 ppm using internal calibration), and high sensitivity (sub-femtomol range for peptides), features which are required for unambiguous protein identification.
This system is suitable for both classical gel-based proteomics and for direct tissue analysis. The available fragmentation techniques are: CID (collision induced dissociation), PQD (pulsed Q collision induced dissociation which enables trapping of low mass fragment ions with m/z 50 - 2000). Moreover, precursor ion selection can be performed in the linear ion trap and fragmentation can be done in the collision cell (HCD) with high resolution accurate mass detection in the Orbitrap mass analyzer (m/z 50 – 4000).
The tissue-imaging solution provides researchers with unparalleled sensitivity and unmatched MSn spectral quality of linear ion trap technology as well as faster sample analysis, compared with the standard practice of homogenizing and extracting from tissue. The Thermo ImageQuest software enables the localization of peptides/small molecules within the analysed tissue, thus being a powerful tool for the presentation of MS images directly from tissue samples.