PLASMA SOURCE ATMOSPHERIC-PRESSURE IONIZATION DETECTION OF LIQUID INJECTION USING AN ION-TRAP STORAGE REFLECTRON TIME-OF-FLIGHT MASS-SPECTROMETER

In this work, the capabilities of an ion trap storage/reflectron time- of-flight mass spectrometer (IT/reTOF-MS) combination have been explor ed for detection of ions generated by liquid injection into plasma sou rce atmospheric pressure ionization mass spectrometry. It is demonstra ted herein that the ion trap provides an effective means of storing ex ternally generated ions from 10 mus to 10 s prior to mass analysis via pulsed dc extraction into the reTOF-MS device. The IT/reTOF storage c apabilities provide the potential for nearly 100% duty cycle in conver ting a continuous ion beam into a pulsed source for TOF. In addition, it is shown that the storage capabilities of the device provide enhanc ed resolution and sensitivity as the storage time is increased. Furthe r, capabilities were developed for trapping of ions for other external injection sources and ions with up to 300 eV have been trapped and st ored for analysis by the IT/reTOF. In addition, the rf voltage was sho wn to be an effective means of eliminating low-mass background peaks f rom the trap and, thus, from the TOF mass spectrum obtained. The sensi tivity of the device is also demonstrated with liquid injection techni ques for a typical sample and found to be in the low-femtomole range.