ABSTRACT
During the past decade, the development of ion trap instruments has continued on a trajectory toward high performance in chemical analysis [1-3]. This objective has been pursued with emphases on high ion trapping capacity, high-mass range, increased mass resolution and high-speed operation. Such efforts are embodied in an increasing number of more complex instruments employing multiple ion traps or combinations of ion traps with other types of mass analyzers [4-6]. In parallel with these trends, there has been a rapid increase in interest in chemical analysis in situ; as a generally applicable method with high sensitivity and specicity, mass spectrometry has been a natural candidate to meet this challenge. The obvious solution has been to develop miniature, portable mass spectrometers, a development that was reviewed [7] in 2000 and which has accelerated strongly since then.
