Typical ESI-MS Settings for SOMA

The mass spectrometer used for the initial development of SOMA and to obtain most of the results presented here was a Finnigan li C ion trap (Thermoquest, San Jose, CA, USA) equipped with an ESI source. SOMA has also been successfully implemented using a Quattro LC, a triple quadrupole ESl-MS (Micromass, Manchester, UK). 

ESl-MS of oligonucleotides was performed in the negative ionisation mode using hexafluoro-2-propanol and methanol as the mobile phase. Typical settings for the LCQ are a spray voltage of -2.5 to -5kV, a heated capillary temperature of 150 to 180°C, a capillary voltage of 0 to -60V and a sheath gas flow rate of 50 to 70 arbitrary units. The ion optics were typically 5 to 7V for the octapole 1 offset, 15 to 40V for the lens voltage and 7 to 9V for the octapole 2 offset. 

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