Solarix 9.4t ft icr mass spectrometer

All experiments were carried out on a SolariX 9.4T FT-ICR Mass Spectrometer (Bruker Daltonik GmbH, Bremen, Germany) under negative mode. For direct infusion ESI-FT-ICR MS experiments, the TD (Acquisition) was set to 1 M and ion accumulation time was 1.000 s. For collision-induced dissociation (CID) MS/MS experiments, the 5−charged precursor ions were isolated in quadrupole using an isolation window of 3–5 m/z. The collision energy was set to 14 V for free ODN15, 13–14 V for mono-platinated ODN15, and 14–15 V for di-platinated ODN15.
Bruker Compass Data Analysis v4.0 (Bruker Daltonik GmbH, Bremen, Germany) was used for data analysis and post processing. All spectra were internally calibrated using a quadratic calibration function and then interpreted and assigned manually with the help of the web-based Mongo Oligo Mass Calculator v2.08 (Hosted by The RNA Institute, College of Arts and Sciences, State University of New York at Albany, NY, USA, http://mods.rna.albany.edu/masspec/Mongo-Oligo). Additionally, theoretical and measured isotopic patterns for all assigned fragments were compared and their mass accuracy was calculated.

Duplicate D. discoideum samples were analyzed in positive ion mode using a ToF SIMS⁵ instrument (ION-TOF, Münster, Germany) and a custom C₆₀ FTICR-SIMS. The custom C₆₀ FTICR-SIMS instrument (more details in refs [21] (link), [23] (link)) utilizes a 40 keV C₆₀ primary ion gun (Ionoptika Ltd., Hampshire, England) that is coupled to a SolariX 9.4T FTICR mass spectrometer (Bruker Daltonics Inc, Billerica, MA). The vacuum pumping scheme of the SolariX cart was modified so that the pressure in the source chamber was reduced to 3×10⁻⁵ mbar instead of the ∼3 mbar at which it typically operates. The C₆₀ FTICR-SIMS images were acquired using 40 keV C₆₀⁺ projectiles over a field of view of approximately 4 mm×6 mm with a pixel size of 125 µm and a total primary ion dose of 2.78×10¹³ ions/cm². Spectra were acquired using a broadband excitation over the 1003⁺ beam over a 500 µm² field of view with a pixel size of 3.9 µm and a total primary ion dose of 8.16×10¹² ions/cm².

The samples were solubilized in a solution of acetonitrile/water/formic acid (49.8/50/0.2 v/v) for molecular mass determination. The mass spectrometric analyses were executed in a Bruker Solarix 9.4T FTICR mass spectrometer (Bruker Daltonics, Bremen, Germany). Positive ions were generated for nano-ESI (electrospray ionization) with a NanoMate (Advion Biosciences, Ithaca, NY, USA). Ions were transferred into the spectrometer through a quadrupole followed by accumulation of data during 1 s in the hexapole. Afterwards, the ions entered the ICR cell, where they were submitted to dynamic trapping. The acquisition of spectra was performed in a mass range of m/z 70–2000 during a transient for which 2 M points provided a mass resolving power around 100,000 (at m/z 400), after FFT processing (the total time per scan was 2 s). CID (collision-induced dissociation) fragments of Glu-1-fibrinopeptide B was used as an external calibration. DataAnalysis 4.0 software (Bruker Daltonics, Bremen, Germany) was applied to processed and to analyse the mass spectra.