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Development of a Novel Mass Spectrometric ... - Jacobs University

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Experimental<br />

flow rate <strong>of</strong> 400-500 µl/hr. MS operating conditions were as follows: nebulizer<br />

pressure <strong>of</strong> 1.6 Bar, a corona discharge <strong>of</strong> 6000 nA, a hexapole RF <strong>of</strong> 200 Vpp, a<br />

dry gas <strong>of</strong> 6 L/min, a drying temperature <strong>of</strong> 200 ˚C and a vaporizer temperature <strong>of</strong><br />

450 ˚C. Calibration <strong>of</strong> APCI was achieved by the general APCI/APPI calibrant for<br />

the desired mass range. However calibration was also achieved by C7-C40<br />

standard as will be discussed in details later on.<br />

Fragmentation patterns were obtained by an Ion trap mass spectrometer fitted with<br />

the APCI source (Bruker Daltonics HCT Ultra, Bremen, Germany) operating in a<br />

manual MS n mode to obtain as desired MS 2 and MS 3 fragmented ions. Alkane<br />

method settings in Iontrap included nitrogen as source gas and helium as collision<br />

gas with corona discharge <strong>of</strong> +4000 nA, a nebulizer gas <strong>of</strong> 30 Bar, a drying<br />

temperature <strong>of</strong> 200 ˚C, a vaporizer temperature <strong>of</strong> 450 ˚C and a compound stability<br />

<strong>of</strong> 100% within a mass range <strong>of</strong> m/z 50-1000. Few parameters like collision energy<br />

amplitude and peak width were adjusted to enhance fragmentation spectra.<br />

35

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