A New Spiral Time-of-Flight Mass Spectrometer for High Mass Analysis

Abstract

A new spiral time-of-flight mass spectrometer orthogonally coupled with an ESI ion source was designed and constructed. The spiral ion optical system consisted of four toroidal electrostatic sectors. Each had fifteen stories made by sixteen Matsuda plates piled up inside a cylindrical electrostatic sector. The ions passed the four toroidal electrostatic sectors sequentially and revolved along a figure-eight-shaped orbit on a certain projection plane. During multiple revolutions, the ion trajectory shifted by 50 mm perpendicular to the projection plane every cycle, thus generating a spiral trajectory. The flight path length of one cycle was 1.3 m so that the maximum flight path length was 20 m when ion turned 15 cycles. The basic performance was tested by using several high molecular weight compounds. A mass resolution was achieved to be more than 55,000 (full width at half maximum) at m/z=3,000. The mass accuracy was remarkably improved to be better than 0.5 ppm in high mass region of up to m/z=3,000. An ion transmission of approximately 100% was observed up to 15 cycles.